Steam reforming of methanol over Cu/ZnO/Al2O3 modified with hydrotalcites

Dilution of a commercial Cu/ZnO/Al2O3 (CZA) catalyst by well-crystallized MgAl hydrotalcite nitrate (HTNO3) and chloride (HTCl) resulted in the formation of the modified samples CZA–HTN and CZA–HTCl, respectively. The samples were characterized by N2 sorption and XRD measurements. The structures of the CZA–HT materials proved to be more compact than those of the pristine clays. The modified samples were investigated as catalysts for the steam reforming of methanol under steady state conditions. The catalytic activity and the long-term stability of CZA–HT were found to depend strongly on the nature of the interlamellar anion of HT. CZA–HTN exhibited a marked catalytic activity and an enhanced thermal stability. It was pointed out that dilution with HTNO3 improved the catalytic performance of CZA by increasing the methanol conversion and decreasing the CO production. The moderate increase in the methanol conversion for CZA–HTN during time-on-stream was attributed to partial delamination of the HT structure under SRM conditions. The application of an enhanced H2O:MeOH ratio of 1.3 for CZA–HTN was found to decrease both the methanol conversion and the CO formation to an appreciable extent.