Table of Contents
Cover
Title
Copyright
Dedication
Preface
1 Introduction
1.1 Green Chemistry and Sustainable Development
1.2 What Is Catalysis and Why Is It Important?
1.3 Tools in Catalysis Research
1.4 Exercises
References
Further Reading
2 The Basics of Catalysis
2.1 Catalysis Is a Kinetic Phenomenon
2.2 Practical Approaches in Kinetic Studies
2.3 An Overview of Some Basic Concepts in Catalysis
2.4 Exercises
References
3 Homogeneous Catalysis
3.1 Metal Complex Catalysis in the Liquid Phase
3.2 Homogeneous Catalysis without Metals
3.3 Scaling Up Homogeneous Reactions: Pros and Cons
3.4 ‘Click Chemistry’ and Homogeneous Catalysis
3.5 Exercises
References
4 Heterogeneous Catalysis
4.1 Classic Gas/Solid Systems
4.2 Liquid/Solid and Liquid/Liquid Catalytic Systems
4.3 Advanced Process Solutions Using Heterogeneous Catalysis
4.4 Exercises
References
5 Biocatalysis
5.1 The Basics of Enzymatic Catalysis
5.2 Applications of Enzyme Catalysis
5.3 Developing New Biocatalysts: Better than Nature’s Best
5.4 Non-enzymatic Biocatalysts
5.5 Industrial Examples
5.6 Exercises
References
6 Computer Applications in Catalysis Research
6.1 Computers as Research Tools in Catalysis
6.2 Modelling of Catalysts and Catalytic Cycles
6.3 Predictive Modelling and Rational Catalyst Design
6.4 An Overview of Data Mining Methods in Catalysis
6.5 Exercises
References
Index
End User License Agreement
List of Tables
1 Introduction
Table 1.1 Annual production and E-factors in the chemical industry.
Table 1.2 Hazard quotient (Q ) values for some common chemical by-products.
Table 1.3 Comparison of the various propene oxide routes by type and by-product.
2 The Basics of Catalysis
Table 2.1 Kinetic parameters for simple chemical reactions.
Table 2.2 Initial reaction rates at various initial concentrations.
Table 2.3 Measured concentrations of alkene A over time.
Table 2.4 Initial methanation rates for various starting concentrations.
3 Homogeneous Catalysis
Table 3.1 Turnover frequencies (TOFs) for the air oxidation of 3-carene.
Table 3.2 Butadiene dimerisation and trimerisation yields with different catalysts.
4 Heterogeneous Catalysis
Table 4.1 Examples of major industrial processes using heterogeneous catalysis.
Table 4.2 Exhaust gas constituent concentrations and their legal limits.
Table 4.3 Average biodiesel emissions compared to conventional diesel.
Table 4.4 A3 coupling catalysed by Cu/Al.a)
Table 4.5 Properties and performance of MoOx −TiO2 catalysts.
5 Biocatalysis
Table 5.1 Abbreviations and residue structures of the 20 natural (L)-α -amino acids.
Table 5.2 The six classes and functions of enzymes, according to the International Enzyme Commission.
Table 5.3 Examples of enzyme applications in the food and detergent sectors [30].
Table 5.4 Examples of amide synthesis with R. rhodochrous nitrile hydratase [109].
6 Computer Applications in Catalysis Research
Table 6.1 Metal and adsorbate descriptors [90].
List of Illustrations
1 Introduction
Figure 1.1 The strategic goal of sustainable development relies on practical approaches such as green chemistry, industrial ecology, and green engineering. These approaches use various operational tools (such as catalysis), and monitoring tools (such as life-cycle assessment).
Figure 1.2 Green chemistry initiatives are driven by government legislation, societal pressure, and economic benefits.
Figure 1.3 The oxidation of diphenyl methanol to benzophenone using stoichiometric amounts of chromium trioxide and sulphuric acid.
Figure 1.4 Electrolysis of water showing the anode and cathode reactions in an acidic environment.
Figure 1.5 Relative efficiency of various engine types. The column on the right shows also the estimated ‘hidden costs’ for obtaining hydrogen in the case of fuel cells. The inset shows a schematic of a solid oxide fuel cell that converts fuel (in this case, hydrogen) directly to electricity.
Figure 1.6 Different routes for producing propane oxide starting from propene: (a) the ideal direct oxidation with oxygen; (b) classic chlorohydrin process; (c) Shell/Lyondell SMPO process; (d) ARCO/Oxirane process; (e) the new BASF/Dow HPPO process.
Figure 1.7 The four stages in life-cycle assessment.
Figure 1.8 Different types of catalysts.
Figure 1.9 Examples of chemoselectivity and diastereoselectivity in the oxidation of α -pinene (a), regioselectivity in the hydroformylation of 1-octene (b) and enantioselectivity in the hydrogenation of the prochiral isopropyl(2-methoxyisopropyl)imine (c, the indicates the asymmetric carbon atoms).
Figure 1.10 Base-catalysed transesterification of triglycerides. The reactants and products are written as part of the stoichiometric reaction equation, but the catalyst is written above the reaction arrow, to show that it is unchanged at the end of the reaction.
Figure 1.11 Proposed catalytic cycle for the Mizoroki–Heck reaction, showing the various catalytic intermediates (a) and ‘black box’ version (b).
Figure 1.12 Catalytic cycle for the hydrogenation of propene to propane in the presence of a supported metal catalyst. The metal crystallite is one of many so-called ‘active sites’ on the porous catalyst particle (right). All of the reactions in this cycle are reversible (the reverse arrows are omitted for clarity).
Figure 1.13 Cyclisation of geraniol (top left) and possible mechanism (bottom left) in the presence of zeolite Y, a solid acid catalyst that has both Brønsted and Lewis acid sites.
Figure 1.14 In the biocatalytic synthesis of acrylamide from acrylonitrile the bacterial cells are immobilised in a (poly)acrylamide gel, and the process is run at pH 8.0–8.5 in semi-batch mode, keeping the substrate concentration below 3%.
Figure 1.15 The classic Du Pont route to adipic acid (left) and Frost’s biosynthetic route using a genetically modified E. coli cell (right, the enzymes and the reagents are omitted for clarity).
Figure 1.16 The classic Ullmann reaction for coupling aryl iodides by reaction with copper metal at high temperatures.
Figure 1.17 Combining two stoichiometric reactions (a, the reductive coupling of halobenzene with Pd0 and the reduction of PdII with hydrogen gas) creates a catalytic cycle where the Pd catalyst shuttles between the Pd0 and PdII species (b).
Figure 1.18 Theoretical waste-free route to biphenyl starting from benzene and benzyne (top left), oxidative coupling of two benzene molecules with stoichiometric PdII Cl2 and regeneration of PdII with molecular oxygen (bottom left), and the resulting catalytic cycle for oxidative coupling (grey inset).
Figure 1.19 Synthesis of ibuprofen: The six-step Boots route (left) and the three-step BHC route (right). In each case, the catalysts are highlighted in grey.
Figure 1.20 Block diagram of the various tools used in catalysis research.
Figure 1.21 Schematic of a sequential pulse injection system for high-throughput catalyst screening using on-line spectroscopy.
Figure 1.22 Schematic of a flow cell for measuring IR spectroscopy during a catalytic reaction (courtesy of Dr. Frederic Thibault-Starzyk).
Figure 1.23 The oxidation of 2-(methylamino)-1-phenyl-propan-1-ol with potassium permanganate.
Figure 1.24 Different production routes to acrylic acid, showing biobased feedstocks (green), biobased platform chemicals (light blue), and existing petrobased routes (grey).
Figure 1.25 Alternative synthesis routes from valencene to nootkatone.
Figure 1.26 The catalytic oxidation of cinnamyl alcohol to cinnamaldehyde.
Figure 1.27 The classic synthesis route to hydroquinone starting from aniline.
Figure 1.28 Life-cycle flow diagram for milk cartons.
Figure 1.29 Catalytic hydrogenation of various aryl ketones and the corresponding kinetic data.
Figure 1.30 Three-step chemical synthesis of glutamic acid, starting from acrylonitrile.
Figure 1.31 Production routes to ε -caprolactam: (a) the classic BASF route; (b) the Sumitomo/EniChem ammoximation process.
2 The Basics of Catalysis
Figure 2.1 Catalysis deals with the transition between reactants and products. It does not affect the overall reaction thermodynamics.
Figure 2.2 The titania-catalysed oxidation of lactic acid with molecular oxygen gives pyruvic acid, water, and oxidation by-products.
Figure 2.3 Fast and slow steps in a catalytic cycle are like the falling of sand grains through an hourglass with narrow and wide openings. The narrow passages will determine the rate of falling sand, regardless of how many wide openings there are.
Figure 2.4 The thermal cis/trans isomerisation of stilbene, the Diels–Alder cycloaddition of butadiene to ethene, and the fluorination of gaseous BF3 in the presence of methane are examples of unimolecular, bimolecular and termolecular reactions, respectively.
Figure 2.5 Proposed catalytic cycle for the Heck reaction between an alkene and an aryl halide in the presence of a homogeneous palladium complex. Each one of the highlighted catalytic intermediates is as much ‘the catalyst’ as any other.
Figure 2.6 Monitoring the concentrations of reactants, intermediates and products over time can help us optimise the yield of the desired products (example shown for two consecutive first-order reactions, with rate constants k 1 = 0.2 min−1 and k 1 = 0.02 min−1 ).
Figure 2.7 An energy/reaction coordinate diagram for a two-step reaction, with two catalytic intermediates and three transition states.
Figure 2.8 The unimolecular reaction of cis -stilbene to trans -stilbene has a clear reaction coordinate: the vibrational degree of freedom that corresponds to the rotation of one of the phenyl groups across the central C=C bond.
Figure 2.9 The traditional diagram of energy vs. reaction coordinate is in fact only a ‘slice’ through the multidimensional space. This slice represents just one of the degrees of freedom of the system. Going one dimension higher, we see that the transition state is not a maximum but a saddle point.
Figure 2.10 Chemical reaction and concentration profile for the isomerisation of cyclopropane to propene at 400 °C.
Figure 2.11 Cartoon of reaction on a catalyst surface that follows the Langmuir–Hinshelwood model.
Figure 2.12 Schematic catalytic cycle for the isomerisation of 2-methylheptane to iso- octane. This cycle has three steps: adsorption of the reactant onto the surface, isomerisation at the active site, and desorption of the product.
Figure 2.13 Typical concentration profile of a steadystate intermediate.
Figure 2.14 The Lineweaver–Burk plot relates the reciprocal reaction velocity to the reciprocal substrate concentration.
Figure 2.15 Energy/reaction coordinate diagrams for a generic parallel reaction. The parallel reaction determines the product selectivity, and may be rate-determining (a) or not (b).
Figure 2.16 Reaction profile showing the substrate conversion in a pre-equilibrium system followed by first-order kinetics. Note the importance of frequent sampling; in this case, sampling every 5 minutes would not show the induction period (compare the ‘+’ and ‘•’ symbols). The inset shows a generic catalytic cycle with a pre-equilibrium step.
Figure 2.17 Dimer-monomer pre-equilibrium and catalytic cycle for the Heck coupling of p -cyano bromobenzene and n -butyl acrylate.
Figure 2.18 Stoichiometric reactions with isolated catalytic intermediates can provide support (or sometimes disprove) for the mechanism.
Figure 2.19 Decomposition of the binuclear complex Pd2 Cl4 (C2 H4 )2 in the presence of water.
Figure 2.20 Examples of volcano plots, showing the reaction rate as a function of the heat of adsorption (a), and the activity of the second-row and third-row transition metal sulphides in the hydrodesulphurisation of dibenzothiophene (b).
Figure 2.21 The development of tetradentate ligand systems for H2 O2 activation.
Figure 2.22 Different aspects of catalyst sintering: Crystallite migration (a), atom migration (b) and phase transformation of the support at high temperatures (c).
Figure 2.23 The reaction profiles obtained by Maria (a) and Yuan (b).
Figure 2.24 The methane asymmetric addition step in the synthesis of lineatin.
Figure 2.25 Epoxidation of cyclobutane to cyclobutane oxide with nitrous oxide.
Figure 2.26 Catalytic hydrodehalogenation of dichloronitrobenzene.
3 Homogeneous Catalysis
Figure 3.1 Hydrogenation of 1-hexene to hexane in the presence of Wilkinson’s catalyst, Rh[P(Ph)3 ]3 Cl (a), and hydroformylation of 1-octene to the linear nonanal and the branched 2-methyloctanal (b) [4]. The 3D representations on the right show the crowding around the Rh atom in each case. As we shall see, the ligand’s bulk and rigidity often govern the catalytic activity and selectivity.
Figure 3.2 The main elementary steps in homogeneous catalysis.
Figure 3.3 Homogeneous complexes are always in a dynamic coordination/dissociation equilibrium.
Figure 3.4 Dissociate (a) and associative (b) ligand exchange from Ni(CO)4 .
Figure 3.5 General scheme for oxidative addition (a) and example of oxidative addition of CH3 I to Vaska’s complex (b).
Figure 3.6 Oxidative addition of benzyl bromide to PtII (bipy)(CH3 )2 gives a trans PtIV complex, that subsequently isomerises to the cis complex.
Figure 3.7 Generic formulas for cyclometallation (a) and examples of formation of a ruthenacyclopentadiene complex via cyclometallation of a diacetylene (b).
Figure 3.8 Generic reductive elimination reaction (a) and reductive elimination of HCN from a nickel complex (b).
Figure 3.9 Carbon-carbon bond formation via reductive elimination from a palladium complex.
Figure 3.10 Examples of CO insertion (a) and CH3 migration (b) in a square planar Pd complex with a P–N chelating ligand. Note that the migration mechanism retains the cis configuration between the CO group and the chelate nitrogen atom.
Figure 3.11 Examples of [1,1] and [1,2] migratory insertion reactions.
Figure 3.12 Generic formula for β -hydride elimination from a transition-metal alkyl complex.
Figure 3.13 Nucleophilic attack of water on coordinated ethylene in the Wacker oxidation cycle (a), and attack of ethoxide on coordinated CO (b).
Figure 3.14 Generic examples of α -elimination (a) and α -abstraction (b).
Figure 3.15 Generic formula (a) and example (b) of σ -bond metathesis.
Figure 3.16 Orthometallation of a Pd-organoimine complex.
Figure 3.17 Schematic drawing and 3D structures of Ni[P(Ph)3 ]4 , showing the reaction pocket created by the dissociation of one of the triphenylphosphine ligands.
Figure 3.18 Schematic drawing and space-filling model showing the calculation of the cone angle for symmetric and non-symmetric ligands, and examples of some ligands with their respective cone angle values.
Figure 3.19 Cartoon of the bulk radius R max , the solid angle Ω max , and the sphere occupation parameter S occ .
Figure 3.20 Ligand dissociation equilibrium from a nickel complex (top), and corresponding structures and space-filling models of the p- tolyl (middle) and o- tolyl (bottom) phosphine ligands. The 3D models show the larger cone angle caused by the ortho methyl groups.
Figure 3.21 Examples of bidentate phosphine ligands and their corresponding bite angles ((a), the numbers in parenthesis show the standard deviation for the angles calculated using various methods [34, 38]), and a flexibility profile for the Xantphos ligand, showing how the energy changes with the bite angle (b).
Figure 3.22 Structures of four similar titanium catalyst precursors with different symmetries, used in the polymerisation of 1-hexene, and the corresponding isotactic polyhexene product yields.
Figure 3.23 Cartoon showing how the ligand donor/acceptor properties influence the C–O bonded trans to this ligand.
Figure 3.24 Examples of organometallic complexes of Co, W, and Ni that exhibit agostic interactions.
Figure 3.25 Chemical structures and optimised geometries of (R )- and (S )-thalidomide.
Figure 3.26 Cartoon showing the concept of asymmetric catalysis using an organometallic complex with a chiral ligand.
Figure 3.27 Chemical structure and 3D representation of L-DOPA (a); some of the chiral ligands tested by Monsanto with their corresponding ee ’s (b), and the Rh-DiPAMP complex used in the large-scale commercial process (c).
Figure 3.28 An (S )-BINAP-Rh complex catalyses the asymmetric isomerisation step in the synthesis of (–)-menthol from myrcene. The inset shows the chemical structure and 3D representation of the (R )-BINAP ligand (2,2′-bis(diphenylphosphanyl)-1,1′-binaphthyl, hydrogen atoms omitted for clarity). Note that BINAP ligands have no asymmetric atoms, but the entire molecule has a C 2 symmetry due to the high barrier for rotation around the naphthyl–naphthyl bond.
Figure 3.29 Two examples of nickel catalyst precursors, highlighting the ‘chelate part’ and the ‘organic part’ (a), and a simplified catalytic cycle for the SHOP oligomerisation step ((b), the reverse reaction arrows are omitted for clarity).
Figure 3.30 The three stoichiometric redox reactions (a) and net reaction (b) of the Wacker oxidation system, and a simplified representation of the Pd and the Cu catalytic cycles (c, the reverse arrows are omitted for clarity).
Figure 3.31 Simplified schematic of the palladium Wacker catalytic cycle for oxidising ethylene to acetaldehyde (the ‘reverse reaction’ arrows are omitted for clarity). The dashed circles represent the copper and oxygen redox cycles.
Figure 3.32 The two-step Ni-catalysed hydrocyanation of butadiene.
Figure 3.33 The hydrocyanation catalytic cycle, starting from a NiL4 catalyst precursor. The dashed curves show the formation of the 2M3BN by-product (the ‘reverse reaction’ arrows are omitted for clarity).
Figure 3.34 (a) Formation of the various products in the second hydrocyanation step, cocatalysed by Lewis acids (LA); (b) bulky Lewis acids such as BPh3 shift the linear : branched product equilibrium towards the desired linear product.
Figure 3.35 Chemical structures of the four stereoisomers of metolachlor (top); 3D representation of the (αR ,1′S ) isomer, showing the chiral axis (bottom left) and the asymmetric imine hydrogenation step (bottom right).
Figure 3.36 The original Josiphos ligand (a), and the Ir-xyliphos complex used in the Ciba–Geigy Metolachlor process (b).
Figure 3.37 Piperidine, an organocatalyst, catalyses the Knoevenagel condensation between dimethyl maleate and butyraldehyde.
Figure 3.38 The general enamine catalytic cycle in the presence of L-proline (a), and an example of an asymmetric Mannich-type addition of cyclohexanone to iminoethyl glyoxalate, catalysed by a proline tetrazole derivative (b).
Figure 3.39 The structure and proposed mode of action of the modified Cinchona alkaloid catalyst (a), and an example of the catalytic Henry reaction between benzaldehyde and nitromethane (b).
Figure 3.40 The cat-in-a cup concept: (a) Photo and schematic of the multilayered porous catalyst separation cup. The alumina membrane pore diameter is 4 nm. (b) Attaching a RuII complex with (S ,S )-N -arenesulfonyl-1,2-diphenylethylenediamine ligands to a third-generation Fréchet-type dendrimer scaffold creates a bulky catalyst that is easily filtered. (c) Photo of the lab-scale membrane reactor [99].
Figure 3.41 The two pathways for the Lewis-acid catalysed ring-opening of aziridines.
Figure 3.42 General reaction scheme for the thermal Huisgen cycloaddition (a), and example of the copper-catalysed reaction between phenylpropargyl ether and benzylazide. (b) The catalytic reaction is performed in the presence of a reductant (sodium ascorbate) and gives just one of the product isomers in high yield.
Figure 3.43 A simplified cycle of the cobalt-catalysed hydroformylation process. Some of the reverse reaction arrows are omitted for clarity.
Figure 3.44 A simplified cycle of the rhodium-catalysed hydroformylation process. Some of the reverse reaction arrows are omitted for clarity.
Figure 3.45 Catalytic cycle for the Pd-catalysed Sonogashira cross-coupling.
Figure 3.46 Pt-catalysed hydrosilylation cycle.
Figure 3.47 Catalytic oxidation of 3-carene to 3-carene-5-one, and molecular structure of deltamethrin, showing the incorporation of the carenone precursor in the final product.
Figure 3.48 Molecular structures of various bidentate phosphine ligands.
Figure 3.49 Catalytic cycle for the dimerisation and telomerisation of butadiene in the presence of Pd complexes.
Figure 3.50 The palladium-catalysed telomerisation of isoprene with glycerol.
4 Heterogeneous Catalysis
Figure 4.1 Cartoon showing a plug-flow catalytic reactor at various zoom-in levels, and the related size domains.
Figure 4.2 The two main mechanisms in gas/solid heterogeneous catalysis: Langmuir–Hinshelwood (a) and Eley–Rideal (b).
Figure 4.3 Schematic representation of a solid catalyst crystal surface. A lot of catalysis occurs as the ‘steps’ and ‘kinks’, partly because the atoms at these sites have a higher energy.
Figure 4.4 Relative rates of dissociative N2 adsorption (grey bars) and ammonia synthesis (hatched bars) on different planes of Fe single crystals.
Figure 4.5 An activity promoter lowers the antibonding LUMO of the incoming N2 molecule, facilitating its dissociation on the catalyst surface.
Figure 4.6 Types and examples of solid catalysts, grouped by preparation method (tm = transition metal).
Figure 4.7 Flowchart summarising the main unit operations and stages in solid catalyst synthesis (different synthesis protocols may include fewer/more operations).
Figure 4.8 Cartoon of the Raney process, in which a metal/aluminium alloy is prepared by fusion, and subsequently the aluminium is dissolved by aqueous NaOH, leaving a ‘metallic sponge’. The images are scanning electron micrographs of the resulting porous metal catalyst, in this case a copper/nickel sponge used for catalysing the dehydrogenation of propane to propene [54].
Figure 4.9 Photo and schematic of a simple lab-scale parallel reactor for vacuum pore impregnation.
Figure 4.10 Schematic of the hydrothermal synthesis of zeolites (top, example showing H-ZSM5 or MFI) and the structures of four common zeolites: LTA, FAU, MFI and BEA (zeolite simulation images courtesy of Dr. David Dubbeldam).
Figure 4.11 Computer simulation of the MFI-type zeolite H-ZSM5 (left, snapshot courtesy of Dr. Edith Beerdsen), and scheme showing the shape-selective formation of p -xylene in the cage (right).
Figure 4.12 Extrusion templates enable the design of catalyst pellets with different shapes and sizes.
Figure 4.13 This nitrogen-doped carbon support can act also as a catalyst by enabling an electron transfer to an incoming oxygen molecule. The metal oxide particles are dispersed on the surface via impregnation, creating an ‘active doughnut’ are where cascade catalysis can occur [32].
Figure 4.14 Pores may vary in size, shape, and connectivity. From left to right: Channel/cage structures (a), polygonal capillaries (b), ‘ink bottle’ pores (c), laminae (d), and slit pores (e).
Figure 4.15 The six types of adsorption isotherms: Type I shows a monolayer (Langmuir isotherm); types II and III show multilayer adsorption; type IV shows first a monolayer, followed by filling of mesopores. The ‘knee’ in isotherms I, II, and IV, shown by a black dot, indicates the point of monolayer formation (point ‘B’).
Figure 4.16 Schematic of a temperature-programmed analysis setup (a), and TPR profile of CeO2 , CuO, and a copper-doped ceria sample, Ce0.9 Cu0.1 O2 , showing the effect of Cu doping on the reduction temperature (b).
Figure 4.17 An electron beam hitting the catalyst surface sets off several processes (a); The electrons that are transmitted through the sample are used for generating the TEM image ((b), showing gold and silver nanoparticles supported on γ -alumina [99]).
Figure 4.18 Scanning electron micrograph of ‘polyelectrolyte onions’, that can trap active metal clusters within their shell thickness, showing the porous three-dimensional structure at the capsule surface.
Figure 4.19 The four different adsorption configurations of CO on metal surfaces can be distinguished by their IR activity.
Figure 4.20 Cartoon showing the monolith, channel washcoat, and supported active metals in the TWC (a), and the chemical oxidation and reduction reactions for converting the three main pollutants (b).
Figure 4.21 Schematic showing the release of oxygen from the ceria fluorite lattice during the rich engine cycle (a), and comparison (b) of the oxygen levels in the exhaust gas in the absence (broken line) and in the presence of an the oxygen reservoir (shaded area). Thanks to Dr. Merijn Schenk for rendering the 3D fluorite crystal structures.
Figure 4.22 The three types of silanol groups on a silica surface (a), and molecular POSS mimics of these groups (b).
Figure 4.23 Second-generation W- and Re-alkylidene metathesis catalysts anchored on silica, with their corresponding TOF and TON values at 25 °C [123].
Figure 4.24 A general process schematic for aqueous biphasic catalysis (a), and examples of water-soluble phosphine ligands (b), and the catalytic cycle for the Ruhrchemie/Rhône-Poulenc hydroformylation of propene (c).
Figure 4.25 The Kuraray hydrodimerisation route to n -octanol and 1,9-nonadiol, which includes two biphasic catalytic steps.
Figure 4.26 Temperature-controlled mixing and separation of fluorous and organic phases (a), and its application in nickel-catalysed oxidation of aldehydes by Klement et al . (b) [137].
Figure 4.27 Examples of ionic liquids based on mim-type cations and py-type cations.
Figure 4.28 Different pathways for PTC: The classic Starks extraction mechanism (a) and the Makosza interfacial mechanism (b).
Figure 4.29 Schematic representation of the solid/liquid HF generation system (a) and examples of synthetic applications (b).
Figure 4.30 Chemical reactions and simplified process schematic for BP’s AVADA ethyl acetate process.
Figure 4.31 A simplified schematic of the AlkyClean process, using three reactors in a cyclic configuration. At any given time, two reactors are used for alkylation and mild regeneration cycles while the catalyst in the third reactor is regenerated with gaseous hydrogen at 250 °C. The photo on the left shows the first commercial unit in Shandong, China (photo courtesy of Albemarle).
Figure 4.32 Simplified schematic of IFP’s Esterfip biodiesel process, based on two consecutive reactor/separator stages.
Figure 4.33 Simplified schematic of the Yellowdiesel catalytic distillation process for making biodiesel from high-FFA oils, by integrating the reaction and separation in one reactive distillation column using a solid acid catalyst.
Figure 4.34 In fatty acid esterification, the support surface hydrophobicity is a key factor. Too few acid sites result in low activity, but too many lead to water adsorption and deactivation.
Figure 4.35 A simplified schematic of the SMART process, showing the ethylbenzene dehydrogenation (inset) and hydrogen combustion energy exchange cycle.
Figure 4.36 Proposed four-step route for the Nafion-catalysed synthesis of t -BuOH.
Figure 4.37 N2 adsorption isotherm (measured at 77 K) of the catalyst before and after the first run.
Figure 4.38 Molecular formula of Cu-phthalocyanine and optimised geometry of the phthalocyanine ligand.
Figure 4.39 Scanning electron micrograph (a), 3D confocal microscopy reconstruction of the particle loaded with rhodamine B (picture taken in fluorescent mode) showing the porosity throughout the catalyst particle (b), transmission electron micrograph (c), and nitrogen adsorption isotherm (d) of the Cu/Al catalyst ‘sponge’, showing the morphology and porous structure.
Figure 4.40 The titania-catalysed air oxidation of ethyl lactate to ethyl pyruvate.
Figure 4.41 TPR profiles of catalysts 1, 3, and 5
Figure 4.42 A possible catalytic cycle for the Mo-catalysed oxidation of ethanol to acetaldehyde.
Figure 4.43 Multi-parameter simulation showing the comparative cost of spherical core–shell catalysts with various metal oxide cores and cobalt shells. The spheres below the abscissa show the relative core : shell sizes [181].
Figure 4.44 The oxidation of glyoxal to glyoxylic acid is done today using hot nitric acid. Overoxidation gives oxalic acid as a by-product.
5 Biocatalysis
Figure 5.1 A host of new industrial sectors (right) are joining the traditional biocatalysis application fields (left).
Figure 5.2 Chemical structures of three common coenzymes, NADH, ATP, and coenzyme A. Since coenzymes and cofactors are often complex and expensive molecules, their regeneration is crucial in industrial biocatalysis applications.
Figure 5.3 Enzyme-substrate binding: Cartoons of Fischer’s lock-and-key model (a) and Koshland’s induced fit model (b).
Figure 5.4 The three-dimensional arrangement of binding residues at the active site (a) enables selective binding of chiral substrates. The ‘wrong’ substrate enantiomer does not match with the residues, resulting in a higher kinetic barrier for the formation of the enzyme-substrate complex. The three-point binding also enables enzymes to differentiate between prochiral groups and Re /Si faces (b).
Figure 5.5 The thermal Diels–Alder reaction proceeds much faster with 1,3-cyclopentadiene than with 1,3-butadiene, because the double bonds in the cyclic diene are always cis to each other.
Figure 5.6 A protonated lysine residue at position #116 facilitates the low pK a observed for the lysine residue #115 at the active site of acetoacetate decarboxylase [23]. This enzyme shows maximum activity at pH = 5.95.
Figure 5.7 Simplified catalytic cycle for vanadium chloroperoxidase, isolated from the fungus Curvularia inaequalis (a) based on crystal structures of the native enzyme (b) and the peroxo intermediate [26]. Thanks to Dr. Teunie van Herk for the enzyme structure image.
Figure 5.8 Amide hydrolysis in the presence of papain, an example of nucleophilic enzyme catalysis.
Figure 5.9 NAD+ /NADH cofactor regeneration: The coupled enzyme approach (top left) and the coupled substrate approach (top right), and examples of the two approaches (bottom) [34, 35].
Figure 5.10 Covalent immobilisation of an enzyme on a Eupergit resin [47].
Figure 5.11 Entrapment of an enzyme in a (poly)acrylamide matrix.
Figure 5.12 The formation of CLEAs is a two-stage process, that combines in essence enzyme separation and immobilisation.
Figure 5.13 The Genecor metabolic route to indigo [40], that starts from glucose and uses a genetically modified E. coli (left), is a complex yet ‘clean’ multi-step process, that delivers a product which is identical to that of the century-old traditional chemical route.
Figure 5.14 Chemical and biocatalytic conversion of penicillin G to 6-aminopenicillanic acid, the core structure of various antibiotics.
Figure 5.15 Generic scheme of dynamic kinetic resolution of alcohols (a), and example of the resolution of a racemic 8-amino-tetrahydroquinoline, where the racemisation is catalysed by the organic ketone 8-aza-1-tetralone ((b), the racemisation cycle is highlighted in grey).
Figure 5.16 The Du Pont chemoenzymatic route to glycolic acid.
Figure 5.17 The ICI chemoenzymatic route to polyphenylene uses genetically altered Pseudomona putida cells, that consume benzene and excrete the dihydrodiol monomer.
Figure 5.18 Schematic showing the main operations workflow in directed evolution.
Figure 5.19 Schematic structure of an antibody protein binding to its specific antigen.
Figure 5.20 Hydrolysis of cocaine catalysed by mAb 15A10. The abzyme was generated using a mimic of the tetrahedral activated complex, with a phosphate group replacing the carboxylic group (inset).
Figure 5.21 Splicing of RNA chains (grey lines) through intramolecular (a) and intermolecular (b) nucleophilic attack in the presence of a base.
Figure 5.22 Simplified block diagram of the High Fructose Corn Syrup process.
Figure 5.23 Stoichiometric acid hydrolysis of acrylonitrile to acrylamide (a), and Raney copper-catalysed hydrolysis (b).
Figure 5.24 Unlike the chemical route, the biocatalytic hydrolysis of acrylonitrile to acrylamide is highly selective, owing to the specific function of the nitrile hydratase enzyme.
Figure 5.25 Simplified schematic representation of the semisynthetic and biosynthetic pathways for producing Paclitaxel.
Figure 5.26 The Tosoh/DSM chemoenzymatic route to aspartame.
Figure 5.27 Simplified schematic of the dual epoxidation/glucose conversion process, with in situ H2 O2 regeneration.
Figure 5.28 One-pot dual-enzyme cascade, starting from dihydroxyacetone and propionaldehyde, with in situ phosphorylation and dephosphorylation steps.
Figure 5.29 Chemoenzymatic route to (S )-lysine, starting from cyclohexanol.
Figure 5.30 Chiral amine synthesis by biocatalytic reductive amination.
Figure 5.31 Base-catalysed and enzyme-catalysed addition of cyanide to benzaldehyde.
Figure 5.32 Chiral amine synthesis by biocatalytic trans-amination.
6 Computer Applications in Catalysis Research
Figure 6.1 Computer applications in catalysis research range all the way from understanding the role of molecular active intermediates to large-scale process simulations.
Figure 6.2 3D atomistic representation and simplified coarse-grained representation of 1-propanol.
Figure 6.3 Three snapshots of MD and Car–Parrinello molecular dynamics simulations of the photoactive yellow protein, showing the entire protein (left), the ‘pocket’ containing the chromophore (middle) and the chromophore itself (right). Simulation snapshots courtesy of Dr. Elske Leenders and Dr. Evert Jan Meijer, University of Amsterdam.
Figure 6.4 Simulated structure of the MFI-zeolite Silicalite-1 (O atoms in dark grey and Si atoms light grey) showing the zigzag channels. The dashed lines indicate the periodic cell boundaries. The alkane molecules (not drawn to scale) are indicated by black dots. Zeolite structure courtesy of Dr. Merijn Schenk, University of Amsterdam.
Figure 6.5 Product distribution for hydrocracking catalysed by an ERI-type zeolite, showing the ‘window effect’ observed by Chen et al . (a), and simulation of n -C13 in an ERI cage ((b), the window size is 0.36 nm × 0.51 nm). Thanks to Dr. David Dubbeldam for the zeolite simulation snapshot.
Figure 6.6 Propagation cycle in the synthesis of (poly)ethylene according to the Cossee mechanism (a), and calculated energy/reaction coordinate diagram for the ethylene insertion step (b).
Figure 6.7 Catalytic oxidation of secondary alcohols to ketones, with a one-pot regeneration of the PdCl2 catalyst by dechlorination of 1,2-dichloroethane to ethene.
Figure 6.8 Three-dimensional simplified representation of the multi-dimensional spaces A, B, and C, containing the catalysts, the molecular descriptor values, and the figures of merit, respectively.
Figure 6.9 Descriptors calculated for phosphines in the trans- Rh(PR3 )2 (CO)Cl catalyst ((a), the deformation coordinate S ′4 is employed as steric measure), and stereo-electronic map showing the distribution of the various PR3 ligands (b).
Figure 6.10 Example of a chiral molecule, (R )-4-chloro-4-(dimethylamino)heptan-3-one (left), indicating the four atoms directly bound to the chiral centre (middle) and their neighbourhood (right, the neighbourhood of atom A is the set of atoms whose distance in number of bonds to A is less than to B, C, and D).
Figure 6.11 Diels–Alder reaction of N -2-alkenoyl-1,3-oxazolidine-2-one with cyclopentadiene. (a), and alignment of all 23 bisoxazoline and phosphinoxazoline ligands used in the CoMFA study (b). Regions of space where steric bulk should enhance or decrease stereo induction are plotted using iso-contour mapping.
Figure 6.12 Newman projection of [(η 5 -C5 H5 )Re(η 2 -olefin)(PPh3 )(NO)]+ , viewed down the olefin centroid-Re axis.
Figure 6.13 Structure, molecular graph, and adjacency matrix of the DIOP ligand. The broken lines indicate the shortest and longest P–P connectivity paths, D P1 −P2 and ΔP1 −P2 , respectively. The adjacency matrix of a molecular graph is a matrix with rows and columns labelled by graph vertices v (i.e. the atoms), with a 1 or 0 in position (vi , vj ) according to whether vi or vj are adjacent or not.
Figure 6.14 Bar graph comparing the analysis capacity, in number of ligands’ bite angles and flexibility ranges calculated per hour, using topological descriptors (2D), and 3D descriptors based on MM forcefields, semi-empirical QM calculations, and ab initio QM calculations. All calculations were performed on a 2.5 GHz desktop computer (analysis capacity will improve with better computers and software, but the 2D : 3D cost-effectiveness ratio will remain).
Figure 6.15 Examples of topological descriptors calculated on backbone and R groups of three bidentate ligands. The broken arrows on the left indicate the minimum P1 −P2 connectivity path (D 1 ) and the second P1 −P2 path (D 2 ). The dotted arrows in the middle structure indicate free-rotating bonds. The R group descriptor SAMR< 3 pertains to the sum of mass units of atoms that are connected within three bonds of the ligating P atoms.
Figure 6.16 Observed and predicted bite angle and flexibility values for a set of biphosphine and biphosphite ligands. The empty dots and the grey lines represent respectively the bite angle and flexibility values calculated on a set of 80 ligand-metal complexes retrieved from the Cambridge crystallographic database. Black dots and lines represent the same values predicted using a 2D-descriptor QSAR model.
Figure 6.17 The catalytic hydrogenation of 5-ethoxymethylfurfural 1 in diethyl carbonate can lead to different products depending on the reaction pathway.
Figure 6.18 Graphical explanation of the four descriptors of the Slater function for each metal, where r is the distance of maximum probability of encountering a valence electron and R(r) is the height of the peak at r . The horizontal line shows the peak width at half maximum (FWHM).
Figure 6.19 Matrix plot comparing observed yields (a) to the yields predicted by the OPLS model (b). The products are grouped in columns; the catalysts and temperatures are grouped in rows. The yields are coded from yellow (low yield) to blue (high yield). Both predicted and observed yields are plotted on the same scale.
Figure 6.20 Structure and optimised geometry of a bidentate ligand-Rh complex of type L1 (R1 )−B(R2 )−L2 (R3 ), generated from the building blocks {5, 23, 18, 28, 12, 27} shown in Figure 6.18.
Figure 6.21 A set of building blocks, with black circles denoting the possible connection points.
Figure 6.22 Graphic representation of the distances in a simplified three-dimensional descriptor space (space B). Catalysts with descriptor values ‘within’ the model are good candidates for optimisation. Those ‘outside’ the model space may lead to new discoveries.
Figure 6.23 Iterative approach flowchart for catalyst optimisation (example shown for homogeneous catalysis).
Figure 6.24 Flowchart showing a general approach to data mining.
Figure 6.25 PCA reduces the dimensionality of the problem by projecting the original dataset onto a lower-dimension PC model, in which the new variables are orthogonal to each other. The distance from point A to the PCA model space equals the residual value for catalyst A.
Figure 6.26 Formation of indoles from dissymmetric ketones by the Fischer indole synthesis.
Figure 6.27 VIP plot for various descriptors in a PLS model for the hydrocyanation of pentenenitrile in the presence of Nibiphosphine/biphosphite complexes. Charge descriptors refer to the Mulliken charge calculated at the ligating atoms. ΔE bind is the energy difference between the free ligand and the metal complex, and can be related to the chelating effect and flexibility of the molecule. Socc is the sphere occupation descriptor and measures the sterics around the metal centre. α is the bite angle. a is the second derivative of the flexibility profile polynomial. Δd is the difference in the interatomic distance between the ligating atoms between the free ligand and the complex.
Figure 6.28 An artificial neural network with a multilayer perceptron topology, showing the pathways from the input xi to the output yi , and the ‘visible’ and ‘hidden’ node layers.
Figure 6.29 TON (a) and TOF (b) classification tree structures for a dataset of 412 Pdcatalysed Heck reactions described by a total of 74 descriptors. The black and white bars represent positive and negative experiments, respectively. In the case of TON, the most relevant splitting condition is the Pd loading, < 0.75%. For the TOF, the first splitting condition is the reaction time, followed by the Pd loading, and the ligand’s LUMO energy and R max (the distance between the bulk of the ligand and the metal centre).
Figure 6.30 Structural formulas and of the DiPAMP, BINAP, and Xyliphos ligands.
Figure 6.31 Six of the Rh-ligand ‘alkene zipper’ isomerisation catalysts.
Figure 6.32 Possible metal precursors for making stable doped perovskite catalysts for in situ diesel soot filter regeneration, with the general formula AA′BB′O3 .
Figure 6.33 Schematic representation of mean-centring and autoscaling.
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e1
Concepts and Green Applications
Second, revised and enlarged edition
Author
Gadi Rothenberg University of Amsterdam Van’t Hoff Institute for Molecular Sciences Science Park 904 1090 XH Amsterdam Netherlands
Cover
Cover picture by Itamar Daube, www.itamardaube.com
All books published by Wiley-VCH are carefully produced. Nevertheless, authors, editors, and publisher do not warrant the information contained in these books, including this book, to be free of errors. Readers are advised to keep in mind that statements, data, illustrations, procedural details or other items may inadvertently be inaccurate.
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© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Boschstr. 12, 69469 Weinheim, Germany
All rights reserved (including those of translation into other languages). No part of this book may be reproduced in any form – by photoprinting, microfilm, or any other means – nor transmitted or translated into a machine language without written permission from the publishers. Registered names, trademarks, etc. used in this book, even when not specifically marked as such, are not to be considered unprotected by law.
Print ISBN 978-3-527-34305-8 ePDF ISBN 978-3-527-80888-5 ePub ISBN 978-3-527-80890-8 Mobi ISBN 978-3-527-80889-2
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I never write metropolis for seven cents, because I can get the same price for city .
Mark Twain
This textbook covers the basics of catalysis from a ‘green chemistry’ perspective. Its main message is that heterogeneous catalysis, homogeneous catalysis and biocatalysis are all one discipline, so you need to understand only once how catalysis works. Chapters 1 and 2 introduce and explain the fundamentals of sustainable chemistry, catalysis, and reaction kinetics. Chapters 3–5 show how these principles are applied in homogeneous, heterogeneous, and biocatalysis. The final chapter covers computer applications in catalysis research, including predictive modelling and data mining.
The book is aimed at senior undergraduate students as well as graduate researchers in chemistry and chemical engineering. Each chapter includes detailed literature references, as well as industrial examples and exercises that embed the knowledge in a practical context. I cite reviews and books when introducing a subject, and articles when discussing specific examples. Chapter 1 also contains a ‘Further Reading’ list of recommended books on specialised subjects. To help you master the catalysis jargon, key terms are printed in bold and defined when they first appear in the text. They are also included in the index.
This second edition is updated with the latest developments in catalysis research. I also added 50 new exercises, following the requests and suggestions of many readers. The free-access website accompanying this book, www.catalysisbook.org, has additional teaching material (lecture slides, hand-outs, and answers to selected exercises) that you’re welcome to download and use.
I thank my wife Live for her patience and support, and my colleagues Francesco Mutti and Gooitzen Zwanenburg for their insightful comments. Thanks also to Itamar Daube, who drew the cover picture, and to the Wiley-VCH editors Gudrun Walter, Elke Maase and Jacqueline Terre. Finally, thanks to all those readers of the first edition who sent in suggestions for improvement. Such emails are always welcome.
As you will see, catalysis is one of the most exciting and fun subjects in chemistry. Hopefully you will share some of my enthusiasm and fascination after reading this book.
Amsterdam, April 2017
Gadi Rothenberg