Engineering the Dynamic Reconstruction of Fe ₂ O ₃ Precursors on HZSM-5 Zeolite for Tandem Syngas-to-Aromatics Conversion

Direct conversion of syngas to aromatics via bifunctional catalysis offers a promising route for chemical production. However, achieving optimal performance requires precise control over the dynamic reconstruction of Fe-based catalysts into active iron carbides, a process that remains difficult to regulate. Herein, we demonstrate that tuning the initial particle size of Fe 2 O 3 nanoparticle precursors provides an effective handle for controlling this transformation pathway. The catalyst with 120 nm Fe 2 O 3 delivers an aromatics space-time yield of 1.8 mmol g cat −1 h −1 . X-ray absorption spectroscopy (XAS) characterization reveals a reconstruction pathway involving sequential reduction, carburization, and fragmentation of the precursor, leading to the formation of highly dispersed Fe 5 C 2 nanocrystals. In situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) further indicates that olefins generated on Fe 5 C 2 migrate to the Brønsted acid sites of ZSM-5 and undergo aromatization. These findings demonstrate that catalytic performance is governed not only by the nature of the active phase but also by its formation pathway, highlighting reconstruction kinetics control as a strategy for designing catalysts for tandem reactions.