Highly selective and multifunctional Cu/ZnO/Zeolite catalyst for one-step dimethyl ether synthesis: Preparing catalyst by bimetallic physical sputtering

Abstract

Generally direct synthesis of dimethyl ether (DME) from syngas (CO+H2) containing CO2 uses physical mixture catalyst composed of methanol synthesis catalyst and solid acidic catalyst for dehydration of methanol. But the distance between these two catalysts is far and easy to become separated. Here we report Cu/ZnO methanol synthesis catalyst which is directly loaded onto acidic zeolite catalyst, to accomplish direct synthesis of DME from syngas. The intimate contact between these two catalysts improves consecutive reaction efficiency, achieving high DME selectivity. Conventional wet impregnation method to prepare this kind of catalyst will make Cu cations adsorbed onto zeolite sites very strongly, which are almost impossible to be reduced due to the very strong interaction from zeolite surface. To solve this problem, we propose a new physical sputtering method here to directly load metallic Cu and Zn clusters onto acidic zeolite catalyst surface, to readily obtain highly selective and multifunctional Cu/ZnO/zeolite catalyst. This dry method does not produce waste water containing NO3+ ion, which is very troublesome in the environment.