Low-pressure methanol/ dimethylether synthesis from syngas on gold-based catalysts

The hydrogenation of carbon monoxide over Au/ZnO catalysts has been re-examined and new data is presented on the way in which the product distribution can be manipulated by choice of coadded solids such as alumina or zeolite-Y. This comparative study reveals that while ZnO itself leads to a high selectivity to methanol, the incorporation of gold drastically alters the product spectrum and leads to a very high selectivity to hydrocarbons. The hydrocarbon selectivity at a reaction temperature of 300oC is in fact much higher than in the case where alumina or zeolite-Y is introduced into a composite catalyst comprising the Au/ZnO and the acidic solid. In the latter case DME is a major product. Significant light hydrocarbon formation on gold-based systems under these circumstances appears not to have been discussed before. The reactions taking place on these catalysts, the selectivities and absolute activities are discussed and the role of gold highlighted.