H2O-Built Proton Transfer Bridge Pronouncedly Enhances Continuous Methane Oxidation to Methanol over Cu-BEA Zeolite

TLDR: In this article, the authors presented a continuous N 2 O-DMTM investigation by simultaneously introducing 10 vol% H 2 O into the reaction system over Cu-BEA zeolites.

Abstract: Direct oxidation of methane to methanol (DMTM) constitutes a big challenge in C 1 chemistry. Herein, we present a continuous N 2 O-DMTM investigation by simultaneously introducing 10 vol% H 2 O into the reaction system over Cu-BEA zeolites. Combining a D 2 O isotopic tracer technique and ab initio molecular dynamics (AIMD) simulation, we for the first time demonstrate that the H 2 O molecules can participate in the reaction through a proton transfer route, wherein the H 2 O molecules can build a high-speed proton transfer bridge between the generated moieties of CH 3 - and OH - over the evolved mono(μ-oxo) dicopper ([Cu-O-Cu] 2+ ) active site, thereby pronouncedly boosting the CH 3 OH selectivity (3.1 → 71.6%), productivity (16.8 → 242.9 μmol g cat -1 h -1 ) and long-term reaction stability (10 → 70 h) relative to the scenario of absence of H 2 O. Unravelling the proton transfer of H 2 O over the dicopper [Cu-O-Cu] 2+ site would substantially contribute to highly efficient catalyst designs for the continuous DMTM.