Catalytic and thermal effects in the upgrading of bitumen-derived heavy oils (Abstract only)

Heavy oils derived from PR Spring bitumen were hydrotreated in the fixed bed reactor as a function of process variables. The presulfided commercial NiMo/y-alumina (HDN) catalyst, Mo supported on y-alumina (HDM) catalyst and sodium-impregnated HDN catalyst support were used in this study to investigate catalytic and thermal reactions during heavy oil hydrotreating. The process variables studied were reactor temperature (625-685 K), liquid hourly space velocity (0.14-0.80 hr-1) and pressure (11.1-16.6 MPa). The hydrogen-to-oil ratio was fixed at 890 m3/m3 (5000 scf H2/bbl) in all experiments. A parallel-consecutive reaction model was used to model nitrogen, sulfur, and nickel removal and Conradson carbon and residuum conversion. Nitrogen removal over the HDN catalyst and the HDM catalyst could be modeled by a power rate law equation A comparison of the catalytic performance of the HDN catalyst, HDM catalyst, and sodium-impregnated HDN catalyst support was made in terms of heteroatom and metalc removal and of Conradson carbon and residuum conversion. The activity of the catalysts for heteroatom and metal removal and for Conradson carbon and residuum conversion was HDN catalyst > HDM catalyst > sodium-impregnated HDN catalyst support. Catalytic activity for heteroatom and metal removal and for Conradson carbon and residuum conversion was influenced by metal loading and catalyst surface area. Hydrogen partial pressure exhibited little influence in feed sulfur removal and on feed Conradson carbon and feed residuum conversion. However, hydrogen partial pressure exhibited a significant influence on the removal of intermediate sulfur and on the conversion of intermediate Conradson carbon and intermediate residuum. It was therefore concluded that conversion of feed moieties consisted of cleavage of alkyl side chains from polynuclear clusters.