Highly Active Catalytic CO2 Hydrogenation to Lower Olefins via Spinel ZnGaOx Combined with SAPO-34.

A key primary method for creating a carbon cycle and carbon neutrality is the catalytic hydrogenation of CO2 into high value-added chemicals or fuels. In this work, ZnGaOx oxides were prepared by parallel co-precipitation and physically mixed with SAPO-34 molecular sieves prepared by hydrothermal synthesis to produce ZnGaOx /SAPO-34 bifunctional catalysts, which were evaluated for the catalytic synthesis of lower olefins (C2 = -C4 = ) from carbon dioxide hydrogenation. It was demonstrated that the reaction process requires oxygen defect activation, synergistic hydrogenation, and CO2 alkaline adsorption of ZnGaOx . The spinel structure of ZnGaOx has more abundant oxygen defects and alkaline adsorption sites than the ZnGaOx solid solution, which effectively enhances the catalytic performance. The CO2 conversion was 28.52%, the selectivity of C2 = -C4 = in hydrocarbons reached 70.01%, and the single-pass yield of C2 = -C4 = was 10.95% at 370 °C, 3.0 MPa, and 4800 mL/gcat /h.