Diffusion-acidity cooperative effect in ZnZrOx/SAPO-34 tandem catalysts for enhanced CO2-to-propylene conversion

Achieving carbon neutrality requires the development of rational catalytic strategies for efficient CO 2 utilization, particularly toward propylene, which global demand continues to increase. Herein, a diffusion-acidity cooperative effect strategy is proposed and implemented using ZnZrO x /SAPO-34 tandem catalysts to enhance propylene selectivity in CO 2 hydrogenation. Compared with a ZnZrO x /conventional SAPO-34 catalyst, which exhibits 29.4% propylene selectivity among hydrocarbons, the optimized ZnZrO x /SAPO-34 system delivers a CO 2 conversion of 19.2% with a substantially improved propylene selectivity of 52.6%, further rising to 57.4% at higher gas hourly space velocity. The results reveal that accelerating molecular diffusion within SAPO-34 promotes the rapid transport and transformation of hydrogenated intermediates formed on ZnZrO x , thereby suppressing undesired secondary hydrogenation pathways. Simultaneously, an increased content of strong Brönsted acid sites associated with Si(0Si,4Al) and Si(1Si,3Al) facilitates selective propylene formation. These findings suggest diffusion-acidity cooperative effect as a possible design principle for efficient CO 2 -to-propylene conversion over ZnZrO x /SAPO-34.