Effect of the property of solid acid upon syngas-to-dimethyl ether conversion on the hybrid catalysts composed of Cu-Zn-Ga and solid acids

Syngas-to-dimethyl ether (STD) conversion was examined on various hybrid ca talysts. The catalyst composed of a methanol-synthesis catalyst and a silic a-rich silica-alumina showed high dimethyl ether (DME) yield (55.5%) with a good selectivity (93.5%). The effects of water on the acid property and on the reaction were examined. At atmospheric pressure, Lewis acid-base pairs were major active sites for methanol dehydration. At higher pressures, how ever, water formed by methanol dehydration was strongly adsorbed on Lewis a cid sites, suppressing the DME formation. The solid-acid catalyst having Br circle divide nsted acid sites with moderate acid strength was the best ca talyst for the STD process. Modification of the methanol-synthesis catalyst s with Pd was effective to enhance the STD activity at low temperatures. (C ) 2000 Elsevier Science B.V. All rights reserved.