Coke and radicals formation on a sulfided NiMo/γ-Al2O3 catalyst during hydroprocessing of an atmospheric residue in hydrogen donor media

Coking on catalyst during hydroprocessing of petroleum residues is an important issue that should be addressed for better catalyst performance. This paper studies reaction and coking behaviors of Maoming atmospheric residue (AR) over a sulfided commercial NiMo/γ-Al2O3 catalyst in the presence and absence of a hydrogen donor solvent, tetrahydronaphthalene (THN), in a micro-reactor at temperatures of 400-460 °C and reaction time of 0-60 min. It reports the changes in yields of CS2 soluble matter (CS2-S), CS2 insoluble matter (coke) and gas, as well as the changes in quantity of coke on the catalyst and in radical concentration of the reaction system, coke on catalyst and CS2-S. It is found that compared with the changes in yields, which are significant at temperatures higher than 420 °C, the changes in radical concentration are significant at 400 °C. The catalyst promotes hydrogen donation of THN, which lowers the amounts of coke formed in the liquid phase, on the catalyst, and the activation energy of coking on the catalyst.