Effect of impregnation sequence of Ce on the performance of Cu/Zn-Al catalysts derived from hydrotalcite precursor in methanol steam reforming

ZnAl-LDHs was prepared by in-situ synthesis method on γ-Al₂O₃ and the Cu/Zn-Al, Ce/Cu/Zn-Al, Cu/Ce/Zn-Al and Cu-Ce/Zn-Al catalysts were then obtained by wet impregnation method for methanol steam reforming. The catalysts were characterized by XRD, XRF, SEM, N₂ sorption, XPS, H₂-TPR and N₂O titration; the effect of impregnation sequence of Ce on the performance of the Cu/Zn-Al catalysts in methanol steam reforming to produce hydrogen was investigated. The results showed that the impregnation sequence of Ce has a significant influence on the reducibility of resultant catalyst, which subsequently affects the catalytic performance. The Ce/Cu/Zn-Al catalyst exhibits the highest activity; over it, the methanol conversion reaches 100% under 250℃ and with a water/methanol molar ratio of 1.2 and gas hourly space velocity of 800 h^-1, which is almost 40% higher than that achieved on the Cu/Zn-Al catalyst.