Enhancing the catalytic performance of ZnZrOx/SAPO-34 bifunctional catalysts through structural modulation

Global warming caused by CO 2 has drawn increasing attention in recent years. Direct hydrogenation of carbon dioxide to light olefins (C 2 = -C 4 = ) is considered a promising strategy for carbon reduction. However, the catalytic performance of metal oxide/zeolite bifunctional catalysts still requires further optimization to enhance CO 2 conversion efficiency and C 2 = -C 4 = selectivity. This study incorporates a hierarchical porous structure into SAPO-34 molecular sieves to modulate their pore channel structure, while Mg doping is introduced into ZnZrOₓ to improve its crystal structure. Characterization results, including NH 3 -TPD and CO 2 -TPD, reveal that structural modifications improve the acidity of the SAPO-34 molecular sieve and enhance the CO 2 adsorption and activation capacity of ZnZrO x . The catalytic performance of the Z/S bifunctional catalyst was evaluated under the following reaction conditions: mass ratio of ZnZrO x to SAPO-34 (Z:S) = 1:1, reaction temperature = 380°C, reaction pressure = 2 MPa, and gas hourly space velocity (GHSV) = 16,000 mL·g cat ⁻¹ ·h⁻¹ . The bifunctional catalyst, composed of ZnZrO x doped with 3 % Mg and SAPO-34 with a mesoporous structure, demonstrated a CO 2 conversion of 10.7 % and a C 2 = -C 4 = selectivity of 78.8 % under these conditions, outperforming other Z/S catalysts. This work offers both theoretical and experimental insights for the design of highly efficient bifunctional catalysts for CO 2 hydrogenation to C 2 = -C 4 = .