Hydrogenation of CO₂ to Dimethyl Ether over Brønsted Acidic PdZn Catalysts

Abstract

Eschewing the common trend toward use of
\ncatalysts composed of Cu, it is reported that PdZn alloys are
\nactive for CO2 hydrogenation to oxygenates. It is shown that
\nenhanced CO2 conversion is achievable through the
\nintroduction of Brønsted acid sites, which promote dehydration
\nof methanol to dimethyl ether. We report that
\ndeposition of PdZn alloy nanoparticles onto the solid acid
\nZSM-5, via chemical vapor impregnation affords catalysts for
\nthe direct hydrogenation of CO2 to DME. This catalyst shows
\ndual functionality; catalyzing both CO2 hydrogenation to
\nmethanol and its dehydration to dimethyl in a single catalyst
\nbed, at temperatures of >270 °C. A physically mixed bed
\ncomprising 5% Pd 15% Zn/TiO2 and H-ZSM-5 shows a
\ncomparably high performance, affording a dimethyl ether synthesis rate of 546 mmol kgcat
\n−1 h−1 at a reaction temperature of 270
\n°C.