An Efficient, Stable Hierarchical Zeolite for CO 2 Hydrogenation to Light Olefins

Direct CO2 hydrogenation to light olefins (C2=–C4=) is attracting significant attention as an effective way to recycle carbon and use renewable energy. However, developing a cost-effective, highly active, and selective catalyst, especially with stable catalytic performance, remains a great challenge. Herein, we report an economical seed-assisted strategy for the synthesis of hierarchical SAPO-34 zeolites without using any post-treatment or mesoporogens by employing triethylamine and micrometer-scale seeds (Sm) as structure-directing agents. When coupling ZnZrOx oxide and the above-synthesized zeolite using an ultralow amount of Sm, high performance for CO2 hydrogenation is obtained with C2=–C4= selectivity of 83.4% (CO-free) and stability for at least 648 h, attributed to the significantly enhanced diffusion rates and feeble acidity of the zeolite. In situ characterizations and computational studies demonstrate that the transformation of CO2 and H2 into C2=–C4= proceeded via a methanol-mediated pathway, which also revealed the reasons for the pronounced selectivity toward propylene among the C2=–C4= products. This SAPO-34 zeolite also exhibits versatile application potential for the efficient conversion of syngas, a CO/CO2/H2 mixture gas, and methanol into light olefins. This work thus develops an eco-friendly approach for facile and large-scale synthesis of hierarchical SAPO-34 zeolites with long-term stability, thus removing a major barrier preventing its practical applications.