KR100497851B1 - Method to manufacture hydrodesulfurization catalyst using sol-gel process - Google Patents

Abstract

Method for producing a hydrodesulfurization catalyst using the sol-gel method according to the present invention comprises the steps of (a) dissolving an aluminum salt in water to form a sol solution; (B) dissolving the aluminum sol solution of step (a) by sequentially adding a cobalt salt of Group VIII metal and a molybdenum salt of Group VIB metal on the periodic table; (C) adding an epoxide to the sol solution of step (b) to form a composite gel; (D) aging the complex gel of step (c); After the aging of step (d) through the dehydration process to reduce the water content and extrusion molding (e); And (f) preparing a hydrodesulfurization catalyst in the form of a complex oxide by drying and then firing the molded body of step (e).

In the present invention, by preparing a catalyst using a sol-gel process instead of the conventional impregnation method, it is possible to significantly increase the content of the active metal components while maintaining a high dispersion degree, it is possible to produce a high active catalyst suitable for ultra-depth hydrodesulfurization . In addition, the hydrodesulfurization catalyst according to the present invention exhibits high hydrodesulfurization activity, obtains a high specific surface area and pore volume, and controls physical properties such as the average pore diameter of the catalyst by changing the sol-gel synthesis conditions. It is also possible to broaden the application range of a manufacturing method.

Description

Method for manufacture hydrodesulfurization catalyst using sol-gel process

The present invention is hydrogenated to remove sulfur components contained in various oil fractions, such as naphtha, kerosene, diesel oil, atmospheric residue oil, vacuum residue oil, etc., fractionated and distilled in a distillation column, in a refinery plant. The present invention relates to a method for preparing a highly active hydrodesulfurization catalyst that can be applied to a hydrodesulfurization process. More specifically, the present invention uses aluminum, cobalt, and mol by using the sol-gel method, which uses a low-cost metal salt as a precursor and environmentally friendly water as a solvent, instead of the conventional impregnation method of supporting an active metal component on an alumina carrier. By preparing a cobalt-molybdenum-alumina composite gel from a common salt of ribbium, and preparing a hydrodesulfurization catalyst, the content of the active metal component can be greatly increased while maintaining the dispersibility of the active metal component. The present invention relates to a process for producing a hydrodesulfurization catalyst using a sol-gel method suitable for ultra-high depth hydrodesulfurization.

Recently, due to the deepening of environmental problems, regulations on sulfur content in fuel oil are becoming more and more strict, and accordingly, development of a high activity hydrodesulfurization catalyst that can satisfy the regulation value is required. In general, the catalyst is composed of an active metal component which acts as an active point of the reaction with the carrier, and the catalyst mainly used in the desulfurization process includes an active metal component such as molybdenum, tungsten, tungsten, and cobalt or nickel, etc. It is composed of alumina, which is a carrier, and usually forms Co-Mo / Al ₂ O ₃ , Ni-Mo / Al ₂ O ₃ , Ni-W / Al ₂ O ₃ , Co-Ni-Mo / Al ₂ O _3, etc. Have

US Pat. No. 4,306,965, which is a prior art for producing a hydrodesulfurization catalyst, impregnates an activated metal inorganic acid salt, such as molybdenum of group VIB, cobalt or nickel of tungsten and group VIII, into a molded alumina carrier, and then calcinates it. A method for producing a hydrodesulfurization catalyst containing an active metal component by converting an active metal inorganic acid salt to an active metal oxide is disclosed. In this method, however, when the content of the active metal component is low, the active metal component may be uniformly dispersed in the carrier, but as the impregnation amount of the active metal component increases, it is difficult to uniformly disperse the active metal component in the carrier.

In order to solve this problem, in US Pat. No. 4,839,028, instead of impregnating an active metal component in a molded alumina carrier, the active metal component of the catalyst is calcined by mixing the active metal inorganic acid salt with an alumina hydrogel and then calcining. In addition, a method for producing a catalyst having excellent dispersibility of an active metal component even in a high case is disclosed. In the above invention, a method for producing an alumina hydrogel includes a method of precipitating an acidic aluminum such as aluminum nitrate with a basic aqueous solution such as ammonia water or a basic aluminum salt such as sodium aluminate, and a basic aluminum salt with an acidic aqueous solution such as nitric acid or an acidic aluminum salt. A method of precipitation is disclosed. However, when the alumina hydrogel is prepared, an acid or base component used as a titration agent is required for 3 equivalents to 1 equivalent of aluminum, so that the titrant is excessively consumed.

In the Republic of Korea Patent No. 10-02914732, in order to solve the problem of the patent, by using a pseudoboehmite hydrogel instead of using alumina hydrogel as a precursor of the desulfurization catalyst carrier, it was possible to reduce the amount of acid used, the ratio of the catalyst Surface area control was made possible and the addition of alcohol prevented the loss of active metal components. In addition, Korean Patent No. 10-02914733 prepared a highly active desulfurization catalyst by using a pseudo boehmite paste to facilitate the adjustment of the catalyst properties in a relatively simple process.

However, the hydrodesulfurization catalyst prepared according to the above patents has a limitation in the high dispersion of the active metal component since the active metal inorganic acid salt is mixed with the precursor of the alumina carrier such as alumina hydrogel, pseudoboehmite hydrogel, and pseudoboehmite paste. In particular, it is difficult to increase the content of the active metal component to 30% or more, and furthermore, there is a limit in the control of the specific surface area or pore size. Therefore, it is urgent to develop a new method to solve the problem more fundamentally to produce a catalyst having a high activity.

The sol-gel method, which has recently been in the spotlight as a new catalyst manufacturing method, is a completely different method from the existing catalyst manufacturing method in that a homogeneous solution obtained by simultaneously mixing and mixing the precursor of the active ingredient and the precursor of the support is a starting material. The catalyst made by this method has a large specific surface area, pore volume, etc., and can significantly increase the dispersibility while maintaining a high content of active metal components. Conventional sol-gel methods for making alumina gels include the Yoldas method (Journal of Materials Science, Vol. 10, pp. 1856 ~) using excess water as a solvent and aluminum alkoxide as a precursor. 1860, 1975) and the use of alcohols as solvents (Chemistry of Materials, Vol. 9, pp. 1903-1905, 1997). However, since all of these processes proceed in an acidic atmosphere, precipitation of ammonium heptamolybdate, which is widely used as a precursor of molybdenum, occurs, and solubility is particularly high when alcohol is used as a solvent. Because of their low content, it is difficult to produce cobalt-molybdenum-alumina composite gels having a uniform but high active metal content. In addition, alkoxides used as precursors of sol-gel reactions are not only relatively expensive, but also have various problems such as being sensitive to moisture.

Itoh et al. (Journal of the Ceramic Society of Japan, Vol. 101, pp. 1081-1083, 1993) used propylene oxide as a gelation promoter to form tetraethoxysilane and chlorides, not alkoxides. Silica-alumina composite gels were prepared from aluminum. Gash et al. (Journal of Non-Crystalline Solids, Vol. 285, pp. 22-28, 2001 and Chemistry of Materials, Vol. 13, pp. 999-1007, 2001) show that the epoxide is hydrogen It has been published about the general sol-gel process for preparing gels such as chromium and iron from inexpensive metal salts and propylene oxide, noting that they slowly consume ions to produce a uniform gel without producing precipitates. However, their findings suggest only manufacturability for several monocomponent materials below trivalent, solvents are mainly organic solvents, and no detailed preparation conditions or synthesis of uniform multicomponent gels are given. It is not.

The present invention is to solve the problems of the prior art as described above, the object of the present invention, instead of the conventional impregnation method of supporting the active metal component on the alumina carrier, using a low-cost metal salt precursor and environmentally friendly water The cobalt-molybdenum-alumina composite gel was prepared by using a sol-gel method using a solvent, and a hydrodesulfurization catalyst was prepared using the same, thereby maintaining a high dispersion of the active metal component while maintaining a high dispersion of the active metal component. The present invention provides a method for preparing a hydrodesulfurization catalyst using the sol-gel method, which is highly suitable for ultra-high depth hydrodesulfurization.

In order to achieve the above object, the method for producing a hydrodesulfurization catalyst using the sol-gel method according to the present invention comprises the steps of dissolving an aluminum salt in water to form a sol solution; (B) dissolving the aluminum sol solution of step (a) by sequentially adding a group VIII metal salt on the periodic table and a group VIB metal salt; (C) adding an epoxide to the sol solution of step (b) to form a composite gel; (D) aging the complex gel of step (c); After the aging of step (d) through the dehydration process to reduce the water content and extrusion molding (e); And (f) preparing a hydrodesulfurization catalyst in the form of a complex oxide by drying and then firing the molded body of step (e).

In the method for producing a hydrodesulfurization catalyst using the sol-gel method according to the present invention, the Group VIII metal salt of step (b) is characterized in that the cobalt oxide or nickel oxide.

In the method for producing a hydrodesulfurization catalyst using the sol-gel method according to the present invention, the Group VIB metal salt of step (b) is characterized in that the molybdenum oxide or tungsten oxide.

In the method for preparing a hydrodesulfurization catalyst using the sol-gel method according to the present invention, the Group VIII metal salt content in the hydrodesulfurization catalyst is 2 wt% to 10 wt%, the Group VIB metal salt content is 15 wt% to 50 wt%, and the rest is It is characterized by being alumina.

In the method for preparing a hydrodesulfurization catalyst using the sol-gel method according to the present invention, the epoxide of the step (c) is selected from ethylene oxide, propylene oxide, or butylene oxide.

In the method for preparing a hydrodesulfurization catalyst using the sol-gel method according to the present invention, the amount of epoxide used in the step (c) is 4 to 20 mol per mole of aluminum salt.

Hereinafter, a method for preparing a hydrodesulfurization catalyst using the sol-gel method of the present invention will be described in detail by taking a cobalt-molybdenum-alumina composite gel catalyst as an example.

In order to prepare the hydrodesulfurization catalyst, first, an aluminum salt, which is a precursor of alumina, is dissolved in water with vigorous stirring at room temperature for 0.5 to 5 hours, preferably 2 hours to form a transparent solution in a sol state. The total amount of water used to prepare the catalyst is 30 to 150 moles per mole of aluminum salt, and this value is fluid depending on the active metal content of the catalyst, so about 55 to 70 moles is suitable for low metal content, and high About 80-100 moles are appropriate. The amount of water used in the preparation of the solution of the aluminum sol state is used in the total amount of water except the amount necessary to dissolve the precursor of the active metal component. After adding the solution which melt | dissolved cobalt salt in this sol solution, it stirs vigorously at normal temperature for 5 to 50 minutes, Preferably it is about 15 to 20 minutes. When the alumina sol solution and the cobalt salt solution are uniformly mixed through the above steps, the sol solution is continuously stirred vigorously, and the solution of molybdenum salt dissolved in water is added for 0.5 to 5 hours, preferably 0.75 to Keep it for about 1.0 hours. When propylene oxide is added to the composite sol solution prepared as above, the gelation reaction proceeds at room temperature, thereby obtaining a cobalt-molybdenum-alumina composite gel. At this time, the amount of propylene oxide used is about 4 to 20 mol per mole of aluminum salt, which is slightly fluid depending on the amount of water, and about 6 to 8 mol when the amount of water is small, and about 8 to 10 mol when the amount of water is large. Is suitable.

Aluminum chloride or aluminum nitrate may be used as the aluminum salt, and as the active metal salt, cobalt nitrate in the case of cobalt salts such as ammonium heptamolybdate and molybdenum acid in the case of molybdenum salt Although any water-soluble salts such as cobalt chloride and cobalt oxide may be used, it is preferable to use aluminum chloride as the carrier component, ammonium heptamolybdate as the main catalyst component, and cobalt nitride as the precursor component. .

The composite gel thus prepared is subjected to aging for 1 to 15 days, preferably 3 to 5 days, followed by dehydration to reduce the water content to 50 to 70 wt% and then extrusion molding. The molded body is dried at a temperature of 20 ~ 200 ℃, preferably 50 ~ 150 ℃ and then fired at a temperature of 300 ~ 900 ℃, preferably 400 ~ 700 ℃ to finally prepare a hydrodesulfurization catalyst in the form of a complex oxide.

In the final composite oxide catalyst, molybdenum oxide (MoO ₃ ) may be manufactured in a range of 15 to 50 wt% and cobalt oxide (CoO) in a range of 2 to 10 wt%, preferably 25 to 40 wt%, respectively. A range of 5-9 wt% is suitable. In addition, the specific surface area of the catalyst prepared by the present invention is 200 ~ 500 m ² / g, the pore amount is 0.3 ~ 1.2 cc / g, the average pore diameter is 7 ~ 11 nm range.

Hereinafter, the configuration and the effects of the present invention will be described in more detail with reference to Examples. The following examples illustrate the content of the invention, but the content of the invention is not limited thereto.

<Example 1>

At room temperature, 169 g of aluminum chloride (AlCl ₃ H ₂ O) was dissolved in 792 ml of ion-exchanged water, and then vigorously stirred for 2 hours to form a transparent sol solution. A solution of 7.27 g of cobalt nitrate (Co (NO ₃ ) ₂ .6H ₂ O) dissolved in 30 ml of ion-exchanged water was added to the above sol solution and stirred for 15 minutes, followed by 60 ml of ion-exchanged water and ammonium hep A molybdenum salt solution prepared by mixing 11.30 g of tamolybdate ((NH ₄ ) ₆ Mo ₇ O ₂₄ .4H ₂ O) was added thereto, followed by stirring for 45 minutes to prepare a uniform complex sol solution. When 490 ml of propylene oxide is added to the composite sol solution thus prepared and the gelation reaction proceeds, a cobalt-molybdenum-alumina composite gel can be obtained in one hour.

The prepared composite gel was dehydrated after 3 days of aging and extruded into trilobe type. The molded product was dried at a temperature of 80 ° C. for 24 hours, and then calcined at an electric furnace for 5 hours at a temperature of 550 ° C. to prepare an oxide hydrodesulfurization catalyst. The amount of the metal salts used herein is calculated by adding the active metal component of the cobalt-molybdenum-alumina catalyst to 4.0 wt% cobalt oxide and 19.7 wt% molybdenum oxide.

<Example 2>

To a sol solution prepared by dissolving 169 g of aluminum chloride in 603 ml of ion-exchanged water and vigorously stirring at room temperature for 2 hours, 10.62 g of cobalt nitrate was added to 30 ml of ion-exchanged water, followed by stirring for 15 minutes. A molybdenum salt solution prepared with 60 ml of ion-exchanged water and 17.34 g of ammonium heptamolybdate was added thereto, followed by stirring for 45 minutes to prepare a composite sol solution. When 294 ml of propylene oxide was added to the sol solution, the gelation reaction proceeded and a cobalt-molybdenum-alumina composite gel could be produced in about 45 minutes. Other procedures were performed in the same manner as in Example 1. The amount of the metal salts used herein was calculated by adding the active metal component of the cobalt-molybdenum-alumina catalyst to 5.2 wt% cobalt oxide and 26.9 wt% molybdenum oxide.

<Example 3>

Hydrodesulfurization catalyst was prepared in the same manner as in Example 2 except that the amounts of cobalt nitrate and ammonium heptamolybdate used in preparing the active metal salt solution were 15.3 g and 25.06 g, respectively. The amount of metal salts used herein was calculated by adding the active metal component of the cobalt-molybdenum-alumina catalyst to 6.6 wt% of cobalt oxide and 34.0 wt% of molybdenum oxide.

<Example 4>

831, 50 and 120 ml of water, 22.7 g of cobalt nitrate and 37.18 g of ammonium heptamolybdate were used to prepare aluminum salt, cobalt salt and molybdenum solution, respectively, and 392 ml of propylene oxide was used for the gelation reaction. A catalyst was prepared in the same manner as in Example 1 except for the point. The amount of metal salts used herein was calculated by adding the active metal component of the cobalt-molybdenum-alumina catalyst to 8.2 wt% cobalt oxide and 42.1 wt% molybdenum oxide.

Comparative Example 1

Hydrodesulfurization catalyst was prepared by the method disclosed in the prior art (Korean Patent No. 10-0291473) utilizing pseudoboehmite paste.

After adding 800 g of pseudoboehmite to the kneader, 575 g of an acetic acid solution in which 33 g of 99.7% acetic acid was dissolved in water was added and kneaded at room temperature for 10 minutes to first gelatinize pseudoboehmite, and then 5.7 g of 62% nitric acid, Mixed bovine aqueous solution diluted with 25.5 g of 85% phosphoric acid was added to 50 g of water, followed by kneading at room temperature for 30 minutes. Secondly, pseudoboehmite was secondly gelatinized. Was prepared. Then, 36 g of hydrogen peroxide and 20 g of monoethanolamine were kneaded with the pseudoboehmite paste, followed by kneading at room temperature for 10 minutes by adding 188 g of ammonium heptamolybdate, and further kneading at room temperature for 1 hour with 121 g of cobalt oxide. It was then extruded into a trilobal in a piston extruder. Then, the resultant was dried at 80 ° C. for 12 hours and then calcined at 550 ° C. for 5 hours in an electric furnace to prepare an oxide hydrodesulfurization catalyst. The amount of the metal salts used herein is calculated by adding the active metal component of the cobalt-molybdenum-alumina catalyst to 4.0 wt% cobalt oxide and 19.7 wt% molybdenum oxide.

Experimental Example 1

1. Performance Evaluation Method of Hydrodesulfurization Catalyst

In order to determine the desulfurization performance of the hydrodesulfurization catalysts prepared according to the present invention, a high-pressure desulfurization reactor was used, and the catalyst performance was evaluated in the following manner.

The reactant crude oil is a direct diesel diesel fraction of Arabian light crude oil. The API Petroleum Institute (API) is about 33-34, and the sulfur content is about 1.29 wt.%. The reactor used was a downflow reactor with a micro reactor with a maximum allowable volume of less than 10 cc. The material was made of stainless steel, and a thermocouple was attached to the reactor to control the reaction temperature. When the catalyst was charged, the catalyst was pulverized to a size of 20-40 mesh, dried, and then mixed with 3 g of inert silicon carbide (SiC) of the same size so as to have a total volume of 5.3 cc. At the time of filling the catalyst, inert silicon carbide was charged at the top and bottom of the reactor to improve contact between the raw material oil and the catalyst, and glass wool was charged to the catalyst layer to prevent the outflow of the pulverized catalyst. After the reactor was mounted in a reaction apparatus, sulfidation was performed at atmospheric pressure using a 10% hydrogen sulfide mixed gas diluted in hydrogen in order to convert the catalyst in the form of an oxide into an activated sulfide form. The flow rate of the crude oil was constantly injected into the reactor by a diaphragm pump, and the total pressure of the reactor was controlled by a pressure regulator. The liquid product after the reaction was used to remove hydrogen sulfide dissolved in the product using nitrogen, and then undecomposed sulfur compounds. Was analyzed by a sulfur analyzer to determine the degree of reaction. The sulfidation and reaction conditions are shown in Table 1 below.

The specific reaction sequence is as follows.

1) After the reactor is filled with the catalyst, 10% hydrogen sulfide / hydrogen mixed gas is introduced into the reactor at normal pressure.

2) The reactor temperature is raised to 400 ^° C. at room temperature and then maintained at this temperature for 2 hours.

3) After cooling the reactor temperature to 200 ^o C, replace the 10% hydrogen sulfide / hydrogen mixed gas with hydrogen gas and pressurized to the reaction pressure.

4) After the reaction pressure is reached, the feedstock oil is started and the feedstock oil is supplied so that the catalyst layer is sufficiently wetted.

5) When it is confirmed that the catalyst layer is sufficiently wetted with the raw material oil, the reactor temperature is gradually raised to the reaction temperature.

6) After reaching the reaction temperature, hold for 8 hours, collect the reaction product in the liquid phase and measure the degree of reaction.

2. Performance Evaluation Results of Hydrodesulfurization Catalyst

Physical properties and performance evaluation results of the hydrodesulfurization catalyst prepared by Examples 1 to 4 and Comparative Example 1 are shown in Table 2 below.

* Specific surface area, total pore volume and average pore size are measured by nitrogen adsorption and desorption method.

* The relative reaction activity is the ratio of the desulfurization rate constant obtained from the desulfurization rate equation according to the temperature, which is a relative value of the desulfurization rate constant of Comparative Example 1 as 100.

Comparing Comparative Example 1 and Example 1 having the same active ingredient content, it can be seen that the hydrodesulfurization activity of the catalyst prepared according to the present invention is about 30% higher than the catalyst prepared from pseudoboehmite paste. This is because the sol-gel process used in the present invention not only significantly improves physical properties such as specific surface area, total pore amount, average pore size, etc., but also greatly increases the dispersibility of the active metal. In addition, when the catalyst is prepared using the sol-gel process, it is possible to increase the content while maintaining a high dispersibility of the active metal components, thereby enabling the production of a catalyst having a high content of the active metal.

As shown in Table 2, the specific surface area and the like tended to decrease with increasing content of the active metal components, but the reaction activity continued to increase until the total active metal content reached 40 wt%. In addition, the activity of the example catalysts for the hydrodesulfurization reaction was confirmed to be superior to the catalysts prepared by the conventional method. That is, the physical properties and the reaction activity of the hydrodesulfurization catalysts prepared by the method presented in the present invention were much better than those of the catalysts prepared by the method of improving the existing supporting method as in the comparative example.

As described above, in the present invention, by preparing a catalyst using a sol-gel process instead of the conventional impregnation method, it is possible to greatly increase the content of the active metal components while maintaining a high dispersion degree, high activity suitable for ultra-depth hydrodesulfurization The catalyst could be prepared. In addition, the hydrodesulfurization catalyst according to the present invention exhibits high hydrodesulfurization activity, obtains a high specific surface area and pore volume, and controls physical properties such as the average pore size of the catalyst by changing the sol-gel synthesis conditions. It is also possible to broaden the application range of a manufacturing method.

In addition, the present invention uses a general metal salt which is inexpensive and easy to handle as a precursor instead of the alkoxide which was mainly used as a precursor in the conventional sol-gel process, the scope of application of the manufacturing process is expanded, and the manufacturing cost can be reduced. Mass production of hydrodesulfurization catalysts is possible.

Claims (6)

Dissolving the aluminum salt in water to form a sol solution (a); (B) dissolving the aluminum sol solution of step (a) by sequentially adding a cobalt salt of Group VIII metal and a molybdenum salt of Group VIB metal on the periodic table; (C) adding an epoxide to the sol solution of step (b) to form a composite gel; (D) aging the complex gel of step (c); After the aging of step (d) through the dehydration process to reduce the water content and extrusion molding (e); And Drying the molded body of step (e) and then calcining to produce a hydrodesulfurization catalyst in the form of a complex oxide comprising the step of manufacturing a hydrodesulfurization catalyst using a sol-gel method characterized in that it comprises a. The method of claim 1, The cobalt salt of step (b) is a method for producing a hydrodesulfurization catalyst using the sol-gel method, characterized in that the cobalt oxide. The method of claim 1, The molybdenum salt of step (b) is a method for producing a hydrodesulfurization catalyst using a sol-gel method, characterized in that the molybdenum oxide. The method of claim 1, Cobalt salt content in the hydrodesulfurization catalyst is 2wt% to 10wt%, molybdenum salt content is 15wt% to 50wt%, the remainder is alumina characterized in that the method for producing a hydrodesulfurization catalyst using the sol-gel method. The method of claim 1, The epoxide of step (c) is selected from ethylene oxide, propylene oxide, or butylene oxide is used for producing a hydrodesulfurization catalyst using the sol-gel method. The method according to claim 1 or 5, Method for producing a hydrodesulfurization catalyst using the sol-gel method, characterized in that the amount of epoxide used in step (c) is 4 to 20 mol per mol of aluminum salt.