A Highly Selective Cr2O3/nano-ZSM-5 Bifunctional Catalysts for CO2 Hydrogenation to Aromatics

The direct conversion of CO2 to aromatics is an effective strategy for simultaneously achieving carbon neutrality and its resource utilization. However, it is a great challenge to efficient CO2 conversion to high value-added aromatics due to the chemical inertness and characteristics of multi-path conversion of CO2. In this work, a series of nanosized ZSM-5 zeolites [NZ5(x)] with different acid amount and strength were synthesized by a seed-induced template-free method via changing the initial gel composition. The Cr2O3 nanoparticle was prepared by simple precipitation method. The performance of the Cr2O3/NZ5(x) bifunctional catalysts composed of Cr2O3 and nano-ZSM-5 zeolites with different acidity, and mixed Cr2O3 with NZ5 (50) by different ways in the CO2 hydrogenation reaction was investigated. The Cr2O3/NZ5(50) catalyst with suitable acidity and closest metal-acid site distance exhibit the highest aromatics selectivity of 87.2% among all hydrocarbon products at CO2 single-pass conversion of 13.6%, which is due to the synergistic effect between the acid sites of the nanosized ZSM-5 zeolite and metal sites provide by Cr2O3 with abundant oxygen vacancies.