Epitaxial Ga/ZSM-5@S-1 core-shell zeolites boost CO₂-coupled propane aromatization

Mitigating climate change necessitates efficient carbon capture and utilization (CCU) strategies. However, current CO₂ conversion technologies are often constrained by their reliance on molecular hydrogen (H₂), which is energy-intensive and economically burdensome to produce. Coupling CO₂ conversion with alkane aromatization offers a promising solution by utilizing in situ hydrogen species from alkanes. However, the efficiency of such systems is often compromised by the random distribution of active sites in conventional catalysts, which leads to competitive adsorption and inefficient H species utilization, ultimately restricting CO₂ conversion. Here, this study reports a Ga/ZSM-5@S-1 catalyst synthesized via epitaxial growth, achieving a high CO₂ conversion of ∼75% alongside ∼73% BTX selectivity in propane (C₃H₈) aromatization. XPS sputtering, in situ X-ray absorption near-edge structure (XANES), wide-angle X-ray scattering (WAXS), and in situ spectroscopic characterization reveal two distinct (Ga₂O₂)²⁺ species in Ga/ZSM-5@S-1: one at the BAS and another at surface hydroxyl sites on the S-1 shell, spatially separated from the BAS. The latter species provides additional adsorption sites for CO₂ during the reaction. Density functional theory (DFT), ab initio molecular dynamics (AIMD) simulations, and isotope-labeled kinetics demonstrate that hydrogen species (H*) preferentially accumulate on (Ga₂O₂)²⁺ sites, which correlates with enhanced CO₂ conversion. Furthermore, GC-MS, in situ MS, and FTIR reveal a novel pathway in which CO₂ serves as an oxygen source, inserting into hydrocarbon chains to form oxygenated intermediates that boost aromatic production. This study establishes a new paradigm for the rational design of bifunctional catalysts, enabling highly efficient, value-added conversion of CO₂ in the presence of alkanes.