Preparation method of titanium-aluminum composite material and middle distillate hydrofining catalyst

Abstract

The invention discloses a preparation method of a titanium-aluminum composite material and a middle distillate hydrofining catalyst, and the preparation method comprises the following steps: S1, adding pseudo-boehmite and potassium dititanate into water, dispersing, sealing and standing; s2, under the stirring state, hydrochloric acid is dropwise added into the material obtained after standing in the step S1, then heating and constant-temperature acidolysis are conducted, and titanium-aluminum sol is formed; s3, adjusting the pH value of the titanium-aluminum sol to 9-10 to form gel, aging, washing with water, and filtering to obtain a titanium-aluminum composite material wet filter cake; and S4, adding diatomite, acetic acid and a lubricant into the wet filter cake, uniformly mixing, carrying out extrusion molding, carrying out vacuum freeze drying treatment, and roasting to obtain the titanium-aluminum composite carrier. The problems that a conventional TiO2 material used for preparing a hydrodesulfurization catalyst carrier is low in specific surface area and few in surface active sites, and a carrier prepared from single-component TiO2 is difficult to form and low in mechanical strength are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrofining, and specifically relates to a preparation method of a titanium-aluminum composite material and a catalyst for hydrofining of intermediate distillate oil. Background Art

[0002] In order to reduce the pollution caused by the use of diesel to the environment, my country has successively formulated and implemented the National III, National IV, and National V diesel standards, which are equivalent to the Euro III, Euro IV, and Euro V standards. The National VI diesel standard currently implemented in my country has put forward more stringent requirements on indicators such as sulfur content, cetane number, and polycyclic aromatic hydrocarbon content in diesel. The quality of automotive diesel is rapidly developing in the direction of low sulfur and low aromatics. At the same time, the degree of heavy and inferior quality of crude oil has intensified, the distillation range of diesel fractions has shifted backward, the number of difficult-to-remove sulfides has increased, and the difficulty of desulfurization has increased. How to achieve the cleaning of inferior raw materials and meet the market's consumer demand for high-quality clean diesel is one of the key tasks of refining and chemical companies.

[0003] The current measures to upgrade the quality of existing diesel hydrotreating units include increasing the severity of the unit reaction, reducing the diesel terminal distillation point, reducing the unit processing volume, and using highly active diesel hydrotreating catalysts. Increasing the severity of the unit reaction, reducing the diesel terminal distillation point, and reducing the unit processing volume have an adverse impact on the production efficiency and production cost of the unit. To solve the above problems, foreign Albemarle, Criterion, IFP and other companies have developed highly active hydrogenation catalysts suitable for deep hydrodesulfurization of diesel and have achieved wide application. Therefore, the development and application of highly active diesel hydrogenation catalysts is the most effective measure for diesel hydrogenation units to upgrade diesel quality.

[0004] TiO 2 As an active catalyst carrier, it is widely used in many aspects. As a hydrodesulfurization catalyst carrier, it can improve the dispersion of active components on the carrier surface and promote the hydrogenation catalytic effect of active components. 2 The carrier prepared by the material has a low specific surface area and few surface active sites. 2 The prepared carrier also has defects such as difficulty in molding and low mechanical strength.

[0005] Patent CN110725005B discloses a mesoporous TiO 2 The preparation method of whiskers, distillate oil hydrodesulfurization catalyst and preparation method thereof include the following steps: firstly prepare TiO 2Whisker material: step 1, add water to potassium dititanate, stir, and then seal and stand for 3 to 15 days; step 2, disperse the solid after standing in water, the solid-liquid ratio is 1:100 to 1:500, then add hydrochloric acid, adjust the pH value to 1 to 10, stir for 18 to 48 hours to perform a first ion exchange reaction; step 3, settle and filter the emulsion after the ion exchange reaction, wash and dry the precipitate to obtain dititanic acid; step 4, immerse the obtained dititanic acid in a KOH aqueous solution to perform a second ion exchange reaction, stand for 2 to 24 hours, filter and dry to obtain TiO 2 Whiskers. Then TiO 2 The whiskers and pseudo-boehmite were added to water in a certain solid-liquid ratio, heated to 40-90°C, the pH of the system was adjusted to 1-2, and acid hydrolyzed at constant temperature for 4-8 hours to form an aluminum-titanium sol; the pH of the aluminum-titanium sol was adjusted to 9-10 to form a gel, which was aged for 2-10 hours, washed with water, filtered, dried, and calcined to obtain mesoporous TiO 2 Whisker / γ-Al 2 O 3 Composite materials. Then mesoporous TiO 2 Whisker / γ-Al 2 O 3 The composite material is used as the substrate and loaded with active components to prepare the distillate oil hydrodesulfurization catalyst. The preparation process of this method is complicated and requires two ion exchanges to prepare TiO 2 Whisker material, and then TiO 2 The whisker material and pseudo-boehmite were composited and washed, filtered, dried and calcined to prepare mesoporous TiO 2 Whisker / γ-Al 2 O 3 Composite materials, and then mesoporous TiO 2 Whisker / γ-Al 2 O 3 The composite material is used as a substrate to load the active component to prepare the catalyst, and there are many factors affecting the preparation process. In addition, the method uses nitric acid, nitrates and other raw materials that can generate nitrogen oxide emissions during the preparation of the carrier and catalyst.

[0006] Patent CN110935460B discloses a method for preparing a highly selective hydrodesulfurization catalyst, wherein the hydrodesulfurization catalyst is composed of a carrier and an active component, wherein the carrier is a potassium-containing mesoporous TiO 2 The carrier is potassium dititanate, which is exchanged twice to obtain dititanate and then mesoporous TiO with controllable potassium content. 2 , the potassium content is 1 to 10 wt%; the active components are molybdenum and nickel, molybdenum and nickel are respectively MoO 3The mass of NiO and NiO respectively accounts for 5-35wt% and 1.56-7.8wt% of the catalyst mass. The hydrodesulfurization catalyst of the invention mainly removes sulfur from sulfur-containing species by direct desulfurization, which can reduce the hydrogen consumption in the desulfurization process. The highly selective hydrodesulfurization catalyst prepared by the method is suitable for gasoline hydrodesulfurization process. Summary of the invention

[0007] The purpose of the present invention is to provide a method for preparing an aluminum-titanium composite material, which solves the problem of conventional TiO 2 The material is used to prepare the hydrodesulfurization catalyst carrier with low specific surface area, few surface active sites, and single-component TiO 2 The prepared carrier is difficult to shape and has low mechanical strength. While improving the catalyst activity and mechanical strength, nitric acid and nitrates are not used, nitrogen oxide emissions are eliminated during the catalyst preparation process, and air pollution is reduced.

[0008] Another object of the present invention is to provide a catalyst for hydrotreating middle distillate oil.

[0009] To achieve the above object, the present invention provides a method for preparing a titanium-aluminum composite material, comprising the following steps:

[0010] S1, adding pseudo-boehmite and potassium dititanate into water, dispersing them, sealing and letting them stand;

[0011] S2, under stirring, adding hydrochloric acid to the material after standing in step S1, and then heating and isothermal acid hydrolysis to form a titanium aluminum sol;

[0012] S3, adjusting the pH of the titanium-aluminum sol to 9-10 to form a gel, aging it, washing it with water, and filtering it to obtain a wet filter cake of the titanium-aluminum composite material;

[0013] S4, adding diatomaceous earth, acetic acid and lubricant to the wet filter cake, mixing evenly and then extruding to form, and then freeze-drying and calcining to obtain a titanium-aluminum composite carrier.

[0014] In the method for preparing the titanium-aluminum composite material of the present invention, in step S1, the mass ratio of pseudo-boehmite to potassium dititanate is 2-6:1, and the mass ratio of the total amount of pseudo-boehmite and potassium dititanate to water is 1:8-20.

[0015] In the method for preparing the titanium-aluminum composite material of the present invention, the sealing standing time in step S1 is 12 to 24 hours.

[0016] In the method for preparing the titanium-aluminum composite material of the present invention, the acid-aluminum ratio in step S2 is 0.2-0.4 mol / mol.

[0017] In the method for preparing the titanium-aluminum composite material of the present invention, the heating temperature in step S2 is 60 to 90° C., and the acid hydrolysis time is 8 to 12 hours.

[0018] In the method for preparing the titanium-aluminum composite material of the present invention, the aging time in step S3 is 2 to 4 hours.

[0019] In the preparation method of the titanium-aluminum composite material described in the present invention, the amount of diatomaceous earth added in step S4 is 3-8% of the total mass of potassium dititanate and pseudo-boehmite, the amount of acetic acid added is 2-5% of the total mass of potassium dititanate and pseudo-boehmite, and the lubricant is one or more of sesbania powder, dry starch and graphite, and the amount added is 2-3% of the total mass of potassium dititanate and pseudo-boehmite.

[0020] In the preparation method of the titanium-aluminum composite material of the present invention, the freeze-drying conditions in step S4 are a temperature of -20 to -30°C, a pressure of 15 to 30 KPa, and a time of 8 to 24 hours.

[0021] In the method for preparing the titanium-aluminum composite material of the present invention, the calcination temperature in step S4 is 420-600° C. and the calcination time is 2-5 hours.

[0022] To achieve the above object, the present invention also provides a catalyst for hydrotreating middle distillate oil, comprising the titanium-aluminum composite material prepared by the above method, and an active component MoO 3 and NiO.

[0023] Beneficial effects of the present invention:

[0024] (1) The method of directly molding the titanium-aluminum composite wet cake simplifies the carrier preparation process, avoids the destruction of the internal accumulation state of the microcrystalline particle aggregates during the drying and calcination process of the catalytic material wet cake, improves the specific surface area and pore diffusion performance of the catalyst, and makes TiO 2 The active carrier function is effectively played. During the sulfidation process, the catalyst TiO 2 The surface is partially sulfided, Ti 4+ Reduced to Ti 3+ , acting as an electron promoter in the hydrodesulfurization reaction, making it easier for electrons to move from TiO 2 Transfer to the 3d orbital of the active component, thereby reducing the Mo-S bond energy, making it easier for sulfur vacancies to appear in the active component and improving the activity of the catalyst.

[0025] (2) Nitrogen oxides are harmful air pollutants that can cause acid rain, generate photochemical smog, increase the concentration of fine particulate matter PM2.5, damage the ozone layer, and intensify the greenhouse effect. The present invention uses acetic acid, hydrochloric acid, basic nickel carbonate, nickel acetate, etc. to replace nitric acid, nitrates, and other raw materials that can generate nitrogen oxide emissions, and combines the titanium aluminum composite wet filter cake direct molding and vacuum freeze drying method to prepare the catalyst, which solves the problem of not being able to use nitric acid and nitrates while improving the activity and mechanical strength of the catalyst, eliminates nitrogen oxide emissions during the preparation of the carrier and the catalyst, and reduces pollution to the atmosphere. DETAILED DESCRIPTION

[0026] The present invention is described in detail below by way of examples. It is necessary to point out that the following examples are only used to further illustrate the present invention and cannot be understood as limiting the scope of protection of the present invention. Those skilled in the art in this field can make some non-essential improvements and adjustments to the present invention based on the above content of the present invention.

[0027] Example 1

[0028] 107 g of pseudo-boehmite (dry basis 70 wt%) and 40 g of potassium dititanate were added to a container containing 2200 ml of deionized water, stirred evenly, sealed and allowed to stand for 20 h to obtain a sample; 18.6 g of hydrochloric acid with a mass concentration of 35% was added to the above sample under stirring, heated to 90°C and kept at a constant temperature for 10 h; then an appropriate amount of KOH was slowly added to adjust the system pH to 9.5 to form a gel, and aged for 2 h; washed with deionized water until neutral, and filtered to obtain a wet cake; 8.8 g of diatomaceous earth, 4 g of sesbania powder, and 6 g of acetic acid were added to the wet cake, mixed evenly, and then extruded into a mold; freeze-dried at 15 KPa and -30°C for 18 h, and calcined at 450°C for 3 h to obtain a carrier; an impregnation solution was prepared using basic nickel carbonate and molybdenum trioxide, and equal volumes of impregnation were used to prepare a nickel-molybdenum supported catalyst, wherein MoO 3 The loading amounts of NiO and NiO are 26wt% and 4wt% respectively. Its main properties are listed in Table 1.

[0029] Example 2

[0030] 115 g of pseudo-boehmite (dry basis 70 wt%) and 32 g of potassium titanate were added to a container containing 1770 ml of deionized water, stirred evenly, sealed and allowed to stand for 24 h to obtain a sample; 16 g of hydrochloric acid with a mass concentration of 35% was added to the above sample under stirring, heated to 80°C and kept at a constant temperature for 8 h; then an appropriate amount of KOH was slowly added to adjust the system pH to 9.5 to form a gel, and aged for 4 h; washed with deionized water until neutral, and filtered to obtain a wet cake; 7.4 g of diatomaceous earth, 4 g of sesbania powder, and 4.5 g of acetic acid were added to the wet cake, mixed evenly, and then extruded into a mold; freeze-dried at 15 KPa and -20°C for 12 h, and calcined at 500°C for 4 h to obtain a carrier; an impregnation solution was prepared using basic nickel carbonate and molybdenum trioxide, and an equal volume of impregnation was used to prepare a nickel-molybdenum supported catalyst, wherein MoO 3 The loading amounts of NiO and NiO are 26wt% and 4wt% respectively. Its main properties are listed in Table 1.

[0031] Example 3

[0032] 122 g of pseudo-boehmite (dry basis 70 wt%) and 24 g of potassium titanate were added to a container containing 1200 ml of deionized water, stirred evenly, sealed and allowed to stand for 15 h to obtain a sample; under stirring, 25.4 g of hydrochloric acid with a mass concentration of 35% was added to the above sample, heated to 60°C and kept at a constant temperature for 8 h; then an appropriate amount of KOH was slowly added to adjust the system pH to 10 to form a gel, and aged for 3 h; washed with deionized water until neutral, and filtered to obtain a wet cake; 4.4 g of diatomaceous earth, 4 g of sesbania powder, and 3 g of acetic acid were added to the wet cake, mixed evenly, and then extruded into a mold; freeze-dried at 20 KPa and -30°C for 8 h, and calcined at 520°C for 3 h to obtain a carrier; an impregnation solution was prepared using basic nickel carbonate and molybdenum trioxide, and an equal volume of impregnation was used to prepare a nickel-molybdenum supported catalyst, wherein MoO 3 The loading amounts of NiO and NiO are 26wt% and 4wt% respectively. Its main properties are listed in Table 1.

[0033] Example 4

[0034] 100 g of pseudo-boehmite (dry basis 70 wt%) and 48 g of potassium dititanate were added to a container containing 3000 ml of deionized water, stirred evenly, sealed and allowed to stand for 12 h to obtain a sample; 28 g of hydrochloric acid with a mass concentration of 35% was added to the above sample under stirring, heated to 70°C and kept at a constant temperature for 12 h; then an appropriate amount of KOH was slowly added to adjust the system pH to 9 to form a gel, and aged for 2 h; washed with deionized water until neutral, and filtered to obtain a wet cake; 11.8 g of diatomaceous earth, 4 g of sesbania powder, and 7.5 g of acetic acid were added to the wet cake, mixed evenly, and then extruded into a mold; freeze-dried at 30 KPa and -25°C for 24 h, and calcined at 600°C for 2 h to obtain a carrier; an impregnation solution was prepared using basic nickel carbonate and molybdenum trioxide, and an equal volume of impregnation was used to prepare a nickel-molybdenum supported catalyst, wherein MoO3 The loading amounts of NiO and NiO are 26wt% and 4wt% respectively. Its main properties are listed in Table 1.

[0035] Comparative Example 1

[0036] According to Example 1 in patent CN110725005B, deionized water was added dropwise to potassium dititanate at a mass ratio of 1.5:1, stirred evenly, sealed and allowed to stand for 7 days to obtain a sample; the sample was dispersed in excess water so that the mass ratio of potassium dititanate to water was 1:300, hydrochloric acid with a mass concentration of 35% was added dropwise, the solution pH was adjusted to 2, and stirred for 24 hours for ion exchange; the emulsion after exchange was precipitated and filtered, and dried to obtain dititanic acid; the dititanic acid was immersed in a 15wt% KOH aqueous solution for secondary ion exchange, allowed to stand for 12 hours, filtered and dried to obtain mesoporous TiO 2 Whiskers.

[0037] Pseudo-boehmite (70 wt% on dry basis) and mesoporous TiO 2 The whisker mass ratio is 6:1, and deionized water is added at a solid-liquid ratio of 1:30, stirred and mixed, placed in an oil bath and heated to 60°C and maintained at a constant temperature; HNO with a mass concentration of 65% is slowly added dropwise 3 Adjust the system pH to 1, acid hydrolyze for 6 hours; then slowly add appropriate amount of ammonia water to adjust the system pH to 9.5 to form a gel, and age for 2 hours; finally wash with deionized water to pH = 7, filter, dry, and calcine at 550 ° C for 2 hours to obtain mesoporous TiO 2 Whisker / γ-Al 2 O 3 Composite material: The composite material is used as a substrate, a molding aid (nitric acid, citric acid, deionized water) is added, and an extrusion molding method is used to obtain a carrier.

[0038] After the carrier preparation is completed, the nickel-molybdenum supported catalyst is prepared by using basic nickel carbonate and molybdenum trioxide to prepare the impregnation solution and the equal volume impregnation method. 3 The loading amounts of NiO and NiO were 28 wt % and 3.5 wt % respectively, and Comparative Example 1 was obtained.

[0039] Comparative Example 2

[0040] 107 g of pseudo-boehmite (dry basis 70 wt%) and 40 g of potassium dititanate were added to a container containing 2200 ml of deionized water, stirred evenly, sealed and allowed to stand for 20 h to obtain a sample; 18.6 g of hydrochloric acid with a mass concentration of 35% was added to the above sample under stirring, heated to 90°C and kept at a constant temperature for 10 h; then an appropriate amount of KOH was slowly added to adjust the system pH to 9.5 to form a gel, and aged for 2 h; washed with deionized water until neutral, filtered and dried to obtain a titanium-aluminum composite material; the above titanium-aluminum composite material was ground and sieved, and then 8.8 g of diatomaceous earth, 4 g of sesbania powder, 6 g of acetic acid, and deionized water were added and mixed evenly and then extruded into a mold; freeze-dried at 15 KPa and -30°C for 18 h, and calcined at 450°C for 3 h to obtain a carrier; an impregnation solution was prepared using basic nickel carbonate and molybdenum trioxide, and an equal volume of impregnation was used to prepare a nickel-molybdenum supported catalyst, wherein MoO 3 The loading amounts of NiO and NiO are 26wt% and 4wt% respectively. Its main properties are listed in Table 1.

[0041] Test Example 1

[0042] The above catalyst was evaluated for its hydrorefining performance in a 200 ml fixed bed reactor. The properties of the raw materials are shown in Table 2. The test conditions were: hydrogen partial pressure 6.5 MPa, reaction temperature 360 ​​°C, space velocity 1.2 h -1 , hydrogen-to-oil ratio 400:1, and the catalyst activity evaluation data are shown in Table 3.

[0043] Table 1 shows the structural characteristics and strength property data of the catalysts obtained in Examples 1 to 4 and Comparative Example 1.

[0044] Table 1 Catalyst properties

[0045]

[0046] Table 2 Raw oil properties

[0047] project Diesel Fuel <![CDATA[Density (20 °C), kg / m 3 > 840 Nitrogen content, ppm 81 Sulfur content, ppm 11900 PAHs, wt% 11.3

[0048] Table 3 Catalyst hydrogenation evaluation results

[0049]

[0050] It can be seen from Table 3 that the hydrodesulfurization activity and aromatic saturation performance of the catalysts provided by Examples 1-4 of the present invention are higher than those of the catalyst of Comparative Example 1. And the metal content of the catalysts provided by Examples 1-4 is lower than that of the catalyst of Comparative Example 1.

[0051] Of course, the present invention may have many other embodiments. Without departing from the spirit and essence of the present invention, technicians familiar with the field may make various corresponding changes and deformations based on the present invention, but these corresponding changes and deformations should all fall within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a titanium-aluminum composite material, It is characterized in that The following steps are involved: S1, adding pseudo-boehmite and potassium dititanate into water, dispersing them, sealing and letting them stand; S2, under stirring, adding hydrochloric acid to the material after standing in step S1, and then heating and isothermal acid hydrolysis to form a titanium aluminum sol; S3, adjusting the pH of the titanium-aluminum sol to 9-10 to form a gel, aging it, washing it with water, and filtering it to obtain a wet filter cake of the titanium-aluminum composite material; S4, adding diatomaceous earth, acetic acid and lubricant to the wet filter cake, mixing evenly and then extruding to form, and then freeze-drying and calcining to obtain a titanium-aluminum composite carrier.

2. The method for preparing the titanium-aluminum composite material according to claim 1, It is characterized in that In step S1, the mass ratio of pseudo-boehmite to potassium dititanate is 2-6:1, and the mass ratio of the total amount of pseudo-boehmite and potassium dititanate to water is 1:8-20.

3. The method for preparing the titanium-aluminum composite material according to claim 1, It is characterized in that The sealing and standing time in step S1 is 12 to 24 hours.

4. The method for preparing the titanium-aluminum composite material according to claim 1, It is characterized in that In step S2, the acid-aluminum ratio is 0.2-0.4 mol / mol.

5. The method for preparing the titanium-aluminum composite material according to claim 1, It is characterized in that The heating temperature in step S2 is 60-90° C., and the acid hydrolysis time is 8-12 hours.

6. The method for preparing the titanium-aluminum composite material according to claim 1, It is characterized in that The aging time in step S3 is 2 to 4 hours.

7. The method for preparing the titanium-aluminum composite material according to claim 1, It is characterized in that In step S4, the amount of diatomaceous earth added is 3-8% of the total mass of potassium dititanate and pseudo-boehmite, the amount of acetic acid added is 2-5% of the total mass of potassium dititanate and pseudo-boehmite, and the lubricant is one or more of sesbania powder, dry starch and graphite, and the amount added is 2-3% of the total mass of potassium dititanate and pseudo-boehmite.

8. The method for preparing the titanium-aluminum composite material according to claim 1, It is characterized in that The freeze-drying conditions in step S4 are a temperature of -20 to -30°C, a pressure of 15 to 30 KPa, and a time of 8 to 24 hours.

9. The method for preparing the titanium-aluminum composite material according to claim 1, It is characterized in that In step S4, the calcination temperature is 420-600° C. and the calcination time is 2-5 hours.

10. A catalyst for hydrotreating middle distillate oil, It is characterized in that A titanium-aluminum composite material comprising a titanium-aluminum composite material prepared by the method according to any one of claims 1 to 9, and an active component MoO 3 and NiO.

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