Presulfurized hydrotreating, hydrocracking or tail gas treating catalyst

#This invention relates to a method of presulfurizing a supported metal oxide catalyst for use in hydrotreating and/or hydrocracking hydrocarbon feed stocks or in treating sulfur-containing effluent gas streams, the presulfurized catalyst composition resulting from such method and a hydrotreating arid/or hydrocracking process or tail gas treating process utilizing such presulfurized metal oxide catalyst.

#A hydrotreating catalyst may be defined as any catalyst composition which may be employed to catalyze the hydrogenation of hydrocarbon feedstocks, and most particularly to hydrogenate particular components of the feed stock, such as sulfur-, nitrogen- and metals-containing organo-compounds and unsaturates. A hydrocracking catalyst may be defined as any catalyst composition which may be employed to crack massive and complex petroleum derived molecules to attain smaller molecules with the concomitant addition of hydrogen to the molecules. A tail gas catalyst may be defined as any catalyst which may be employed to catalyze the conversion of hazardous effluent gas streams to less harmful products, and most particularly to convert oxides of sulfur to hydrogen sulfide which can be recovered and readily converted to elemental sulfur.

#Catalyst compositions for hydrotreating and/or hydrocracking or tail gas treating are well known to those of ordinary skill in the art and several are commercially available. Metal oxide catalysts which come within this definition include cobalt-molybdenum, nickel-tungsten, and nickel-molybdenum supported usually on alumina, silica and silica-alumina, including zeolite, carriers. Also, transition element catalysts may be employed for these purposes. In general catalysts comprising at least one element selected from V, Cr, Mn, Re, Co, Ni , Cu, Zn, Mo, W, Rh, Pd, Pt, Ag, Au, Cd, Sn, Sb, B i and Te have been disclosed as suitable for these purposes.

#According to the present invention porous catalyst particles are contacted with elemental sulfur under conditions which cause the sulfur to be incorporated into the pores of the catalyst by sublimation, by melting or by a combination of both sublimation and melting. The sulfur-incorporated catalyst particles are contacted with a liquid olefin at elevated temperatures and times sufficient to cause the sulfur-incorporated catalyst particles to have enhanced resistance to sulfur stripping during startup in a hydrotreating and/or hydrocracking reactor in the presence of a hydrocarbon feedstock. Also, when such olefinically treated presulfurized catalysts are used for tail gas treating, they can be started up more rapidly than conventional catalysts.

#The mechanism by which the heating of the sulfur-incorporated catalyst becomes more resistant to sulfur stripping upon heating at elevated temperatures in the presence of the olefin is not known and will be referenced herein as "reaction" or "reacts" for lack of better terminology. In any event, the result of this mechanism can readily be determined without undue experimentation by measuring the resistance to sulfur stripping of catalysts subjected to differing temperature/time treatments with the olefin and without the olefin and measuring the resistance to sulfur stripping of the resulting catalysts. Catalysts falling within the scope of the instant invention will have enhanced resistance to sulfur stripping. A suitable method for determining sulfur stripping resistance is described in the Illustrative Embodiment below wherein acetone is used as a stripping agent.

#The catalysts referred to herein as "sulfidable metal oxide(s) catalysts" can in fact be catalyst precursors, that is, they are used as actual catalysts while in the sulfided form and not in the oxide form. While reference is made to metal oxide(s) catalysts, it is understood that while the normal catalyst preparative techniques will produce metal oxide(s), it is possible to utilize special preparative techniques to produce the catalytic metals in a reduced form, such as the zero valent state. Since metals in the zero valent state will be sulfided as well as the oxides when subjected to sulfiding conditions, catalysts containing such sulfidable metals even in reduced or zero valent states will be considered for the purposes of this invention as sulfidable metal oxide(s) catalysts. Further, since the preparative technique of the instant invention can be applied to regenerated catalysts which may have the metal sulfide not completely converted to the oxides, "sulfidable metal oxide(s) catalysts" also refers to these catalysts which have part of their metals in the sulfided state.