Highly Selective Conversion of Carbon Dioxide to Aromatics over Tandem Catalysts

Abstract

Summary Conversion of CO2 to aromatics is a promising route to realize the proposal on carbon capture and utilization based on strategic CO2 carbon resource. In this work, CO2 is converted to aromatics with aromatics selectivity up to 73% at CO2 conversion of 14%, and the selectivity of CO was suppressed down to 44% over a tandem catalyst ZnZrO/ZSM-5, which was constructed by using ZnZrO solid solution and H-ZSM-5 zeolite. The selectivity of aromatics can reach to 78% at the space velocity of 1,800 mL/gcat/h. Tandem catalysis enables the direct hydrogenation of CO2 to aromatics favorable in thermodynamics through the coupling of CO2 hydrogenation over ZnZrO and aromatics formation over H-ZSM-5. The H2O generated through CO2 hydrogenation over ZnZrO can obviously increase the selectivity of aromatics and the CO2 in the reaction system promotes the formation of aromatics. Interestingly, it is found that the presence of H2O and CO2 significantly suppresses the generation of polycyclic aromatics and consequently enhances the stability of the tandem catalyst; therefore, no obvious deactivation of tandem catalysts was observed for at least 100 hr in the reaction stream.