New Tricks for an Old Dog: Grubbs Catalysts Enable Efficient Hydrogen Production from Aqueous-Phase Methanol Reforming

Herein, we report a new application of the prize-winning Grubbs catalysts, which have been widely applied for olefin metathesis, for hydrogen production from aqueous-phase methanol reforming under easily achievable conditions (1 atm, <100 °C) with negligible CO formation. Out of the catalysts tested, the best turnover frequency (158 h^-1) and turnover number (11424, 72 h) were both achieved with a third-generation Grubbs catalyst (G-III). The best TOF was achieved with G-III and is competitive when compared with some of the best results reported ( Chem. Rev. 2018, 118, 372−433). Also, G-III is found to be a versatile catalyst for the dehydrogenation of ethanol and formic acid. Mechanistic studies and DFT calculations shed light on the reaction mechanism, which involves an unusual substrate (solvent)-assisted six-membered-ring (σ-bond) metathesis pathway. This work should open up new opportunities in catalyst design in connection with the hydrogen economy and, more generally, with the development of clean and renewable energies.