Structure–performance correlations in the hybrid oxide-supported copper–zinc SAPO-34 catalysts for direct synthesis of dimethyl ether from CO2

Abstract

Growing CO2 emissions lead to global warming, which is currently one of the most challenging environmental phenomena. Direct catalytic hydrogenation to dimethyl ether over hybrid catalysts enables CO2 utilization, hydrogen and energy storage and produces sustainable fuels and an important platform molecule. In this paper, we evaluated structure–performance correlations in the bifunctional hybrid copper–zinc SAPO-34 catalysts for direct synthesis of dimethyl ether via CO2 prepared using zirconia, alumina and ceria used as oxide carriers. Higher copper dispersion and higher CO2 conversion rate were uncovered over the alumina and zirconia supported catalysts followed by ceria supported counterpart. The CO2 hydrogenation seems to be principally favoured by higher copper dispersion and to a lesser extent depends on the concentration of Bronsted acid sites in the studied catalysts. Because of lower reverse water gas-shift activity, the alumina supported catalyst exhibited a higher dimethyl ether yield compared to the zirconia and ceria supported counterparts.