Catalysis at Surfaces

Catalysis is at the heart of the chemical industry, which uses solid catalysts for the large-scale production of commodity chemicals. Catalysis at surfaces is also the basis for the ongoing transition to a sustainable energy supply, which requires molecules such as hydrogen, ammonia or methanol to store energy in chemical bonds, and environmental protection equally relies on heterogeneous catalysis. Catalysis at surfaces is a truly interdisciplinary field, which requires profound knowledge from chemistry, physics and engineering as provided by this textbook. All essential tools are described ranging from the synthesis and modification of porous solids over bulk- and surface-sensitive characterization techniques to currently applied theoretical methods. A close-up to the important aspects of surface catalysis is provided, which comprises the established knowledge about mechanisms and active sites, promotors and poisons in redox and acid-base catalysis. This advanced textbook is recommended for Master and PhD students, for whom it provides the fundamentals and all relevant aspects of catalyst synthesis, characterization and application in suitable reactors. It is not only thermal catalysis that is covered in depth, but also photo- and electrocatalysis as emerging fields in the Energiewende. Interdisciplinary approach, catalysis from a chemical and materials science view. definitions and basics of fundamentals, synthesis, characterization, application and computational methods. Cover Half Title Also of interest Catalysis at Surfaces Copyright Preface Contents 1. Introduction 1.1 Catalysis, reaction rate, and equilibrium 1.2 Catalyst and reactant phases 1.3 Catalysis and daily life 1.4 Basic concepts of surface catalysis 1.4.1 Reaction rate 1.4.2 Activity, selectivity, and stability 1.4.3 Catalyst and catalytic process 1.5 Surface catalysis: an art or a science? 1.6 Catalyst research: an overview References 2. Surface catalysis: the scene and the play 2.1 Solids 2.2 Surfaces 2.2.1 Surface structures 2.2.2 Surface chemistry 2.3 Particle architecture in catalytic materials 2.3.1 Size, porosity, and structural heterogeneity of catalyst particles 2.3.2 Supports for heterogeneous catalysts 2.3.2.1 Silica (SiO2) 2.3.2.2 Alumina (Al2O3) 2.3.2.3 Alumosilicates/zeolites 2.3.2.4 Metal-organic frameworks 2.3.2.5 Titania, zirconia, ceria 2.3.2.6 Carbon materials 2.3.3 Support and supported species 2.3.4 Alternative catalyst architectures 2.4 Adsorption 2.4.1 Adsorption and desorption: phenomena and classification 2.4.2 Physisorption and chemisorption 2.4.3 Description of equilibria in gas-phase adsorption 2.4.4 Description of equilibria in liquid-phase adsorption 2.5 Surface reactions 2.5.1 Thermal catalysis 2.5.2 Photocatalysis 2.6 Reaction mechanisms and reaction kinetics in thermal catalysis 2.6.1 Reaction kinetics of surface processes 2.6.2 Influences of transport limitations on reaction rates 2.7 Electrochemistry and electrocatalysis 2.8 Reactors for surface-catalytic reactions 2.8.1 Ideal and real reactors 2.8.2 Reactors for thermocatalytic processes 2.8.3 Reactors for photocatalytic processes 2.8.4 Reactors for electrochemical conversions References 3. Tools of catalysis research 3.1 Catalyst preparation 3.1.1 Formation of solids from fluid phases 3.1.1.1 Precipitation and coprecipitation 3.1.1.2 Crystallization: synthesis of zeolites and MOFs 3.1.1.3 Sol-gel transition 3.1.1.4 Solidification of melts 3.1.1.5 Solids from the gas phase 3.1.1.6 Flame-based synthesis routes 3.1.2 Shaping of catalyst pellets 3.1.3 Deposition of active components on the internal surface of porous supports 3.1.3.1 Equilibrium adsorption and ion exchange 3.1.3.2 Impregnation 3.1.3.3 Deposition-precipitation 3.1.3.4 Anchoring, grafting, and surface organometallic chemistry 3.1.3.5 Deposition of colloids and melt infiltration 3.1.3.6 Deposition of precursors from the gas phase 3.1.3.7 Solid-state methods 3.1.4 Thermal conditioning 3.1.5 Activation 3.1.6 Preparation of catalytically active electrodes 3.2 Rate measurements in surface catalysis 3.2.1 Thermal catalysis 3.2.2 Reactors for photocatalytic rate measurements 3.2.3 Measuring electrochemical reaction rates 3.3 Application-oriented characterization of solid catalysts 3.3.1 Density and porosity of particles and beds 3.3.2 Stability toward mechanical stress 3.4 Research-oriented characterization of solid catalysts 3.4.1 Analysis of surface area and porosity 3.4.1.1 Capillary phenomena in pores 3.4.1.2 Measuring adsorption data 3.4.1.3 Specific surface area: the BET method 3.4.1.4 Porosity analysis by physisorption 3.4.1.5 Porosity Analysis by mercury intrusion 3.4.1.6 Analysis of particle dispersion by chemisorption 3.4.2 Thermal analysis and calorimetry 3.4.2.1 Standard methods: DTA and DTG 3.4.2.2 Calorimetry in stationary and dynamic modes 3.4.2.3 Temperature-programmed desorption (TPD) and adsorption (TPA) 3.4.2.4 Temperature-programmed surface reaction (TPSR) 3.4.2.5 Temperature-programmed reduction (TPR), oxidation (TPO), and sulfidation (TPS) 3.4.3 Scattering and diffraction 3.4.3.1 Elastic and inelastic scattering 3.4.3.2 Elastic scattering at ordered arrays: diffraction 3.4.3.3 X-ray diffraction (XRD) 3.4.3.4 Other diffraction and scattering techniques 3.4.4 X-ray absorption fine structure (XAFS) 3.4.4.1 Fine structure in X-ray absorption 3.4.4.2 Acquisition and interpretation of X-ray absorption spectra 3.4.4.3 XAFS in examples 3.4.5 Surface analysis by photoemission techniques 3.4.5.1 Photoemission and surface sensitivity 3.4.5.2 Measuring and assigning photoelectron spectra 3.4.5.3 Sources of analytical information 3.4.5.3.1 Binding energies 3.4.5.3.2 Opportunities based on XPS line shapes 3.4.5.3.3 Surface sensitivity and quantitative analysis 3.4.5.3.4 Structural sensitivity by combining XPS and XAES 3.4.5.3.5 Ultraviolet photoelectron spectroscopy 3.4.5.4 XPS: examples for the interpretation of spectra 3.4.6 Surface analysis with ions: Secondary ion mass spectrometry (SIMS) and Low-energy ion scattering (LEIS) 3.4.6.1 Interactions between low-energy ions and solids 3.4.6.2 Secondary ion mass spectrometry (SIMS) 3.4.6.3 Low-energy ion scattering (LEIS) 3.4.7 Spectroscopy of electronic transitions: absorption of UV and visible light 3.4.7.1 Electron transitions and their diagnostic potential 3.4.7.2 Measuring UV-Vis spectra 3.4.7.3 Typical applications of UV-Vis spectroscopy in catalyst research 3.4.8 Vibrational spectroscopy 3.4.8.1 Vibrations and vibrational spectra 3.4.8.2 Excitation processes and spectroscopies 3.4.8.3 Measuring IR spectra of heterogeneous catalysts 3.4.8.4 IR spectroscopy with catalysts: typical applications 3.4.8.5 Measuring Raman spectra of heterogeneous catalysts 3.4.8.6 Raman spectroscopy in catalysis: typical applications 3.4.9 Magnetic resonance spectroscopy 3.4.9.1 Magnetism and magnetic resonance 3.4.9.2 Electron paramagnetic resonance spectroscopy (EPR) 3.4.9.3 Nuclear magnetic resonance spectroscopy (NMR) 3.4.10 Mössbauer spectroscopy 3.4.10.1 The Mössbauer effect 3.4.10.2 Spectroscopy with the Mössbauer effect 3.4.11 Imaging 3.4.11.1 Transmission electron microscopy (TEM) 3.4.11.2 Scanning electron microscopy (SEM) 3.4.11.3 Scanning probe microscopy 3.4.12 Electrochemical characterization techniques 3.5 Computational chemistry in catalysis research 3.5.1 Wave function-based quantum chemistry and density functional theory 3.5.2 Cluster and periodic models 3.5.3 Quantum chemistry in catalysis research: typical applications References 4. A close-up to some important aspects of surface catalysis 4.1 A preface 4.2 Structure and activity 4.2.1 The Sabatier principle 4.2.2 Electronic structure and catalytic activity on metal surfaces 4.2.3 Spatial structure and catalytic activity 4.2.4 Promoting activity 4.3 Structure and selectivity 4.3.1 Side products and strategies 4.3.2 Shape selectivity 4.3.3 Selective oxidation in the gas phase 4.3.4 Selective hydrogenation 4.3.5 Promoting selectivity 4.4 Stability, regeneration, and reactivation 4.4.1 Mechanisms of catalyst deactivation 4.4.1.1 Poisoning and fouling 4.4.1.2 Loss of active component 4.4.1.3 Thermal effects 4.4.1.4 Mechanical degradation 4.4.2 Preventing catalyst decay/promoting stability 4.4.3 Regeneration of catalysts and the end of their life cycle 4.5 Types of reaction mechanisms 4.5.1 Getting insight into surface processes 4.5.2 Reaction types and catalytic mechanisms: catalysis on Brønsted sites, with nucleophilic oxygen, and via metal-carbon bonds 4.5.2.1 Reactions catalyzed by solid Brønsted acids 4.5.2.2 Allylic oxidation of propene 4.5.2.3 Mechanisms involving metal-carbon bonds 4.5.3 Site isolation and catalytic mechanism 4.5.4 Mechanisms depending on transport steps 4.5.5 Mechanisms involving pools of secondary species 4.5.6 The multiplicity of sites and mechanisms 4.6 Microkinetic modeling 4.7 Heterogeneous catalysis in liquids: what is special? 4.8 Structure and performance in photocatalysis 4.9 Structure and performance in electrocatalysis 4.9.1 Electrocatalytic reaction mechanisms 4.9.2 Recent topics of electrocatalysis References 5. With catalysis into the Anthropocene age: strategies and a look ahead References Appendix A1. Basic information on applications of (thermal) catalysis, photocatalysis, and electrocatalysis Ammonia synthesis (Haber–Bosch process) Ammonia oxidation (Ostwald process) Methanol synthesis Selective oxidation of methanol Fischer–Tropsch (FT) reaction Higher alcohol synthesis (HAS) Steam reforming of methane (SRM) Dry reforming of methane (DRM) Catalytic partial oxidation (POX) of methane Methanation Oxidative coupling of methane (OCM) Water-gas shift Hydrogenation Selective hydrogenation of unsaturated hydrocarbons Selective hydrogenation of unsaturated aldehydes/ketones Hydrotreatment Hydrodesulfurization (HDS) Hydrodenitrogenation (HDN) Hydrodemetallization (HDMe) Hydrocracking Fluid catalytic cracking (FCC) Naphtha reforming Light naphtha isomerization Isobutane alkylation Friedel–Crafts alkylation Synthesis of alkyl tert-butyl ethers Xylene isomerization Dehydrogenation of propane Dehydrogenation of ethylbenzene Metathesis of propene Polymerization with Ziegler–Natta or Phillips catalysts Allylic oxidation of propene Electrophilic oxidation of acrolein Ammoxidation of propene Oxidative dehydrogenation (ODH) and (amm)oxidation of propane ODH and (amm)oxidation of ethane Oxidation of n-butane to maleic anhydride (MA) Oxidation of o-xylene to phthalic anhydride (PA) Epoxidation of ethene Epoxidation of propene with O2 (a), O2/H2 (b), or H2O2 (c) Other selective oxidations with H2O2 Preferential oxidation of CO in the presence of H2 (PROX) Oxychlorination of ethene Deacon process Three-way catalysis Diesel oxidation catalysts (DOC) Selective catalytic reduction (SCR) of NO with NH3 NOx storage A2. Derivation of some equations presented in this book A2.1 BET equation (2.16) A2.2 Derivation of a Hougen–Watson rate law – First order reaction with rate-limiting adsorption of A A2.3 Solution of eq. (2.42) A2.4 Derivation of eq. (2.51) within the porous sphere model References Index