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Catalytic significance of gold oxidation states

16 November 2011

Gold Chloride

A team from the School of Chemistry at Cardiff, consisting of Dr Phil Davies, Prof Mike Bowker, Dr Albert Carley and Dr David Willock have been awarded a major grant by EPSRC (EP/I038748/1) to investigate the processes, intermediates and active sites involved in the hydrochlorination of ethyne over gold chloride nanoparticles supported on carbon surfaces.

The hydrochlorination of ethyne is an alternative route to vinyl chloride which is polymerised to polyvinyl chloride (PVC) an important polymer with widespread applications in the construction and electronics industries. At present, vinyl chloride is manufactured by a two step process involving the oxychlorination of ethene but sixty years ago it was almost exclusively made by the direct hydrochlorination of ethyne which derives from coal, over a mercury chloride catalyst. The availability of inexpensive ethene from oil led to a change of manufacturing route despite the lower yields, lower product purity and higher costs for waste treatment. Now, dwindling oil reserves and increasing environmental awareness are dictating a search for alternatives to the oxychlorination route. The safety and environmental issues posed by HgCl2 prevent a return to the former catalyst but the director of the Cardiff Institute of catalysis, Prof Graham Hutchings and co-workers showed a few years ago that gold supported on carbon is a viable alternative [1].

The new project will make use of a powerful combination of surface spectroscopy, surface microscopy and surface kinetic methods applied in conjunction with computational chemistry will be focussed on identifying and characterising the active states of gold in ideal models of the hydrochlorination catalyst. The aim is not only to inform the development of effective hydrochlorination catalysts but also to provide a new insight into the important field of gold catalysis.

[1] Conte, M.; Carley, A. F.; Heirene, C.; Willock, D. J.; Johnston, P.; Herzing, A. A.; Kiely, C. J.; Hutchings, G. J. J. Catal. 2007, 250, 231-239