Research for structure and composition of coke on spent commercial residue hydrotreating catalysts along HDM bed

The spent residue hydrotreating catalysts were taken out from the different HDM bed axial position of a fixed-bed residue hydrotreating reactor of Petro-China. The coke on spent catalysts were studied by the technologies such as EA, TG, XPS, FT-IR and ¹³C NMR to get the structure characteristics and parameters. The results showed that the coke on spent residue hydrotreating catalysts located on different beds positions share some characteristics such as the kind of coke, the functional group, but the structure and composition were different from each other. Based on the result of each characterization technique, chemical structure models of coke were established. In order to ensure the accuracy of the structures, a software called gNMR helped to calculate the chemical shifts and predict the NMR spectra of the structure models. The model structures can be corrected to match the experimental results through comparing experimental spectra and the predicted ones.