Arsenic Poisoning of Hydrodesulfurization Catalysts

An XPS study of the sulfidation-regeneration cycle of a hydroprocessing catalyst

“…At complete sulfidation of the nickel and tungsten in catalyst "A", the sulfur content as NiS and WS2 would be 9.3% and 7.0%, respectively, assuming no Ni or W is lost from the catalyst during sulfidation. In fact, only insignificant losses of Ni or W are expected during the sulfidation process (Merryfield et al, 1985). Thus 16.3% of sulfur would be in this catalyst if sulfidation were complete whereas the measured sulfur content is roughly half this value, which is in good agreement with the observation of Brown and Ternan (1984).…”

“…Most of the research to date has been directed at laboratory-prepared Co-Mo HP catalysts, while Ni-W and in particular industrial Ni-W HP catalysts have received less attention (Arteaga et al, 1986(Arteaga et al, , 1987Yoshimura et al, 1988, Breysse et al, 1988, Ouafi et al, 1988. Many researchers (Merryfield et al, 1985, Arteaga et al, 1986, George et al, 1988 noted that sulfates are formed during the presulfidation or/and hydrodesulfurization processes, and that the industrial oxyregeneration process does not eliminate the sulfate completely. Nevertheless, systematic studies of these sulfates, their forming conditions, their fate in the regeneration process and the exact nature of the sulfate species are still missing.…”