Synthesize High Efficiency CuO/Mullite Catalysts for Methanol Steam Reforming to Produce Hydrogen: On the SMSI Effect...

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·g_cat. ^-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.