Bifunctional catalyst consisting of In-modified GaZrOx ternary solid solution oxide and SAPO-34 for efficiently converting CO2 into light olefins

Abstract

Converting CO2 into light olefins (C2=–C4=) using oxide–zeolite bifunctional catalyst is a new strategy for producing light olefins. Herein, a series of bifunctional catalysts comprising In-doped GaZrOx oxides and SAPO-34 molecular sieves for CO2 hydrogenation to light olefins are reported, and their catalytic mechanisms are investigated using in situ spectroscopy. After optimizing the In doping amount, oxide calcination temperature, oxide coupling mode with SAPO-34, and reaction conditions, the bifunctional catalysts achieved 82.8% C2=–C4= selectivity, 24% CO2 conversion, and up to 10.1% C2=–C4= yield. Furthermore, no considerable deactivation was observed after 100 h of the reaction. Various characterization and experimental results indicate that adding In to GaZrOx promotes oxygen-vacancy generation and enhances the adsorption activation of CO2 and H2, thereby promoting the formation of formate (HCOO*) and methoxy (CH3O*) intermediates and improving the catalytic performance of the C2=–C4= synthesis from CO2.