H2 O-Built Proton Transfer Bridge Enhances Continuous Methane Oxidation to Methanol over Cu-BEA Zeolite.

Direct oxidation of methane to methanol (DMTM) is a big challenge in C1 chemistry. We present a continuous N2 O-DMTM investigation by simultaneously introducing 10 vol % H2 O into the reaction system over Cu-BEA zeolites. Combining a D2 O isotopic tracer technique and ab initio molecular dynamics (AIMD) simulation, we for the first time demonstrate that the H2 O molecules can participate in the reaction through a proton transfer route, wherein the H2 O molecules can build a high-speed proton transfer bridge between the generated moieties of CH3 - and OH- over the evolved mono(μ-oxo) dicopper ([Cu-O-Cu]2+ ) active site, thereby pronouncedly boosting the CH3 OH selectivity (3.1→71.6 %), productivity (16.8→242.9 μmol gcat -1  h-1 ) and long-term reaction stability (10→70 h) relative to the scenario of absence of H2 O. Unravelling the proton transfer of H2 O over the dicopper [Cu-O-Cu]2+ site would substantially contribute to highly efficient catalyst designs for the continuous DMTM.