KR100241174B1 - Hydrodesulfurization catalyst of heavy oil and process for preparing thereof - Google Patents

Abstract

The present invention relates to a catalyst having improved catalytic activity, a process for preparing the catalyst and a process for using the catalyst for hydrodesulfurization of a metal-containing heavy feedstock. The catalyst comprises 70% by volume pores having a diameter of 70 to 130 mm 3 and occupies 70% by volume of the pore volume and contains the Group VIB and Group VIII metals or metal compounds on the support made of alumina.

Description

Catalysts for Hydrodesulfurization of Heavy Oils and Methods for Producing the Same

1 shows the pore diameter distribution of the catalyst of the present invention.

2 shows the pore diameter distribution of prior art catalysts.

FIG. 3 shows the reactor temperature required to maintain a 55% trace carbon residue (MCR) conversion rate at 0.35 liquid hourly space velocity feed flow rate of 760 ° F. + Arab heavy atmospheric residue.

The present invention relates to a method for preparing a catalyst carrier, a hydrocarbon desulfurization catalyst prepared using a carrier, and a method for hydrodesulfurizing a hydrocarbon feedstock using the catalyst described above. More particularly, the present invention relates to a method for producing a porous catalyst containing almost no macropore (with a diameter of 1000 mm or more) and containing at least one metal and / or metal compound of Group VIB and Group VIII elements. Even more particularly, the present invention relates to a catalyst having almost no macropores, having a specific micropore size distribution, and comprising mainly alumina carrier components containing the metals and / or metal compounds described above. The present invention also relates to hydrodesulfurization of hydrocarbons using catalysts.

The strong need for desulfurization of hydrocarbon oils obtained from petroleum is well known. When these raw materials are burned as fuel in a conventional manner, the sulfur present in hydrocarbons becomes a serious air pollutant in the form of sulfur dioxide gas.

Typical operating conditions for the hydrodesulfurization process include reaction zone temperatures of 600 ° F. to 900 ° F., pressures of 200 to 3000 psig, hydrogen feed rates of 500 to 15,000 SCF per barrel of oil feed, and nickel or cobalt and molybdenum or tungsten on porous refractory supports. Catalysts such as these are included.

A problem that has been recognized in hydrodesulfurization of heavy oils is that if heavy oils contain organometallic compounds, the effective catalytic activity tends to decrease relatively quickly, especially in the case of metals of about 10 to 200 ppm or more, such as nickel and vanadium in which impurities are dissolved. Is that there is. These metal impurities are said to be deposited on the surface and in the pores of the hydrodesulfurization catalyst.

The approach to the problem of metal impurity deactivation of hydrodesulfurization catalysts was to alter the pore structure of the catalyst. However, the answer to which pore structure is best is not easily found, and in practice contradictions remain in the answers limited by the prior art. US Patent No. 4,066,574, which is incorporated herein by reference; No. 4,113,661; And 4,341,625, hereinafter referred to as Tom'574, Tom'661 and Tom'625, respectively, addressed problems in the art and suggested solutions.

Tom's patents were prepared by impregnating metal-containing heavy oil feedstocks, particularly residual oil feedstocks, by impregnating Group VIB and Group VIII metals or metal compounds in an alumina-containing support having a pore volume of at least 70% of pores with a diameter of 80 to 150 microns. It is described as being hydrodesulfurized using a catalyst. Particularly significant hydrogenation desulfurization catalysts in terms of very low deactivation rates are obtained using the alumina support of the pore size distribution.

In Tom'661, the catalyst is prepared by taking predominantly alpha-alumina monohydrate that ranges in size up to 500 microns and treating it with a certain amount of monobasic acid. The acid and the resulting mixture are then mixed at least partially with an aqueous solution of a nitrogen base such as aqueous ammonia. This solution contains 0.6 to 1.2 equivalents of base per equivalent of acid. The treated and neutralized product is converted into a catalyst carrier by molding, drying and calcining as needed. Finally, the catalyst support is impregnated with the metals described above.

It would be advantageous if the catalysts and methods of tom'574, '661 and' 625 could be improved by giving the catalyst greater catalytic activity over a longer period of time.

According to the present invention, a hydrocarbon feedstock containing a metal is impregnated under a hydrodesulfurization condition by impregnating Group VIB and Group VIII metals or metal compounds in an alumina-containing support having a pore volume of at least 70% by volume of pores having a diameter of 70 to 130 mm 3. Characterized by contact with the prepared catalyst, a method of hydrodesulfurizing a hydrocarbon feedstock containing a metal is provided. Total pore volume of the support is about 0.5 to about 1 cm per gram³Range of pore volume Less than 5% are pores with a diameter of 300 mm 3 or more, and less than 2% of pore volumes are pores with a diameter of 1000 mm or more.

The present invention is based on the discovery that unexpectedly active catalysts are obtained from small changes in pore size distribution. In another aspect of the invention, the apparent pore size distribution is achieved by an improvement in the method of making the catalyst support. Especially the support

(a) treating the particulate solid by mixing a peptizable particulate solid consisting primarily of alpha-alumina monohydrate with an acidic solution to a pH in the range of about 3.0 to 4.5;

(b) neutralizing at least a portion of the mixed acid by mixing an aqueous solution of nitrogen base containing in the range of about 0.2 to 0.5 equivalents of base per equivalent of acid in the treated solid;

(c) forming a neutralized or partially neutralized solid;

(d) The shaped solids are prepared by drying at a temperature in the range of about 150 ° F. to 1700 ° F. and firing to complete the support.

In another aspect of the present invention, back-neutralization reduces the number of nitrogen base equivalents to peptising acids, and reducing the firing temperature as compared to tom'661, Smaller pore catalysts are produced that are more active than the catalyst. The catalyst of the present invention produces better quality, ie lower nitrogen, vacuum gas oil. The catalyst of the present invention is particularly useful when using a feedstock having a relatively low metal content.

The catalytic process of the present invention is primarily directed to a residual oil feedstock as opposed to a gas oil feedstock. Residual oils typically contain more than 10 ppm metal, while gas oil almost necessarily contains less than 10 ppm metal. Therefore, representative sources for the present invention are crude oil atmospheric distillation column residues (reduced crude oil or atmospheric column residues), or vacuum distillation column residues (vacuum residues). The metal is believed to exist as an organometallic compound of porphyrin or chelate-type structure, but the concentration of metals mentioned herein is calculated as pure metal in ppm.

Alumina may be combined with other refractory support materials such as silica or magnesia, but is a preferred support material for the catalyst used in the process of the invention.

Alpha-alumina monohydrate preferably used in the present invention can be obtained from various commercial sources such as Catapal or Versal. It can also be prepared as described in Tom'661.

The support material consisting of alumina should have a distribution of the pore sizes described above to provide a catalyst in accordance with the conditions of the present invention. In the case of the aluminum support used to prepare the finished catalyst, the pore size distribution is almost similar to the finished catalyst pore size distribution, since there is little change in pore size distribution when the support is impregnated with Group VIB and Group VIII metal compounds. Do. Relatively pure alumina is available from various sources as spray dried powders, amorphous powders or crystalline hydrate powders. These materials are suitable for extrusion when mixed with water only after the addition of an extrusion aid. Two commonly used auxiliaries are inorganic strong acids or combustible organic lubricants. Inorganic strong acids usually produce high density extrudates and combustible organic lubricants produce pore size distributions containing significant micropore volumes, but none of these are acceptable in the residual oil desulfurization catalyst supports according to the present invention. The tom patents already introduced herein describe a procedure by which such materials can be used to obtain moderate to low density aluminas having a pore volume of at least 97%, usually at least 99%. It is in the region of less than about 500 mm pore diameter.

In the present invention, the method of the tom patents is characterized in that the pore size distribution is varied from 70% of the pore volume of the pores with a diameter of 80 to 150 mm 3 to 70% of the pore volume with the pore size distribution of the pores with a diameter of 70 to 130 mm 3. By improvement of, it is improved. The acidic particulate solid alumina monohydrate, as pointed out in tom'661, is partially prepared by mixing an aqueous solution of nitrogen base containing an amount of base in an amount ranging from about 0.6 to 1.2 equivalents per equivalent of acid added to the treated solid. Is neutralized. This method is sometimes known as "back-titration." It is one aspect of the present invention to perform post-titration using a solution of nitrogen bases containing a base in an amount ranging from about 0.2 to 0.5 equivalents per equivalent of said pre-added acid.

In order to prepare an alumina support or carrier having a pore size distribution consistent with the pore size distribution required by the present invention, the alumina is prepared as described above (Tam '661) with a suitable monobasic acid, preferably nitric acid or an equivalent thereof (e.g. Hydrochloric acid, hydrofluoric acid, and hydrobromic acid).

As will be appreciated acid treated alumina is satisfactory for the production of processed carriers with little macropores. However, this is not satisfactory for the production of a catalyst carrier having an appropriate pore volume used in the preparation of the residual oil desulfurization catalyst. Satisfactory residual desulfurization catalyst carriers and catalysts should have a pore volume of at least about 0.5 cc / gm, preferably at least 0.65 cc / gm. In general, when the micropore distribution and the macropore content are satisfactory, the higher the pore volume, the longer the catalyst life. In order to achieve useful pore volume and to provide the appropriate micropore distribution required for the processed carrier and catalyst, some of the mixed acid in the treated feed must be neutralized with nitrogen bases, where the base is intimately mixed. Mix thoroughly in the feed.

As used herein, “nitrogen base” means a base of the general formula R ₃ N and its corresponding hydroxide form, R ₃ HNOH, wherein the R groups are the same or different, and hydrogen and carbon atoms of 1 to 3 It is selected from the group consisting of alkyl groups. Aqueous ammonia is preferred.

The prior art suggests that "normally about 0.6 equivalents of base are required per equivalent of acid used in processing." The prior art argues that in the case of neutralization, the use of large relative amounts of base is increasingly advantageous to some extent. It is then undesirable to use larger relative amounts. According to Tom'661, remarkable results are generally obtained in terms of processed carriers when the relative amounts of bases in aqueous solutions per equivalent of acid range from about 0.6 to 1.2 equivalents, and the carriers produced at about 1.6 of this ratio are typically Not satisfactory

It is a finding of the present invention that in the case of an improved high activity residual catalyst, the relative amount of base in the neutralized aqueous solution per equivalent of acid should be in the range of about 0.2 to 0.5 equivalents, preferably at least about 0.35 equivalents per equivalent of acid.

The nature of the mixture resulting from the neutralization of the treated alumina varies with its volatile content. This mixture may be a flowable solid or a viscous paste. In a preferred form for use as the extrusion feed, this mixture is a flowable solid having a volatile content in the range of 50 to 70% by weight. As used herein, the term "volatile material" is a material that occurs during high temperature drying of 900 ° F or more. Various molding methods can be used to produce precursors of the catalyst carrier from the treated and neutralized solids. Molding is preferably affected by extrusion. In preparing the processed carriers, the drying and firing steps of the process of the present invention are generally carried out at temperatures in the range of about 150 ° F to 1700 ° F, preferably in the range of 1050 ° F to 1700 ° F. The drying step is typically carried out at a temperature in the range from about 150 ° F. to 500 ° F., followed by drying in a dry or wet atmosphere, in the range from about 500 ° F. to 1700 ° F., preferably in the range from 1050 ° F. to 1700 ° F., most preferably. Firing is carried out at temperatures below 1400 ° F.

The method of the invention preferably has a pore volume of at least about 98% of the micropore region, in particular a total pore volume of at least 70% of the pores having a pore diameter in the range of 70 to 130 mm 3, and a total pore volume of pores having a diameter of at least 300 mm 3. A catalyst carrier of moderate to low density, mainly alumina, having a pore diameter of less than 5% and a pore diameter of 1000 mm 3 or more is less than 2%. Table 1 shows a typical distribution of pore volume in pore diameter for the prior art catalysts described in toms' 661, '574 and' 625. Table 2 shows typical pore volume distribution in the pore diameter of the catalyst of the present invention.

The pore volume described herein is the volume of the liquid adsorbed in the pore structure of the new material under saturated medium pressure, provided that the adsorbed liquid has the same density as the bulk density of the liquid. The liquid used in this analysis was liquid nitrogen. Procedures for measuring pore volume by nitrogen physisorption are also described in DH Everett and FS Stone, Proceedings of the Tenth Symposium of the Colstom Research Society, Bristol, England: Academic Press, March 1958, pp. 109-110. It is.

TABLE 1

TABLE 2

The hydrocarbon hydrodesulfurization catalyst of the present invention contains at least one hydrogenating agent and preferably contains a combination of these two hydrogenating agents. Sulfides and oxides of metals and / or compounds of metals, especially Group VIB (particularly molybdenum and tungsten) and Group VIII (particularly cobalt and nickel) in the elements are generally satisfactory catalytic materials and are prepared by the process of the present invention. It is suggested for use with a carrier with few pores. Combinations of cobalt, nickel and molybdenum catalyst materials are preferred.

The catalyst material required for the catalyst composition of the present invention may be incorporated into the calcined carrier by a suitable method, in particular by impregnation procedures generally used in the field of catalyst manufacture. Particularly notable catalysts are not only when the alumina used has the pore size distribution required according to the invention, but also the one-step impregnation of the alumina with the catalyst using a solution of cobalt or nickel salts and heteropolymolybdic acid, for example phosphomolybdic acid. It was found that even when manufactured by.

The following example shows a method of making the catalyst of the present invention.

[Examples]

Example A

[Production of Catalyst Support]

Alumina feedstock consisting of 60% Catapal alumina and 40% Versal 250 alumina was peptized with 7.6% nitric acid and post-neutralized with 35% aluminum hydroxide to 63% by weight of volatiles. Is generated. In particular, 1260 g of catapal and 840 mg of Versal were maintained at a temperature of 130 ° F. to 140 ° F. on the basis of no volatiles, and 228 g of concentrated nitric acid at about 150 cc / min in a mixer for 15 minutes until paste. Mix with 1515 g deionized water. Slurrying 20 g of paste in 80 cc of deionized water gives a pH of 3.4. 55 g ammonium hydroxide (58 wt% ammonium hydroxide) are mixed with 1145 g deionized water, added to the mixer at a rate of about 150 cc / min and then mixed for an additional 15 minutes. The volatiles content is 61.9% by weight. Paste temperature is 133 ° F. The paste is extruded into a 2 inch extruder using a 0.039 inch cylindrical die. The extrudate is air dried and heated in an oven at 250 ° F. for 2 hours. It is then heated for an additional 2 hours at 400 ° F. The weight recovered is 2,345.5 g. The dried extrudate is fired at 1400 ° F. for 1 hour at an air velocity of 1 cubic foot of dried air per hour. The processed particles have the following properties. The particle diameter is 0.0318 inch, the particle density is 1.056 g / cc, the total pore volume is 0.6188 cc / g, and the surface area is 185 m ² / g. This support material is then impregnated using nickel and molybdenum in the following manner. A mixture of molybdenum oxide dissolved in ammonium hydroxide is acidified with phosphoric acid to pH 2.8 and nickel nitrate hexahydrate is added. The catalyst is prepared by impregnating the support with this mixture. The catalyst is dried at 250 ° F. for 2 hours at 400 ° F. for 6 hours. The catalyst is then calcined by 20 cubic feet of dry air per hour for 4 hours at 450 ° F., 4 hours at 750 ° F., and 5 hours at 950 ° F. The processed catalyst contains 8.62 wt% molybdenum, 3.16 wt% nickel and 1.93 wt% phosphorus. The average pore diameter is 111 mm 3, which is smaller than prior art catalysts. The surface area is 159 m ² / g (see Figure 1).

Example B

The catalyst of Example A is compared to the catalyst of the prior art similarly prepared in the standard activity experiment (see Table 1 and Figure 2 ... Tom'574, '625 and' 661). In this experiment, the conversion catalyst is charged to the reactor under a layer of commercially available standard demetallization catalyst, and both catalysts are previously sulfided using dimethyldisulfide. These catalysts are then contacted with 760 ° F. + Arabian heavy residues under 0.35 LHSV and a total pressure of 2000 psi and with an once-through hydrogen flow of 5000 SCF / bbc. Experiments with the feed speed of 0.35hr ^-1 LHSV to about 0.50hr ^-1 LHSV range over a catalyst system that has a layer 750 at a temperature range of 700 to 750 ℉ ℉. The liquid product from which light gas is removed from the reactor is tested for trace carbon residues (MCR) as defined by ASTM D4530-85. 3 shows the theoretical temperature needed to maintain 55% MCR conversion. According to the results shown in FIG. 3, the catalyst of the present invention is significantly more active than the reference catalyst, as indicated by the lower reactor temperature needed to maintain the desired MCR conversion.

Claims (17)

A pore volume of 0.5 to 1.1 cm ³ per g and a pore having a pore diameter of 70 to 130 mm ³ is 70% or more of the pore volume and a pore having a pore diameter of 300 mm or more is 5% or less of a pore volume and a pore diameter of 1,000 mm or more. An alumina support having pores of 2% or less of the pore volume; And a Group VIB component and a Group VIII component selected from the group consisting of metals, oxides, and sulfides of Group VIB and Group VIII elements. The catalyst composition according to claim 1, wherein the pore volume of the pores having a pore diameter of 70 to 130 mm 3 is 80% or more. The catalyst composition of claim 1 wherein the Group VIB and Group VIII compounds are selected from the group consisting of compounds of cobalt, nickel and molybdenum. The catalyst composition according to claim 1, wherein the pore volume of the pores having a pore diameter of 140 GPa or more is 5% or less. The catalyst composition according to claim 1, wherein the pores having a pore diameter of 1000 mm 3 or more are 1% or less of the pore volume. The catalyst composition of claim 1, wherein the catalyst composition contains 3 weight percent nickel and 9 weight percent molybdenum. (a) treating a peptizable particulate solid containing predominantly alpha-alumina monohydrate by mixing with an aqueous acid solution of pH 3.0 to 4.5; (b) neutralizing at least a portion of the mixed acid by mixing the treated solid with an aqueous solution containing 0.2-0.5 equivalents of nitrogen base per acid equivalent; (c) forming a neutralized or partially neutralized solid; (d) produced by drying and calcining the molded solid at a temperature of 150 to 1700 ° F., the pores having a pore volume of at least 0.5 cm ³ per g and having a pore diameter of 70 to 130 mm ^{3 and at} least 70% of the pore volume At least one catalyst material or catalyst precursor selected from the group consisting of Group VIB and Group VIII compounds, wherein the porous support having pores having a pore diameter is 5% or less of the pore volume and pores having a pore diameter of 1,000 mm or more is 2% or less A method for producing a high activity catalyst for hydrodesulfurization of heavy oil, characterized by drying and firing the resulting impregnated support after impregnation in an aqueous solution containing. The process according to claim 7, wherein the pore volume of the pores having a pore diameter of 70 to 130 mm 3 in the catalyst is at least 80%. 8. The process of claim 7, wherein the Group VIB and Group VIII compounds in the catalyst are selected from the group consisting of compounds of cobalt, nickel and molybdenum. The method according to claim 7, wherein the pore volume of the pores having a pore diameter of 140 GPa or more in the catalyst is 5% or less. 8. The method of claim 7, wherein the pores having a pore diameter of at least 1000 mm 3 in the catalyst is less than or equal to 1% of the pore volume. 8. The method of claim 7, wherein the acid solution is selected from acid solutions of nitric acid, hydrochloric acid, hydrofluoric acid and hydrobromic acid. 8. The method of claim 7, wherein the alpha-alumina monohydrate is less than 500 microns in size. 8. The method of claim 7, wherein the nitrogen base is R ₃ N or R ₃ NHOH, wherein R ₃ is independently selected from the group consisting of hydrogen and alkyl of 1 to 3 carbon atoms. 8. The method of claim 7, wherein the aqueous solution is a solution of cobalt or nickel salts and heteropolymolybdic acid and the impregnation is carried out in one step. 8. The process of claim 7, wherein the catalyst contains 3 weight percent nickel and 9 weight percent molybdenum. 8. The method of claim 7, wherein the solution of nitrogen base contains 0.35 equivalents of base per acid equivalent.