DESIGNING GOLD CATALYSTS FOR THE UTILISATION OF BIO-RENEWABLE FEEDSTOCKS

This proposal seeks to find a new class of important catalysts for use in green oxidation processes. In particular, we will study heterogeneous catalysts, where the reactants and products are in a different phase from the catalyst. Heterogeneous catalysis plays an important role in the well being of the UK economy since it is inherently involved in the manufacture of most finished products from pharmaceuticals to electrical devices. Catalysis is a cornerstone of green technology; however, most of our fuels and feedstocks for manufactured goods such as paints and polymers come from fossil reserves of hydrocarbons. Considerable interest has recently been focussed on the potential sensitivity of the lifestyle within the UK to the possible variation in the availability and price of these hydrocarbon feedstocks. This is becoming increasingly acute for the UK as stocks of economically viable North Sea oil are now declining and the UK will be heavily dependent on imported energy and chemical feedstocks. Against this background there is a current move to increase the utilisation of bio-diesel which is derived from the reaction of methanol with vegetable oils. At present it is permissible to add 5% of bio-diesel to commercial diesel, but this is expected to increase. Unfortunately, bio-diesel production provides large quantities of glycerol as a by-product, for which there is no current large scale use. This is potentially limiting for the take up of biodiesel. Hence glycerol is widely available as a bio-renewable feedstock for which potential green uses have yet to be developed. In addition, there is a range of bio-renewable feedstocks available in the form of carbohydrates. The aim of this research project is to design selective oxidation catalysts that can be used for the oxidation of a wide range of substrates and in addition provide the basis for the efficient utilisation of these bio-renewable feedstocks in new green technologies. Such an approach is desperately needed at present as, even today, many non-green approaches are currently being advocated for selective oxidation. At the heart of this proposal lies the recent discoveries, in the research group of the applicants at Cardiff, that supported gold-palladium nanoparticles are exceptionally effective catalysts for the oxidation of hydrogen to hydrogen peroxide, and the oxidation of alcohols to aldehydes with turnover frequencies >25 times higher than the previously reported best catalysts for this important reaction. We now seek to extend the range of reactions for which these catalysts can be effective and in this way provide a toolbox for selective oxidation reaction of specific functionalities. This approach has two intended outcomes. The first is that we aim to design gold catalysts that can be used in the laboratory as a standard synthetic methodology. In the second, we aim to show that these catalysts can be used also for the oxidation of the significantly more complex bio-renewable feedstocks such as sugars and terpenes. At present we have conducted experiments in autoclave reactors, which are suitable for our initial aim to establish supported gold catalysts as a standard laboratory reagent; we will use a combined discovery catalysis and chemical engineering approach to evaluate options for continuous processes.