A sustainable society requires the efficient use of energy and renewable matter. It consequently demands selective new methodologies for the preparation of advanced materials. In this context and as resources based on fossil reserves are rapidly depleting, there are two requirements: first, a change from traditional stoichiometric, high energy methods that produce huge amounts of chemical waste to mild and clean catalytic processes; second, a major step change in chemicals production with fossil fuels being replaced by renewable resources as chemical starter units. The long term aim and vision of catalysis research at EaStCHEM and of this Critical Mass proposal in particular is to develop all-catalytic routes to useful chemicals from renewable resources. We will provide a research environment that both improves and expands the wide range of catalytic processes used in the chemical and pharmaceutical industries. To do this we will exploit renewable and alternative feedstocks including CO2, lignocellulose and other feedstocks formed on multimillion tonnes scale as waste products from agriculture and wood processing. This proposed change in how we access our essential chemicals requires a new generation of catalysts. The challenge is even larger because the renewable substrates are not only difficult to activate (CO2, lignin) but are often available not as pure substrates but as components of a very diverse crude mixtures (e.g. methyl oleate in tall oil). Therefore, novel robust catalysts are required which are capable of combining high activity with superb selectivity and substrate compatibility. The required selectivity resulting in high atom economy, efficiency and environmental factor will only be feasible through the development of new scientific and technological tools. To achieve this challenging objective, existing catalysts must undergo major improvements and new catalysts must be designed for as yet uncatalyzed reactions. As we believe homogenous catalysts offer the unique combination of unprecedented activities and high selectivity, it is timely to combine EaStCHEM's strengths in homogeneous catalysis in this critical mass program to develop sustainable production methods by changing to all-catalytic conversions of renewable feedstocks. The switch to a society which relies on chemical production from all-renewable resources is a challenge of GRAND proportions, and a roadmap for this change must be broken down into smaller components with suitable experts addressing achievable goals. In this proposal we have assessed the strengths in catalysis across EaStCHEM and have designed projects at a variety of risk levels that will significantly impact on the overall change necessary in the challenging move "from oil to biomass". We will: 1. use CO2 as an ever abundant C1 building block in chemical processes that exploit newly developed state-of-the-art catalytic transformations for C-H activation/carboxylation, polymer formation, as well as electro- and chemical reduction processes. 2. We will develop optimal catalysts for ether cleavage in 'real life samples' of lignin for maximising the potential of lignocellulose as a source of fuels and fine chemicals. By combining our expertise in ligand design and computational methods we will develop efficient catalyst based on N-heterocyclic carbenes, wide bite angle phosphines and oxidative enzymes and chemocatalysts. 3. We will develop novel catalytic methods to convert renewable and waste feedstocks to important products such as fuels, chemicals and polymers. As we anticipate that this combined effort will include the de-novo development of new catalyst we will also create a ligand and catalyst synthesis and discovery centre which will support the catalyst development process of all the workpackages for the full duration of the project and thereafter. By focusing our experience and skills in catalysis, we will contribute to a post-fossil fuels world.

The quest for more highly selective, cleaner and more efficient catalysts e.g for olefin trimerisation or tetramerisation remains a high priority for the chemical industry. Achieving these targets demands a detailed understanding of the catalytic cycle(s) and the nature of the active species. Characterisation of the individual stages in a homogeneous catalytic cycle is not easily achieved since the active species are likely to be highly reactive and often very transient, making their crystallographic characterisation highly unlikely. Furthermore, for the paramagnetic e.g. Cr-based catalysts NMR spectroscopy is not informative. Under this project we will develop and use a unique freeze-quench cell to allow the transient and active species to be trapped at various selected stages through the cycle, allowing in situ spectroscopic analysis by extended X-ray absorption fine structure (EXAFS) and X-ray absorption near edge structure (XANES) spectroscopy techniques. We will prepare and characterise a series of related metal complexes based on Cr, Mo and Sc in the presence of a selected set of N-, S-, N/S- and N/P-donor ligands, including complexes of the industrially important NH(CH2CH2Sdecyl)2 and iPrN(PPh2)2. Using a range of techniques (UV-visible, EPR, 45Sc NMR spectroscopy), in conjunction with XAFS and XANES data using the set-up described above, we will probe in detail the oxidation state and structures at various stages through the activation and catalysis to provide a much more detailed understanding of the mechanisms at work. We also expect to demonstrate the potential of the new rapid (millisecond) freeze-quench XAFS/XANES approach much more widely to provide key information regarding other homogeneous catalysis systems.

Catalysis is an extremely important branch of science, which is vital in our modern society. It is estimated that about 90% of all processed chemical compounds have, at some stage of their production, involved the use of a catalyst. As a result catalysis is recognized as a key strategic priority area by EPSRC. In general, catalytic reactions are more energy efficient and, at least in the case of highly selective reactions, lead to reduced waste and undesirable compounds, which is an important consideration with dwindling global reserves of raw materials. New catalysts are being developed for use in alternative energy sources and new conversion technologies, for manufacturing of new materials, for synthesis of molecules such as pure drugs, and for the production of chemicals with minimal energy input. The importance of these developments cannot be overstated. In the past 10 years alone the Nobel Prize in Chemistry was awarded on three separate occasions for the outstanding achievement of scientists whose work has a strong bias in catalysis. Their combined work has revolutionized the field of fine chemical synthesis and chiral feedstock production using well defined and discrete homogeneous organometallic catalysts. Despite the phenomenal success of these homogeneous catalysts, further improvements and developments of new asymmetric catalysts, bio-catalysts and indeed heterogeneous catalysts will benefit from a greater understanding of the mechanistic pathways involved in the catalytic cycles. Undoubtedly a greater understanding of the mechanism can lead to enhanced performance, even with well established systems. Therefore this advancement in our mechanistic understanding of how catalysts function and operate will require the application and development of new techniques that can probe the catalytic reaction and reveal the inner workings of the mechanism in unsurpassed detail. One approach to address this is the development of a unique high pressure system enabling advanced Electron Paramagnetic Resonance (EPR) methods to be used for the first time to study catalytic reactions under extreme conditions. In many cases, paramagnetic metal centers or reaction intermediates are involved in catalytic cycles, so that EPR spectroscopy and the related hyperfine techniques, such as ENDOR and ESEEM, are ideal characterization tools to study reactions at high pressures as a means to gain further insights into reaction mechanism. Since pressure is a primary thermodynamic parameter of central importance in reaction kinetics, chemical equilibria, molecular conformations and molecular interactions, it is very important in catalysis, and becomes a crucial and available parameter to study the reaction mechanisms. Since the equilibria, selectivity, population of states, conformations of the catalyst - substrate intermediates, role of solvent interactions, can all be affected, HP-EPR will be able to examine these properties. The structure, redox states, electronic and spin states, dynamics, non-covalent interactions, conformation changes, relaxation behavior, can all be analysed by these advanced EPR techniques, using the high pressure facility as a means of controlling and enhancing mechanistic variables in order to facilitate their investigations. Pressure also influences the outcome of most chemical processes, and therefore the HP-EPR facility developed in this project can also be applied to a range of other problems in chemistry involving free radicals, from organic and inorganic reactions, to electron transfer and activation of small molecules. Specific collaborative projects in heterogeneous catalysis, spin crossover phenomena, and electron spin states in condensed media, will all be explored using this new HP-EPR assembly.

This project sets out the ambitious goal of achieving atom efficiency and enhanced catalytic activity in "hydrogen free" hydrogenation in continuous flow operation. The work brings together two established research groups with expertise in heterogeneous catalyst preparation, characterisation and reaction engineering (Keane, Chemical Engineering, Heriot-Watt University) and catalytic surface science (Baddeley, Chemistry, St. Andrews University). The synergy that results from this collaboration allows innovation with respect to catalyst design and optimisation with the integration of fundamental and in situ surface science measurements into catalyst synthesis/characterisation and testing. Prior work has established ultra-selectivity in nitro- and carbonyl- group reduction over supported Au catalysts. However, reaction rates were appreciably lower than standard non-selective (Pt, Pd and Ni) metal catalysts due to the activation energy barrier for H2 dissociative adsorption on Au. Gold promoted hydrogenation is conducted in excess H2 that remains unreacted, resulting in fundamental process inefficiency and unsustainability. We propose an innovative coupling of catalytic dehydrogenation (as a source of reactive hydrogen) with hydrogenation. Preliminary data provide proof of concept for the coupling of 2-butanol dehydrogenation with furfural hydrogenation (to furfuryl alcohol) over physical mixtures of oxide supported Au and Cu. We have recorded (orders of magnitude) enhanced H2 utilisation in the coupled system and elevated selective hydrogenation rate relative to the single component Au catalyst. Furfural is a biomass derived heterocyclic aldehyde that can serve as a non-petroleum based renewable feedstock. The target furfuryl alcohol product is a high value chemical used to manufacture resins/rubbers/adhesives and as a chemical building block for drug synthesis. Our proposed coupling reaction is step changing and closes the sustainability gap in terms of unreacted hydrogen. As Au in effect 'borrows' hydrogen generated in situ via Cu promoted dehydrogenation, the coupled system circumvents the use of compressed H2, which has important safety implications for large scale chemical production. We have set out to gain a fundamental understanding of coupled dehydrogenation/ hydrogenation through a programme of surface science measurements involving STM, RAIRS, XPS, TPD and DRIFTS analysis that will provide critical information on reactant/product surface interactions. The work will first focus on reaction coupling over supported Au and Cu physical mixtures, addressing sensitivity to metal particle size and electronic character, the role of the metal/support interface, hydrogen spillover, transport and reactivity. The molecular-level mechanistic understanding provided by the surface science methodologies coupled with a determination of the influence of the gas phase species on surface composition (MEIS) will inform synthesis of supported bimetallics (Au-Cu) with a programme of rational catalyst design directed at achieving the catalyst formulation that delivers the optimum hydrogen utilisation efficiency. Collaboration with Syngenta and Sasol Technology UK as industrial partners will ensure that the work delivers real commercial impact. The ultimate deliverable is a catalytic process than can deliver 100% selectivity at elevated rates in the sustainable hydrogen free hydrogenation of renewable furfuran platform reactants. This proposal fits well with the EPSRC shaping capability agenda, notably the "catalysis" theme, underpinning "energy efficiency", "sustainability" and "frontier manufacturing" priorities. Moreover, the work tackles head on the "Dial-a-Molecule-100% Efficient Synthesis" Grand Challenge with a programme of work directed at the "catalytic paradigms for 100% efficient synthesis" theme.

Aldehydes are important intermediates for the preparation of a large variety of fine- and bulk-chemicals. Applications of these compounds are found in the pharmaceutical industry, aroma and flavour industry, and in the production of agrochemicals and detergents. Many of these products are currently prepared via stoichiometric reactions which often results in large amounts of chemical waste. There is an increasing demand for new production methods based on mild and selective reactions with a very high atom efficiency , thus reducing the chemical waste problem. The rhodium catalysed hydroformylation of alkenes is an example of such a mild and clean process for the production of high-quality aldehydes, using only CO and H2 as reagents and therefore producing no waste products at all.In this project we will develop a new generally applicable catalyst system capable of converting both internal alkenes and conjugated dienes into high value-added aldehydes and / or esters. Atom economic and clean hydroformylation technology of butadiene to the intermediate 1,6-hexanedial would create a major contribution to the sustainable production of polyamides. Many industries and academic researchers, however, have studied the rhodium-catalyzed hydroformylation of butadiene, but generally the reported selectivity for the desired product 1,6-hexanedial is very low. This is caused by the formation of deleterious Rh allyl and enolate complexes, which can be suppressed by simultaneous activation of both alkene functions using properly designed bimetallic catalysts.Therefore, we will develop well-defined tetraphosphine ligand systems for the formation of bimetallic complexes capable of activating otherwise unreactive substrates by mutual interactions with functional groups by both metals. Starting point will be a successful class of bidentate ligands, already developed by the PI, which will be modified in such a way that they can be bridged straightforwardly by condensation with diacids. The resulting tetraphosphines will provide novel bimetallic complexes that will be applied in the hydroformylation of conjugated dienes. In a later stage the novel ligands systems will be explored in different reactions like palladium catalyzed alkoxycarbonylation of dienes. The exact ligand structures can be optimized by subtle changes in steric, electronic and bite-angle properties. In another approach we will aim at coupling of two different ligand backbones which opens the possibility of the formation of heterobimetallic complexes. Differences in the structure of the ligand backbone will have impact on the complexation constants of different transition metals. It is anticipated that this can be employed to influence the preferential coordination of one transition metal over another. It will be investigated if this will lead to the selective formation of heterobimetallic complexes based on rhodium and palladium without interference of homometallic binuclear compounds. We will explore the use of these rhodium palladium heterobimetallic complexes as catalyst for one-pot hydroformylation / methoxycarbonylation of dienes. The formation of these alpha,omega-aldehyde esters via a two-step process has been investigated intensively by DSM/DuPont.The design of the new chiral catalysts will be supported by fundamental spectroscopic (including kinetic) studies of the catalytic species present under actual reaction conditions. HP-NMR will be used to study the structure of the bimetallic complexes under static conditions. The effect of the metal-metal distance on the interaction with bifunctional substrates will be investigated. HP-IR will be used to study these complexes under actual catalytic conditions.