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Homogeneous vs. heterogeneous catalysis Dr. habil. Marko Hapke Leibniz-Institut für Katalyse e.V. an der Universität Rostock Heterogeneous Catalysis Homogeneous Catalysis 2 Biocatalysis Homogeneous vs. heterogeneous catalysis Dr. habil. Marko Hapke July 2, 2015 2 2 Catalyst and reactant(s) are in the same phase. Heterogeneous Catalysis Definitions Homogeneous Catalysis Catalyst and reactant(s) are in different phases. General features: General features: Different reaction phases possible: „classic“ gas/solid; liquid/solid or liquid/liquid systems. High industrial relevance (about 85% of all catalytic processes are heterogeneously catalysed). In general wide range of operating conditions (high temperatures/pressures). Specialised set of analytic methods required (e.g. X-ray methods, Operando spectros.). Major advantage: Ease of separation of reactants/products/catalysts. Liquid phase reactions dominate the field. 3 Industrially less relevant; but complex organic or asymmetric transformations possible! Reaction conditions milder than required for heterogeneous reactions (-78 °C - ~200 °C). Investigation of reactions by spectroscopic methods (NMR, MS, IR, UV-Vis) directly in solution possible. Fine-tuning of catalyst properties using different ligands/additives easy possible. Major challenge: Separation of products and catalysts/additives. Homogeneous vs. heterogeneous catalysis Dr. habil. Marko Hapke July 2, 2015 3 3 porous carrier (catalyst support) Heterogeneous Catalysis bed of catalyst particles reactants substrate product reactor reaction desorption adsorption products catalyst support 4 Technical setup: active site substrate A product C substrate B Mechanism: C B A catalyst surface Langmuir-Hinshelwood catalyst surface Eley-Rideal Source: Gadi Rothenberg, Catalysis – Concepts and Green Applications, Wiley-VCH, 2008 Homogeneous vs. heterogeneous catalysis Dr. habil. Marko Hapke July 2, 2015 4 4 Major industrial processes using heterogeneous catalysis Heterogeneous Catalysis Process Catalyst Reactants Products Application Haber-Bosch process Magnetite (Fe) H2, N2 NH3 Fertiliser, explosives Methanol synthesis Cu/ZnO/Al2O3 CO, CO2, H2 Methanol 5 Bulk chemicals, fuel Fischer-Tropsch process Co, Fe Coal, natural gas C5-C11 hydrocarbons Automotive fuel Cracking Clays Long alkanes, C12+ C7-C9 alkanes Fuel, detergents Alkylation Zeolites, Clays, Silicates C3-C5 alkanes C7-C9 isoalkanes High-octane fuel Dehydrogenation/ Reforming Pt/Al2O3 Alkanes Alkenes Polymers, bulk chemicals Polymerisation Ti, Ziegler-Natta Ethylene Polyethylene Polymers Homogeneous vs. heterogeneous catalysis Dr. habil. Marko Hapke July 2, 2015 5 5 Major industrial processes using heterogeneous catalysis Heterogeneous Catalysis An example from daily life: the three-way catalyst -alumina washcoat ceramic monolith catalytic converter CO + 1/2O2 HC's + O2 Pt, Pd Pt, Pd CO2 CO2 + H2O CO + NO H2 + NO 6 1 m 1 mm Homogeneous vs. heterogeneous catalysis Dr. habil. Marko Hapke Pt/Pd/Rh catalyst Rh Rh CO2 + 1/2N2 H2O + 1/2N2 July 2, 2015 6 6 reactants Heterogeneous Catalysis Setup: aqueous phase recycle The Ruhrchemie/RhônePoulenc Hydroformylation (the oxo process) organic phase Ligand L is "tppts": NaO3S products 7 aqueous phase H2 L CO Rh L H SO3Na P SO3Na CO Source: Gadi Rothenberg, Catalysis – Concepts and Green Applications, Wiley-VCH, 2008 Homogeneous vs. heterogeneous catalysis Dr. habil. Marko Hapke July 2, 2015 7 7 General procedure: s t ate en r v t l s So ub PrecaSta lyst s ive dit Ad Homogeneous Catalysis Reaction mixture h 8 Mechanism for Pd-cataysed reactions – crosscoupling and carbonylation: Homogeneous vs. heterogeneous catalysis Dr. habil. Marko Hapke July 2, 2015 8 8 Major industrial processes using homogeneous catalysis The Monsanto process /Cativa Process Acetic acid Catalyst system: Rh / Ir complexes The Shell Higher Olefins Process (SHOP) Oligomerization of ethen to medium and long-chain -olefins (C4-C20) Catalysts: Ni(II)-complexes Homogeneous Catalysis The Wacker Oxidation Process Oxidation of olefins to carbonyl compounds Catalyst system: Pd(II)- and Cu(I)-salts, 9 oxygen The Ciba-Geigy Metolachlor Process Enantioselective Hydrogenation of an imine Catalyst system: Josiphos-Ir complexes The DuPont Adiponitril Synthesis Hydrocyanation of butadiene to hexanedinitrile Catalyst system: Ni(0)-complexes Homogeneous vs. heterogeneous catalysis Dr. habil. Marko Hapke July 2, 2015 9 9 CH3COOH H2O O I Me I Ir CO CO CH3I I I I O I CH3 Ir CO I Reaction mechanism CO I I CH3 CO Ir CO CO I I CH3 CO Ir CO Homogeneous Catalysis CO The Cativa process: Synthesis of acetic acid 10 Source: http://www.catalysis-ed.org.uk/ethacid/ethacid9.htm Homogeneous vs. heterogeneous catalysis Dr. habil. Marko Hapke July 2, 2015 10 10 Interplay: homogeneous and heterogeneous catalysis BHC process Traditional synthesis 11 Heterogeneous Catalysis Homogeneous Catalysis Gadi Rothenberg, Catalysis – Concepts and Green Applications, Wiley-VCH, 2008 Homogeneous vs. heterogeneous catalysis Dr. habil. Marko Hapke July 2, 2015 11 11 Heterogeneous Catalysis Homogeneous Catalysis 12 Biocatalysis Homogeneous vs. heterogeneous catalysis Dr. habil. Marko Hapke July 2, 2015 12 12 Final example: Artificial metalloenzymes Merging the advantages of different types of catalysis – here: enzymatic and transition metal catalysis 13 Highlight: M. Hapke, C. C. Tzschucke, Angew. Chem. 2013, 52, 3317 Homogeneous vs. heterogeneous catalysis Dr. habil. Marko Hapke July 2, 2015 13 13 Manuskript der Vorlesung unter: 14 http://www.catalysis.de/Cycloadditionen.42.0.html Homogeneous vs. heterogeneous catalysis Dr. habil. Marko Hapke July 2, 2015 14 14
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