Hydrogenation of CO2 to dimethyl ether over nanosized WOx-ZrO2/Cu-ZnO-ZrO2 catalysts

Abstract

In this study, tungsten-zirconia (WOx/ZrO2) catalysts were synthesized by the impregnation method and combined with the CuO-ZnO-ZrO2 catalyst of methanol synthesis for dimethyl ether (DME) by direct hydrogenation of CO2. The calcination temperature of the WOx/ZrO2 catalysts played a vital role in determining their physicochemical properties. The synthesized catalysts were characterized by XRD, FE-SEM, BET, TPD, and XANES/EXAFS to elucidate their composition, morphology, and acidity. At calcination temperatures between 600 and 700 °C, the WOx/ZrO2 catalysts changed slightly in textural properties, while at 800–900 °C, the catalysts specific surface area was lost significantly. The highest surface density and catalytic activity observed for the WOx/ZrO2 catalyst calcined at 800 °C. The combination of CuO/ZnO/ZrO2 and WOx/ZrO2 catalysts, calcination was conducted at 800 °C provided the highest DME selectivity (63.3%), DME yield (9.3%), and CO2 conversion (18.5%) at 240 °C and 30 bar. Cost/benefit analysis estimates a payback period of approximately 3.13 or 1.84 years for a plant design of CO2 catalytic conversion to DME with a capacity of 10– or 20–TPD production.