Efficient Conversion of CO2 to Hydrocarbons over the InOx@NPC/(Zn,Al)Beta Tandem Catalysts

Abstract

The hydrogenation of CO₂ to hydrocarbon compounds is a promising approach for CO₂ resource utilization and environmental sustainability. Nevertheless, its efficient conversion to valuable chemicals remains a challenge because of the substantial activation energy barrier associated with CO₂. In this work, yInO_x@NPC materials with varying In contents loaded on N,P-doped carbon (NPC) were prepared through the adsorption of In³⁺ on the amino-phosphoric acid chelating resin D418, followed by carbothermal reduction. Beta zeolite was hydrothermally synthesized, and a series of (Zn,Al)Beta–S_x samples with diverse acidity modified subsequently by Zn isomorphous substitution were prepared via the post-synthesis method. The influence of the In content and electronic properties of carbon-confined yInO_x@NPC, as well as the acidity of the Zn-modified Beta zeolite on the catalytic performance of CO₂ hydrogenation over yInO_x@NPC/(Zn,Al)Beta–S_x tandem catalysts obtained by mixing the powders of yInO_x@NPC and (Zn,Al)Beta–S_x was comprehensively investigated. The results revealed that 1InO_x@NPC/(Zn,Al)Beta–S₂ with the maximum oxygen vacancy density, milder Brønsted acid strength and higher Lewis acid strength enhanced the conversion capability of CO₂ and methanol intermediates, as well as increased the selectivity toward aromatics and C₄ hydrocarbons. Under the optimized reaction conditions, C₄ hydrocarbons selectivity of 41.8% and aromatics selectivity of 42.3% were obtained under CO₂ conversion of 18.8%, and a minimum selectivity of 8.6% for unwanted CO was achieved. The present work provides valuable insights into the development of tandem catalysts with high selectivity for C₄ hydrocarbons and aromatics due to the synergistic catalysis of metal and acid sites.