The role of H2O and oxidized copper species in methanol steam reforming on a Cu/CeO2/Al2O3 catalyst prepared by one-pot sol–gel method

A Cu/CeO2/Al2O3 catalyst prepared by a single-step sol–gel method was studied for methanol steam reforming (SRM) to gain information on the oxidation state of Cu and the role of oxidized Cu species. The catalyst was tested in a new laboratory-made flow apparatus that allowed on-line analysis of the products and measurement of the oxidation state and dispersion of Cu in situ. The catalyst pre-reduced in H2 was more active and selective than the not pre-reduced one. The oxidation state, evaluated after SRM tests, suggested the presence of a layer of oxygen atoms on the metallic Cu surface. Treating the pre-reduced catalyst with H2O vapour at 250 °C caused dissociative H2O chemisorption and led to a partial oxidation of Cu. The H2O oxidized sample reacted with CH3OH producing CO2 and H2 as long as oxygen was present on the Cu surface. The results support an oxidation–reduction mechanism.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideResearch highlights▶ Treating a Cu/CeO2/Al2O3 catalyst with H2O at 250 °C oxidizes Cu superficially. ▶ The H2O oxidized catalyst reacts with CH3OH at 200–300 °C producing CO2 and H2. ▶ After SRM test, Cu average oxidation state of 0.45 is measured. ▶ The catalyst is more active and selective for SRM after pre-reduction with H2.