Abstract: The spent catalyst in a domestic resid hydrotreating unit after long-term operation was collected , and a comprehensive analysis was conducted. The deposition of Ni and V on the catalyst in the unit showed a trend of first increasing and then decreasing along the flow direction, and mainly deposited on the HDM catalyst in the reactors R1-R3. The R1-HDM3 catalyst had the highest Ni and V deposition, reaching 31.3% and 92.2%, respectively. Fe and Ca were mainly deposited on the protective agent. The amount of carbon deposits decreased gradually along the flow direction, and mainly deposited on the R1 catalyst. The deposition of Ni in the catalyst was relatively uniform, Fe and V tended to deposit in the pore, and the distribution of sulfur was highly correlated with that of V.After a long period of operation, the pores of resid hydrotreating catalysts, especially the demetallization catalysts,are seriously blocked by deposited metals, thus reducing their activity.

Key words: resid hydrotreating, catalyst, metal deposition, carbon deposit, element distribution, pore structure