... mechanism [13;14]. More recently, two new reaction mechanisms have been proposed by Osawa and co-workers. In the first one [3;4], these authors argued based on their in situ IR data that the reaction involves i) a dimerisation step of aqueous HCOOH, followed by the formation of two HCOO ads , and ii ...
THE ADSORPTION OF CO, N2 AND Li ON Ru(109) AND Ru(001
... vibrational bands, attributed to molecular nitrogen adsorbed on the terrace and step sites, respectively, are observed after thermal ordering of the adlayer. Nitrogen adsorbed on the iii ...
... vibrational bands, attributed to molecular nitrogen adsorbed on the terrace and step sites, respectively, are observed after thermal ordering of the adlayer. Nitrogen adsorbed on the iii ...
Isopropanol oxidation by pure metal oxide
... respect to oxygen, which suggests that lattice oxygen, rather than gas phase oxygen, is directly involved in metal oxide catalysts [11,13,14]. Decomposition studies have indicated that at sufficiently high partial pressures of isopropanol the reaction rate also becomes pseudo zero-order with respect ...
... respect to oxygen, which suggests that lattice oxygen, rather than gas phase oxygen, is directly involved in metal oxide catalysts [11,13,14]. Decomposition studies have indicated that at sufficiently high partial pressures of isopropanol the reaction rate also becomes pseudo zero-order with respect ...
Effect of nature and surface density of oxygen species on product
... surface chemistry and homogeneous gas-phase processes on reaction pathways and product distribution. In this work propeneto-ethylene ratio is used as such a criterion during the modelling of the ODP reaction. The catalysts were chosen taking into account the fact they differ in their ability for gen ...
... surface chemistry and homogeneous gas-phase processes on reaction pathways and product distribution. In this work propeneto-ethylene ratio is used as such a criterion during the modelling of the ODP reaction. The catalysts were chosen taking into account the fact they differ in their ability for gen ...
Thermal Diffusion and Partial Molar Enthalpy Variations of n
... and ngb is the number of moles of butane in the gas. We verified that the ideal gas assumption was a good approximation by calculating the compressibility factor of the gas phase, which was equal to unity with an accuracy of 1% for the range of simulated pressures and temperatures. For simulations a ...
... and ngb is the number of moles of butane in the gas. We verified that the ideal gas assumption was a good approximation by calculating the compressibility factor of the gas phase, which was equal to unity with an accuracy of 1% for the range of simulated pressures and temperatures. For simulations a ...
Chapter 6-States of Matter: Gases, Liquids, and Solids
... buildup of greenhouse gases – primarily carbon dioxide, methane, and nitrous oxide Dalton's Law of Partial Pressures John Dalton studied the effect of gases in a mixture. He observed that the Total Pressure of a gas mixture was the sum of the Partial Pressure of each gas. P total = P1 + P2 + P3 + .. ...
... buildup of greenhouse gases – primarily carbon dioxide, methane, and nitrous oxide Dalton's Law of Partial Pressures John Dalton studied the effect of gases in a mixture. He observed that the Total Pressure of a gas mixture was the sum of the Partial Pressure of each gas. P total = P1 + P2 + P3 + .. ...
Astrochemistry and Star Formation
... their spectra are so rich and diverse that they can be used to understand the details of their surroundings and even heterogeneities in these details, and (ii) chemical processes that both form and destroy molecules yield strong constraints on the history and lifetimes of the sources. Among the most ...
... their spectra are so rich and diverse that they can be used to understand the details of their surroundings and even heterogeneities in these details, and (ii) chemical processes that both form and destroy molecules yield strong constraints on the history and lifetimes of the sources. Among the most ...
Ch 8 LAN 7th Intro Chem Gases Liquids and Solids
... – Understood since Toricelli in previous section ...
... – Understood since Toricelli in previous section ...
Theoretical Study of Atomic Layer Deposition Reaction Mechanism
... intermediate complex can dissociate to release either the initial gas reactant or methane molecule. Because there is no tight transition state in the adsorption process, the desorption reaction back to the reactants is more competitive than the continuous dissociation process. From Figure 7, it can ...
... intermediate complex can dissociate to release either the initial gas reactant or methane molecule. Because there is no tight transition state in the adsorption process, the desorption reaction back to the reactants is more competitive than the continuous dissociation process. From Figure 7, it can ...
Kinetics of Oxygen Reduction in Aprotic Li–O2 Cells: A Model
... presents the simulated Tafel plots for a wide range of τ. In Figure 2a and b, τ has been color-coded from blue for a very large desorption time constant (1010 s), to magenta for sufficiently small τ (10−4 s). A linear trend is obtained over the full range of potential (current) for extreme values of τ ...
... presents the simulated Tafel plots for a wide range of τ. In Figure 2a and b, τ has been color-coded from blue for a very large desorption time constant (1010 s), to magenta for sufficiently small τ (10−4 s). A linear trend is obtained over the full range of potential (current) for extreme values of τ ...
Molecular Dynamics Simulation Study of Single DNA Nucleotides
... consider each atom as a sphere with radius equal to its van der Waals radius. ...
... consider each atom as a sphere with radius equal to its van der Waals radius. ...
Removal of Oxygen from Biogas via Catalytic Oxidation of Methane
... 0.25 vol.-% propane (or LPG) are applied for this task. This is due to the significant differences in partial pressures of the fuel gases, as the LPG content needs to be adapted to the amount of oxygen, while methane is available in large surplus in-situ in the gas stream. Furthermore, Fig. 6 shows ...
... 0.25 vol.-% propane (or LPG) are applied for this task. This is due to the significant differences in partial pressures of the fuel gases, as the LPG content needs to be adapted to the amount of oxygen, while methane is available in large surplus in-situ in the gas stream. Furthermore, Fig. 6 shows ...
Interaction of Hydrogen Chloride with Ice Surfaces: The Effects of
... desorption was initiated. This suggests both reversible adsorption processes on the surface and processes that are irreversible on the time scale of the experiment. All subsequent exposures resulted in adsorption that was observed to be reversible on the time scale of the experiment (several minutes ...
... desorption was initiated. This suggests both reversible adsorption processes on the surface and processes that are irreversible on the time scale of the experiment. All subsequent exposures resulted in adsorption that was observed to be reversible on the time scale of the experiment (several minutes ...
supplementary information
... non-enhancement of the shell material can be substantially boosted to obtain total enhancement factors up to 104–105.11 (Fig. S2) With such a high enhancement, one is able to obtain SERS signal of water molecules adsorbed on transition (VIII B group) metals (e.g., Pd, Pt, Rh, Fe, Co, Ni), which were ...
... non-enhancement of the shell material can be substantially boosted to obtain total enhancement factors up to 104–105.11 (Fig. S2) With such a high enhancement, one is able to obtain SERS signal of water molecules adsorbed on transition (VIII B group) metals (e.g., Pd, Pt, Rh, Fe, Co, Ni), which were ...
Principles in heterogeneous catalysis
... CATEGORIES OF HETEROGENEOUS CATALYSTS : Bulk catalysts / Supported catalysts / Malaxed-agglomerated catalysts MORPHOLOGY OF HETEROGENEOUS CATALYSTS : Grain-micrograin-particule / Structuration / Concept of dispersion PRINCIPLES FOR THE PREPARATION OF HETEROGENEOUS CATALYSTS: major operations for the ...
... CATEGORIES OF HETEROGENEOUS CATALYSTS : Bulk catalysts / Supported catalysts / Malaxed-agglomerated catalysts MORPHOLOGY OF HETEROGENEOUS CATALYSTS : Grain-micrograin-particule / Structuration / Concept of dispersion PRINCIPLES FOR THE PREPARATION OF HETEROGENEOUS CATALYSTS: major operations for the ...
Surface-Mediated Visible-Light Photo-oxidation
... states, and almost no attention has been paid to the surface state because powder materials with inhomogeneous surfaces, in which the surface states are not controllable, have been used. In the present study, we investigated the effect of the unique “lattice-work structure” of a TiO2(001) surface on ...
... states, and almost no attention has been paid to the surface state because powder materials with inhomogeneous surfaces, in which the surface states are not controllable, have been used. In the present study, we investigated the effect of the unique “lattice-work structure” of a TiO2(001) surface on ...
14 - the Research Group of Angelika Kühnle
... A. Kühnle / Current Opinion in Colloid & Interface Science 14 (2009) 157–168 ...
... A. Kühnle / Current Opinion in Colloid & Interface Science 14 (2009) 157–168 ...
Adsorption
Adsorption is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface. This process creates a film of the adsorbate on the surface of the adsorbent. This process differs from absorption, in which a fluid (the absorbate) permeates or is dissolved by a liquid or solid (the absorbent). Adsorption is a surface-based process while absorption involves the whole volume of the material. The term sorption encompasses both processes, while desorption is the reverse of it. Adsorption is a surface phenomenon.Similar to surface tension, adsorption is a consequence of surface energy. In a bulk material, all the bonding requirements (be they ionic, covalent, or metallic) of the constituent atoms of the material are filled by other atoms in the material. However, atoms on the surface of the adsorbent are not wholly surrounded by other adsorbent atoms and therefore can attract adsorbates. The exact nature of the bonding depends on the details of the species involved, but the adsorption process is generally classified as physisorption (characteristic of weak van der Waals forces) or chemisorption (characteristic of covalent bonding). It may also occur due to electrostatic attraction.Adsorption is present in many natural, physical, biological, and chemical systems, and is widely used in industrial applications such as activated charcoal, capturing and using waste heat to provide cold water for air conditioning and other process requirements (adsorption chillers), synthetic resins, increase storage capacity of carbide-derived carbons, and water purification. Adsorption, ion exchange, and chromatography are sorption processes in which certain adsorbates are selectively transferred from the fluid phase to the surface of insoluble, rigid particles suspended in a vessel or packed in a column. Pharmaceutical industry applications, which use adsorption as a means to prolong neurological exposure to specific drugs or parts thereof, are lesser known.However, it should be remarked that the distinction between adsorption and absorption vanishes as we go from perfectly crystalline macroscopic materials to porous/structured materials, aggregates and composites made out of increasingly smaller grains, viz., micron-sized particles to nanoparticles, sub-nano particles and finally molecules (or atoms). In such nano-composites, the internal surface area of particulate matter is very large. Then the adsorption on internal surfaces simply becomes absorption when viewed from the bulk. Then the distinction between adsorption and absorption vanishes. On the other hand, the distinction is clearest between bulk solids without internal structure, but having only surfaces where only adsorption can occur on the outer surfaces, and nanocomposites or aggregates with internal structure where absorption by the host material is simply adsorption on internal surfaces of the host material. As an example, we may consider a crystalline piece of silicon dioxide (quartz) which can adsorb water molecules on its surface. However, if the quartz is ground into very fine sand, the pile of sand (an aggregate) has a very large internal surface area. A very large amount of water can be adsorbed by the ""internal"" surfaces of the grains in the pile of sand, and this absorption is simply ""internal adsorption. If water is made to flow thorugh such a pile of sand, ions and toxins in the water may be preferentially adsorbed by the surfaces of the grains of sand, providing a simple, well-known water purification application.The word ""adsorption"" was coined in 1881 by German physicist Heinrich Kayser (1853-1940).