Directing CO2 Hydrogenation to Light Aromatics via Molecular Traffic Control in a Dual‑Zeolite Catalyst

Abstract

The direct hydrogenation of CO2 to light aromatics (BTX) suffers from poor product selectivity owing to uncontrolled intermediate evolution and divergent reaction pathways. Herein, we report a rationally designed trifunctional GaZnZrOx/SAPO-34/ZSM-5 catalyst that enables highly efficient CO2-to-aromatics conversion via an integrated relay strategy. The system operates through a spatially organized relay process: CO2 is hydrogenated to methanol over GaZnZrOx, subsequently undergoing cascade C−C coupling and aromatization reactions within a hierarchically structured dual-zeolite domain. The pivotal innovation lies in the kinetic molecular-sieving function of SAPO-34, which discriminatively regulates intermediate diffusion. It preferentially facilitates ethylene transport (diffusion coefficient: 19.0 Å2/ps) to the adjacent ZSM-5 while selectively retarding heavier olefins, thereby effectively channeling the key intermediate toward BTX aromatization. The optimized catalyst exhibits 25.0% CO2 conversion with 81.8% aromatic selectivity under 360 °C and 30 bar. Notably, the BTX space-time yield reaches 78.4 mgproduct·gcat.−1·h−1, accounting for 49.5% of total aromatics and substantially exceeding the performance of single-zeolite counterparts. In situ spectroscopic studies further identify a sustained cracking-aromatization cycle that upgrades polycyclic and heavy intermediates into lighter BTX. This work elucidates the decisive role of precision molecular diffusion management in hierarchical zeolite catalysis, establishing a catalyst design principle for the selective conversion of CO2 to valuable aromatics.