Understanding Liquid Phase Heterogeneous Catalysis to Develop Catalytic Processes

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This project is associated with the understanding of heterogeneous catalysts for liquid phase reactions. In particular, we aim to develop a number of techniques by which to probe the reactions within the pores of the heterogeneous catalysts in order to correlate the activity-selectivity of the catalyst with the specific surface and liquid phase interactions. This research will bridge the knowledge gap between understanding the properties of liquids confined in the pores of typical heterogeneous catalysts, and their applications. This lack of understanding of the multiphase interactions underpinning the chemical efficacy of these complex systems is one of the major factors restraining the advancement of many sustainable catalytic processes which involve complex solid/liquid and solid/liquid/gas interfaces. For example, diffusion processes as well as adsorption are critically important in determining the selectivity of these multiphase reactions. However, within the pores of the catalyst in liquid phase reactions it is difficult to evaluate their relative contributions as the observed global kinetics observed are a combination of surface reaction kinetics as well as mass transport. A range of complementary NMR and neutron scattering techniques will be established from which, for example, the diffusion characteristics, pore liquid phase structure and adsorption modes will be elucidated under reaction conditions. The information from these new techniques will be combined with X-ray absorption and infra-red spectroscopy data as well as Density Functional Theory calculations and kinetic modelling in order to obtain a complete description of a gas/liquid reaction within a porous heterogeneous catalyst system under reaction conditions. In order to develop the techniques two families of exemplar selective hydrogenation reactions will be used. The hydrogenation of phenylacetylene to styrene and ethylbenzene will provide a test bed for the techniques which requires low pressures and temperatures and is a sequential reaction. Once established, higher pressure and temperature cells will be developed to enable the study of aromatic acid hydrogenation. The catalyst for this reaction can be tailored to favour a number of products including the aromatic alcohol, ring hydrogenated alcohol or toluidyl derivatives and presents a more challenging process with multiple pathways but one which is industrially very relevant. The project will be undertaken by the Queen's University of Belfast, University of Cambridge, ISIS and Johnson Matthey in close collaboration.