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Gold catalysts for the hydrochlorination of acetylene

Davies, Catherine 2013. Gold catalysts for the hydrochlorination of acetylene. PhD Thesis, Cardiff University.
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Abstract

The direct, gas-phase hydrochlorination of acetylene is a method by which vinyl chloride monomer (VCM) is produced industrially. VCM is polymerised to produce poly-vinyl chloride (PVC), one of the world’s most widely used plastics. Although other methods, using oil-derived ethene, are now more widely used, hydrochlorination of acetylene, which is coal-derived, is still the preferred method in areas where coal is a cheap and widely available resource. However, there are numerous problems associated with the mercury based catalysts which are traditionally used for this process, largely for environmental reasons, and therefore a new catalyst is desirable. Gold based catalysts have been shown to be active and particularly selective for this reaction, but deactivation with use is still an issue restricting commercial application. Previously it has been demonstrated that Au3+ is likely to be the active site for acetylene hydrochlorination by Au/C catalysts, and that deactivation of the catalysts during reaction above 120°C is due to reduction of this species to Au0. Therefore Au/C catalysts have been investigated in detail, in order to investigate the true importance of the Au3+ species. Catalysts were prepared with numerous variations in the method used, including the acid used for impregnation and the drying temperature, and subjected to oxidation and reduction treatments. Characterisation was carried out by temperature programmed reduction (TPR) in addition to XPS which has been typically used to identify the surface species of such catalysts. TPR was found to be a technique which is able to provide an extensive amount of information about both the gold and the carbon support and enabled it to be shown that whilst Au3+ is important for catalytic activity, its presence alone is not sufficient and the reducibility of this species is a key factor.

Item Type: Thesis (PhD)
Status: Unpublished
Schools: Chemistry
Subjects: Q Science > QD Chemistry
Date of First Compliant Deposit: 30 March 2016
Last Modified: 04 Jun 2017 05:02
URI: http://orca-mwe.cf.ac.uk/id/eprint/47618

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