Selective light olefin synthesis with high ethylene abundance via CO2 hydrogenation over (Ga-In)2O3/SSZ-13 catalysts

Abstract

Direct light olefin synthesis from CO₂ hydrogenation is a new pathway to decarbonize the chemical industry. Inspired by the promising catalytic activity of Ga₂O₃-based catalysts in alkane dehydrogenation, this study reveals that optimizing Ga content in the Ga_xIn_2-xO₃/SSZ-13 catalytic system can narrow the product distribution toward light olefins. The optimized catalyst exhibits light olefin and C₂H₄ selectivity up to 84 % and 45.9 %, respectively, amongst C₂₊ hydrocarbons with a maximum olefin/paraffin ratio of 6.4 and a CO₂ conversion of 14.8 % at 20 bar and 653 K. In particular, a sevenfold increase in C₂H₄ space-time yield compared to pure metal oxides on SSZ-13 was observed, along with the gradual suppression of C₃H₈ formation. Herein, we established a catalyst structure-performance relationship as a function of chemical composition. As such, CO and paraffin formation rates can be suppressed, and light olefin formation rates can be enhanced. Therefore, the change in light olefin STY upon gallium incorporation could be ascribed to modulations in the structural and electronic properties, as well as alterations in the surface adsorption and acidic strengths. The findings presented here provide a strategy to tune CO₂ hydrogenation product distributions toward specific target products.