Highly Active ZnO-ZrO2 Aerogels Integrated with H-ZSM-5 for Aromatics Synthesis from Carbon Dioxide

Bifunctional catalysis coupling CO2 to methanol and methanol to hydrocarbons is a promising strategy for the direct hydrogenation of CO2 into high-value chemicals. However, bifunctional catalysts suffer from low productivity due to the inertness of CO2 and high activation energy of C-C coupling. Herein, we report a highly active bifunctional catalyst consisting of a ZnO-ZrO2 aerogel and zeolite H-ZSM-5 for the hydrogenation of CO2 into aromatics with 76% selectivity at a singlepass CO2 conversion of 16%. The selectivity of CH4 is lower than 1% at the same time. The space-time yield of aromatic hydrocarbons is as high as 0.24 g g(oxide)(-1) h(-1) under the reaction conditions of 340 degrees C and 40 bar over ae-ZnO-ZrO2/H-ZSM-5 catalyst, which outperforms the previously reported catalysts, including modified Fischer-Tropsch catalysts. We demonstrate that the ZnO-ZrO2 aerogel catalyst, which is prepared by a combined sol-gel and subsequent supercritical drying method, not only possesses high surface area but also provides large amounts of oxygen vacancies. The formation rate of the methanol intermediate over ZnO-ZrO2 is dominated by the total amount of oxygen vacancies. Moreover, the stable performance of the bifunctional catalyst under industrially relevant conditions suggests promising prospects for industrial applications.