Investigation on the performance of bimetallic catalysts for methanol-to-aromatics: Active site regulation and enhancement of formaldehyde-mediated reaction pathways

Methanol-to-aromatics (MTA) technology represents an important approach for the efficient utilization of coal resources; however, conventional ZSM-5 zeolites suffer from low BTX selectivity and susceptibility to coking deactivation. This paper proposes a bimetallic co-impregnation strategy that directs methanol conversion toward a formaldehyde-mediated Prins aromatization pathway by tuning the distribution of active sites and the reaction pathway. The optimized ZnNi/Z5 catalyst exhibits excellent performance in a fixed-bed reactor: BTX selectivity reaches 56.54%, methanol conversion remains at 100% for 32.0 h, total lifetime extends to 45.3 h, and coke deposition is only 9.79%, significantly lower than that of monometallic Zn/Z5 (24.03%). Combining density functional theory (DFT) and molecular dynamics (MD) simulations, the microscopic mechanism of the bimetallic synergy is revealed: the introduction of Ni promotes the formation of highly active Zn(OH) + species (increasing their proportion from 61% to 70%), optimizes the acid strength distribution, and regulates the adsorption and diffusion behaviors of key intermediates such as CH 2 O and C 2 H 4 O, enhancing CH 2 O diffusion capacity and tuning the d-band center position, thereby supporting the formaldehyde-mediated selective aromatization pathway. This study provides new insights into metal synergy and reaction pathway engineering, as well as a theoretical basis for the design of high-performance MTA catalysts.