Modified Fischer–Tropsch Pathway for CO2 Hydrogenation to Aromatics: Impact of Si/Al Ratio of H-ZSM-5 Zeolite on Light Aromatics Selectivity

This is the authors' abstract. We don't add key points for this paper.

Despite significant advancements in designing tandem catalysts for CO2 hydrogenation to aromatics, the role of zeolite acid property in regulating the selectivity of light aromatics (benzene, toluene, and xylene, abbreviated as BTX) remains unclear. Herein, we report H-ZSM-5 zeolite (denoted as HZ-X, where X represents the Si/Al ratio) integrated with a Na-promoted FeCo-based catalyst (NaFeCo) for CO2 hydrogenation into aromatics via a modified Fischer–Tropsch synthesis pathway. This study systematically modulates the Si/Al ratio of acidic zeolite and examines its critical role in influencing the light aromatics selectivity. The optimized NaFeCo/HZ-50 catalyst achieves a CO2 conversion of 43% with an aromatics selectivity of 41%, including a BTX fraction of 57% in total aromatics. Multiple characterization techniques (NH3-TPD, Py/DTBPy-IR, 27Al NMR, etc.) clarify that acidic zeolite HZ-50 exhibits appropriate acid density and lower external surface acid sites, which synergistically boost the efficient aromatics and BTX synthesis while suppressing the undesirable alkylation and isomerization reactions on the external acid sites. This work develops a highly efficient multifunctional catalyst for CO2 hydrogenation to light aromatics, especially offering guidance for the rational design of acidic zeolite with unique shape-selective functions.