Commercialization of methane dehydroaromatization (DHA) to produce H
2 and aromatics requires designing catalysts that can be used for long-term cyclic reaction-regeneration [1]. The most commonly aluminosilicate MFI zeolite supports (Al-MFI) irreversibly deactivate with successive DHA cycles due to exposure to hydrothermal conditions (>823 K, >2 kPa H
2O) during regeneration that lead to dealumination and loss of H
+ sites and, in turn, the fraction of ion-exchanged Mo species that are active site precursors for methane DHA [2]. Here, we synthesized Mo supported on small-pore zeolites (e.g., CHA, AEI, RTH) with varying crystallite size and morphology, and Al-free MFI zeolites (i.e., Si-MFI), leading to improved stability compared to Mo/Al-MFI through several DHA cycles (>10). Kinetic measurements show that H
2 and ethene yields measured on Mo/Al-CHA and Mo/Si-MFI are similar to yields measured on Mo/Al-MFI, and that aromatics formation rates (950 K, 90 kPa CH
4) remain invariant over successive DHA cycles for Mo/Al-CHA and Mo/Si-MFI, but not for Mo/Al-MFI. High-resolution TEM imaging, H
+ site titration, and H
2 TPR provide evidence that framework Al sites in CHA are more stable than in MFI, allowing regeneration of Mo active site precursors. H
2 TPR and IR spectroscopy show that silanol nest vacancies in Si-MFI, that serve as anchoring points for Mo redispersion, also remain stable during DHA cycles. Moreover, cumulative carbon (i.e., coke) selectivity measured on Mo/Al-CHA and Mo/Si-MFI is ~1.5–2x larger than on Mo/Al-MFI, which we interpret by comparison alongside zeolite frameworks (e.g., FAU, BEA, TON) with varying pore and cavity size. Kinetic measurements and H
2 TPR data on various Mo-zeolites reveal that both zeolite confinement and pore size influence the extent of aromatics dehydrogenation to form coke. Taken together, our work provides guidance on zeolite material properties that determine rate, selectivity, and stability for methane DHA to aromatics, ethene and H
2.
