The Characterization of CuZnZrY Oxide Catalyst in the Steam Reforming of Methanol by EPR and XPS Spectroscopies

摘要

In this paper we have developed the characterization of catalyst containing mainly CuO and ZnO with the addition of zirconium and yttrium oxides,using electron paramagnetic resonance(EPR)and X-ray photoelectron(XPS)spectroscopies.The obtained results support the stepwise reduction mechanism of Cu2+ ions.For the catalyst before the steam reforming of methanol reaction(SRM)the copper species were identified as isolated Cu2+ ions.The values of EPR parameters indicate the coordination of four oxygen atoms around Cu(II)in distorted axial configuration.For the catalyst after SRM reaction the EPR spectrum is complex and four types paramagnetic copper species(S1-S4)could be identified.From the XPS results it is evident that the copper is in a reduced state in the catalyst after reaction.The fitting of O1 s spectrum proves the presence of hydroxide and carbonate anions apart from oxide surface phase.Combining the results of EPR and XPS methods it can be suggested that the S2-S4 species are present on a surface.