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

摘要

Syngas-to-dimethyl ether (STD) conversion was examined on various hybrid catalysts. The catalyst composed of a methanol-synthesis catalyst and a silica-rich silica-alumina showed high dimethl 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, however, water formed by methanol dehydration was strongly adsorbed on Lewis acid sites, suppressing the DME formation. The solid-acid catalyst having Brdirectsted acid sites with moderate acid strength was the best catalyst for the STD process. Modification of the methanol-synthesis catalysts with Pd was effective to enhance the STD activity at low temperatures.