TEMPERATURE-PROGRAMMED OXIDATION STUDIES OF AGED HYDROPROCESSING CATALYSTS

Temperature-programmed oxidation tests were carried out on catalysts w hich were aged in a bench-scale unit, using either a vacuum gas oil (V GO) feed or a Kuwait atmospheric feed. The VGO-aged catalysts displaye d one CO2 peak from oxidation of coke and two SO2 peaks from oxidation of inorganic sulfur on the catalyst. The temperature at which the CO2 peak appeared increased with the coke content. For the Kuwait-aged ca talysts, a second, high-temperature carbon oxidation peak was observed when moderate amounts of vanadium were present. The carbon oxidation peaks were closely accompanied by SO2 peaks. The coke in the latter ca talysts essentially covered the inorganic sulfur phase as well as adso rbed nitrogen compounds. It was found that the aged catalysts could lo se a considerable amount of sulfur during the extraction procedure if too high a temperature was used during post-drying.