Designing Cu0−Cu+ dual sites for improved C−H bond fracture towards methanol steam reforming

Abstract Copper-based catalysts serve as the predominant methanol steam reforming material although several fundamental issues remain ambiguous such as the identity of active center and the aspects of reaction mechanism. Herein, we prepare Cu/Cu(Al)O x catalysts with amorphous alumina-stabilized Cu 2 O adjoining Cu nanoparticle to provide Cu 0 −Cu + sites. The optimized catalyst exhibits 99.5% CH 3 OH conversion with a corresponding H 2 production rate of 110.8 μmol s −1 g cat −1 with stability over 300 h at 240 °C. A binary function correlation between the CH 3 OH reaction rate and surface concentrations of Cu 0 and Cu + is established based on kinetic studies. Intrinsic active sites in the catalyst are investigated with in situ spectroscopy characterization and theoretical calculations. Namely, we find that important oxygen-containing intermediates (CH 3 O* and HCOO*) adsorb at Cu 0 −Cu + sites with a moderate adsorption strength, which promotes electron transfer from the catalyst to surface species and significantly reduces the reaction barrier of the C−H bond cleavage in CH 3 O* and HCOO* intermediates.