Hydrodesulfurization shutdown method

Claim 1

In a process for the hydrodesulfurization of a sulfur-containing residual hydrocarbon feedstock wherein said hydrocarbon feedstock is contacted under hydrodesulfurization conditions in a hydrodesulfurization zone with hydrogen and a catalyst, wherein said catalyst consists essentially of a hydrogenating metal selected from Group VI-B and at least one hydrogenating metal selected from Group VIII, said hydrogenating metals being in the sulfided form and being supported on a refractory oxide carrier selected from the group consisting of alumina, a silica-stabilized alumina containing up to about 5 percent by weight based upon the carrier of silica, silica gels, acid leached boro-silicate glass, and spinels and wherein said catalyst is being promoted with from about 1.0 to about 10.0 weight percent of a Group IV-B metal; a shutdown procedure for said process which comprises lowering the reaction temperature in said hydrodesulfurization zone while maintaining the flow of residual hydrocarbon feedstock and hydrogen to said hydrodesulfurization zone, substituting a distillate feed for the residual hydrocarbon feedstock to said hydrodesulfurization zone after said temperature has been lowered, eliminating the flow of hydrogen to said hydrodesulfurization zone after said substituting step, and continuing to cool said catalyst in the absence of hydrogen by passing said distillate hydrocarbon through said hydrodesulfurization zone.