INSTABILITY OF ZEOLITE-Y SUPPORTED COBALT SULFIDE HYDROTREATING CATALYSTS IN THE PRESENCE OF H2S

The influence of the sulfidation temperature of dehydrated ion exchang ed CoNaY on the catalytic activity and structure was studied by thioph ene I-IDS activity measurements, overall sulfur analysis, temperature programmed sulfidation, Xe adsorption measurements in combination with Xe-129 NMR, EXAFS and ESR. It was shown that up to a sulfidation temp erature of 573 K small highly active Co sulfide clusters were formed i n the supercages. Sulfidation above 573 K led to decomposition of thes e Co sulfide particles by a protolysis reaction resulting in the forma tion of H2S and a blue colored Co compound having almost no HDS activi ty.