Abstract: In order to study the deacidification, desulfurization and denitrification activities of hydrotreating catalysts under different conditions and the reasons for the activity reduction, the hydrogenation experiments were carried out with WO3-NiO/Al2O3 as the catalyst and Suizhong vacuum gas oil as feed. The activity stability of the catalysts under severe conditions was investigated byraising temperature and pressure. The results showed that the activity of the catalyst decreased after 600 h ofreaction under high temperature and high pressure, but the specific surface area, pore volume, average pore size and pore size distribution of the catalyst changedslightly compared with the same catalyst without temperature and pressure rise. The results of catalyst characterization show that the reasons for the decrease of activity are the higher carbon content, the reduced content of W4+ and NiWS phase with high activity and the increased content of NiS, W5+ and W6+ with low activity in the active component.

Key words: high acid crude oil, hydrodeacidification, catalyst activity, catalyst characterization