Synthesize High Efficiency CuO/Mullite Catalysts for Methanol Steam Reforming to Produce Hydrogen: On the SMSI Effect Originating from the Strong CuO-Support Interaction.

Methanol steam reforming (MSR) is a promising and potential technology to supply H2 for on-board power systems utilizing proton exchange membrane (PEM) fuel cells. Developing high-performance catalysts at low temperature is still a great challenge. Herein, CuO-supported on different AMn2O5 mullites (A = Pr, Sm, Eu, Y) have been designed in this work. It has been discovered that CuO/YMn2O5 demonstrates a superior H2 production rate (219.7 µmol·gcat. -1·s-1) with ultra-low CO selectivity (0.12%) at 240°C. XAFS, XRD, Raman, FTIR, and DFT calculations have testified that abundant Cu-O-M (M═Y, Mn) interface bonds are formed as reactive sites, due to a strong metal oxide support interaction (SMOSI) occurring between CuO and YMn2O5, which is confirmed by a significant H2 spillover effect. In situ XPS and 18O2 tracing have proved that the surface oxygen exchange and electron transfer rates can be accelerated, thus forming abundant active surface oxygen sites. Meanwhile, the SMOSI effect remarkably improves the contents of surface Cu0/Cu+ and alkaline sites, and active Cu metallic surface. The synergistic interaction of these factors promotes the activation of CH3OH and H2O molecules and the generation of a great amount of reactive formate intermediates, yielding a catalyst with superior MSR performance.