GB1602469A - Hydrosulphurization catalyst and use thereof - Google Patents

Description

(54) HYDROSULFURIZATION CATALYST AND USE THEREOF (71) We, UOP INC, a corporation organized under the laws of the State of Delaware United States of America, of Ten UOP Plaza, Algonquin & Mt. Prospect Roads, Des Plaines, Illinois, United States of America, do hereby declare the invention, for which we pray that a Patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following Statement: The present invention relates to catalytic composites and their use in the desulfurization of hydrocarbonaceous material.

According to the present invention there is provided a process for preparing a desulfurization catalyst comprising an inorganic oxide carrier material, a Group VIB metal component and a Group VIII metal component which process comprises (a) extruding at least 10% but not all of the Group VIII metal component in metal salt form with the inorganic oxide carrier material. in the absence of the Group VI B metal component, and (b) impregnating the resulting extrudate with the Group VIB metal component and the remainder of the Group VIII metal component in amounts sufficient to yield a finished catalyst containing the requisite metallic component content.

The invention also provides a process for desulfurizing a sulfurous hydrocarbon charge stock which comprises reacting said charge stock and hydrogen, at desulfurization condition selected to convert sulfurous compounds into hydrogen sulfide and hydrocarbon, in contact with a desulfurization catalyst according to the invention.

The desulfurization conditions for conversion of sulfurous compounds into hydrocarbon and H2S suitably include a maximum catalyst bed temperature of 93" C. to 4820 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 the carrier material be co-extruded with at least 10% but not all of the Group VIII metal component in the absence of the Group VIB metal component. It is preferred that the carrier material be an adsorptive, high-surface area support. The carrier material may be an amorphous refractory inorganic oxide such as alumina titanic zirconia, silica, chromia, magnesia, boria or hafnia, or a mixture of two or more thereof such as alumina-zirconia, silica-alumina, or alumina-silicaboron phosphate. In many applications of the present invention, the carrier material will consist of a crystalline aluminosilicate. This may be naturally-occurring or synthetically prepared, and includes mordenite. faujasite and Type A and Type U molecular sieves.

Following 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 6490C., in an atmosphere of air, for a period of 0.5 to 10 hours or more. When the carrier material comprises a crystalline aluminosilicate, it is preferred that the calcination temperature not exceed 538"C.

The second essential feature of the present invention is that the resulting extrudates are impregnated with the Group VIB metal component and remainder of the Group VIII metal component in amounts sufficient to yield a finished catalyst containing the requisite metallic component content.

Reference to Group VIB herein is intended to allude to the Group as defined in the Periodic Table of the Elements, E.H. Sargent & Co., 1964, i.e. the group comprising chromium, molybdenum and tungsten. The preferred Group VIB component is molybdenum. Furthermore, reference to Group VIII herein is intended to denote 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 suitably 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 10% by weight of the Group.VIII component, calculated at the elemental metals.

The catalyst is suitably prepared as follows: The initial step involves commingling the preformed carrier material, for example, alumina, with a salt of the desired metallic component. The solid mixture is ground to a talc-like powder, from 20 to 100 mesh, preferably from 30 to 50 mesh, and intimately admixed with a relatively minor quantity of a suitable acid such as hydrochloric acid or nitric acid, or any other suitable peptizing agent. A preferred technique involves mulling the acidic mixture, which is subsequently aged for a period of 15 minutes to 24 hours. The resulting plastic-type mass is extruded under a suitable pressure, as a rule 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/D ratio of 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 hydrocracking process. Although the precise form of the chemistry of association of the halogen component with the carrier material and the metallic components is not accurately known, it is customary in the art to refer to the halogen component as being combined with one or other of the ingredients of the catalyst. The halogen may be fluorine, chlorine, iodine or bromine, or a mixture of two or more thereof, with fluorine and chlorine being particularly preferred. The quantity of halogen is generally such that the final catalytic composite 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 catalytic composite is generally subjected to a substantially water-free reduction technique. Substantially pure and dry hydrogen (less than 30 vol. ppm. of water) is suitably employed as the reducing agent. The calcined catalytic composite is suitably contacted at a temperature of 204"C. to 538"C., for a period of 0. to 10 hours which effective to substantially reduce metallic components.

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. The presulfiding treatment is suitably effected in the presence of hydrogen and a sulfur-containing compound such as hydrogen sulfide, a lower molecular weight mercaptan, any of various organic sulfides or carbon disulfide. 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.

For desulfurization, the hydrocarbon charge stock and hydrogen are contacted with a catalyst of the type described above in a hydrocarbon conversion zone at desulfurization conditions. The contacting may be accomplished by using the catalyst in a fixed-bed system, a moving-bed system, a fluidized-bed system, or 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 to be understood, of course, that the hydrocarbon conversion zone may consist of one or more separate reactors having suitable means therebetween to ensure that the desired conversion temperature is maintained at the inlet to the one or more catalyst beds. The reactants may be contacted with the catalyst in either upward, downward 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 experienced as the hydrogen and charge stock traverse the catalyst bed. It is desirable to maintain the maximum catalyst bed temperature below 482"C., which temperature is virtually identical to that which may be conveniently measured at the outlet of the reaction zone. In order to ensure that the catalyst bed temperature does not exceed the maximum allowed, conventional quench 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 is presented in illustration of the catalyst of this invention and a method of preparation thereof.

Example This example describes the preparation and testing of four alumina-cobalt-molybdenum catalysts, catalysts 1-3 being comparative and catalyst 4 being according to the invention.

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: TABLE I Vacuum Gas Oil Charge Stock Properties Gravity, "API 19.8 Sulfur, wt.% 2.65 Nitrogen, wt.% 0.16 Distillation "C IBP 293 10% 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 catalyst which contained 2.7 wt. % cobalt and 9.0 wt. % molybdenum, calculated 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 quantities of cobalt and molybdenum salts to produce an extruded carrier material containing 0.9 wt. % cobalt and 3.3 wt. % molybdenum, constituting 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 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 3 was tested for desulfurization activity in the same manner as was Catalyst 1 and the relative activity for Catalyst 3 was 164.

Catalyst 4 was prepared according to the present invention and finely divided alumina was admixed with a sufficient quantity of cobalt salt to produce an extruded carrier material containing 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 1 and the relative actvity for Catalyst 4 was 185. The extraordinary increase in desulfurization activity is extremely impressive and the significance of such an improved catalyst will be readily discerned by those skilled in the art. The results obtained from desulfurizing the hereinabove described vacuum gas oil with the above-mentioned catalysts are presented in tubular form in Table II.

TABLE II Evaluation For Desulfurization Activity Metals in Carrier Total Metals Relative Catalyst Carrier Wt. % Cobalt Wt. % Molybdenum Wt. % Cobalt Wt. % Molybdenum Activity 1 Alumina 0 0 2.7 9.0 100 2 Alumina 0 0 3.4 11.6 102 3 Alumina 0.9 3.3 3.4 11.6 164 4 Alumina 0.9 0 3.4 11.6 185

Claims (16)

WHAT WE CLAIM IS:

1. A process for preparing a desulfurization catalyst comprising an inorganic oxide carrier material, a Group VIB metal component and a Group VIII metal component, which process comprises (a) co-extruding at least 10% but not all of the Group VIII metal component in metal salt form with the inorganic oxide carrier material, in the absence of the Group VIB metal component and (b) impregnating the resulting extrudate with the metal component and the remainder of the Group VIB Group VIII metal component in amounts sufficient to yield a finished catalyst containing the requisite metallic component content.

2. A process as claimed in claim 1 wherein sufficient Group VIB metal component is employed to provide a catalyst containing from 0.1 wt. % to 20% of Group VIB metal component, calculated as the elemental metal.

3. A process as claimed in claim 1 or 2 wherein sufficient Group VIII metal component is employed in total to provide a catalyst containing from 0.1 wt. % to 10 wt. % of Group VIII metal component, calculated as the elemental metal.

4. A process as claimed in any of claims 1 to 3 wherein the inorganic oxide carrier material is alumina.

5. A process as claimed in any of claims 1 to 4 wherein after extrusion but before impregnation the extrudate is dried at from 93 to 3160C for at least 2 hours and is then calcined at a temperature of from 371 to 6490C in an atmosphere of air for 0.5 to 10 hour provided that if the carrier comprises a crystalline aluminosilicate the calcination temperature does not exceed 538"C.

6. A process as claimed in any of claims 1 to 5 wherein the impregnated material, having been dried and oxidized at 427 to 7600C, is adjusted to a substantially water-free reduction technique.

7. A process as claimed in claim 6 wherein the reduced material is presulfided to incorporate therein from 0.5 to 8% by weight of sulfur, on an elemental basis.

8. A process for preparing a desulfurization catalyst carried out substantially as hereinbefore described for catalyst 4 in Example I.

9. A desulfurization catalyst when prepared by a process as claimed in any one of claims 1 to 8.

10. A desulfurization catalyst as claimed in claim 9 wherein the Group VIB metal is molybdenum and the Group VIII metal is cobalt.

11. A desulfurization catalyst as claimed in claim 9 or 10 which also contains a halogen component in an amount of from 0.1 to 3.5% by weight, calculated as elemental halogen.

12. A process for desulfurizing a sulfurous hydrocarbon charge stock which comprises reacting said charge stock and hydrogen, at desulfurization conditions selected to convert sulfurous compounds into hydrogen sulfide and hydrocarbon, in contact with a desulfurization catalyst as claimed in any of claims 9 to 11.

13. A process as claimed in claim 12 wherein the desulfurization conditions include a maximum catalyst bed temperature of 93 to 482"C, a pressure of 200 to 5,000 psig, an LHSV of 0.1 to 10 and a hydrogen circulation rate of 500 to 50,000 scf/bbl.

14. A process as claimed in claim 12 or 13 wherein a vacuum gas oil charge stock is employed.

15. A desulfurized hydrocarbon material when obtained by a process as claimed in any of claims 12 to 14.

16. A hydrocarbon product when obtained from a desulfurized material as claimed in claim 15 by one or more petroleum refining operations.