Beyond equilibrium shift: Unveiling the kinetic promotion in a methanol steam reforming membrane reactor

Abstract Membrane reactors (MRs) are widely recognized for enhancing thermodynamically limited reactions by continuously removing a product. However, how such in situ selective separation directly impacts intrinsic reaction kinetics and mechanisms has remained ambiguous and lacks direct spectroscopic evidence. Here, we address this fundamental question using a MR integrating a commercial Cu/ZnO/Al 2 O 3 catalyst with carbon molecular sieve (CMS) membranes for methanol steam reforming. The CMS membrane‐based MR exhibits a remarkable one‐fold enhancement in methanol conversion over a conventional reactor at 180°C, while simultaneously reducing CO selectivity by 61.3%. Crucially, in situ Fourier Transform Infrared Spectroscopy provides direct evidence that this enhancement stems from a profound kinetic acceleration of the rate‐determining methoxy dehydrogenation step. This acceleration is driven by efficient removal of H 2 , which alleviates product inhibition on the catalyst's active sites. This work elucidates a powerful kinetic promotion mechanism, shifting the paradigm of membrane catalysis beyond its thermodynamic role.