Reactions of methanol and ethylene glycol on Ni/Pt: Bridging the materials gap between single crystal and polycrystalline bimetallic surfaces

The catalytic decompositions of methanol and ethylene glycol on polycrystalline Ni/Pt surfaces were used as model probe reactions to explore oxygenate reforming for H-2 production. In the current study we evaluated whether favorable chemistry observed on single crystal Ni/Pt(111) can be extended to more commercially relevant polycrystalline surfaces, thus bridging the materials gap. Auger electron spectroscopy (AES) confirmed that two distinct bimetallic configurations can be formed for the Ni/Pt system, each possessing unique chemical properties: one with the surface enriched in Ni atoms, designated NiPtPt, and the other with the subsurface region enriched in Ni atoms. designated PtNiPt. Consistent with single crystal studies, temperature programmed desorption (TPD) revealed that the NiPtPt configuration was more active for reforming to CO and H-2 than either polycrystalline Pt or PtNiPt. High-resolution electron energy loss spectroscopy (HREELS) confirmed the presence of strongly bound reaction intermediates on NiPtPt, including aldehyde-like species, which was also observed on Ni-Pt-Pt(111). The strongly bound reaction intermediates most likely contribute to the high reforming activity observed on NiPtPt. Overall. TPD and HREELS results on polycrystailline surfaces were in general consistent with their single crystal counterparts for the reforming of oxygenates. (C) 2009 Elsevier B.V. All rights reserved.