Effect of sodium impregnation on catalyst performance when hydrotreating a coal-derived liquid

Abstract

A commercial Ni-Mo/alumina catalyst was loaded with percentage quantities of sodium and tested for activity and activity maintenance while hydrotreating a coal-derived distillate under high severity conditions. The original catalyst exhibited a large high-temperature peak during the temperature-programmed desorption of tert-butylamine. This peak, which is an indicator of catalyst acidity, was reduced and ultimately eliminated by impregnating the catalyst with increasing amounts of sodium. At 5 wt % Na/sub 2/O, no acid peak remained. The sodium loadings had little effect on activity or activity maintenance for hydrogen uptake or specific gravity reduction as compared to the original catalyst. The hydrodenitrogenation activity was reduced, however. Activity maintenance for both the original catalyst and the sodium-treated catalyst was excellent, so it was not possible to observe an effect of sodium addition on activity decline. The sodium-loaded catalyst was coked to a lesser extent than the original catalyst.