The deactivation of a commercial Ni/Al2O3 catalyst in the liquid phase hydrogenation of crude 1,4-butanediol aqueous solution was investigated. A significant deactivation trend was observed during the operation time of 5000 h. The fresh and deactivated catalysts were characterized by ICP-AES, N-2 physisorption, H-2-TPR, TEM, TPD, FTIR and XRD. The results indicate that, during the reaction process, the Al2O3 support transforms into its hydrate boehmite (gamma-AlO(OH)), which further results in the aggregation of metal Ni, the decrease of BET specific surface area and the reduction of pore volume. The hydration of Al2O3 support is the main reason for the deactivation of Ni/Al2O3 catalyst. The promotion effect of SiO2 on the activity and stability of Ni/Al2O3 catalyst was also investigated. The results suggest that the introduction of SiO2 effectively inhibits the hydration of Al2O3 support and prevents the active decay of Ni/Al2O3 catalyst. (C) 2011 Elsevier B.V. All rights reserved.