Replacement of mercuric chloride catalysts to produce vinyl chloride monomer from acetylene, the precursor to PVC, is needed due to widespread environmental damage of leached mercury. Cationic gold catalysts, which have been recently commercialised, represent a more environmentally benign alternative. However, new catalysts are required to limit the atomically dispersed cationic Au from agglomeration due to reduction under reaction conditions. Several strategies are available to stabilise the Au active sites such as the use of sulphur containing ligands or to use heteroatom doped carbon as the support. Here we prepared two types of doped carbon supports; spheres derived via a hard template methodology and secondly, doped commercial activated carbon. In both cases the Au supported on S-doped carbon was superior in comparison to the undoped analogue; the acetylene conversion was enhanced by 1.6 times over the S-doped carbon sphere catalyst and 2 times over the S-doped Norit catalyst at 60 min time-on-line. The stability and activity of the gold centres are discussed with respect to the heteroatom used, in this case either sulphur, nitrogen, or a combination of the two, and compared to the unmodified supports.
Cartwright et al. (Wed,) studied this question.