Properties Analysis of Spent Commercial Residue Hydrotreating Catalyst: Surface Property Changes of Spent Catalysts in Commercial Residue Hydrotreating Unit

Abstract

In this study, the changes of the surface properties of 14 spent catalysts, which were sampled from a commercial residue hydrotreating unit at the end of an operation cycle, were analyzed and compared with the corresponding fresh catalysts. It was found that the changes in the surface properties do not have change laws along the bed height. Furthermore, the pore size, pore volume and surface area of most of the catalysts decreased after reaction and the number of micropores of the spent catalysts increased, due to the fact that the coke and metals deposited in the catalyst to alter the pore distribution. But some catalysts with high coke content, the pore size and pore volume decreased with the increase of surface area, which was a result of the forming of massive micro/mesopores (the pore size is mainly ranged from 3 to 10 nm), when partial soft coke desorbed under the action of the deposited active metals and micro/mesopores were formed in macropores or large mesopores. The surface properties of the spent catalysts were not only related to the deposition amounts, but also to the deposition configurations of the coke and metals on the catalysts.