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Transcript
2014 Removal of SOx and NOx Gases From Stationary Sources Using Copper Zeolite Based Catalysts Submitted in fulfillment of the requirements for degree of master science in Environmental Engineering Qatar University College of Engineering Environmental Engineering Master Program DONE BY: HUSSEIN MOHAMED KASEM ZEID SADAN Supervisors: • Dr. Peter Van Den Broeke • Dr. Mohammed Ali H. Saleh QATAR UNIVERSITY | FALL 2014 ABSTRACT 0B This project focuses on the different aspects associated with NO x and SO x emissions, including R R R R the impact of NO x and SO x in the environment, the various emission sources, and technologies R R R R for NO x and SO x removal. There are a number of different technologies available for NO x and R R R R R R SO x removal, which will be discussed and a comparison is made between the different removal R R methods. In this study, the NO x removal based on Selective Catalytic Reduction (SCR) will be explored; R R the chemistry and dynamics are explained briefly with the referral to the different important parameters affecting the performance of the catalyst. Different types of catalysts are being used for NO x removal; here we focus on Cu-zeolite-based catalyst. Catalyst’s preparation is a crucial R R step because it affects the properties and behavior of the catalyst during the NO x removal R R process. One of the objectives of this project is to develop catalysts with high performance. CuZSM-5 and Cu-Beta zeolite based catalysts were prepared using Ion Exchange (IE) method. A series of experiments were carried out to study the variation of preparation parameters such as support type, temperature, ‘ion-exchange’ time and the concentration of the (precursor) salt. All prepared catalysts and the two parent zeolites were characterized by the following techniques: BET, ICP-MS, EDX, and SEM. As a result, ZSM5 (Si/Al=23) is showing the highest Cu loading at 160 and 2000 ppm precursor concentration (1.48 and 6.42 wt% Cu loading, respectively) and representative BET surface area (230.0 and 207.5 m2/g, P P respectively) which gives good indication about the catalyst activity for NO x experiment. R R Based on the various results, obtained for the different conditions, it is expected to have high NO x conversion, mainly because of the high copper content, in terms in of wt% and R R dispersion, of the prepared catalysts. SCR experiment will be conducted to test the activity of the catalysts when the dedicated equipment is calibrated and ready to use. The results obtained in this project demonstrate the potential of synthesizing Cu-based zeolite catalyst for NO x removal, with as the main purpose to reduce the atmospheric NO x emissions by R R using SCR technology. Master Thesis| P a g e 1 R R ACKNOWLEDGEMENT 1B First and foremost, thank you Allah for giving me the strength to finish up this report, without your willingness I would not have been able to complete any work. It would be impossible to acknowledge adequately all the people who have been influential, directly or indirectly in providing me with a great assistance in understanding the process. Many thanks to my professors from chemical engineering department at Qatar University, Dr. Peter Van Den Broeke and Dr. Mohammed Ali Saleh who have been abundantly helpful and offered invaluable assistance, support and guidance. Deepest gratitude is also due to technical assistance, Dr. Ahmed Al-Khatat, without his knowledge and assistance this report would not have been completed successfully. Additionally, it is my pleasure to recognize Dr. Mohammed Jaber Al-Marri, the head of the Gas Processing Centre (GPC) at Qatar University for his direct support during the experimental work and the help from GPC staff. Finally, the biggest and most important thanks and happy feelings to my family for the support, praying to me and for their encouragement, without their strong words I would not be able to finish my project. Master Thesis| P a g e 2 LIST OF ABBREVIATIONS 2B BET Cu/ZSM5 Cu/BETA CTO CVD DRE EBSD EDX EPA FGR GHG ICP-OES LNBs MOE Mt MW NASA Nm3: NOx OFA OMI PM rpm SEM Si/Al sccm SCR SNCR Short Ton SOx SO2 SRU TPD TPR USEIA USEPA WIE ZSM5 Brunauer–Emmett–Teller Copper Zeolite (ZSM5 support) Copper Zeolite (BETA support) Consent To Operate Chemical Vapor Disposition Destruction Removal Efficiency Electron Back Scattered Diffraction Energy Dispersive X-ray spectroscopy Environmental Protection Agency Flue Gas Recirculation Greenhouse Gases Inductively Coupled Plasma Atomic Emission Spectroscopy technique Low NOx burners Ministry Of Environment Metric Ton Mega Watt National Aeronautics and Space Administration normal cubic meter Nitrogen Oxides Over fire air Ozone Monitoring Instrument Particular Matter round per minute Scanning Electron Microscope Silica to Alumina Ratio Standard cubic centimeter per minute at 0°C and 1 atm Selective Catalytic Reduction Selective Non Catalytic Reduction A unit of mass, it is equal to 907.185 kg Sulfur oxides Sulfur Dioxide Sulfur Recovery Unit Temperature Programmed Desorption Temperature Programmed Reduction United States Energy Information Administration United States Environmental Protection Agency Wet Ion Exchange Zeolite Socony Mobil–5 Master Thesis| P a g e 3 Table of Contents ABSTRACT ....................................................................................................................1 6T 6T ACKNOWLEDGEMENT ...................................................................................................2 6T 6T LIST OF ABBREVIATIONS ................................................................................................3 6T 6T chapter 1: Introduction ..................................................................................................9 6T 6T chapter 2: Literature Review ........................................................................................ 12 6T 6T 2.1 Definition and Sources of SO x & NO x .............................................................. 12 6T 6T 6T R R R R6T 2.1.1 Sulfur Oxides (SOx): .............................................................................. 12 6T 6T 6T 6T 2.1.2 Nitrogen Oxides (NOx): ......................................................................... 14 6T 6T 6T 6T 2.2 NO x and SO x Sources .................................................................................... 15 6T 6T 6T R R R R 6T 2.3 NO x and SO x Environmental Impacts .............................................................. 18 6T 6T 6T R R R R 6T 2.3.1 Nitrogen oxides (NOx):.......................................................................... 19 6T 2.4 Process Technologies .................................................................................... 21 6T 6T 6T 6T 2.4.1 Low NOx Burners (LNBs) ....................................................................... 21 6T 2.4.2 Over Fire Air (OFA) ............................................................................... 22 6T 2.4.3 Re-burning........................................................................................... 22 6T 2.4.4 Flue Gas Recirculation........................................................................... 23 6T 2.4.5 Selective Non-catalytic Reduction (SNCR) ............................................... 24 6T 2.4.6 Selective Catalytic Reduction (SCR) ........................................................ 24 6T 2.5 Chemistry and Dynamics of SCR process ......................................................... 26 6T 6T 6T 6T 2.6 Types of Catalysts ......................................................................................... 29 6T 6T 6T 6T 2.7 Zeolites ....................................................................................................... 32 6T 6T 6T 6T 2.7.1 Structure of zeolites ............................................................................. 33 6T 2.7.2 Catalytic activity of zeolite..................................................................... 33 6T 2.7.3 Zeolite of type ZSM-5............................................................................ 34 6T chapter 3: preparation................................................................................................. 36 6T 6T 3.1 Introduction................................................................................................. 36 6T 6T 6T 6T 3.2 Preparation Methods.................................................................................... 37 6T 6T 6T 6T 3.2.1 Impregnation Method .......................................................................... 37 6T 3.2.2 Wet Ion Exchange Method .................................................................... 37 6T 3.2.3 Solid-state ion exchange ....................................................................... 38 6T 3.2.4 Chemical vapor deposition .................................................................... 39 6T 3.3 Experimental set up ...................................................................................... 39 6T 6T 6T 6T 3.3.1 Materials used ..................................................................................... 39 6T Master Thesis| P a g e 4 3.3.2 Equipment used ................................................................................... 41 6T 3.3.3 Safety.................................................................................................. 41 6T 3.4 Procedure.................................................................................................... 42 6T 6T 6T 6T chapter 4: Characterization .......................................................................................... 47 6T 6T 4.1 Introduction................................................................................................. 47 6T 6T 6T 6T 4.2 Characterization Methods ............................................................................. 48 6T 6T 6T 6T 4.2.1 ICP-AES Elemental Analysis.................................................................... 48 6T 4.2.2 BET analysis ......................................................................................... 49 6T 4.2.3 SEM analysis ........................................................................................ 52 6T chapter 5: Results & Discussion: ................................................................................... 54 6T 6T 5.1 Effect of precursor salt and different support zeolites ...................................... 54 6T 6T 6T 6T 5.2 Effect of different Si/Al Ratio ......................................................................... 56 6T 6T 6T 6T 5.3 Effect of different concentrations of Cu(COOCH 3 ) 2 .......................................... 57 6T 6T 6T R R R R6T 5.4 Effect of time of ion exchange on Copper loading ............................................ 59 6T 6T 6T 6T 5.5 Effect of temperature of ion exchange on Copper loading ................................ 60 6T 6T 6T 6T 5.6 SEM Results: ................................................................................................ 62 6T 6T 6T 6T chapter 6: Catalytic Investigation of NO x -SCR on Cu-ZSM5 .............................................. 65 6T R R 6T 6.1 Introduction................................................................................................. 65 6T 6T 6T 6T 6.2 SCR Experiment: ........................................................................................... 65 6T 6T 6T 6T 6.3 Experimental Tools and Procedure: ................................................................ 66 6T 6T 6T 6T 6.4 Experimental Results and Discussion: ............................................................. 68 6T 6T 6T 6T Conclusion and Recommendations: .............................................................................. 69 6T 6T references: ................................................................................................................. 71 6T 6T APPENDIX ................................................................................................................... 76 6T 6T Master Thesis| P a g e 5 LIST OF FIGURES Figure 2.1 National Summary of Nitrogen Oxides Emissions in 2011 ............................... 16 Figure 2.2 The concentration of NO2 in the atmosphere above southwestern Asia. ............ 17 Figure 2.3 Qatar Environmental statistics for NO x & SO x emissions in 2012 & 2013......... 18 Figure 2.4 The trend in permitted amounts of NO x and Particulate Matter (PM) in Europe as set by the European legislation with time. Euro VI, initially planned for 2013, is to be implemented in two stages during the 2015-2017 period ................................................. 19 Figure 2.5 Capital cost and total levelized costs of SCR for a standardized new coal-fired power plant (500 MW, medium sulfur coal, 80% NOx removal), as of 1983. Solid diamond symbols are earlier studies based on low-sulfur coal plants, which have lower SCR capital cost. Empty circles are studies evaluated prior to any commercial SCR installation on a coal fired utility plant. ........................................................................................................ 26 Figure 2.6 Maximum performance for NH 3 -SCR of NO x . ............................................... 28 Figure 2.7 Temperature limitations of SCR-NO x catalysts .............................................. 29 Figure 2.8 The Fast SCR reaction of NH 3 , NO and NO 2 at low temperature ..................... 30 Figure 2.9 Systems commonly used and tested for SCR of NO in the presence of different reducing agents at different temperature ranges ............................................................ 31 Figure 2.10 The development of the three dimensional structure of zeolite of type ZSM5. ... 33 Figure 2.11 Structure of zeolite with Bronsted acid site. .................................................. 34 Figure 2.12 Schematic Pore structure of Zeolite. ............................................................ 35 Figure 3.1 Different types of support zeolites ................................................................. 40 Figure 3.2 Preparation procedure ................................................................................ 44 Figure 3. 3 Preparation template for 160 ppm precursor salt concentration and CBV 2314 zeolite for 1 day at 65 oC .............................................................................................. 45 Figure 3. 4 Preparation template for 2000 ppm precursor salt concentration and CBV 2314 zeolite for 1 day at 65 oC .............................................................................................. 45 Figure 4.1 Inductively Coupled Plasma- Atomic Emission Spectrometry ........................... 49 Figure 4.2 Adsorption isotherm of Cu-ZSM5 catalyst ...................................................... 51 Figure 4.3 Illustration of how SEM works...................................................................... 52 Figure 4.4 SEM scan of Cu-ZSM5................................................................................. 53 Figure 5.1 Cu loading based on a precursor salts conc. 160 ppm and different zeolites, at 23 oC and 1 Day.......................................................................................................... 55 Figure 5.2 Cu loading based on a precursor salts conc. 160 ppm and different zeolites, at 65 oC and 1 Day.......................................................................................................... 56 Figure 5.3 Cu loading and BET surface area based on different Zeolites .......................... 57 Figure 5.4 Cu loading and BET surface area based on 160 ppm concentrations of Cu(COOCH 3 ) 2 ........................................................................................................... 58 Figure 5.5 Cu loading and BET surface area based on 2000 ppm concentrations of Cu(COOCH 3 ) 2 ........................................................................................................... 58 Figure 5.6 Cu loading and BET surface area based on 1 day time of ion exchange with respect to Cu(COOCH 3 ) 2 ............................................................................................ 59 6TU U6T 6TU U6T 6TU UR 6TU UR U RU UR RU U6T UR U U6T 6TU U6T 6TU UR RU 6TU UR UR 6TU UR RU RU U6T U6T RU UR RU U6T 6TU U6T 6TU U6T 6TU U6T 6TU U6T 6TU U6T 6TU U6T 6TU UP P 6T UP P 6T 6TU 6TU U6T 6TU U6T 6TU U6T 6TU U6T 6TU UP PU U6T UP PU U6T 6TU 6TU U6T 6TU UR R R R6T UR R R R6T 6TU 6TU UR Master Thesis| P a g e 6 R R R6T Figure 5.7 Cu loading and BET surface area based on 7 days time of ion exchange with respect to Cu(COOCH 3 ) 2 ............................................................................................ 60 Figure 5.8 Cu loading and BET surface area based on 23 oC of ion exchange with respect to Cu(COOCH 3 ) 2 ........................................................................................................... 62 Figure 5.9 Cu loading and BET surface area based on 65oC of ion exchange with respect to Cu(COOCH 3 ) 2 ........................................................................................................... 62 Figure 5.10 SEM images of (a) H 51, (b) H 75, (c) H 60, (d) H 64, (e) H 69, (f) H 81, (g) H 83 and (h) H 85 ........................................................................................................... 64 6TU UR R R R6T 6TU UP UR R R R6T 6TU UP UR R R PU R6T 6TU U6T Master Thesis| P a g e 7 PU LIST OF TABLES Table 3.1 Formulas and properties of different types of support zeolites ........................... 40 Table 3.2 Precursor salt and its properties .................................................................... 40 Table 3.3 Preparation summary.................................................................................... 46 Table 5.1 Cu loading based on a precursor salts conc. 160 ppm and different zeolites, at 23 oC and 1 Day.......................................................................................................... 54 Table 5.2 Cu loading based on a precursor salts conc. 160 ppm and different zeolites, at 65 oC and 1 Day.......................................................................................................... 55 Table 5.3 Cu loading and BET surface area based on different zeolites ............................ 56 Table 5.4 Cu loading and BET surface area based on different concentrations of Cu(COOCH 3 ) 2 ........................................................................................................... 57 Table 5.5 Cu loading and BET surface area based on different time of ion exchange with respect to Cu(COOCH 3 ) 2 for 160 ppm concentration ..................................................... 59 Table 5.6 Summery of Elemental analysis (ICP-AES) and BET surface area results. .......... 60 Table 5.7 Cu loading and BET surface area based on different temperature of ion exchange with respect to Cu(COOCH 3 ) 2 ..................................................................................... 61 Table 6.1 Standard Gas Cylinders concentrations used for this experiments ...................... 66 Table 6.2 Mass flow meter details used in SCR process ................................................... 67 6TU U6T 6TU U6T 6TU U6T 6TU UP PU U6T UP PU U6T 6TU 6TU U6T 6TU UR R R R6T 6TU UR R R RU U6T 6TU U6T 6TU UR R R R6T 6TU U6T 6TU U6T Master Thesis| P a g e 8 CHAPTER 1: INTRODUCTION The emissions of nitrogen oxides (NO x ) and sulfur oxides SO x into the atmosphere R R R R contribute to many environmental and health issues. NO x and SO x are mainly emitted as part R R R R of flue gas from large stationary sources. In general, emissions of flue gases contribute to acid rain and to low level smog formation. Furthermore, flue gases are one of the main sources that cause global warming. More specifically, NO x gases are produced in combustion R R processes, partly from nitrogen compounds in the fuel, but mostly by the direct combination of atmospheric oxygen and nitrogen in the flames. A lot of effort have been put forward by (environmental) engineers around the world in order to develop an efficient NO x removal technique. Catalytic Reduction (SCR) showed to be a R R very efficient technology with many promising results for NO x removal. Different types of R R catalysts have been used with the SCR method, such as noble metals (Pt, Rh and Pd), metal oxides, and metal-based zeolites. Among the different zeolite catalysts, ZSM-5 based catalysts show the most promising results, in terms of high efficiency for removing NO x R R gases from (flue) gases emitted by in chemical plants. ZSM-5 is a type of zeolite that has a high silica to alumina ratio (Si/Al). It has been shown to be an active and selective catalyst for the SCR reactions. In addition, ZSM-5 has good resistance to thermal excursions as compared to metal oxide zeolites. As mentioned, several zeolite-based catalysts are used for NO x reduction, but the most active type of catalysts for NH 3 -SCR are transition metal R R R R exchanged ZSM-5 catalyst (Skalska, 2010). Sources of atmospheric pollution are increasing as a result of an increase in industrial activities and because of an increase of the number of cars and trucks in the transportation sector. To minimize the impact of the the NO x and SO x emissions, the various industries R R R R must work on sustainable development to minimize the release of gaseous emissions from point sources. NO x emission is one of these main pollutants and there are many areas that R R require research to develop an efficient technology that works at different temperatures to achieve the maximum reduction of NO x released to environment (Deka, 2013). R R The aim of this work is to study the usage of Cu-Zeolite based catalyst, since metal based zeolite catalysts can withstand temperatures higher than 250 °C. In addition, the focus will be on the preparation, characterization, and testing of Cu-ZSM-5 catalyst in order to predict the behavior of the catalyst among different conditions and to study the selectivity of the prepared catalyst to convert NO x to N 2 . R Master Thesis| P a g e 9 R R R This report is covering the main parts required to understand the methodology, previous research, and a comparison is made between the results from the experimental work and results reported in the literature. The chapters are organized as: Chapter Two: In Chapter 2 a literature review is given, covering the main NO x and SO x U U R R R R definitions and sources, statistics, real data about the environmental impact of the gases, and what is the main process applicable for NO x abatement. An overview is given of the various R R methods used for NOx removal, for six technologies the main advantages and disadvantages are discussed and evaluated. Based on this evaluation is concluded that SCR gives the best results (after benchmarking the process), because of the high percentage of conversion from NO x to N 2 using Copper Zeolite Based Catalysts. R R R R Chapter Three: Preparation of the catalysts is a very important aspect, because it affects the U U activity of the catalyst during the SCR reactions. Copper-zeolites, especially Cu-ZSM-5, are being studied to be use as NO x removal catalysts. In this Chapter, first an overview of the R R catalyst preparation methods will be given. Second, the NO x abatement experimental setup R R and procedure for the catalyst used in Selective Catalytic Reduction (SCR) process will be described briefly, in terms of the precursor salt and support materials used achieve a high metal loading. Chapter Four: In this Chapter, the main characterization methods will be discussed. The U U following methods have been used to characterize the samples: Inductively Coupled Plasma Atomic Emission Spectroscopy technique (ICP-AES), Energy Dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) analysis, Scanning Electron Microscope (SEM) analysis, and Temperature Programmed Reduction (TPR). Chapter Five: In this Chapter, the focus is on the preparation of the samples. A syntheses U U temperature of 65 oC is chosen in order to compare the results with data from published P P scientific papers. Each characterization technique used gave good results to have a proper understanding about the properties of the catalyst. The results obtained in this study are compared with previous researches to study the effect of the preparation method on the catalysts behavior. Chapter Six: The copper zeolite catalysts is to be investigated and tested to study the factors U U that affects the catalyst activity and stability to improve the performance of these catalysts for future work. Experimental set-up and procedure had been followed and there are many Master Thesis| P a g e 10 challenges faced at this stage. Finally, test results will be discussed in details and compared with the literature, several recommendations will be mentioned. Master Thesis| P a g e 11 CHAPTER 2: LITERATURE REVIEW 2.1 Definition and Sources of SO x & NO x 3B R R R The energy produced by stationary sources (around the world) shows a steady increase, especially in industrial countries. The United States Energy Information Administration report (US EIA) expected based on many factors and researches that the world coal consumption will increase by 60% by 2030 (Abbasian, 2012). One example of stationary sources are power plants. The combustion of coal for electricity generation in power plants around the world has increased every year, and during the period of 1980 to 2009 the amount of coal has increased from 2,780 to about 5,000 Mt (Million metric tons) (Xu, 2010). Consequently, the sulfur and nitrogen oxides emissions have increases gradually from the many different energy sources. Some of these sources are generating some pollutants that could affect the environment and human health regardless of providing the countries with the economic growth and industrial development (Abbasian, 2012). SO x and NO x are the major gaseous pollutants generated from flue gases in stationary R R R R sources. These pollutants must be minimized in order to reduce the exposure to the environment as much as possible. In addition, wastes or pollutants could be generated by other sources, not only from industries; it can be also from automobiles and human activities. The concentration of SO 2 and NO x , ranges from hundreds to thousands of ppm, and tens to R R R R hundreds of ppm, respectively (Xu, 2010). From a political point of view, governments and agencies have to agree on some regulations and limitations to reduce the gaseous emissions and force the point sources emission producer to develop and commercialize those processes to reduce SO x and NO x concentration. In addition to the atmospheric hazards, the air R R R R pollutants can lead to water and soil pollution which cause health problems, such as respiratory damage, heart disease and cancer (Xu, 2010). The conversion of these pollutants to environmental friendly components is a big challenge and needs to be studied and tested to have a safer and more economical solution. In the next paragraphs a brief description of SO x R R and NO x will be given. R R 2.1.1 Sulfur Oxides (SOx): In the early 1900s, the industrial smog distribution started to have worldwide attention for SO x . Many researches tried to elucidate the causes and effects of the air pollutants on R R Master Thesis| P a g e 12 environment and human health. As a result, the regulations agreed by governments to minimize the industrial gas emissions and to have a sustainability solutions of the negative effects on the human health as well as environment (Xu, 2010). SO x refer to all sulfur oxides, R R which considered as major atmospheric pollutants. Sulfur oxides could be referred to a mixture of oxygen and sulfur such as: • Lower sulfur oxides (SnO, S 7 O 2 and S 6 O 2 ) • Sulfur monoxide (SO) • Sulfur dioxide (SO 2 ) • Sulfur trioxide (SO 3 ) • Higher sulfur oxides (SO 3 and SO 4 and polymeric condensates of them) • Disulfur monoxide (S 2 O) • Disulfur dioxide (S 2 O 2 ) R R R R R R R R R R R R R R R R R R R R R R In the list of gases above, sulfur dioxide (SO 2 ) and sulfur trioxide (SO 3 ) have the highest R R R R impacts. The combustion of fossil fuel at power plants and industrial facilities processes are considered as the largest sources of sulfur dioxide emissions (EPA, 2014). SO 2 is highly R R reactive gas; any release of this gas easily cause an environmental problem presented by the formation of acid rain and ozone layer destruction. SO x gases are formed by the reaction of sulfur and oxygen wherever there is combustion, R R especially at high temperatures. The SO x formation depends on local combustion conditions R R and sulfur content in the fuel burned. SO 2 dissolves in water vapor to form acid, and interacts R R with other gases and particles in the air to form sulfates and other products that can be harmful to people and environment. Over 65% of SO 2 released to the air, or more than 13 R R million tons per year, comes from electric utilities, especially those that burn coal. Other sources of SO 2 are industrial facilities that derive their products from raw materials like R R metallic ore, coal, and crude oil, or that burn coal or oil to produce process heat (Arbor, 2008). Master Thesis| P a g e 13 2.1.2 Nitrogen Oxides (NOx): NO x gases are formed during combustion reaction at high temperature. NO x , a generic term R R R R for a group of nitrogen oxides, are one of the pollutants that have many negative impacts on the environment. Nitrogen oxides could be referred to a mixture of oxygen and nitrogen such as: • Nitric oxide (NO), also known as nitrogen monoxide. • Nitrogen dioxide (NO 2 ).Nitrous oxide (N 2 O). • Nitrosylazide (N 4 O). Nitrate radical (NO 3 ). • Dinitrogen trioxide (N 2 O 3 ). • Dinitrogen tetroxide (N 2 O 4 ). • Dinitrogen pentoxide (N 2 O 5 ). • Trinitramide (N (NO 2 ) 3 ). R R R R R R R R R R R R R R R R R R R R R R R R The first three compounds (NO, NO 2 and N 2 O) are considered as the main gases that are R R R R presented in NO x group. NO and N 2 O are odorless and colorless gases but nitrogen dioxide R R R R (NO 2 ) can often be seen as a reddish-brown layer along in the air. R R Bosch and Janssen separated the NO x formation during the combustion processes into three R R different categories which are thermal, fuel and prompt NO x (B.V., 1988) (Madras, 2009) R R (Miller, 2011). Thermal NO x , is formed through oxidation of nitrogen in the combustion air at high R R temperature. The formation reaction is as following Equation (1): 𝑜 𝑁2 + 𝑂2 ↔ 2𝑁𝑁, ∆𝐻298 = 180.6 𝑘𝑘 𝑚𝑚𝑚 (1) The above reaction is occurring at a temperature more than 1,300 K and follows the Zeldovich mechanism (Flagan, 1988) for the activated atoms for nitrogen and oxygen; Equation (2) & (3): 𝑁2 + 𝑂∗ → 𝑁𝑁 + 𝑁 ∗ 𝑁 ∗ + 𝑂2 → 𝑁𝑁 + 𝑂∗ Master Thesis| P a g e 14 (2) (3) The NO x emissions can be controlled by lowering the temperature of the source for the R R combustion process under excess air but the results are not very effective. The rate of formation for the second reaction increases as temperature increases. Fuel NO x , is formed during combustion of ionized nitrogen that is presented in fuel, such as R R heavy oils and coal. On the other hand of thermal NOx, the temperature in this category is useless; any increasing in temperature will not affect the NO x formation at normal R R combustion temperature. Prompt NO x is formed from the reaction of hydrocarbon radicals with atmospheric nitrogen R R but it is minor compared to the overall quantity of NO x generated from combustion. NO x R R R R formation is sensitive to temperature for the first type so that increasing in temperature will increase and speed up NO x formation. On the other hand, the second and third type depends R R on local combustion conditions and nitrogen content in the fuel which will effect NO x R R formation. In this type, NO can react to NO 2 and N 2 O in the present of oxygen as the R R R R following reactions; Equation (4) & (5): 𝑁𝑁 + 1�2 𝑂2 ↔ 𝑁𝑁2 , 𝑜 ∆𝐻298 = −113 2𝑁𝑁 ↔ 𝑁2 𝑂 + 1�2 𝑂2 , 2.2 𝑜 ∆𝐻298 = −99 NO x and SO x Sources 4B R R R 𝑘𝑘 𝑚𝑚𝑚 (4) 𝑘𝑘 𝑚𝑚𝑚 (5) R Nitrogen oxides formation from fossil fuels combustion processes, partly from nitrogen compounds in the fuel, but mostly by direct combination of atmospheric oxygen and nitrogen in flames. The main two examples of NO x formation process are the petroleum for vehicle R R engines and coke for power generation (Madras, 2009). Nitrogen oxides could be produced naturally due to: • The extreme heat of lightning (N 2 to NO x ). • Biomass burning such as forest fires, grass fires, trees, bushes, grasses, and yeasts. R R R R The sources of NO x emissions can be categorized mainly into mobile sources and stationary R R sources. The figure below shows the different sources of NO x emissions worldwide. R Master Thesis| P a g e 15 R Figure 2.1 National Summary of Nitrogen Oxides Emissions in 2011, statistics (USEPA, Air Emission Sources, 2011) and bi-chart (USEPA, Bad Nearby, 2011). As shown in Figure 2.1, the main source of NO x is motor vehicles by total emission R R production equal 8,919,374 tons in 2011 (56%), while fuel combustion or utilities are responsible for 3,754,756 tons (22%) of the total emissions. In addition, 1,305,090 tons (17%) of NO x is produced by industrial / commercial / residential fuel combustion. As can be R R seen, there are other sources, such as biogenic, fires, miscellaneous, solvent, agriculture and dust, which produces 5% of NO x total emissions. The total NO x emission production in 2011 R R R R was 15,517,527 short tons (short ton is a unit of mass, it is equal to 907.185 kg) (USEPA, Air Emission Sources, 2011) (USEPA, Bad Nearby, 2011). Master Thesis| P a g e 16 Figure 2.2 The concentration of NO2 in the atmosphere above southwestern Asia (Watchers, 2013). Figure 2.2 shows a satellite map of the Middle East and southwestern Asia and illustrates the nitrogen dioxide (NO 2 ) concentration or total column density in (x 1015 molecules/cm2) R R P P P P presents in the atmosphere. The NO 2 concentration in the map presented as shades of orange, R R while the non-usable data are shown in gray at different locations. The motoring data were acquired by the Ozone Monitoring Instrument (OMI) on National Aeronautics and Space Administration (NASA) satellite. OMI measures the visible and ultraviolet light scattered and absorbed by Earth’s atmosphere and surface. The presence of NO 2 causes certain R R wavelengths of light to be absorbed (Watchers, 2013). Additionally, Figure 2.2 shows the NO 2 total column density in Qatar. As per the legend, R R NO 2 concentration is high (between 10 to 15 x1015 molecules/cm2) which mean that total R R P P P P emission is increasing resulted in increasing of other gases leads to GHG or ozone depletion. Qatar is facing major challenges to maintain air quality in parallel with the increase of industrial production. The non-greenhouse gas emissions, which includes NO x and SO x are R R R R major pollutants generated by industries in Qatar. The emissions are limited and documented by the Ministry of Environment (MOE) in the Consent to Operate (CTO) for each single Master Thesis| P a g e 17 company. In industries, if any planned/unplanned exceedance of emissions during operation or shutdown, notification must be reported and faxed to MOE. The continuous target is to reduce the emissions for the combustion sources and stacks. Many air emission monitoring systems are installed and several pollution prevention and reduction are commissioned as quick solutions to solve the problem. Industries should plan and draw their sustainable strategies and goals to achieve the target of emission reduction and abatement. In 2013, 31 Qatari companies reported 63,378 tonnes of NO x emissions, which is lower than R R 2012, with NO x emissions of approximately 9%. On the other hand, 30 companies reported R R SO x emissions of 295,424 tonnes in 2013, which is an increase of about 109% as compared R R to the emissions for 2012. The vast majority of this increase is related to the shutdown and start-up of a large Sulfur Recovery Unit (SRU), while the remainder is a combination of seven companies increasing SO x emission levels. See Figure 2.3 (Industry, 2013). R R Figure 2.3 Qatar Environmental statistics for NO x & SO x emissions in 2012 & 2013 (Industry, 2013). R 2.3 R R R NO x and SO x Environmental Impacts 5B R R R R One of the most important ramifications of SO x and NO x emissions to the atmosphere is R R R R their contribution to the acid rain phenomena. SO 2 and NO react with water present in rain at R R the high levels of the atmosphere, to form sulfuric acid (H 2 SO 4 ) and nitric acid (HNO 3 ) R R R R R R respectively. Ultimately, the formed acid rain will return to earth’s surface which can cause environmental and health problems. The unexpected increasing on acidity of the water surfaces can revoke fishes or other organisms. The reactions of SO 2 and NO can form tiny R Master Thesis| P a g e 18 R particles which can contribute to respiratory problems, dry coughing and headaches while inhaled the emitted particles (Xu, 2010). 2.3.1 Nitrogen oxides (NOx): Nitrogen oxides (NO x ) are one of the main pollutants generated from both mobile and R R stationary sources that can affect human health and harm the environment (Zhang, 2001). The European countries studies confirm that the NO x emissions come from the mobile R R sources equal approximately 40% of the total production and the remaining is mostly from the energy sources. The last twenty years have observed a reduction of approximately 95% in NO x generated from diesel engines after installing the NO x reduction technologies (Deka, R R R R 2013). Figure 2.4 shows the decreasing of the total NO x and PM production in exhaust stream as R R per European legislations. The early standards only required a fine treatment of the exhaust gases. Since 2005, continuous gas monitoring has been done which have led to catalytic treatment to minimize the NO x emissions. For Euro VI standards, which will be applied in R R 2015-2017, the new technology demand that using catalysts for NO x emission abatement R R must be recognized and optimized for the stationary sources (Deka, 2013). Figure 2.4 The trend in permitted amounts of NO x and Particulate Matter (PM) in Europe as set by the European legislation with time. Euro VI, initially planned for 2013, is to be implemented in two stages during the 2015-2017 period (Deka, 2013). R R The maximum permissible limit for emissions of nitrogen oxides is 125 mg\Nm3 P internationally. However, the Qatari Ministry of Environment is more stringent with NO x R R regulation for industries to minimize NO x less than 55 mg\Nm3 (MOE, 2002). It might R Master Thesis| P a g e 19 R P P P produce pollutants known as photochemical oxidants, principally ozone, when they react with carbon monoxide and volatile organic compounds (VOCs), such as methane, in the presence of sunlight. These photochemical oxidants would affect the ground-level ozone in which air quality will be affected. All over the world, environmental regulations are strict about reducing NO x in order to have a clean environment to live in (Sjocall, 2006). NO x is R R R R considered dangerous to humans and the environment as the following: • Formation of ground-level ozone, which can trigger serious respiratory problems. • Formation of acid aerosols, which also cause respiratory problems. • Contribution of formation of acid rain, which causes acidification of lakes and forests. Prior to falling to the ground, sulfur dioxide (SO 2 ) and nitrogen oxides (NO x ) gases R R R R contribute to smog formation, plant degradation and harm public health. • Deterioration of water quality, which could have additional nitrogen that could cause eutrophication. This leads to oxygen depletion and fish death. • Formation of ground-level ozone which is formed in the air by the photochemical reaction of sunlight and nitrogen oxides (NO x ). In addition, it may cause biological R R mutations. [O 3 O 2 +O.] R • R R R P P Contribution of N 2 O to global warming which is expected to raise earth temperature, R R raise the sea level and loss of coastal areas (Giridhar, 2009). • NO x gases are play a big role on the troposphere and stratosphere photochemistry in R R which the nitrogen oxides will catalyzed the ozone via the following reactions; Equations (6) & (7): 𝑁𝑁 + 𝑂3 → 𝑁𝑁2 + 𝑂2 𝑁𝑁 + 𝑂 → 𝑁𝑁 + 𝑂2 (6) (7) Both reactions are affecting the ozone in the high levels at different times of the year (Ravishankara, 2003). • Acid rain which can kill the microorganisms in rivers and lakes. The pollutants that are formed from NO x can be transported or carried by winds over long R R distances in a short period of time, even across the oceans. This means that problems associated with NO x are not confined to areas where NO x are emitted. Therefore, controlling R R Master Thesis| P a g e 20 R R NO x is often most effective if done from a regional perspective, rather than focusing on R R sources in one local area. 2.4 Process Technologies Among the different technologies that are used to reduce NO x removal, six R R technologies will be discussed in this paragraph. The study of the available technologies and the research for information about these technologies will be summarized. NO x control R R technologies can be categorized as combustion modifications and post-combustion process. • Combustion modifications, which reduce NO x formation during combustion process, R R includes such technologies as the following: o Low NO x burners (LNBs) R R o Over fire air (OFA) o Re-burning. o Flue gas recirculation (FGR). • Post-combustion processes, which reduce NO x formation after it has been formed, R R includes such technologies as the following: o Selective catalytic reduction (SCR) o Selective non-catalytic reduction (SNCR). 2.4.1 Low NOx Burners (LNBs) The most common NO x reduction strategy is the use of low NO x . This technology R R R R has three different zones, which are: (1) primary combustion, (2) fuel re-burning, (3) and final combustion. Both kinds of this technology use pulverized coal-fired boilers. The first technology uses individual small burners around the boiler walls, while second one uses a large fireball near the center of the boiler. The two technologies involve direct and radiant tube, fired burners which can be designed for the produced cold or hot air from the regenerators. This can be one of the least expensive pollution prevention technologies with high Destruction Removal Efficiency (DRE). LNB have had some design problems, which had flame attaching to the burners, resulting in a need for maintenance. However, it is believed that these design problems are part of the past and they do not exist anymore. Master Thesis| P a g e 21 LNB is one of the many successful technologies in reducing the peak temperature and is considered as a pollution prevention method, as it reduces thermal pollution by the decrease of fuel usage in combustion. Additionally, LNB is considered as a pollution prevention method, since it successfully reduces NO x chemicals by removing oxygen from the Nitrogen R R Oxide groups (Clean Air Technology Center, 1999) (Alberta Research Council INC, 2001). In this technology there are many of advantages and disadvantages as follows: Advantages: • Reducing oxygen concentrations which are reacting with nitrogen to produce NO x . R R Oxygen will be reduced by minimizing excess air. • Reducing the temperature of flame which produces NO x at high temperature by R R minimizing intensity of mixing. • The capacity of reduction NO x emissions up to 80%. • The most cost effective method to reduce NO x emissions from an operating cost R R R R perspective. Disadvantages: • LNB might evolve as a "reducing atmosphere" next to heat exchanger surfaces which can result in corroding the surface. • Moderately high capital cost. 2.4.2 Over Fire Air (OFA) Over Fire Air is another technique in which air is injected into the furnace above the normal combustion zone. Generally when OFA is employed, the burners are operated at a low air-to-fuel ratio, which reduces NO x formation. OFA, which is frequently used in R R conjunction with LNBs, completes the combustion process at a lower temperature. Although this technology has low operation cost, but it needs high capital cost to install it (National Energy Technology Laboratory, 2007). 2.4.3 Re-burning In this technology, the flue gas is recycled and injected with fuel in the flare. It is typically used only for large boilers firing coal or residual oil in utility power plants. Re-burning involves the Master Thesis| P a g e 22 staged addition of fuel into two combustion zones: (1) the primary combustion zone where coal is fired; and (2) the re-burn zone where additional fuel (the re-burn fuel) is added to create a reducing (oxygen deficient) environment. This will convert the NO x produced in the R R primary zone to molecular nitrogen (N 2 ) and water. Above the re-burn zone is a burnout zone R R in which OFA is added to complete the combustion. Each zone has a unique stoichiometric air ratio (the ratio of the air used to that theoretically required for complete combustion) as determined by the flows of primary fuel, burner air, re-burn fuel, and OFA (Alberta Research Council INC, 2001). Advantages: (Clean Air Technology Center, 1999) • Oxidizing remaining hydrocarbon. • 10 to 25% of heat input is supplied by the return fuel. • Re-burning can reduce NO x emissions by 60%. • Moderate operation and capital cost. R R Disadvantages: • Extends residence time in flare. • Other recycle fuel such as coal and biomass can result in high level of unburned carbon in ash. 2.4.4 Flue Gas Recirculation Flue Gas Recirculation (FGR) in which part of the flue gas is recirculated to the furnace, can be used to modify conditions in the combustion zone (lowering the temperature and reducing oxygen concentration) to reduce NO x formation. FGR is also used as a carrier R R to inject fuel into a re-burn zone to increase penetration and mixing. Most of the early FGR work was done on boilers and investigators found that recirculating up 25% of the flue gases through the burner could lower NO x emissions to as little as 25% of their normal levels R R (Genesys Combustion).Word of this success has spread and now operators of industrial processes are interested in learning if FGR can do the same for them. Although FGR reduces high amounts of NO x emissions, it has a moderately high capital cost and operating cost R R (Choi, 2011). Master Thesis| P a g e 23 2.4.5 Selective Non-catalytic Reduction (SNCR) Nitrogen oxides reduction by ammonia or urea in the absence of catalysts and presence of excess oxygen is called selective non-catalytic reduction (SNCR). The main purpose of this technology is to reduce NO x emissions from stationary sources by injection R R of urea or ammonia reagent into either the upper furnace or convective pass of the boiler. In this technology urea or ammonia is dissolved in water. Critical factors in applying SNCR are sufficient residence time in the appropriate temperature range and uniform distribution and mixing of the reducing agent across the full furnace cross section to avoid ammonia slip (Javed, 2007). After the mixing, this solution is sprayed into the hot flue gas. The urea breaks down into several other similar compounds that react with NO x to form elemental R R nitrogen (Alberta Research Council INC, 2001). Advantages: • Catalyst is not required. • Lower installation cost. • The NO x removal efficiency is about 70%. R R Disadvantages: • High temperature operated between 900 and 1000 °C which is important so that there will not be ammonia slips or more NO x is generated instead of reducing it (Staudt, R R 2000). • Injection of ammonia has to be varied with boilers load to avoid ammonia slip within the temperature range. 2.4.6 Selective Catalytic Reduction (SCR) Although all the previous technologies are commercially used, in general these technologies suffer from a low efficiency, and this means that not always the various regulations at met. As a result, there should be technologies that have higher efficiency than the previous technologies for NO x removal, and a good candidate for this is selective R R catalytic reduction (SCR). The SCR technology is used since the end of the 1960s with different catalysts. Ammonia is injected into flue gas ahead of the selective catalytic reduction which promotes the reduction of NO x by ammonia to produce nitrogen. SCR is R R installed for high level of NO x removal especially in urban areas where ozone and R Master Thesis| P a g e 24 R photochemical smog is presented. In this process, ammonia (NH 3 ) is blown into the exhaust R R gas, allowing the NH 3 to selectively react with nitrogen oxides NO x (NO, NO 2 ), and convert R R R R R R them into water vapor (H 2 O) and nitrogen (N 2 ) (Olsson, 2010) (R. Bonzi L. , 2010). That is R R R R depending on the type of catalyst which will be chosen and the selectivity of converting NO x R R to N 2 . Commercial selective catalytic reduction systems are typically found on large utility R R boilers, industrial boilers, and municipal solid waste boilers. More recent applications include diesel engines (Abu-Jrai, 2014), such as those found on large ships, diesel locomotives, gas turbines and even automobiles. There are some factors that could increase the cost of this technology which are NO x reduction required, catalyst performance and lifetime, system R R configuration and boilers conditions. Before 1980s, the cost of the SCR installation was difficult to assess, because it depends on a range of aspects like operating conditions and the amount of sulfur and metal content in the fuel. The studies on SCR technology began in Germany and Japan followed by US (Yeh S. , 2012). Figure 2.5 shows the historical trend for the cost estimation of SCR technology for a coal-fired plant in U.S. These facilities demonstrated increasingly lower capital and operating costs, longer catalyst lifetimes and lower catalyst prices than assumed in earlier studies. However, installing the SCR process in GCC countries is easier and cheaper than U.S. due to the improvement in the firing fuel. Recently, gas fuels are used for boilers and furnaces instead of liquid fuels which are emitting the environment more with many pollutants and increase the capital cost of emission reduction processes. Advantages: • One of the most effective NO x abatement technique. • Operating temperature range from 300 to 400 oC based on catalyst type (for this case R R P P V 2 O 5 is used). However, Metal zeolite catalysts are much cheaper than vanadium R R R R oxide nowadays. • Maximize NO x reduction and minimize ammonia slip which is depending on NH 3 to R R NO x Ratio. R R • The NO x removal efficiency could reach up to 90% (Abbasian, 2012). • Catalysts are made from zeolites, precious and base metals. R R Master Thesis| P a g e 25 R R Disadvantages: • Using of catalyst would make this method the most expensive method when it is compared with other methods. • Possibility the catalyst poisoning (Devadas, 2006). Figure 2.5 Capital cost and total levelized costs of SCR for a standardized new coal-fired power plant (500 MW, medium sulfur coal, 80% NOx removal), as of 1983. Solid diamond symbols are earlier studies based on low-sulfur coal plants, which have lower SCR capital cost. Empty circles are studies evaluated prior to any commercial SCR installation on a coal fired utility plant (Edward S. Rubin, 2006) (Yeh S. E., 2005). 2.5 Chemistry and Dynamics of SCR process 7B The selective catalytic reduction process is considered nowadays as the most effective method of the leading post combustion abatement technologies for NO x removal in R R stationary applications such as chemical industries (Abbasian, 2012) (Zhang, 2001). SCR can be classified based on types of reluctant used. The main types of SCR include Ammoniabased SCR, Urea-based SCR, and the Hydrocarbon-based SCR. Each one of these processes has advantages over the other, where the urea-based SCR is mainly applied onto the automotive industry (mobile applications). The ammonia-based SCR is the most suitable technology for the chemical industries, which is the main concentration of this research. Additionally, the NH 3 -SCR is more advantageous than the urea-SCR since R R the ammonia is comparatively cheaper than urea, the reactions below show decomposition of urea to NH 3 and CO 2 in SCR technology as shown in reaction Equations (8) & (9) R R R R (Copplestone & Kirk, 2008): Master Thesis| P a g e 26 𝑁𝐻2 𝐶𝐶𝐶𝐻2 + 𝐻2 𝑂 ↔ 𝑁𝐻2 𝐶𝐶𝐶𝐶𝐻4 N𝐻2 COON𝐻4 ↔ C𝑂2 + 2N𝐻3 (8) (9) The selective catalytic reduction process depend on the following major points, which are the concentration of oxygen, the inhibition of ammonia, the ratio of ammonia to NO x , and the R R temperature of the process. The process chemistry can be summarized by the following reactions. There are two desired reactions and two undesired reactions that could have an inverse effect on the process. The overall selective catalytic reduction reactions are as following Equations (10) & (11) (Abbasian, 2012): 𝑥𝑥𝑥 + 𝑦𝑁𝑁3 + ��3�4�𝑦 − �1�2�𝑥� 𝑂2 = �1�2�(𝑥 + 𝑦)𝑁2 + �3�2�𝑦 𝐻2 𝑂 (10) 𝑥𝑥𝑂2 + 𝑦𝑁𝑁3 + ��3�4�𝑦 − 𝑥� 𝑂2 = �1�2�(𝑥 + 𝑦)𝑁2 + �3�2�𝑦 𝐻2 𝑂 (11) Selective reaction Equations (12) & (13) (Khanh-Quang Tran, 2008) (R. Bonzi L. L., 2010): U U 4𝑁𝑁 + 4𝑁𝐻3 + 𝑂2 → 4𝑁2 + 6𝐻2 𝑂 2𝑁𝑂2 + 4𝑁𝐻3 → 3𝑁2 + 6𝐻2 𝑂 Non-selective reaction Equations (14) & (15) (Khanh-Quang Tran, 2008): U (12) (13) U 4𝑁𝐻3 + 5𝑂2 → 4𝑁𝑁 + 6𝐻2 𝑂 3𝑂2 + 4𝑁𝐻3 → 2𝑁2 + 6𝐻2 𝑂 (14) (15) The temperature of the process is the main factor that decides upon the favorability of the undesired reactions. The temperature range for these two types of reaction is from 150 to 500 °C, and this is shown by Figure 2.6 and 2.7 which shows the relation between the NO x R R conversion and the temperature. In general, Figure 2.6 shows that there are two parallel reactions lead to lowering the NO x conversion at high temperature at which Ammonia Oxidation R R occurs. These parallel reactions perform a curve which gives a rise of conversion up to certain temperature for different catalysts which has different operation temperature ranges shown in Figure 2.6. Many materials such as noble metals, metal oxides, and zeolite catalysts have been studied as catalysts for the ammonia SCR process in order to overcome the temperature limitations that are faced (Sjocall, 2006). Master Thesis| P a g e 27 Figure 2.6 Maximum performance for NH 3 -SCR of NO x (Khanh-Quang Tran, 2008). R R R R The rate of NO x removal can be determined by the rate equation, where the major three R R factors of the process mentioned previously are included within Equation (16). Schuler (A. Schuler, 2009) studied the NO x removal over iron exchanger zeolite catalysts are formed and R R the rate is covered by this equation: 𝑟𝑁𝑁 Where: 𝑋𝑂2 𝛽 𝐸𝐴,𝑁𝑁 𝐶𝑁𝑁 . 𝜃 = 𝑘𝑂,𝑁𝑁 . 𝑒𝑒𝑒 �− �. .� � 𝑅. 𝑇 1 + 𝐾 . 𝜃 0.06 𝑁𝐻3 (1 − 𝜃) r = rate of reaction (mol m−3 s−1) P � 𝐶𝑁𝑁 .𝜃 1+𝐾𝑁𝐻3 . 𝜃 (1−𝜃) P P P � = the inhibition of ammonia; (𝛽) Denominator = oxygen concentration. (A. Schuler, 2009) 𝜃 = surface coverage of NH 3 R 𝑋𝑂2 =Molar ratio of oxygen 𝑘𝑂 =pre-exponential factor (mol m−3 s−1; s−1) P P P P P P T= temperature (K or ◦C) P P 𝐸𝐴,𝑁𝑁 =activation energy for ammonia (J mol−1) P 𝐾𝑁𝐻3 =Parameter for ammonia inhibition 𝐶𝑁𝑁 = Concentration (mol L-1) P Master Thesis| P a g e 28 P P (16) 2.6 Types of Catalysts 8B The main types of catalysts involved in NO x selective catalytic reduction process are as R R follows: • Noble metals (Pt, Rh and Pd) • Metal oxides • Metal based zeolites Many of these catalysts are investigated in different conditions and technologies (Xu, 2010). Noble metals are active for NO x reduction, but their major drawback is that the oxidation R R capacities of these catalysts are high and thereby undesired reactions are formed. The temperature range in which these catalysts will be active is around 260-300 °C. See Figure 2.7. Figure 2.7 Temperature limitations of SCR-NO x catalysts (Khanh-Quang Tran, 2008). R R Among the various investigated metal oxide mixtures, V 2 O 5 and TiO 2 oxides which are R R R R R R promoted with tungsten or molybdenum oxide are proven to be quite superb catalysts. This is due to their high activity and selectivity but also because of their resistance towards poisoning by SO 2 at temperature around 300 oC (Abbasian, 2012). Their activity is limited of R R P P temperature ranges between 320-380°C as can be seen in Figure 2.7. However, at higher temperatures, the selectivity of N 2 and H 2 O is decreased, the formation of N 2 O will be R R R R R R enhanced, and the risk of volatile vanadium emissions increases at temperatures higher than 390°C. The SCR process is classified into two fields; one is the standard SCR process is based on standard enthalpies of formation according to the National Institute of Standards Master Thesis| P a g e 29 and Technology (Skalska, 2010). The second is the fast SCR which is one of many modifications applied to the standard NH 3 -SCR that is based upon the usage of vanadium R R and removal methods in order to improve the SCR process; Figure 2.8 shows the reaction mechanism for NO x SCR over V 2 O 5 –WO 3 /TiO 2 (Devadas, 2006) (Tronconi, 2004). R R R R R R R R R R Metal based zeolites catalysts are usually used for temperatures higher than 400-600°C, and they function as more resistant to thermal excursions. Currently, metal based zeolite catalysts are under development in order to make them withstand temperatures up to 900°C. "Zeolite based catalysts such as mordenite, faujasite, and pentasil are used for NO x reduction, but the R R most active type for NH 3 -SCR is transition metal exchanged ZSM5” (Skalska, 2010). R R The study of other metal zeolites such as nano-crystalline sodium in Y zeolite (NaY) and nano-crystalline copper (CuY) showed an enhanced and a faster rate of NO x removal than R R the standard SCR by 30%, which makes nano-crystalline copper as a good candidate for the catalyst selection of SCR. Figure 2.8 The Fast SCR reaction of NH 3 , NO and NO 2 at low temperature (Devadas, 2006). R R R R The catalysts containing vanadium have several drawbacks when used for this application. Poisonous vanadium can be lost during the process and released into the environment, the catalyst exhibits low activity at low temperatures, and a low selectivity is observed at high temperatures due to competitive ammonia oxidation. During the last 20 years, much research has been carried out concerning zeolite catalysts for the NH 3 -SCR reaction. Different zeolite materials, such as MOR, MFI, Y, BEA, FER loaded R R with various metals, i.e. Cu, Co, Fe and Pt, have been investigated. Especially, copper-based zeolites have been examined thoroughly because these materials were the first metal zeolites found to be active in SCR. Master Thesis| P a g e 30 Cu-ZSM5 zeolites were initially showing a good efficiency of NO decomposition rates and the activity of the SCR to NOx technology. More recently, Cu-BETA zeolites have been shown to have good activity in the NH 3 -SCR of NO x , and metal-exchanged beta zeolites are R R R R generally found to have better hydrothermal stability than similar ZSM5 catalysts (GonzálezVelasco, 2012). Cu-zeolites are found to be active both when using Hydrocarbon and NH 3 as R R reducing agents. It has been widely used due to the high activity at higher temperature compared to V 2 O 5 based catalyst for different reduction applications of NO x decomposition R R R R R R with NH 3 -SCR technology (Sjocall, 2006) (Sultana, 2013). Copper oxide (CuO) is cheaper R R than V 2 O 5 in cost and it can remove the SO 2 and NO x simultaneously with high activity R R R R R R R R which will provide furthermore studies in this field (Irfan, 2012). Figure 2.9 illustrates the most active catalysts used for SCR of NO x compared to their R R maximum activity at specific temperatures. At lower temperature, the NO x conversion of R R noble metals (e.g. Pt) is lower than the others, N 2 O gas is forming and it has high costs R R (Burch, 2004). SCR using zeolites are promising conversion of NO x to be more than 95% R R without poisoning the environment which will provide a good commercialization for the coming future. In addition, it is showing high activity and selectivity to N 2 , high stability in R R SCR with ammonia, zeolites are not expensive which will make the metal-exchanged zeolite more attractive to use for such mobile and stationary emission control applications. Figure 2.9 Systems commonly used and tested for SCR of NO in the presence of different reducing agents at different temperature ranges (Deka, 2013). The Cu-ZSM-5/Beta catalysts seem as promising catalysts at this moment. From the last studies, Cu-ZSM5 catalyst were testing there activities and showing a high NO x conversion R Master Thesis| P a g e 31 R to nitrogen using NH 3 -SCR. On the other hand, Cu-BETA catalyst was showing their good R R activity and activity of the NOx reduction at higher temperature using the same technology (González-Velascoa, 2014). Furthermore, Cu (II) catalysts are considered to be desirable because of the high activity of the catalyst in present of the oxide and sulfate forms (Abbasian, 2012). The SCR catalyst should have some criteria to be an attractive technology, such as (Pie Lu, 2014): • High activity at different temperatures • Resistance to sulfur oxides and water • Resistance to dust • Low cost • Mechanical strength. 2.7 Zeolites Zeolite is a Greek word which means "boiling stone". The first observation of zeolites was in 1756 as sedimentary rocks, they are formed as a result of a chemical reaction between volcanic lava and saline water under hydrothermal condition. The main functions of zeolites (Devadas, 2006): • To use zeolites as a heterogeneous catalysts in industrial field • For research, to understand more about the chemistry of zeolites because they are used in a variety of applications during these days. There are two kinds of zeolites, synthetic and natural zeolites. There are differences between them (ZEO Incorporation, 2009): • Synthetics zeolites appear from energy consuming chemicals while naturals are processed from natural ore bodies. • Natural zeolites do not break down in a mildly acid environment, where synthetic zeolites do. Master Thesis| P a g e 32 2.7.1 Structure of zeolites Synthetic and natural zeolites are crystalline hydrated alumino-silicates of group 1 and 2 elements. The symmetrically stacked of Zeolite is tetrahedron of alumina and silica. In all, 225 different framework structures are now known (IZA, 2008).The structure of zeolite is framework hydrated alumino-silication, which is based in three-dimensional network of AlO 3 and SiO 3 tetrahedral linked to each other by oxygen. The structure has negative charge R R R R within the pores which is neutralized by positively charged ions such as sodium, potassium, magnesium, and calcium (Devadas, 2006). Zeolites structure formula can be expressed for the crystallographic unit cell as: M x/n [(AlO 2 ) x (SiO 2 ) y ] wH 2 O R R R R R R R R R R R R M is expression for cation of valence n, w is the number of water molecules and the ratio (y/x) has values between 1 and 1000 depending upon to the structure. Additionally, the ratio of two tetrahedral (AlO 2 , SiO 2 ) is illustrating the framework of composition. The sum of (y R R R R + x) is the number of tetrahedral in the unit cell. Zeolite (3-D) is consisted several construction units, check Figure 2.10. From the primary construction units, an oxygen atom is linked to another construction unit to make a sample ring and prisms of various sizes. The formation steps of zeolites and illustrates the three dimension structures ZSM5 zeolite type. The zeolites are based on TO 4 tetrahedral, where (T= tetrahedral) is an aluminum or silicon R R atom as showing in figure below. Figure 2.10 The development of the three dimensional structure of zeolite of type ZSM5 (Devadas, 2006). 2.7.2 Catalytic activity of zeolite Zeolite has a specific characteristics represented in void structure and acidity, where it is used as a heterogeneous catalyst. The void structure could be central or board types. The acidity has a big influence on the activity of catalysts, where it is represented in Bronsted and Master Thesis| P a g e 33 Lewis acid sites. Bronsted acid can donate protons. On the other hand, Lewis acid can accept a pair of electrons. Bronsted acid in zeolites may change into Lewis acid under condition of heating (Devadas, 2006). Figure 2.11 Structure of zeolite with Bronsted acid site (Devadas, 2006). While the electro-negativity of the metal is increased (XFe > XGa > XAl), the Bronsted acids sites decrease and Lewis acids are present. Figure 2.11 shows Bronsted acid sites in the lattice structure. The strength of acidity can be influenced by the following: • The ratio of SiO 2 / AlO 2 • Type of trivalent cation other than Al3+ such as Fe3+ , and Ga3+ R R R P P P P P P 2.7.3 Zeolite of type ZSM-5 Among different zeolite, ZSM-5 based catalyst has shown promising results (high efficiency for removing the NO x gases) in chemical plants. ZSM5 is a type of zeolite which R R contains high silica to alumina ratio. The substitution of Al3+ for a Si4+ requires the additional P P P P presence of a proton. This additional increase in activity, gives a high level of acidity of zeolite. ZSM5 is a highly porous material. This Zeolite has an intersecting two-dimensional pore structure. There are two types of pores as seen in Figure 2.12. First type has straight and elliptical in cross section with channel dimensions [5.1 Å x 5.5 Å], while the second type has intersect of the straight pores at right angles in a zigzag pattern and are circular in cross Master Thesis| P a g e 34 section with dimensions [5.4 Å x 5.6 Å] (1 Å = 0.1 nm); both of them are forming by 10 membered oxygen rings (Devadas, 2006). Figure 2.12 Schematic Pore structure of Zeolite (Devadas, 2006). Powder Cu-ZSM5 is used for the physico-chemical characterization, in order to explore the structural aspects of the catalyst. By combining the catalytic and characterization investigation the functionality of this catalyst type is explained (Skalska, 2010). The structure of the zeolite is very important to understand how the support material will work during the process as it will affect also the metal content during the catalysts preparation experiment. Master Thesis| P a g e 35 CHAPTER 3: PREPARATION 3.1 Introduction 10B In this chapter, an overview of the catalyst preparation methods will be explained. Then, the NO x abatement experimental setup and procedure for the catalyst used in Selective R R Catalytic Reduction (SCR) process will be described briefly, in terms of the precursor salt and support materials used have the higher metal loading. Furthermore, some information regarding the characterization techniques used for the prepared catalysts to illustrate the physical and chemical properties, followed by the selective catalytic reduction experiment to study the activity of the catalysts. SCR with NH 3 is an effective technology for NO x abatement from stationary sources, R R R R widely used in power generation and industrial field. There are several catalysts that can be used, such as metal oxides, noble metals or metal-exchanged zeolites. Cu/zeolite is a promising catalyst for the NO x abatement from the stationary sources. It has many R R attracting factors, such as cheap in price, nontoxicity, high activity and selectivity to nitrogen (Deka, 2013). Preparation of catalyst is a very important stage because it affects the activity of the catalyst during SCR reactions. Copper-zeolites, especially Cu-ZSM-5, are being studied to use them as NO x removal catalysts. The literature review (González-Velascoa, 2014) R R shows that Cu-ZSM-5 efficiency of NO x conversion is more than 98% at a specific R R temperature. Cu-ZSM-5 can be prepared by different methods, but there is only one method that will be used in this project, which is the ion exchange method in an aqueous solution of precursor salt, such as Cu(CH 3 COOH) 2 . This method is affecting the catalyst R R R R activity by increasing the dispersion of the copper ions inside the pores. There are several different methods to prepare copper-zeolite catalysts such as: 1. Impregnation method 2. Wet ion exchange method 3. Solid-state ion exchange 4. Chemical vapor deposition There are different supported zeolites such as ZSM-5 with different Si/Al ratio and Betazeolite. Further investigations from the other previous works proved the removal of NO x R Master Thesis| P a g e 36 R over Cu-ZSM-5 and Cu-Beta catalysts were found to be highly active for the SCR reactions (González-Velascoa, 2014). 3.2 Preparation Methods 1B 3.2.1 Impregnation Method Many types of catalyst are produced by impregnation method. There are two ways for impregnation methods which are wet and dry methods. The liquid method consists of repeated dipping of porous support pellets into a solution containing a desired catalytic agent. The liquid penetration into the pellets is hindered by air trapped in the pellet pores. The impregnation method involves two steps (Perego, 1997) 1. Contacting the support with the impregnating solution for a certain period of time. 2. Drying the support to remove the excess liquid. Then, the catalyst is activated either by calcination, reduction or other appropriate treatment. The second method is dry impregnation in which the solution of precursor salt is equal to volume of pore of the catalyst. The drying will be done by measuring pore size of the catalyst and use an equal amount of solutions; then dry it. This method has many advantages include its relative simplicity, rapidity and capability for depositing the precursor at high metal loadings. A principle disadvantage is that sometimes material is non-uniformly deposited along pores and through the pellet; the tendency for deposited base metal precursors to be oxidized in the aqueous solution to oxides that interact strongly with alumina or silica support and which are difficult to reduce (Bartholomew & Farrauto, 2005). 3.2.2 Wet Ion Exchange Method Wet Ion Exchange (WIE) is the most common method to prepare metal-exchanged zeolites. Typically, the copper salt dissolved in deionized water and added to the zeolite at once. The exchange carried out at different conditions. The catalysts prepared by adding zeolite in water suspension drop-wise to the dissolved copper salt under continuous stirring; see Equation (17). For filtration and washing, centrifuging has been used for separation and washing the solutions at least three times for each (Pieterse, Master Thesis| P a g e 37 2004). 𝑀/𝑆𝑆𝑆𝑆 + 𝑁𝐻4 /𝑧𝑧𝑧𝑧𝑧𝑧𝑧 → 𝑀/𝑧𝑧𝑧𝑧𝑧𝑧𝑧 + 𝑁𝐻4 /𝑆𝑆𝑆𝑆 Where, (17) M: Metal which be used in preparation of catalyst. Salt: The solution which contain the metal in it. Zeolite: Any one of a family of hydrous aluminum silicate minerals. These are advantages and disadvantages of using the wet ion exchange method in catalyst preparation (APEC). Advantages: U • Removes dissolved inorganics effectively. • Re-generable (service deionization). • Relatively inexpensive initial capital investment Disadvantages: U • Does not effectively remove particles, pathogens or bacteria. • DI beds can generate resin particles and culture bacteria. • High operating costs over long-term. WIE is easier than impregnation. The catalyst shows a higher activity of NO x abatement R R than solid ion exchange and the NO x conversion reached 99.9% approximately. But, it R R needs two-steps to prepared and longer time (Yang, 2004). A limitation of this technique is the difficulty to have full ion exchange (Pieterse, 2004). 3.2.3 Solid-state ion exchange An efficient solid-state reaction between the starting zeolite and the salt, which contains the desired in-going cation, requires an intimate mixture of the solids. This can be achieved, for instance, by careful milling or grinding the two components together. In cases where an intense milling or grinding of the mixture may affect the integrity of the zeolite structure, it is preferable to prepare a suspension of the powdered salt and the Master Thesis| P a g e 38 zeolite in an inert solvent. When the components have been thoroughly mixed by moving the suspension, the solvent may easily be removed. The mixture obtained in either way is subsequently heated in a stream of inert gas or in high vacuum to remove volatile products such as hydrogen halides, ammonia and water. In some instances, the reaction between the solids (salts and zeolites) can be facilitated in the presence of an oxidizing agent (Abu-Zied, 2008). 3.2.4 Chemical vapor deposition Chemical process refers to the modification of one or multiple chemical compounds that can occur independently or via an outside force. The chemical vapor disposition (CVD) method is a chemical process used in the production of solid and high purity materials. CVD method is affecting the activity of the catalyst offers many advantages in thin film deposition. With the use of new precursors, the deposition temperature can usually be lowered considerably. By lowering the total pressure, extremely sharp interfaces with respect to chemical composition and topography can be obtained. The atmospheric pressure CVD is attractive in many applications with its high deposition rates and hence short process times. A stable activity of the prepared catalysts by using CVD can be noticed in SCR process of N 2 O and NO with propane in the off-gas from chemical processes (Centri, Grasso, R R Vazzana, & Arena, 2000). CVD method gives a high loading of copper content released during the NOx abatement process but it produce chloride which is not good and cost more than the other methods. 3.3 Experimental set up 12B In this section, material used, equipment and procedure will be discussed. 3.3.1 Materials used • Zeolites: Different zeolites were used to prepare Cu-zeolite by ion exchange method. Figure 3.1 shows different types of support zeolites with its codes followed by Table 3.1 that is showing formulas and properties of each type. Master Thesis| P a g e 39 Zeolites ZSM-5 CBV 2314 Beta-Zeolite CBV 3024E CBV 5524G CP 814E Figure 3.1 Different types of support zeolites Table 3.1 Formulas and properties of different types of support zeolites Code of Zeolite Framework Type Si/Al ratio* Molecular Formula * P P Surface Area, m2/g* P CBV 2314 CBV 3024E |NH 4 n (H 2 O) 16 | [Al n Si 96-n O 192 ]-MFI , n < 27 R MFI R R R R R R R R R R R CBV 5524G CP 814E BEA |NH 4 7 | [Al 7 Si 57 O 128 ]-*BEA R R R R R R R R R R P 23 425 30 405 50 425 25 680 * This notation refers to (Baerlocher, 2007) from the References section. • Precursor Salts: Different salts were used for ion exchange with support zeolites. Table 3.2 shows the properties of the salt used. This salt will be added to deionized water to be dissolved in order to prepare the solution needed for the catalyst preparation using wet ion exchange method. Table 3.2 Precursor salt and its properties Type of Salt Formula Copper (II) Acetate hydrate Cu(CH 3 COOH) 2 ∙H 2 O Master Thesis| P a g e 40 R R R R R R Molecular weight (g/mol) Solubility in water (g/L)* Color 199.95 72.0 Green * This notation refers to (Biotechnology) from the References section. 3.3.2 Equipment used The listed equipment were used in the experimental work as following: • Stirrer Hot Plate, Volumetric Flask and Magnetic Bar • Water Bath and Floc Illuminator • Balance, Conical Flask, Beakers, Bottles, Graduating Cylinder, pH Meter • Centrifuge and Rotor • Oven • Mass Spectrometer (MS) • Stainless Steel Reactor 3.3.3 Safety • Zeolite: Mask should be worn because zeolite could cause irritations. U • U Water bath: Extra care should be taken from Hot surface, Hot water and U U Wire connection. • Centrifuge: It is provided with safety look for the door to prevent opening the U U door during equipment operation in which it may cause physical hazards such as injries for the user. • Oven: Heating gloves should be worn during handling of samples to prevent U U burnes. • Special precautions: Glass wear, gloves and shose should be worn during U U experiment to prevent injuries in which if there some equipments is broken. Lab coat and safety shoes are improtant for any spill of the presarsor salt. Master Thesis| P a g e 41 3.4 Procedure 13B Preparation (Step by step) for aqueous ion exchange method will be presented as following (González-Velascoa, 2014): 1) Salt Solution Preparation Calculate and measure the needed weight of the precursor salt to be used to prepare a specific concentration of the solution depending on the conditions needed to be studied. Generally, the amount needed to be calculated is based on the concentration to be achieved. Make sure to dissolve the precursor salt completely in the deionized water. In the precursor preparation, the concentration of the copper solutions were increasing (160 and 2000 ppm) in order to have different loading of copper on supported zeolites. The samples preparation calculation of salt solutions in Appendix A. 2) Adding salt solution with zeolite: Measure 8g of zeolite to be added in a conical flask. Then, add the prepared salt solution and seal the conical flask perfectly in order to prevent any side reactions from happening. For solutions that had been prepared, 8g of zeolite was added in 1L of deionized water. For each experiment, three replicates were prepared in order to make sure about the variation in the results of copper loading. 3) Stirring the solution: Put the solution with constant stirring speed by using a magnetic stirrer for 24 hours at room temperature in which ion exchange occur. However, some of the prepared solutions will be stirred for more than 24 hours or heated simultaneously on a hot plate, to study the effect of time and temperature on the zeolite. 4) Filtering and washing After stirring the solution for 24 hours or more, centrifuging method was used to separate solution from precipitate, at high speed. For perfect separation, the speed of the rotor is 10,000 rpm for 5 minutes, or to fix the speed to 5,000 rpm but for 10 minutes. Hence, increasing the speed for more than 10,000 rpm may lead freezing of the solution to be filtered. After filtration, the precipitate was washed more than three Master Thesis| P a g e 42 times with de-ionized water to remove any excess salt solution. After each wash, centrifuge was used to separate the catalyst from water. 5) Drying and grinding: The obtained catalyst was dried to inform paste at temperature of 110°C in an oven P P overnight .Once dried; it was grinded, balanced, and stored. The following Figure 3.2 illustrates the procedure for the preparation of Cu-ZSM-5 catalyst by using the wet ion exchange method. Table 3.3 shows the condition used to study the preparation of copper-Zeolite catalysts. The studied variables include zeolite support, concentration of the precursor salt, temperature and time of ion exchange. Figure 3.3 and 3.4 are showing sample’s template for all preparation steps and the calculation done in this chapter. For additional information, see Appendix B. Master Thesis| P a g e 43 Prepartion of Catalysts Precursor Solution preparation Cu(CH3COOH)2 Zeolite Washing & Separation Ion Exchange 1- ZSM-5 1- Type of zeolite (Si/Al Ratio) 2- Beta 2- Temperature ( 23, 65 ) oC Separation by Centrifuging 3- Time ( 1, 3 and 7 days ) Drying 1- Time (24 h or more) 2- Temperature (110 °C) 4- Concentration (160 & 2,000) ppm 1- No. of washs ( At least 3 ) 2- Time (12 min) 3- Speed (5000 rpm ) Figure 3.2 Preparation procedure Master Thesis| P a g e 44 Storing Granding Figure 3.3 Preparation template for 160 ppm precursor salt concentration and CBV 2314 zeolite for 1 day at 65 oC P P Figure 3.4 Preparation template for 2000 ppm precursor salt concentration and CBV 2314 zeolite for 1 day at 65 oC P Master Thesis| P a g e 45 P Table 3.3 Preparation summary No Code of zeolite 1 CBV 2314 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 CBV 2314 CBV 5524G CBV 5524G CBV 3024E CBV 3024E CP 814E CP 814E CBV 2314 CBV 5524G CBV 3024E CP 814E CBV 2314 CBV 5524G CBV 3024E CBV 2314 CBV 2314 CBV 5524G CBV 5524G CBV 3024E CBV 3024E CP 814E CP 814E Conditions Precursor Salts Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Cu (COOCH 3 ) 2 . H2O Master Thesis| P a g e 46 R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R R Si/Al Ratio Concentration (ppm) Temperature (℃) Time (days) R R R R 23 160 25 1 R R R R 23 2000 25 1 R R R R 50 160 25 1 R R R R 50 2000 25 1 R R R R 30 160 25 1 R R R R 30 2000 25 1 R R R R 25 160 25 1 R R R R 25 2000 25 1 R R R R 23 160 25 3 R R R R 50 160 25 3 R R R R 30 160 25 3 R R R R 25 160 25 3 R R R R 23 2000 25 7 R R R R 50 2000 25 7 R R R R 30 2000 25 7 R R R R 23 160 65 1 R R R R 23 2000 65 1 R R R R 50 160 65 1 R R R R 50 2000 65 1 R R R R 30 160 65 1 R R R R 30 2000 65 1 R R R R 25 160 65 1 R R R R 25 2000 65 1 CHAPTER 4: CHARACTERIZATION 4.1 Introduction 14B Predicting the behavior of the zeolite is done by using the prepared zeolite into many investigations, which is done by characterizing the sample using the many methods available. In this work, the main characterization methods used will be the Inductively Coupled Plasma Atomic Emission Spectroscopy technique (ICP-AES) and Energy Dispersive X-ray spectroscopy (EDX) to determine the copper loading on the prepared catalysts, Brunauer–Emmett–Teller (BET) analysis, and regarding the surface area and pore size and Scanning Electron Microscope (SEM) analysis, which focuses on identifying the structures and patterns of the zeolite. The results from the available characterization techniques assigned to the prepared catalysts will be compared with data, trends, and historical findings from the work done by other researchers. The characterization process will give an indication about the accuracy of the preparation technique and procedure, and how these catalysts vary from the expected trend and behavior. Other characterization methods can be applied for the case of analyzing the zeolite which gives more information about the catalyst and give probable explanations to anomalous results. Additionally, the characterization process should be done a number of times with great precision and accuracy in order to eliminate any errors and great deviation. Master Thesis| P a g e 47 4.2 Characterization Methods 15B 4.2.1 ICP-AES Elemental Analysis Inductively Coupled Plasma- Atomic Emission Spectrometry (ICP/AES) is one of the most powerful and popular analytical tools for the determination of trace elements. In this experiment, ICP-AES has been used to determine the actual amount of copper loading in the prepared catalysts (González-Velascoa, 2014) (González-Velasco, 2012) (Vemuri Balakotaiah, 2012). ICP/AES is emission spectrophotometric techniques that use the excited electrons that emit energy at a given wavelength as they return to ground state after excitation by high temperature Argon Plasma to determine the elements based on wavelength. The fundamental characteristic of this process is that each element emits energy at specific wavelengths depending on its atomic character. The energy transfer for electrons when they fall back to ground state is unique to each element as it depends upon the electronic configuration of the orbital. The energy transfer is inversely proportional to the wavelength of electromagnetic radiation; see Equation (18). 𝐸= ℎ𝑐 𝜆 (18) (Where h is Planck's constant, c the velocity of light and λ is wavelength), and hence the wavelength of light emitted is also unique (J.N, 1989). An inductively coupled plasma (ICP) is a very high temperature (7000-10,000 K) excitation source that efficiently vaporizes, excites, and ionizes atoms. Molecular interferences are greatly reduced with this excitation source but are not eliminated completely. ICP sources are used to excite atoms for atomic-emission spectroscopy and to ionize atoms analysis. The procedures of the ICP-AES method are summarized in the steps below: 1. The sample is nebulized and entrained in the flow of plasma support gas, which is typically Argon (Ar). 2. The plasma torch consists of concentric quartz tubes. The inner tube contains the sample aerosol and Ar support gas and the outer tube contains flowing gas to keep the tubes cool. Master Thesis| P a g e 48 3. A radio frequency (RF) generator produces an oscillating current in an induction coil that wraps around the tubes. The induction coil creates an oscillating magnetic field, which produces an oscillating magnetic field. 4. The magnetic field in turn sets up an oscillating current in the ions and electrons of the support gas (argon) (Plasma, 2006). Figure 4.1 below represents the instrumentation of the Inductively Coupled PlasmaAtomic Emission Spectrometry. Figure 4.1 Inductively Coupled Plasma- Atomic Emission Spectrometry (Plasma, 2006). 1T 1T 4.2.2 BET analysis BET (Brunauer-Emmett-Teller) analysis provides precise specific surface area 1T evaluation of materials by nitrogen or krypton multilayer adsorption measured as a function of relative pressure using a fully automated analyzer. The technique provides external area and pore area evaluations to determine the total specific surface area in (m2/g) yielding important information in studying the effects of surface porosity and P P particle size in many applications. Any inert gas can be used in the BET analysis but the preferred gases are either nitrogen or krypton. The nitrogen is better used for materials that are expected to have surface Master Thesis| P a g e 49 areas of 2 m2/g and higher, while the krypton is used for smaller expected surface areas. P P The BET method is performed by mixing the adsorbate (gas to be adsorbed) with the non-condensable inert, that acts as a carrier gas (usually helium) by an amount of 5-30 wt. %. The sample is then kept at a temperature of 150 °C and is degassed for 12 hours, to be ready for BET analysis. The BET analysis will give many results and information about the catalyst. It will give an indication of the BET surface area, the adsorption isotherms and how they look, and the pore volume which is related to Cu ions loading onto the catalyst (Sjocall, 2006) (Asima Sultana, 2010) (González-Velascoa, 2014) (González-Velasco, 2012). The adsorption isotherm of the catalyst is a main factor in determining the BET surface area of the prepared catalyst. Figure 4.2 shows an adsorption isotherm of the original sample catalyst. The isotherm consists of two curves representing two different phenomena that happens during the N 2 adsorption/desorption process. These curves are R R generated by incrementally increasing the N 2 partial pressure (adsorption), giving R R enough time for equilibrium state to be reached, and then reversing this process incrementally and recording data (desorption). Master Thesis| P a g e 50 Figure 4.2 Adsorption isotherm of Cu-ZSM5 catalyst Each N 2 molecule that is adsorbed occupies a surface area comparable to its cross R R sectional area. Measuring the number of N 2 molecules that were adsorbed at a monolayer, R R the surface area of the catalyst available can be calculated. The typical method of calculating the BET surface area is by taking the data of P/P o in the range of 0.05 – 0.30 R R and plot them. This range is taken as it was stated in literature that it gives the most reliable and accurate results. From Equations (19) & (20), the slope of the linear curve will be used in the BET equation below, to calculate the BET surface area by finding the mono layer volume, V m , and then multiplying it by Avogadro number to get the BET R R surface area (Bartholomew & Farrauto, 2005). (𝑐 − 1) 𝑥 1 (𝑐 − 1) = 𝑥+ → 𝑦 = 𝑚𝑚 + 𝑐 → 𝑚 = 𝑠𝑠𝑠𝑠𝑠 = 𝑉(1 − 𝑥) 𝑐𝑉𝑚 𝑐𝑉𝑚 𝑐𝑉𝑚 𝑚2 𝑐𝑐3 (𝑆𝑆𝑆) 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚 𝐵𝐵𝐵 𝑆𝑆 � � = 𝑉𝑚 � � × �6.02 × 1023 � �� 𝑔 𝑔 𝑚𝑚𝑚𝑚 × 𝐴𝐴𝐴𝐴 𝑜𝑜 𝑒𝑒𝑒ℎ 𝑁2 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚 � Master Thesis| P a g e 51 𝑚2 � 𝑚𝑚𝑚𝑚𝑚𝑚𝑚𝑚 (19) (20) 4.2.3 SEM analysis The Scanning Electron Microscopy (SEM) is a microscope that works by focusing high energy electrons into a specific sample. Once those accelerated electrons hit the surface of the specimen, they decelerate and those reflected electrons are further analyzed in order to extract information about the sample such as, chemical composition, its topography, its electrical conductivity, its crystalline structure and their orientation. The SEM has a magnification range from 20X to approximately 30,000X. 1T The first signal received by the SEM machine from the scattered electrons is called the Electron Back Scattered Diffraction (EBSD), which is basically the primary electrons that were scattered from the surface at an angle of 70 degrees to hit a phosphor screen. A camera indicates these scatters on the phosphor screen as lights, where information of the sample's structure and orientation can be obtained. Figure 4.3 below is a schematic diagram of the SEM equipment. Figure 4.3 Illustration of how SEM works Furthermore, the other signals that are detected by the SEM images are the secondary electrons signal. The difference between the primary electrons and the secondary electrons is that when the primary electrons hit the atom, these electrons are reflected back to the phosphor screen, where in the secondary electrons case, the primary electrons excites the high levels of the atom electron felid resulting in taking the place of one of the electrons and sending it out of the atom. The secondary electrons are usually best for illustrating contrasts in composition in multiphase sample (Egerton, 2005). 1T Master Thesis| P a g e 52 1T Figure 4.4 SEM scan of Cu-ZSM5 Figure 4.4 above shows a SEM shot of unloaded ZSM-5 catalyst with a 10,000 times magnification. This photo shows that small amounts of Fe 2 O 3 crystallites are present R R R R outside the zeolite micro-pores and in between the zeolite particles. Master Thesis| P a g e 53 CHAPTER 5: RESULTS & DISCUSSION: Preparation is very important to determine the activity and selectivity of the catalyst. Wet Ion Exchange (WIE) was used for the preparation of all catalysts. In this section, different parameters that affect WIE were studied to evaluate their effects on copper loading. Copper loading can be used as an indication of the catalyst activity. Parameters include Support material, Si-to-Al ratio, precursor-salt solution’s concentration, time of ion exchange and temperature during the ion exchange. All experiments were carried out in triplet check Appendix C for details of all runs. Additionally, SEM analysis and detailed information about BET surface area are provided as separate attachment by CD. 5.1 Effect of precursor salt and different support zeolites 16B Table 5.1 shows how copper loading could be affected by using a salt with different zeolites. Table 5.1 Cu loading based on a precursor salts conc. 160 ppm and different zeolites, at 23 oC and 1 Day P ID Zeolite type Si/Al ratio R H6 H19 ZSM-5 (Si/Al=23) Beta (Si/Al=25) 23 25 P Cu loading, wt% Cu(COOCH 3 ) 2 0.78 0.76 R R Figure 5.1 gives a clear view of the effect of the salt with 160 ppm on different support zeolites. This would give a result of the best support zeolite that would be used for SCR reactions. It can be noticed that more copper was loaded in the ZSM-5 zeolite compared to the Beta zeolite. Furthermore, the precursor salt used in this experiment was playing a role on the copper loading during the preparation stage. Master Thesis| P a g e 54 Cu loading, wt% Effect of support and salt precursor 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00 Cu(COOCH3)2 ZSM-5 ZSM-5 ZSM-5 Beta (Si/Al=23) (Si/Al=30) (Si/Al=50) (Si/Al=25) Zeolite type Figure 5.1 Cu loading based on a precursor salts conc. 160 ppm and different zeolites, at 23 oC and 1 Day P P Figure 5.1 conclude that ZSM5 (Si/Al=23) has the highest Cu loading compared to other zeolites in the presence of Cu(COOCH 3 ) 2 at room temperature for 1 day. R R R R However, Table 5.2 shows how copper loading could be affected by using a salt with different zeolites at higher temperature. Table 5.2 Cu loading based on a precursor salts conc. 160 ppm and different zeolites, at 65 oC and 1 Day P ID Zeolite type Si/Al ratio Cu loading, wt% Cu(COOCH 3 ) 2 1.48 1.07 R H69 H85 ZSM-5 (Si/Al=23) Beta (Si/Al=25) 23 25 P R R Figure 5.2 gives a clear view of the effect of the salt with 160 ppm on different support zeolites. This would give a result of the best support zeolite that would be used for SCR reactions. Master Thesis| P a g e 55 Cu loading, wt% Effect of support and salt precursor 1.60 1.40 1.20 1.00 0.80 0.60 0.40 0.20 0.00 Cu(COOCH3)2 ZSM-5 ZSM-5 ZSM-5 Beta (Si/Al=23) (Si/Al=30) (Si/Al=50) (Si/Al=25) Zeolite type Figure 5.2 Cu loading based on a precursor salts conc. 160 ppm and different zeolites, at 65 oC and 1 Day P P Figure 5.2 conclude that ZSM5 (Si/Al=23) has the highest Cu loading compared to other zeolites in the presence of Cu(COOCH 3 ) 2 at 65oC for 1 day. On the other hand, ZSM-5 R R R R P P (Si/Al=30) shows the lowest Cu loading in the presence of Cu(COOCH 3 ) 2 compared to R R R R Beta and other ZSM-5 zeolites at the same conditions. Although the results above gives the highest Cu loading for ZSM5 (Si/Al=23) compared to all cases, it was found in literature that the removal of NO x over Cu-ZSM-5 catalysts R R were found to be highly active for the SCR reactions (González-Velascoa, 2014). As the copper loading percent is increasing with temperature in this experiment as well as in literature, the following results will be conducted for the results with temperature of 65oC. P P The remaining will be available in the attachment. 5.2 Effect of different Si/Al Ratio 17B Table 5.3 shows the effect of varying Si/Al of ZSM5 zeolite on Cu loading and BET surface area. Table 5.3 Cu loading and BET surface area based on different zeolites ID H69 H81 H83 Salt ZSM-5 (Si/Al=23) ZSM-5 (Si/Al=30) ZSM-5 (Si/Al=50) Cu loading, wt% 1.48 0.88 1.00 BET surface area, m2/g 230.0 293.5 294.9 P P Figure 5.3 shows the effect of different Zeolites on the precursor salt. It shows that the Si/Al ratios of ZSM-5 zeolite play a significant factor in increasing the Cu content Master Thesis| P a g e 56 loading. The copper loading is depending on type of zeolite and the concentration of the precursor salt. This gives an indication of the best zeolite and the precursor concentration (ppm) to use when preparing the catalyst. Furthermore, the BET of Beta zeolite was high comparing to other ZSM-5 zeolites, however Cu loading was lower than ZSM-5 (with Si/Al=23) by around 50%. 600 500 400 300 200 100 0 Cu loading, wt% 2.00 1.50 1.00 0.50 0.00 ZSM-5 (Si/Al=23) ZSM-5 (Si/Al=30) ZSM-5 (Si/Al=50) Beta (Si/Al=25) BET surface area, m2/g Effect of the precursor salts on different zeolites Different Zeolites BET surface area Cu loading, wt% Figure 5.3 Cu loading and BET surface area based on different Zeolites 5.3 Effect of different concentrations of Cu(COOCH 3 ) 2 18B R R R Representation of the effect of Cu(COOCH 3 ) 2 on Cu loading and BET surface area with R R R R varying the concentration of the solution can be seen in Table 5.4. Table 5.4 Cu loading and BET surface area based on different concentrations of Cu(COOCH 3 ) 2 R R R ID Zeolite type Concentration, ppm Cu loading, wt% BET surface area, m2/g H69 H81 H83 H85 H69 H81 H83 H85 ZSM-5 (Si/Al=23) ZSM-5 (Si/Al=30) ZSM-5 (Si/Al=50) Beta (Si/Al=25) ZSM-5 (Si/Al=23) ZSM-5 (Si/Al=30) ZSM-5 (Si/Al=50) Beta (Si/Al=25) 160 160 160 160 2000 2000 2000 2000 1.5 0.9 1.0 1.1 6.4 3.1 4.0 5.2 230.0 293.5 294.9 498.0 207.5 296.6 300.0 431.1 Master Thesis| P a g e 57 P P The effect of different concentrations of Cu(COOCH 3 ) 2 on ZSM-5 is presented in Figure R R R R 5.4 & 5.5. It shows that the increase of concentration of the salt solution will reflect an increase on the Cu content for different zeolites (Si/Al Ratio). On the other hand, BET surface area is inversely related to the copper loading since the copper is loaded onto the catalyst. 1.6 1.4 1.2 1.0 0.8 0.6 0.4 0.2 0.0 600.0 500.0 400.0 300.0 200.0 100.0 0.0 ZSM-5 (Si/Al=23) ZSM-5 (Si/Al=30) ZSM-5 (Si/Al=50) BET surface area, m2/g Cu loading, wt% Effect of salt precursor concentration Beta (Si/Al=25) Concentration, 160 ppm BET surface area Cu loading, wt% Figure 5.4 Cu loading and BET surface area based on 160 ppm concentrations of Cu(COOCH 3 ) 2 R R R 7.0 500.0 450.0 400.0 350.0 300.0 250.0 200.0 150.0 100.0 50.0 0.0 Cu loading, wt% 6.0 5.0 4.0 3.0 2.0 1.0 0.0 ZSM-5 (Si/Al=23) ZSM-5 (Si/Al=30) ZSM-5 (Si/Al=50) BET surface area, m2/g Effect of salt precursor concentration Beta (Si/Al=25) Concentration, 2000 ppm BET surface area Cu loading, wt% Figure 5.5 Cu loading and BET surface area based on 2000 ppm concentrations of Cu(COOCH 3 ) 2 R Master Thesis| P a g e 58 R R 5.4 Effect of time of ion exchange on Copper loading 19B Table 5.5 shows how different time of ion exchange with zeolites could affect Cu loading and BET surface area. Table 5.5 Cu loading and BET surface area based on different time of ion exchange with respect to Cu(COOCH 3 ) 2 for 160 ppm concentration R ID H6 H21 H15 H19 H43 H71 H17 H24 Zeolite type ZSM-5 (Si/Al=23) ZSM-5 (Si/Al=30) ZSM-5 (Si/Al=50) Beta (Si/Al=25) ZSM-5 (Si/Al=23) ZSM-5 (Si/Al=30) ZSM-5 (Si/Al=50) Beta (Si/Al=25) R R R Time, day 1 1 1 1 3 3 3 3 Cu loading, wt% 0.78 0.82 0.62 0.76 0.80 0.95 0.67 0.83 BET surface area, m2/g 223.7 282.3 315.1 511.3 211.0 280.0 295.5 466.8 P P As the period of ion exchange increases, copper content increases onto the catalyst as shown in Figure 5.6 & 5.7. Cu loading could be increased by extending the time of ion exchange or number of ion exchange (Hanna, 2006). 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00 600.0 500.0 400.0 300.0 200.0 100.0 BET surface area, m2/g Cu loading, wt% Effect of time of ion exchange 0.0 ZSM-5 (Si/Al=23) ZSM-5 (Si/Al=30) ZSM-5 (Si/Al=50) Beta (Si/Al=25) Time, 1 day BET surface area Cu loading, wt% Figure 5.6 Cu loading and BET surface area based on 1 day time of ion exchange with respect to Cu(COOCH 3 ) 2 R Master Thesis| P a g e 59 R R 500.0 450.0 400.0 350.0 300.0 250.0 200.0 150.0 100.0 50.0 0.0 1.00 0.90 0.80 0.70 0.60 0.50 0.40 0.30 0.20 0.10 0.00 ZSM-5 (Si/Al=23) ZSM-5 (Si/Al=30) ZSM-5 (Si/Al=50) BET surface area, m2/g Cu loading, wt% Effect of time of ion exchange Beta (Si/Al=25) Time, 7 day BET surface area Cu loading, wt% Figure 5.7 Cu loading and BET surface area based on 7 days time of ion exchange with respect to Cu(COOCH 3 ) 2 R R R 5.5 Effect of temperature of ion exchange on Copper loading 20B The summery of the elemental analysis and catalyst surface area of Cu-ZSM5 catalysts at high temperature (65 oC) are presented in Table 5.6. P P Table 5.6 Summery of Elemental analysis (ICP-AES) and BET surface area results. Catalyst nomenclature Support Si/Al Copper initial concentration (ppm) ** Copper content (wt. %) *BET Surface area (m2/g) P P H51 ZSM5 23 2000 6.42 207.50 H57 ZSM5 50 2000 3.99 300.00 H60 ZSM5 30 2000 3.08 296.60 H64 BETA 25 2000 5.23 431.10 H69 ZSM5 23 160 1.48 230.00 H81 ZSM5 50 160 0.88 293.50 H83 ZSM5 30 160 1.00 294.90 H85 BETA 25 160 1.07 498.00 * Determined from low temperature nitrogen adsorption analysis. ** Determined from ICP-AES analysis. Master Thesis| P a g e 60 From the results above, copper content and BET analysis for the support materials of ZSM5 (Si/Al = 30 and Si/Al = 50) are mostly similar for both precursors concentration (160 and 2000 ppm) while BETA zeolite (Si/Al = 25) is showing the highest BET surface area of all samples using different precursors salt. Additionally, the highest copper loading is presented on the sample (H51) of 6.42 wt% copper which was prepared by using ZSM5 (Si/Al = 23) with precursor concentration of 2000 ppm. All the catalysts above are prepared using wet ion exchange method at 65 oC. P P Table 5.7 shows the relation between different temperatures of ion exchange with respect Cu loading and BET surface area. Table 5.7 Cu loading and BET surface area based on different temperature of ion exchange with respect to Cu(COOCH 3 ) 2 R R R ID H6 Zeolite type ZSM-5 (Si/Al=23) Temperature, °C 23 Cu loading, wt% 0.78 BET surface area, m2/g 223.7 H21 H15 H19 H69 H81 H83 H85 ZSM-5 (Si/Al=30) ZSM-5 (Si/Al=50) Beta (Si/Al=25) ZSM-5 (Si/Al=23) ZSM-5 (Si/Al=30) ZSM-5 (Si/Al=50) Beta (Si/Al=25) 23 23 23 65 65 65 65 0.8 0.6 0.8 1.5 0.9 1.0 1.1 282.3 315.1 511.3 230.0 293.5 294.9 498.0 P Figure 5.8 & 5.9 shows the effect of different temperature of ion exchange on Cu loading. The copper content at T = 65°C was increased more than loading provided at T = 23°C, P P P P which indicates how important it is to select the temperature of ion exchange while preparing the catalyst. Unfortunately, the effect of temperature was not studied with respect to time more than one day, which might have a similar behavior; however, this needs to be proven practically. Master Thesis| P a g e 61 P 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.0 600 500 400 300 200 100 BET surface area, m2/g Cu loading, wt% Effect of temperature of ion exchange 0 ZSM-5 (Si/Al=23) ZSM-5 (Si/Al=30) ZSM-5 (Si/Al=50) Beta (Si/Al=25) Temperature, 23°C BET surface area Cu loading, wt% Figure 5.8 Cu loading and BET surface area based on 23 oC of ion exchange with respect to Cu(COOCH 3 ) 2 P R R P R Effect of temperature of ion exchange Cu loading, wt% 1.4 500.0 1.2 400.0 1.0 300.0 0.8 0.6 200.0 0.4 100.0 0.2 BET surface area, m2/g 600.0 1.6 0.0 0.0 ZSM-5 (Si/Al=23) ZSM-5 (Si/Al=30) ZSM-5 (Si/Al=50) Beta (Si/Al=25) Temperature, 65°C BET surface area Cu loading, wt% Figure 5.9 Cu loading and BET surface area based on 65oC of ion exchange with respect to Cu(COOCH 3 ) 2 P P R R R 5.6 SEM Results: 21B This technology is illustrated the structure and shape of the catalyst. It showing how much is the spacing between the partials and in addition to the size for each sample. Figure 5.10 is showing Scanning Electron Microscope (SEM) for all samples at 1 µm size. From SEM Master Thesis| P a g e 62 results, BET surface area can be confirmed because the particle size can be seen clearly. SEM analysis (b), (c), (e), (f) & (g) mostly have small particles and many pores while (a) & (h) have normal size of pores and catalysts particle. Sample (d) is showing big catalyst size with normal pore size. All of catalysts will be used in SCR experiment and the effect of particle size will be discussed more in that chapter. The shape is become different due to the preparation conditions such as temperature, mixing, Si/Al of the zeolite and experiment time period. (a) (c) (e) Master Thesis| P a g e 63 (b) (d) (f) (g) (h) Figure 5.10 SEM images of (a) H 51, (b) H 75, (c) H 60, (d) H 64, (e) H 69, (f) H 81, (g) H 83 and (h) H 85 Additional investigations have been done for the catalysts to study the metal loading other than ICP elemental analysis. EDX method has been used to double check the realty of metal loading in additional to ICP-AES. Appendix C is showing clearly the results for each method at the same preparations conditions. Nonetheless, BET and adsorption isotherms are studied and provided in the attachment as a CD to have more understanding about the prepared catalysts from its surface area and the physical shape. Master Thesis| P a g e 64 CHAPTER 6: CATALYTIC INVESTIGATION OF NOXSCR ON CU-ZSM5 R R 6.1 Introduction 2B Cu-exchanged zeolites (Cu-ZSM5) have high activity of nitrogen oxides reduction to nitrogen in SCR process (Asima Sultana, 2010). Therefore, the copper zeolite catalysts are to be investigated and tested to study the factors that affect the catalyst activity and stability to improve the performance of these catalysts in the future work. 6.2 SCR Experiment: 23B The NH 3 -SCR experiments were done mostly at the same conditions of Juan R. GonzálezR R Velasco (González-Velascoa, 2014). A stainless steel reactor contained the reactor tube contains Cu-ZSM5 catalyst. The catalysts of SCR experiments are performed inside the reactor tube into a furnace for the reaction heating requirement. The furnace is introducing the temperature which can be measured by a thermocouple from 200 to 500 degree Celsius. In addition to the parameters of the flue gas composition, the feed gas mixture introduced as Table 6.1. The gases was fed into the system by using mass flow controllers to measure, control and set the flow rate to be at 3000 ml min-1 and a Gas Hourly Space P P Velocity (GHSV) of 90,000 h-1. Meanwhile, Mass Spectrometer (MS) is to be used for P P measuring and monitoring the concentration of exit gases (N 2 , NO, NO 2 , NH 3 and N 2 O) R R R R R R R R every 40 oC. P P As mentioned in the literature review, the reaction of NO x , NH 3 and O 2 is starting at R R R R R R o temperature of 200 C approximately, but the highest selectivity of NO x to N 2 is at a P P R R R R higher temperature using Cu-ZSM5 catalysts. Because of that, the temperature is gradually increasing to study the effect of temperature on the prepared catalysts during SCR process. Any huge variance of the temperature, it will adversely affect the reaction and ammonia oxidation will occur. Additionally, catalysts activity and behavior are depending on the nature of zeolite used and copper loading on the supported material which may cause partial blockage of the zeolite pores. This potential blockage is reducing the surface area of having a complete Master Thesis| P a g e 65 and effective reaction, increasing the residence time of the process and adding the total cost. Several parameters affect the extent of NO reduction in the selective catalytic reduction process using ammonia as the reducing agent. In this work, the effect of space velocity, concentration of the reducing agent and NO inlet concentration will be studied (Gupta, 2003). 6.3 Experimental Tools and Procedure: 24B The experimental set-up is consisting of four different systems: 1. The standard gas cylinders utilized for the simulation of SCR experiment. 2. Mass flow meters and controller. 3. The reactor is consist of a ceramic tube contains the palletized catalyst samples (Cu-ZSM5) into a furnace. 4. Mass Spectrometer (MS) system to measure and analyze the inlet and output gas concentration. The standard gas cylinders used for this experiment must be in proper location and close to each other rounded by a chain to avoid any movement during the test. The gases and gas mixture concentrations of each standard cylinder is presented in Table 6.1. Table 6.1 Standard Gas Cylinders concentrations used for this experiments Species Mixture (%) N2 99.99% N 2 NO 0.01% NO, 0.01% He, 99.98% Ar N2O 0.01% N 2 O, 0.01% He, 99.98% Ar NH 3 0.099% NH 3 , 2.0% O 2 , 0.01% He, 97.891% Ar NH 3 0.01% NH 3 , 0.01% He, 98.98% Ar H2 10.0% H 2 , 90.0% Ar R R R R R R R R R R R R R R R R R The mass flow meters were calibrated separately with several gases (NO, NH 3 , O 2 , and R R R R N 2 ) and had accuracies ± 1.0% of full scale. In this experiment, 3 mass flow meters were R R used for different gases. The summery of the manufacturer of the controllers, flow capacity and gases used is presented in Table 6.2. Master Thesis| P a g e 66 Table 6.2 Mass flow meter details used in SCR process Manufacturer Flow capacity Gas used Bronkhorst 500 sccm NO x + He + Ar Bronkhorst 500 sccm NH 3 + O 2 + He + Ar Bronkhorst 250 ml/min N 2 + H 2 + He + Ar R R R R R R R R R R The gases are to be connected into Tie-point for mixing before entering the reactor. Before the gas introduced into the reactor, a bypass line is to be connected to measures the feed composition using MS system at normal temperature and pressure. After that, mixed gases are to be entered the reactor which should be installed as a tube contains the catalyst inside a furnace with thermocouple. The maximum gas flow capacity for NO and NH 3 is equal to R R 500 sccm and 250 sccm for inert gases. The outlet gas stream after the reaction must be analyzed using MS system and MS is creating an Excel spreadsheet contains the time, temperature, initial and final compositions of the gases with all reaction parameters and calibration data. Finally, analyzed gases will be vented out to the atmosphere using an exhaust line. Leak test must be done before doing SCR run and all connections must be tighten well to avoid any release of the gas. Additionally, Laboratory has a gas detector system catching the gases at specific level of gas concentration. The following Figure 6.1 is showing the experimental apparatus for SCR process: Figure 6.1 Schematic of the experimental system for SCR process Master Thesis| P a g e 67 Pretreatment of the catalyst sample is to be done by exposing the catalyst sample to only a particular gas (in our case, hydrogen using a 5% H 2 and balance N 2 mixture) at the flow R R R R rate of 1100 sccm. Pretreatment must be completed prior to the beginning of the experiments. This step was performed for time duration of 1 hour while keeping the reactor at a temperature of 300°C. At the end of the time period, the reactor was cooled back to the ambient temperature before starting the usual flow of NO, NH 3 , and the other R R species. Space velocity is one of the main factors which can affect the activity of the catalysts and conversion efficiency. It's defined as the ratio of gas flow rate volume (in unit volume/time) to the catalyst volume (in unit volume). The relation of space velocity and catalyst volume is inversely proportional at a constant gas inlet rate, means if the catalyst volume decreased, increasing of space velocity will be observed. 6.4 Experimental Results and Discussion: 25B • Conversion and Selectivity Calculation: The NO x and NH 3 conversion is to be calculated by using the following Equation (21) & R R R R (22): 𝑖𝑖 𝑜𝑜𝑜 − 𝐹𝑁𝑁 𝐹𝑁𝑁 𝑥 𝑥 𝑋𝑁𝑁𝑥 = 𝑖𝑖 𝐹𝑁𝑁 𝑥 𝑖𝑖 𝑜𝑜𝑜 − 𝐹𝑁𝑁 𝐹𝑁𝑁 3 3 𝑋𝑁𝑁3 = 𝑖𝑖 𝐹𝑁𝑁 3 × 100 (21) × 100 (22) In addition, selectivity of N 2 , N 2 O and NO 2 can be calculated by using Equations (23), R R R R R R (24) & (25) below: 𝑆𝑁2 = 𝑆𝑁2 𝑂 = 2𝐹𝑁𝑜𝑜𝑜 2 𝑖𝑖 𝑖𝑛 𝐹𝑁𝑁 𝑋 + 𝐹𝑁𝑁 𝑋𝑁𝑁 3 𝑁𝑁3 𝑖𝑖 𝑖𝑖 𝐹𝑁𝑁 𝑋 + 𝐹𝑁𝑁 𝑋𝑁𝑁 3 𝑁𝑁3 𝑆𝑁𝑁2 = Master Thesis| P a g e 68 𝐹𝑁𝑜𝑜𝑜 2𝑂 𝑜𝑜𝑜 𝐹𝑁𝑁 2 × 100 (23) × 100 (24) 𝑖𝑖 𝑖𝑖 𝐹𝑁𝑁 𝑋 + 𝐹𝑁𝑁 𝑋𝑁𝑁 3 𝑁𝑁3 × 100 (25) CONCLUSION AND RECOMMENDATIONS: The objective of this work was to study the effect of ion exchange conditions on the copper loading of different catalysts. These catalysts have been used for NO x Selective R R Catalytic Reduction (SCR) experiments to study the conversion and selectivity of NO x to R R N 2 at different conditions. The zeolite catalysts were prepared using wet ion exchange. R R Two different supports were used during the preparation of the Cu-catalysts, namely ZSM-5 and Beta. Twenty five samples of Cu-zeolite were prepared by aqueous ion exchange method at different conditions. Conditions such as Cu concentration in the precursor solution, temperature, Si/Al ratio and preparation time, for the zeolite have been studied, and how these conditions affect the final copper loading. The effect of the different preparation conditions have been analyzed and characterized by ICP-AES, EDX, BET, and SEM techniques. These techniques have been used in order to get more information on the behavior of the catalyst by evaluating various properties, such as the BET surface area and liquid nitrogen adsorption isotherms, catalyst morphology, and the elemental analysis of the Cu ions loaded on the zeolite surface. From these different characterization methods various results have been obtained for each sample, with a total of 25 different conditions carried out in triplet. After studying the results many factors and trends were observed that affect the efficiency of the prepared Cu-based zeolites. The results from the characterization methods used in this project are showing good Cu loading for most of the samples, which is supported by clear reduction in BET surface area for the relevant samples. Based on varying the conditions of the ion exchange, Cu-ZSM-5 catalyst showed that an increase of the Cu loading on the catalyst is related to: 1. An increase of the concentration up to 2000 ppm of Cu in the prepared precursor solution, 2. Usage of different Si/Al ratio, 3. The total period of the ion exchange, 4. An increase in temperature. Master Thesis| P a g e 69 It should be noticing that, not all the zeolites supports could have an increase in Cu loading at the mentioned conditions, it depends on the behavior of each zeolite. Out of this stage, it is expected to have high NO x reduction during the planned test whenever the R R equipment is ready. As a recommendation, applying more characterization techniques helps to have clear and sufficient understanding about the physical and chemical properties of prepared catalysts. Consequently, this will support to optimize the best catalyst to increase the NO x R R conversion to N 2 . 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Master Thesis| P a g e 75 APPENDIX Appendix A: Preparation calculations of salt solutions: U Preparing 160 ppm of Cu (COOCH 3 ) 2 solutions in 3 Liters: R R R R 𝑺𝑺𝑺𝑺: 𝐶𝐶(𝐶𝐶𝐶𝐶𝐶3 )2 ∙ 𝐻2 𝑂 , 𝑴𝒘 = 199.65 𝑔 𝑚𝑚𝑚 Calculating how much amount of salt needed to be dissolved in 3 L of deionized water to prepare 160 ppm of the solution: 𝐴𝐴𝐴𝐴𝐴𝐴 𝑜𝑜 𝑠𝑠𝑠𝑠 𝑛𝑛𝑛𝑛𝑛𝑛 = 0.160 𝑔 1 𝑚𝑚𝑚 𝑔 × × 3.0 𝐿 × 199.65 = 0.48 𝑔 𝐿 199.65 𝑔 𝑚𝑚𝑚 Preparing 2000 ppm of Cu (COOCH 3 ) 2 solutions in 3 Liters: R 𝑺𝑺𝑺𝑺: 𝐶𝐶(𝐶𝐶𝐶𝐶𝐶3 )2 ∙ 𝐻2 𝑂 , R R R 𝑴𝒘 = 199.65 𝑔 𝑚𝑚𝑚 Calculating how much amount of salt needed to be dissolved in 3 L of deionized water to prepare 160 ppm of the solution: 𝐴𝐴𝐴𝐴𝐴𝐴 𝑜𝑜 𝑠𝑠𝑠𝑠 𝑛𝑛𝑛𝑛𝑛𝑛 = 2.0 Master Thesis| P a g e 76 𝑔 1 𝑚𝑚𝑚 𝑔 × × 3.0 𝐿 × 199.65 = 6.0 𝑔 𝐿 199.65 𝑔 𝑚𝑚𝑚 Appendix B: 1) Preparation of 160 ppm precursor salt concentration and different zeolite for 1 day at 23 oC P P Date: 31 / 12 / 2013 Precursor Concentration Cu(COOCH3)2 Zeolite Used Zeolite (g) Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) ppm (mg/L) g/L 160.0 0.16 MW of Cu (COOCH3)2 199.65 Type CBV 2314 Si/Al Ratio 23 Mass (g) per 1L 8 Sample 1 Sample 2 Sample 3 8 6.74 6.66 1 Room Temp. 7.43 7.9 7.95 24 110 8 6.74 6.16 1 Room Temp. 7.03 7.44 7.5 24 110 8 6.74 6.55 1 Room Temp. 7.3 7.65 7.7 24 110 ppm (mg/L) 160 g/L 0.16 MW of Cu (COOCH3)2 199.65 Type CBV 5524G Si/Al Ratio 50 Mass (g) per 1L 8 Sample 1 8 5.4 5.72 1 Room Temp. 6.2 6.5 6.55 24 110 Sample 2 8 5.42 5.84 1 Room Temp. 5.85 6.31 6.41 24 110 Sample 3 8 5.43 5.41 1 Room Temp. 5.77 6.24 6.52 24 110 Volume, L 3 Mass of Cu (COOCH3)2 0.48 Comment (Observation) Date: 19 / 01 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Zeolite (g) Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) Master Thesis| P a g e 77 Volume, L 3 Mass of Cu (COOCH3)2 0.48 Comment Date: 20 / 01 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Zeolite (g) Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) ppm (mg/L) 160 g/L 0.16 MW of Cu (COOCH3)2 199.65 Type CBV 3024E Si/Al Ratio 30 Mass (g) per 1L 8 Sample 1 Sample 2 Sample 3 8 5.19 5.52 1 Room Temp. 5.6 5.69 5.84 24 110 8 5.17 5.53 1 Room Temp. 5.82 6.13 6.21 24 110 8 5.18 5.17 1 Room Temp. 5.26 5.71 5.85 24 110 Volume, L 3 Mass of Cu (COOCH3)2 0.48 Comment (Observation) Date: 21 / 01 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Zeolite (g) Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) Master Thesis| P a g e 78 ppm (mg/L) 160 g/L 0.16 MW of Cu (COOCH3)2 199.65 Type CP 814E Si/Al Ratio 25 Mass (g) per 1L 8 Sample 1 8 5.17 5.48 1 Room Temp. 5.58 5.96 6.15 24 110 Sample 2 8 5.19 5.8 1 Room Temp. 5.99 6.02 6.21 24 110 Sample 3 8 5.18 5.34 1 Room Temp. 5.56 6.14 6.22 24 110 Volume, L 3 Mass of Cu (COOCH3)2 0.48 Comment 2) Preparation of 2000 ppm precursor salt concentration and different zeolite for 1 day at 23 oC P P Date: 15 / 01 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Zeolite (g) Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) ppm (mg/L) g/L 2000 2 MW of Cu (COOCH3)2 199.65 Type CBV 2314 Si/Al Ratio 23 Mass (g) per 1L 8 Sample 1 8.02 5.9 6.01 1 Room Temp. 6.27 7.3 7.96 24 110 Sample 2 8.03 5.94 5.93 1 Room Temp. 6.72 6.93 7.41 24 110 Sample 3 8.04 5.95 5.56 1 Room Temp. 6.33 7.1 7.62 24 110 Volume, L 3 Mass of Cu (COOCH3)2 6 Comment Date: 27 / 01 / 2014 ppm (mg/L) g/L 2000 2 MW of Cu (COOCH3)2 199.65 Type CBV 5524G Si/Al Ratio 50 Mass (g) per 1L 8 Sample 1 Sample 2 Sample 3 Zeolite (g) 8 8 8 Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) 5.75 5.83 1 Room Temp. 5.7 6.09 6.25 24 110 5.77 5.82 1 Room Temp. 5.88 6.09 6.47 24 110 5.72 5.72 1 Room Temp. 5.9 6.27 6.47 24 110 Precursor Concentration Cu(COOCH3)2 Zeolite Used Master Thesis| P a g e 79 Volume, L 3 Mass of Cu (COOCH3)2 6 Comment Date: 26 / 01 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Zeolite (g) Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) ppm (mg/L) g/L 2000 2 MW of Cu (COOCH3)2 199.65 Type CBV 3024E Si/Al Ratio 30 Mass (g) per 1L 8 Sample 1 Sample 2 Sample 3 8 5.67 5.74 1 Room Temp. 5.64 6.09 6.25 24 110 8 5.68 5.81 1 Room Temp. 6.2 6.29 6.3 24 110 8 5.65 5.54 1 Room Temp. 6.46 6.67 6.7 24 110 Volume, L 3 Mass of Cu (COOCH3)2 6 Comment (Observation) Date: 22 / 01 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Zeolite (g) Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) Master Thesis| P a g e 80 ppm (mg/L) g/L 2000 2 MW of Cu (COOCH3)2 199.65 Type CP 814E Si/Al Ratio 25 Mass (g) per 1L 8 Sample 1 8 5.51 5.63 1 Room Temp. 5.83 6.11 6.28 24 110 Sample 2 8 5.51 5.62 1 Room Temp. 6.1 6.25 6.44 24 110 Sample 3 8 5.51 5.46 1 Room Temp. 5.57 5.83 6.09 24 110 Volume, L 3 Mass of Cu (COOCH3)2 6 Comment 3) Preparation of 160 ppm precursor salt concentration and different zeolite for 3 days at 23 oC P P Date: 16 / 01 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Zeolite (g) Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (day) Drying Temp. (oC) ppm (mg/L) g/L 160 0.16 MW of Cu (COOCH3)2 199.65 Type CBV 5524G Si/Al Ratio 50 Mass (g) per 1L 8 Sample 1 8.02 5.97 5.95 3 Room Temp. 6.5 6.88 6.9 24 110 Sample 2 8 5.88 5.93 3 Room Temp. 6 6.2 6.3 24 110 Sample 3 8 5.85 5.51 3 Room Temp. 5.72 6.02 6.22 24 110 Volume, L 3 Mass of Cu (COOCH3)2 0.48 Comment Date: 23 / 01 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Zeolite (g) Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) Master Thesis| P a g e 81 ppm (mg/L) g/L 160 0.16 MW of Cu (COOCH3)2 199.65 Type CP 814E Si/Al Ratio 25 Mass (g) per 1L 8 Sample 1 Sample 2 Sample 3 8 5.46 5.56 3 Room Temp. 5.46 5.81 6.12 24 110 8 5.45 5.15 3 Room Temp. 5.62 5.88 5.99 24 110 8 5.44 5.23 3 Room Temp. 6.39 6.44 6.58 24 110 Volume, L 3 Mass of Cu (COOCH3)2 0.48 Comment (Observation) Date: 16 / 02 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Zeolite (g) Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) ppm (mg/L) g/L 160 0.16 MW of Cu (COOCH3)2 199.65 Type CBV 2314 Si/Al Ratio 23 Mass (g) per 1L 8 Sample 1 Sample 2 Sample 3 8 5.87 6.76 3 Room Temp. 6.98 7.35 7.41 1 110 8 6 6.5 3 Room Temp. 6.6 7 7.2 1 110 8 5.82 6 3 Room Temp. 6.7 7.6 7.07 1 110 ppm (mg/L) 160 g/L 0.16 MW of Cu (COOCH3)2 199.65 Type CBV 3024E Si/Al Ratio 50 Mass (g) per 1L 8 Sample 1 Sample 2 Sample 3 8 5.4 5.81 3 room 6.67 6.87 7 24 110 8 5.42 5.95 3 room 6.4 6.78 6.9 24 110 8 5.43 5.8 3 room 6.4 6.9 6.85 24 110 Volume, L 3 Mass of Cu (COOCH3)2 0.48 Comment (Observation) Date: 13 / 03 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Zeolite (g) Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) Master Thesis| P a g e 82 Volume, L 3 Mass of Cu (COOCH3)2 0.48 Comment (Observation) 4) Preparation of 2000 ppm precursor salt concentration and different zeolite for 7 days at 23 oC P P Date: 28 / 01 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Zeolite (g) Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) ppm (mg/L) g/L 2000 2 MW of Cu (COOCH3)2 199.65 Type CBV 5524G Si/Al Ratio 50 Mass (g) per 1L 8 Sample 1 Sample 2 Sample 3 8 5.6 5.69 7 Room Temp. 5.81 5.95 6.16 24 110 8 5.61 5.62 7 Room Temp. 5.6 5.99 6.11 24 110 8 5.63 5.58 7 Room Temp. 5.57 6.11 6.2 24 110 Volume, L 3 Mass of Cu (COOCH3)2 6 Comment (Observation) Date: 03 / 02 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Zeolite (g) Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) Master Thesis| P a g e 83 ppm (mg/L) g/L 2000 2 MW of Cu (COOCH3)2 199.65 Type CBV 2314 Si/Al Ratio 23 Mass (g) per 1L 8 Sample 1 Sample 2 Sample 3 8 5.57 5.61 7 Room Temp. 6.07 7.13 24 110 8 6.63 5.6 7 Room Temp. 5.82 6.22 6.81 24 110 8 5.66 5.48 7 Room Temp. 5.66 6.1 6.4 24 110 Volume, L 3 Mass of Cu (COOCH3)2 6 Comment Date: 09 / 02 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Zeolite (g) Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) Master Thesis| P a g e 84 ppm (mg/L) g/L 2000 2 MW of Cu (COOCH3)2 199.65 Type CBV 3024E Si/Al Ratio 30 Mass (g) per 1L 8 Sample 1 Sample 2 Sample 3 8 5.4 5.84 7 Room Temp. 6.1 6.4 5.98 7 110 8 5.5 5.72 7 Room Temp. 5.97 6.47 6.5 7 110 8 5.55 5.7 7 Room Temp. 5.62 5.82 5.9 7 110 Volume, L 3 Mass of Cu (COOCH3)2 6 Comment (Observation) 5) Preparation of 160 ppm precursor salt concentration and different zeolite for 1 day at 65 oC P P Date: 12 / 03 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Zeolite (g) Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) ppm (mg/L) g/L 160.0 0.16 MW of Cu (COOCH3)2 199.65 Type CBV 2314 Si/Al Ratio 23 Mass (g) per 1L 8 Sample 1 8 6.74 6.6 1 65 8.37 8.39 7.87 24 110 Sample 2 8 6.74 6.42 1 65 7 7.2 7.3 24 110 Sample 3 8 6.74 5.9 1 65 6.6 7.01 7.05 24 110 ppm (mg/L) 160 g/L 0.16 MW of Cu (COOCH3)2 199.65 Type CBV 3024E Si/Al Ratio 30 Mass (g) per 1L 8 Sample 1 Sample 2 Sample 3 8 5.19 5.41 1 65 7.7 7.7 7.8 24 110 8 5.17 5.41 1 65 7 6.88 6.95 24 110 8 5.18 5.42 1 65 6.4 6.55 6.58 24 110 Volume, L 3 Mass of Cu (COOCH3)2 0.48 Comment Date: 16 / 03 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Zeolite (g) Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) Master Thesis| P a g e 85 Volume, L 3 Mass of Cu (COOCH3)2 0.48 Comment (Observation) Date: 17 / 03 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used ppm (mg/L) 160 g/L 0.16 MW of Cu (COOCH3)2 199.65 Type CBV 5524G Si/Al Ratio 50 Mass (g) per 1L 8 Sample 1 Sample 2 Sample 3 8 5.97 5.8 1 65 7.4 6.6 6.9 24 110 8 5.88 5.75 1 65 6.1 6.1 6.22 24 110 8 5.85 5.86 1 65 5.86 6 6.2 24 110 ppm (mg/L) 160 g/L 0.16 MW of Cu (COOCH3)2 199.65 Type CP 814E Si/Al Ratio 25 Mass (g) per 1L 8 Sample 1 Sample 2 Sample 3 8 5.46 5.54 1 65 6.03 6.1 6.54 24 110 8 5.45 5.45 1 65 5.98 6.37 6.82 24 110 8 5.44 5.14 1 65 6.15 6.66 6.82 24 110 Zeolite (g) Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) Volume, L 3 Mass of Cu (COOCH3)2 0.48 Comment (Observation) Date: 18 / 03 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Zeolite (g) Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) Master Thesis| P a g e 86 Volume, L 3 Mass of Cu (COOCH3)2 0.48 Comment (Observation) 6) Preparation of 2000 ppm precursor salt concentration and different zeolite for 1 day at 65 oC P P Date: 08 / 03 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) ppm (mg/L) g/L 2000 2 MW of Cu (COOCH3)2 199.65 Type CBV 2314 Si/Al Ratio 23 Mass (g) per 1L 8 Sample 1 Sample 2 Sample 3 5.8 5.45 1 65 6.68 6.9 7 1 110 5.8 5.47 1 65 6.44 6.7 6.77 1 110 5.8 5.14 1 65 6.59 6.88 6.83 1 110 Volume, L 3 Mass of Cu (COOCH3)2 6 Comment (Observation) Date: 09 / 03 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) Master Thesis| P a g e 87 ppm (mg/L) g/L 2000 2 MW of Cu (COOCH3)2 199.65 Type CBV 5524G Si/Al Ratio 50 Mass (g) per 1L 8 Sample 1 Sample 2 Sample 3 5.75 5.68 1 65 6.5 6.25 6.39 24 110 5.77 5.45 1 65 5.82 6.1 6.37 24 110 5.72 5.55 1 65 5.84 6.25 6.47 24 110 Volume, L 3 Mass of Cu (COOCH3)2 6 Comment (Observation) Date: 10 / 03 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) ppm (mg/L) g/L 2000 2 MW of Cu (COOCH3)2 199.65 Type CBV 3024E Si/Al Ratio 30 Mass (g) per 1L 8 Sample 1 Sample 2 Sample 3 5.67 5.42 1 65 6.58 6.68 6.53 24 110 5.68 5.4 1 65 6.58 6.77 6.8 24 110 5.65 5.13 1 65 6.3 6.79 6.8 24 110 Volume, L 3 Mass of Cu (COOCH3)2 6 Comment (Observation) Date: 11 / 03 / 2014 Precursor Concentration Cu(COOCH3)2 Zeolite Used Initial pH Final pH Stirring Time (day) Stirring Temp. (oC) pH after 1st washing pH after 2nd washing pH after 3rd washing Drying Time (hr) Drying Temp. (oC) Master Thesis| P a g e 88 ppm (mg/L) g/L 2000 2 MW of Cu (COOCH3)2 199.65 Type CP 814E Si/Al Ratio 25 Mass (g) per 1L 8 Sample 1 Sample 2 Sample 3 5.51 5.47 1 65 6.2 6.4 6.5 24 110 5.51 5.34 1 65 5.9 6.4 6.5 24 110 5.51 5.34 1 65 5.9 6.05 6.3 24 110 Volume, L 3 Mass of Cu (COOCH3)2 6 Comment (Observation) Appendix C: Characterization Methods Results: 1) ICP-AES , EDX and BET Surface Area Results (relative weight %) for elements Cu(COOCH3) 2 Cu(COO CH3)2 Cu(COOCH3) 2 12/31/2013 H8 H9 H10 1/15/2014 H11 H12 H13 1/16/2014 H17 H14 H15 1/19/2014 H16 Cu(COOCH3) 2 H7 Cu(COOCH3) 2 H6 Cu(COOCH3) 2 H5 Cu(COOCH3) 2 CBV 2314 CBV 2314 12/24/2013 CBV 2314 H3 CBV 5524G 31943.3 12/3/2013 H4 H18 H19 1/21/2014 1/22/2014 H27 H28 H23 1/26/2014 H29 Cu(COOCH3) 2 H26 Cu(COOCH3) 2 H32 Cu(COOCH3) 2 H22 CBV 3024E 1/20/2014 CBV 814E H20 CBV 3024E H25 H21 Conc. (ppm) 19963.3 H1 H2 Salt CBV 2314 Zeolite CBV 5524G Date CP 814E Sample ID 160 2000 160 160 160 160 2000 2000 Time (Day) 1 1 1 1 3 1 1 1 1 1 Temp. © 85 1/27/2014 H34 Master Thesis| P a g e 89 Cu(COOCH3)2 H33 CBV 5524G H31 160 Cu(COO CH3)2 CP 814E 1/23/2014 2000 3 1 ICP-AES Analysis O Al Si Cu Al Cu Si 42.56 3.52 34.08 19.81 2.44 10.05 24.76 12.20 49.63 4.14 39.54 6.69 3.10 4.50 35.41 5.65 50.38 3.99 37.56 8.07 3.56 6.15 28.28 7.07 48.21 4.03 39.09 8.66 3.17 5.38 37.49 9.74 48.88 4.16 40.79 6.17 Error Error Error 21.40 56.31 4.22 38.55 0.93 3.23 0.78 35.95 223.70 50.27 4.32 43.95 1.46 3.13 0.80 29.86 22.70 50.76 4.38 43.26 1.59 3.29 0.88 40.00 43.80 51.91 4.06 39.73 4.29 Error Error Error 20.40 49.21 4.11 41.79 4.89 3.29 2.73 36.64 20.10 49.59 4.15 41.67 4.58 3.27 2.72 36.21 19.70 53.11 2.07 43.96 0.83 1.63 0.65 39.96 234.20 49.04 2.25 47.84 0.87 1.50 0.65 41.78 312.30 50.69 2.18 46.34 0.78 3.40 0.67 20.70 295.50 50.93 2.15 46.06 0.86 4.38 0.56 Error 317.50 52.11 2.16 45.06 0.67 1.50 0.62 30.80 315.10 51.57 2.15 45.66 0.62 3.29 0.46 Error 302.66 52.35 4.16 42.56 0.94 3.01 0.70 37.13 479.30 51.27 4.29 43.49 0.95 2.51 0.76 32.11 511.30 58.81 3.47 37.23 0.48 3.13 0.75 39.63 488.00 53.34 3.41 42.33 0.92 2.65 0.78 39.86 277.40 51.95 3.44 43.59 1.04 2.72 0.82 39.63 282.30 55.56 3.35 40.36 0.72 2.21 0.75 29.98 298.30 52.84 4.26 39.93 2.97 3.05 2.51 38.30 450.10 54.01 4.13 39.36 2.50 3.13 2.49 39.23 449.00 49.76 4.23 42.00 4.01 3.02 2.49 32.14 463.80 48.79 3.35 44.96 2.90 2.56 1.81 36.14 293.00 52.08 3.44 42.22 2.27 Error 2.68 Error 286.90 53.11 3.31 41.28 2.30 2.70 1.87 38.32 284.40 50.72 4.16 43.73 1.39 3.09 0.75 37.40 404.80 47.74 3.72 47.57 0.97 2.83 0.83 34.93 466.80 49.61 4.32 44.76 1.31 3.12 0.79 38.05 462.50 51.06 2.04 44.91 1.99 1.46 1.50 23.12 308.80 51.72 2.18 44.22 1.88 1.46 1.48 32.31 283.70 65 23 23 23 23 23 23 23 23 H30 H24 EDX Analysis BET Surface Area (m2/g) 23 23 H72 H49 H50 3/8/2014 H51 H55 H56 3/9/2014 H57 H58 H59 3/10/2014 H60 Cu(COOCH3) 2 Cu(COOCH3) 2 Cu(COOCH3) 2 3/13/2014 Cu(COOCH3) 2 H71 Cu(COOCH3) 2 H70 Cu(COOCH3) 2 H46 Cu(COOCH3) 2 2/9/2014 Cu(COOCH3) 2 H45 CBV 3024E H44 CBV 3024E H47 CBV 2314 2/16/2014 CBV 5524G H43 CBV 2314 H42 H64 H65 3/11/2014 H66 3/12/2014 CBV 2314 H67 H68 H69 3/16/2014 CBV 3024E H79 H80 3/17/2014 H84 H85 H86 3/18/2014 H87 Master Thesis| P a g e 90 CP 814E H83 CBV 5524G H81 H82 Cu(COOCH3) 2 H41 Cu(COO CH3)2 2/3/2014 CBV 3024E H40 Cu(COOC H3)2 H39 Cu(COOCH 3)2 H38 Cu(COO CH3)2 1/28/2014 CP 814E H37 CBV 5524G H36 CBV 2314 H35 2000 2000 160 2000 160 2000 2000 2000 2000 160 160 160 160 7 7 3 7 3 1 1 1 1 1 1 1 1 23 23 23 23 23 65 65 65 65 65 65 65 65 53.37 2.20 42.70 1.73 1.50 1.58 36.41 277.30 55.99 2.16 40.12 1.73 1.48 1.50 34.51 304.70 53.48 2.18 42.51 1.83 1.47 1.55 37.39 277.40 50.17 4.32 41.18 4.32 1.55 1.57 40.75 256.40 51.99 4.20 39.62 4.21 3.37 2.79 39.36 230.42 51.00 2.23 44.55 2.22 Error Error Error 214.70 49.65 4.35 41.55 4.44 3.41 2.89 37.75 223.84 49.72 4.34 44.22 1.72 3.26 0.78 34.36 216.80 51.87 4.20 42.46 1.47 3.16 0.80 33.64 211.00 52.00 4.40 42.56 1.04 3.25 0.64 42.13 210.40 51.57 3.31 42.43 2.68 2.32 2.54 36.14 250.70 52.54 3.39 41.40 2.68 2.20 2.16 35.79 161.90 50.08 3.45 43.92 2.55 2.36 2.06 38.80 246.20 50.20 3.49 45.09 1.21 2.28 0.69 41.09 293.40 51.35 3.41 43.79 1.44 2.62 0.95 37.73 280.00 49.59 3.56 45.55 1.31 2.48 0.91 35.69 279.30 49.94 4.17 39.87 6.02 3.83 5.79 34.41 211.50 48.31 4.16 40.90 6.63 3.40 6.35 36.90 200.30 48.55 4.16 40.44 6.85 3.44 6.42 34.38 207.50 ND ND ND ND 1.17 3.19 39.27 295.30 47.26 2.09 46.93 3.71 1.30 3.31 41.81 289.50 53.78 2.01 40.07 4.14 0.93 3.99 39.64 300.00 54.04 3.32 39.64 3.00 2.28 2.77 34.49 159.30 ND ND ND ND 2.78 3.98 36.29 195.60 52.91 3.31 40.27 3.51 2.12 3.08 36.27 296.60 46.34 3.69 44.25 5.72 3.35 5.23 37.96 431.10 47.30 3.69 44.40 4.61 2.93 4.21 38.79 449.20 50.87 3.68 41.64 3.80 2.96 3.65 36.52 454.00 52.82 3.69 42.13 1.36 2.55 1.13 41.70 234.00 53.66 3.71 41.59 1.04 2.50 0.76 36.44 231.60 50.72 3.94 43.72 1.62 2.94 1.48 38.26 230.00 49.95 3.69 45.15 1.22 3.35 0.70 39.69 290.40 54.82 3.39 41.02 0.78 2.63 0.29 37.02 288.30 51.09 3.57 44.06 1.28 2.85 0.88 38.00 293.50 53.11 2.29 43.67 0.39 1.15 0.88 33.81 297.40 49.43 2.42 47.01 1.14 1.21 1.00 38.19 294.90 52.90 2.25 43.90 0.95 1.25 0.43 37.61 293.00 52.40 4.29 41.75 1.56 3.08 1.07 36.14 498.00 52.53 4.33 42.45 0.68 3.54 0.28 37.33 473.00 53.25 4.27 41.38 1.11 3.19 0.96 40.95 ND
