Modification of CuO–ZrO2–ZnO Mixed Oxide Catalyst with Mn, Ga, Ni: Impact on Physicochemical Properties and Hydrogen Production via Low Temperature Steam Reforming of Ethanol

Abstract

The influence of CuO/ZrO₂/ZnO (Cu/Zr/Zn) catalyst modification with Mn, Ni, Ga on the physicochemical properties and activity toward hydrogen production in steam reforming of ethanol (SRE) reaction has been evaluated. The increase in hydrogen yield and the lowest selectivity to acetaldehyde were observed upon Cu/Zr/Zn modification with Mn and Ga. The physicochemical characterisation of spent catalysts revealed changes in catalysts phase compositions and reducibility. In the case of Cu/Zr/Zn, Cu/Zr/Zn/Ni and Cu/Zr/Zn/Ga catalysts, the CuO phase was reduced to metallic phase and Cu₂O. Therefore, these spent catalysts exhibited lower reduction degree (Rd) in comparison with fresh catalysts. On the other hand, the addition of Mn preserved the copper on + 2 oxidation state during SRE reaction as indicated by XRD and XPS. The µRaman experiments showed that carbon deposit is formed only on the surface of Cu/Zr/Zn/Ni catalyst, which is the reason for the vast deactivation and the lower total activity of this catalyst in SRE. This was also supported by XPS which additionally showed interaction of carbon containing by-products with the surface active sites. In the case of other synthesised catalysts, no carbon formation was stated.