CA1090769A - Hydrodesulfurization catalyst and use thereof - Google Patents

Abstract

ABSTRACT
A desulfurization catalyst which demonstrates superior desul-furization activity and which contains an inorganic oxide carrier material, a Group VIB metal component and a Group VIII metal component. The cata-lyst is prepared by (a) extruding at least 10% of the Group VIII metal component with the inorganic oxide carrier material, and (b) impregnating the resulting extrudate with a sufficient quantity of Group VIB and Group VIII metal components to yield a finished catalyst containing the requisite metallic component content.

Description

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HYDROD~SULFURIZATION CATALYST AND USE THEREOF
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The present invention provides a novel catalytic composite for use in the desulfurization of hydrocarbonaceous material.
Another object provides an improved process for desulfurizing a sulfurous hydrocarbon charge stock, which is effected utilizing a catalytic S composite comprising an inorganic oxide carrier material, a Group VIB
metal component and a Group VIII metal component.
In one embodiment, the present invention relates to a desul-furization catalyst comprising an inorganic oxide carrier material, a Group YIB metal component and a Group VIII metal component wherein said , 10catalyst is prepared by (a) extruding at least 10% of the Group VIII
metal component with the inorganic oxide carrier material, and (b) impreg-nating the resulting extrudate with a sufficient quantity of Group VIB
and Group VIII metal components to yield a finished catalyst containing the requisite metallic component content.
15The desulfurization conditions include a maximum catalyst bed temperature of 93 ~.- to 482 C., a pressure of 200 to 5000 psig., an LHSV
of 0.1 to 10 and a hydrogen circulation rate of 500 to 50,000 scf/bbl.
An essential feature of the present invention is that t~e por-ous carrier material be co-extruded with at least 10% of the Group VIII
metal component. It is preferred that the porous carrier material be an adsorptive, high-surface area support. Carrier materials are selected from the group of amorphous refractory inorganic oxides including alumina, titania, zirconia, silica, chromia, magnesia, boria, hafnia, and mixtures of two or more, including alumina-zirconia, silica-alumina, alumina-silica-boron phosphate, etc. In many applications of the present inven-tion, the carrier material will consist of a crystalline aluminosilicate.
This may be naturally-occurring or synthetically prepared, and includes - mordenite, faujasite, Type A or Type U molecular sieves, etc. Following.
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the formation of the extrudate, the composite will generally be dried at a temperature in the range of 93 C. to 316 C., for a period of from

2 to 24 hours or more, and finally calcined at a temperature of 371 C
to 649 C., in an atmosphere of air, for a period of 0.5 to 10 hours.
When the carrier material comprises a crystalline aluminosilicate, it is preferred that the calcination temperature not exceed about 538 C.
The econd essential feature of the present invention is that the resulting extrudates are impregnated with a sufficient quantity of Group VIB and Group VIII metal components to yield a finished catalyst containing the requis;te metallic component content.
' Reference to Group VIB herein is intended to allude to the Periodic Table of the Elements, E. H. Sargent & Co., 1964, and includes chromium, molybdenum and tungsten. The preferred Group VIB component is molybdenum. Furthermore, reference to Group VIII herein is intended to include iron, cobalt, nickel, ruthenium, rhodium, palladium, osmium, iridium and platinum. The preferred Group VIII component is cobalt.
Proportions of the Group VIB and VIII metallic components are utilized which will result in a final catalytic composite comprising from 0.1% to 20% by weight of the Group VIB component and from 0,1% to 1 20 10% by weight of the Group VIII component, calculated as the elemental i metals.
The initial step in the catalyst preparation method involves : commingling the preformed carrier material, for example, alumina, with I salts of the desired metallic component. The solid mixture is ground to a talc-like powder, about 20 to 100 mesh, and preferably from 30 to 50 . mesh, and intimately admixed with a relatively minor quantity-of a suit- -able acid such as hydrochloric acid, nitric acid, or any other suitable . peptizing agent. A preferred technique involves mulling the acidic mix-. -2-' ' ' ' ' ' ' ''' , ' ' ' .

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ture which is subsequently aged for a period of 15 minutes to 24 hours. The resulting plastic-type mass is extruded under a suitable pressure in the range of 100 to 10,000 psig. to form extrudates of the desired size, e.g., about 1/16" diameter extrudate with L/0 ratio of about 2 to 4. After drying and calcining in the manner hereinbefore set forth, the remaining required metallic components are added to the dried extrudate by an impregnation technique. Suitable soluble metallic salts are selected to prepare an impregnating solution for the immersion of the extrudates. The impregnated extrudates are then dried and oxidized at 427 C. to 760 C.
Although not essential to successful hydro-processing, it is often advisable to incorporate a halogen component into the catalytic composite, particularly where the same is to be utilized in a hydrocrack-ing process. Although the precise form of the chemistry of association of the halogen component with the carrier material and the metallic com-ponents is not accurately known, it is customary in the art to refer to the halogen component as being combined with one or the other ingredients of the catalyst. The halogen may be either fluorine, chlorine, ;odine, bromine, or mixtures thereof, with fluorine and chlorine being particu-larly preferred. The quantity of halogen is such that the final catalyticcomposite contains 0.1% to 3.5% by weight, and preferably from 0.5% to 1.5% by weight, calculated on the basis of the elemental halogen.
Prior to its use in the conversion of hydrocarbons, the cata-lytic composite is generally subjected to a substantially water-free reduction technique. Substantially pure and dry hydrogen (less than about 30.0 vol. ppm. of water) is employed as the reducing agent. The calcined catalytic composite is contacted at a temperature of 204 C.
to 538 C., for a period of 0.5 to 10 hours and effective to substantially reduce metallic components.

7 ~;9 Additional improvements are generally obtained when the reduced composite is subjected to presulfiding for the purpose of incorporating therein from 0.5% to 8.0~ by weight of sulfur, on an elemental basis.
This presulfiding treatment is effected in the presence of hydrogen and a sulfur-containing compound such as hydrogen sulfide, lower molecular weight mercaptans, various organic sulfides, carbon disulfide, etc.
The preferred technique involves treating the reduced catalyst with a sulfiding gas, such as a mixture of hydrogen and hydrogen sulfide having about 10 mols of hydrogen per mol of hydrogen sulfide, at conditions selected to effect the desired incorporation of sulfur. It is generally considered a good practice to perform the presulfiding technique under substantially water-free conditions. The catalyst may also be sulfided with a charge stock containing sulfur.
The hydrocarbon charge stock and hydrogen are contacted with a catalyst of the type described above in a hydrocarbon conversion zone.
The contacting may be accomplished by using the catalyst in a fixed-bed system, a moving-bed system, and a fluidized-bed system, or in a batch-type operation. In view of the risk of attrition loss of the catalyst, and further in view of the technical advantages attendant thereto, it is preferred to utilize a fixed-bed system. In this type of system, a hydrogen-rich vaporous phase and the charge stock are preheated by any suitable heating means to the desired initial reaction temperature, the mixture being passed into the conversion zone containing the fixed-bed of the catalytic composite. It is understood, of course, that the hydrocarbon conversion zone may consist of one or more separate reactors having suitable means therebetween to insure that the desired conversion -temperature is maintained at the inlet to one or more catalyst beds. The reactants may be contacted with the catalyst in either upward, downward, 0~()'76 .
or radial flow fashion, with a downward/radial flow being preferred.
Hydroprocessing reactions are generally exothermic in nature, and an increasing temperature gradient will be experience as the hydro-gen and charge stock traverse the catalyst bed. It is desirable to main-tain the maximum catalyst bed temperature below about 482 C., which tem-perature is virtually identical to that which may be conveniently measured at the outlet of the reaction zone. In order to insure that the catalyst bed temperature does not exceed the maximum allowed, conventional guench streams, either normally liquid or normally gaseous, and introduced at one or more intermediate loci of the catalyst beds, may be utilized.
- The following examples are presented in illustration of the catalyst of this invention and a method of preparation thereof, and are not intended as an undue limitation on the generally broad scope of the inven-tion as set out in the appended claims.
EXAMPLE
This example describes the preparation and testing of four - alumina-cobalt-molybdenum catalysts. Each of these four catalysts was tested to determine the ability to desulfurize a vacuum gas oil charge stock having the properties indicated in the following Table I:
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TABLE I
Yacuum Gas Oil Charge Stock Properties Gravity, API 19.8 Sulfur, wt.% 2.65 Nitrogen, wt.~ 0.16 Distillation, C.
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% 388 30% 426 50% 455 70% ' 486 90% 531 E.P. 576 Catalyst 1 was prepared by impregnating 1/16-inch alumina spheres with an aqueous solution of water-soluble salts of cobalt and molybdenum and by subsequently drying and calcining the spheres to yield a finished cata-lyst which contained 2.7 wt. % cobalt and 9.0 wt. % molybdenum, calculat-ed as the elemental metals. Catalyst 1 was tested with a vacuum gas oil charge stock which is hereinabove described and the relative activity (RA) for desulfurization of this catalyst was arbitrarily set equal to 100.
Such a catalyst is commercially acceptable for the desulfurization of hydrocarbons.
Catalyst 2 was prepared in the same manner as Catalyst 1 with the exception that the metals' levels were increased to 3.4 wt. % cobalt and 11.6 wt. % molybdenum. Catalyst 2 had a relative activity of 102.
Catalyst 3 was prepared by admixing a finely divided alumina with sufficient ~uan~ities o~ cobalt and molybdenum salts to produce an extruded carrier materia'l containing 0.9 wt. % cobalt and 3.3 wt. % molyb-denum of 26% and 28.5% respectively of the total required metals of the finished'catalyst. The admixture of finely divided alumina and metal salts was extruded and the extrudates were formed into spheres by the extrudates in a marumerizer. The spheres were dried, calcined and then impregnated with an aqueous solution of water-soluble salts of cobalt and molybdenum to yield a finished catalyst which contained 3.4 wt. b cobalt and 11.6 wt. % molybdenum, calculated as the elemental metals. Catalyst

3 was tested for desulfurization activity in identically the same manner as was Catalyst 1 and the relative activity for Catalyst 3 was 164.

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Oatalyst 4 was prepared according to the method of the present invention and wherein finely divided alumina was admixed with a sufficient quantity of cobalt salt to produce an extruded carrier material contain-ing 0.9 wt. % cobalt or 26% of the total required cobalt of the finished catalyst. The admixture of finely divided alumina and cobalt metal salt was extruded and the extrudates were formed into spheres by spinning the extrudates in a marumerizer. The spheres were dried, calcined and then impregnated with an aqueous solution of water-soluble salts of cobalt and molybdenum to yield a finished catalyst which contained 3.4 wt. %
cobalt and 11.6 wt. % molybdenum, calculated as the elemental metals.
Catalyst 4 was tested for desulfurization activity in identically the same manner as was Catalyst l and the relative activity for Catalyst 4 was 185. The extraordinary increase in desulfurization activity is ex-tremely impressive and the significance of such an improved catalyst will be readily discerned by those skilled in the art. The results ob-tained from desulfurizing the hereinabove described vacuum gas oil with the above-mentioned catalysts are presented in tabular form in Table II.

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Claims (5)

1. A desulfurization catalyst comprising an inorganic oxide carrier material, a Group VIB metal component and a Group VIII metal component wherein said catalyst is prepared by (a) extruding at least 10% of the Group VIII metal component with the inorganic oxide carrier material, and (b) impregnating the resulting extrudate with a sufficient quantity of Group VIB and Group VIII metal components to yield a finished catalyst containing the requisite metallic component content.

2. The catalyst of Claim 1 further characterized in that said Group VIB metal component is present in an amount from about 0.1 wt. %
to about 20 wt. %, calculated as the elemental metal.

3. The catalyst of Claim 1 further characterized in that said Group VIII metal component is present in an amount from about 0.1 wt. %
to about 10 wt. %, calculated as the elemental metal.

4. The catalyst of Claim 1 further characterized in that said inorganic oxide carrier material is alumina.

5. A process for desulfurizing a sulfurous hydrocarbon charge stock which comprises reacting said charge stock and hydrogen, at desul-furization conditions, selected to convert sulfurous compounds into hy-drogen sulfide and hydrocarbon in contact with a desulfurization catalyst comprising an inorganic oxide carrier material, a Group VIB metal com-ponent and a Group VIII metal component wherein said catalyst is prepared by (a) extruding at least 10% of the Group VIII metal component with the inorganic oxide carrier material, and (b) impregnating the resulting extrudate with a sufficient quan-tity of Group VIB and Group VIII metal components to yield a finished cata-lyst containing the requisite metallic component content.