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

Abstract

The application discloses a preparation method of a titanium-aluminum composite material and a middle distillate oil hydrorefining catalyst, and the preparation method comprises the following steps: S1, adding pseudo-boehmite and potassium dititanate into water, and sealing and standing after dispersion; S2, under the state of stirring, adding hydrochloric acid drop by drop into the material after standing in step S1, and then heating and constant-temperature acidolysis to form a titanium-aluminum sol; S3, adjusting the pH of the titanium-aluminum sol to 9-10 to form a gel, and obtaining a titanium-aluminum composite material wet filter cake after aging, water washing and filtering; and S4, adding diatomite, acetic acid and a lubricant into the wet filter cake, uniformly mixing, and then extruding into a shape, and obtaining a titanium-aluminum composite carrier after vacuum freeze-drying treatment and calcination. The problems of low specific surface area and few surface active sites of a conventional TiO2 material used for preparing a hydrodesulfurization catalyst carrier, and the problems of difficult molding and low mechanical strength of a carrier prepared by using a single-component TiO2 are solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of hydrofining, and particularly relates to a preparation method of titanium-aluminum composite material and a middle distillate oil hydrofining catalyst. BACKGROUND

[0002] In order to reduce the pollution caused by using diesel to the environment, China has formulated and implemented national III, national IV and national V diesel standards equivalent to European III, European IV and European V standards. At present, the national VI diesel standard implemented in China puts forward more stringent requirements on the sulfur content, cetane number and polycyclic aromatic hydrocarbon content in diesel. The quality of vehicle diesel is rapidly developing towards low sulfur and low aromatic hydrocarbon. At the same time, the degree of heavy and poor quality of crude oil is intensified, the diesel distillation range is shifted backward, the number of difficult-to-remove sulfides is increased, and the difficulty of desulfurization is increased. How to realize the cleanization of poor quality raw materials and meet the market demand for high-quality clean diesel is one of the key works of refining enterprises.

[0003] In order to upgrade the quality of the existing diesel hydrogenation device, the main means that can be taken at present mainly include improving the reaction severity of the device, reducing the final boiling point of diesel, reducing the processing capacity of the device and using high-activity diesel hydrogenation catalyst. Improving the reaction severity of the device, reducing the final boiling point of diesel and reducing the processing capacity of the device have adverse effects on the production efficiency and production cost of the device. In order to solve the above problems, foreign Albemarle, Criterion and IFP companies have developed high-activity hydrogenation catalysts suitable for diesel deep hydrodesulfurization reaction, and have achieved wide application. Therefore, the development and application of high-activity diesel hydrogenation catalysts is the most effective measure for diesel hydrogenation devices to upgrade diesel quality.

[0004] TiO2 is widely used as an active catalyst carrier in many aspects. As a hydrogenation desulfurization catalyst carrier, it can improve the dispersion of active components on the surface of the carrier and promote the hydrogenation catalytic effect of the active components. However, the carrier prepared by conventional TiO2 material has low specific surface area and few surface active sites. At the same time, the carrier prepared by single-component TiO2 also has defects such as molding difficulty and low mechanical strength.

[0005] ​Patent CN110725005B discloses a preparation method of mesoporous TiO2 whisker, a distillate oil hydrodesulfurization catalyst and a preparation method thereof, comprising the following steps. First, prepare TiO2 whisker material: step 1, add water to potassium dititanate, stir, then seal and stand for 3-15 days; step 2, disperse the solid after standing into water, the solid-liquid ratio is 1:100-1:500, then add hydrochloric acid dropwise, adjust the pH value to 1-10, stir for 18-48 h for the first ion exchange reaction; step 3, sedimentation and suction filtration of the emulsion after ion exchange reaction, washing and drying of the precipitate to obtain dititanic acid; step 4, immerse the obtained dititanic acid in KOH aqueous solution for the second ion exchange reaction, stand for 2-24 h, then filter and dry to obtain TiO2 whisker. Then add TiO2 whisker and pseudoboehmite into water according to a certain solid-liquid ratio, heat to 40-90℃, adjust the system pH to 1-2, constant temperature acidolysis for 4-8 h to form aluminum titanium sol; adjust the pH of aluminum titanium sol to 9-10 to form gel, after aging for 2-10 h, wash with water, suction filtration, drying and calcination to obtain mesoporous TiO2 whisker / γ-Al2O3 composite material. Then load active components on the mesoporous TiO2 whisker / γ-Al2O3 composite material to prepare a distillate oil hydrodesulfurization catalyst. The preparation process of this method is complex, which needs to prepare TiO2 whisker material through two ion exchanges, then composite TiO2 whisker material and pseudoboehmite, and prepare mesoporous TiO2 whisker / γ-Al2O3 composite material through water washing, suction filtration, drying and calcination, and then load active components on the mesoporous TiO2 whisker / γ-Al2O3 composite material to prepare catalyst, so there are many factors affecting the preparation process. In addition, the raw materials used in the preparation process of the carrier and the catalyst of this method can produce nitrogen oxide emissions such as nitric acid and nitrate.

[0006] Patent CN110935460B discloses a preparation method of high selectivity hydrodesulfurization catalyst, the hydrodesulfurization catalyst is composed of carrier and active component, the carrier is potassium-containing mesoporous TiO2, wherein the carrier is obtained by two ion exchanges of potassium dititanate, first obtaining dititanic acid and then obtaining mesoporous TiO2 with controllable potassium content, the potassium content is 1-10wt%; the active component is molybdenum and nickel, the mass of MoO3 and NiO is 5-35wt% and 1.56-7.8wt% of the mass of the catalyst respectively. The hydrodesulfurization catalyst of the invention mainly removes sulfur in sulfur-containing species in the form of direct desulfurization, which can reduce the hydrogen consumption in the desulfurization process, and the high selectivity hydrodesulfurization catalyst prepared by this method is suitable for gasoline hydrodesulfurization process. SUMMARY

[0007] The application aims to provide a preparation method of an aluminum-titanium composite material, solve the problems of low specific surface area and few surface active sites of a conventional TiO2 material used for preparing a hydrogen desulfurization catalyst carrier, and the problems of difficulty in forming the carrier prepared by a single-component TiO2 and low mechanical strength of the carrier.

[0008] The application also aims to provide a middle distillate oil hydrofining catalyst.

[0009] To achieve the above-mentioned purposes, the application provides a preparation method of a titanium-aluminum composite material, comprising the following steps:

[0010] S1, adding pseudo-boehmite and potassium dititanate into water, dispersing and then sealing and standing;

[0011] S2, under the state of stirring, adding hydrochloric acid into the material after standing in step S1, and then heating and constant-temperature acidolysis to form a titanium-aluminum sol;

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

[0013] S4, adding diatomite, acetic acid and a lubricant into the wet filter cake, uniformly mixing, extruding into a shape, and then performing vacuum freeze-drying treatment and calcination to obtain a titanium-aluminum composite carrier.

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

[0015] In the preparation method of the titanium-aluminum composite material, the sealing and standing time in step S1 is 12-24h.

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

[0017] In the preparation method of the titanium-aluminum composite material, the heating temperature in step S2 is 60-90℃, and the acidolysis time is 8-12h.

[0018] In the preparation method of the titanium-aluminum composite material, the aging time in step S3 is 2-4h.

[0019] The preparation method of the titanium-aluminum composite material, in step S4, the diatomic earth addition amount is 3-8% of the total mass of the potassium dititanate and the pseudoboehmite, the acetic acid addition amount is 2-5% of the total mass of the potassium dititanate and the pseudoboehmite, and the lubricant is one or more of the sesbania powder, dry starch and graphite, and the addition amount is 2-3% of the total mass of the potassium dititanate and the pseudoboehmite.

[0020] The preparation method of the titanium-aluminum composite material, in step S4, the freeze drying condition is that the temperature is-20 to-30 DEG C, the pressure is 15-30 KPa, and the time is 8-24 h.

[0021] The preparation method of the titanium-aluminum composite material, in step S4, the calcination temperature is 420-600 DEG C, and the calcination time is 2-5 h.

[0022] To achieve the above object, the application further provides a middle distillate oil hydrofining catalyst, which comprises the titanium-aluminum composite material prepared by the above method, and active components MoO3 and NiO.

[0023] The application has the following beneficial effects:

[0024] (1) The method of directly forming the titanium-aluminum composite material wet filter cake simplifies the carrier preparation process, avoids the damage to the internal accumulation state of the microcrystalline particle aggregates in the drying and calcination process of the wet filter cake, improves the specific surface area and pore diffusion performance of the catalyst, and makes the TiO2 active carrier effectively play a role. In the sulfuration process, the TiO2 surface is partially sulfurized, Ti 4+ is reduced to Ti 3+ , which acts as an electronic assistant in the hydrodesulfurization reaction, makes the electrons more easily transfer from the TiO2 to the 3d orbit of the active component, thereby reducing the Mo-S bond energy, making the active component more easily appear sulfur vacancies, and improving the activity of the catalyst.

[0025] (2) Nitrogen oxides are harmful atmospheric pollutants, which can cause acid rain, produce photochemical smog, increase the concentration of fine particulate matter PM2.5, damage the ozone layer, and intensify the greenhouse effect. The application uses acetic acid, hydrochloric acid, basic nickel carbonate, nickel acetate and the like to replace raw materials such as nitric acid and nitrate salts that can produce nitrogen oxide emissions, and combines the method of directly forming the titanium-aluminum composite material wet filter cake and vacuum freeze drying to prepare the catalyst, thereby solving the problem that nitric acid and nitrate salts cannot be used while improving the activity and mechanical strength of the catalyst, eliminating the nitrogen oxide emissions in the carrier and catalyst preparation process, and reducing the atmospheric pollution. DETAILED DESCRIPTION

[0026] The application will be described in detail below by way of examples. It is necessary to point out here that the following examples are only used to further illustrate the application and cannot be understood as limiting the scope of protection of the application, and those skilled in the art can make some non-essential improvements and adjustments to the application according to the above description of the application.

[0027] Example 1

[0028] A container containing 2200 ml of deionized water was added with pseudo-boehmite (dry basis 70 wt%) 107 g, potassium dititanate 40 g, and stirred uniformly, sealed and left for 20 h to obtain a sample; under stirring, 18.6 g of hydrochloric acid with a mass concentration of 35% was added dropwise to the above sample, heated to 90°C and kept constant for 10 h; then a proper amount of KOH was slowly added dropwise to adjust the pH of the system to 9.5 to form a gel, and aged for 2 h; washed with deionized water to neutral, and suction filtered to obtain a wet filter cake; diatomite 8.8 g, sesbania powder 4 g, and acetic acid 6 g were added to the wet filter cake, mixed uniformly, and then extruded into a shape; 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 by using basic nickel carbonate and molybdenum trioxide, and a nickel-molybdenum supported catalyst was prepared by equal-volume impregnation, wherein the loadings of MoO3 and NiO were 26 wt% and 4 wt%, respectively. The main properties are listed in Table 1.

[0029] Example 2

[0030] A container containing 1770 ml of deionized water was added with pseudo-boehmite (dry basis 70 wt%) 115 g, potassium dititanate 32 g, and stirred uniformly, sealed and left for 24 h to obtain a sample; under stirring, 16 g of hydrochloric acid with a mass concentration of 35% was added dropwise to the above sample, heated to 80°C and kept constant for 8 h; then a proper amount of KOH was slowly added dropwise to adjust the pH of the system to 9.5 to form a gel, and aged for 4 h; washed with deionized water to neutral, and suction filtered to obtain a wet filter cake; diatomite 7.4 g, sesbania powder 4 g, and acetic acid 4.5 g were added to the wet filter cake, mixed uniformly, and then extruded into a shape; 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 by using basic nickel carbonate and molybdenum trioxide, and a nickel-molybdenum supported catalyst was prepared by equal-volume impregnation, wherein the loadings of MoO3 and NiO were 26 wt% and 4 wt%, respectively. The main properties are listed in Table 1.

[0031] Example 3

[0032] To a container containing 1200 ml of deionized water, add 122 g of pseudoboehmite (dry basis 70 wt%), 24 g of potassium dititanate, stir evenly, seal and stand for 15 h to obtain a sample; under stirring, add 25.4 g of 35% hydrochloric acid to the above sample dropwise, heat to 60°C and keep constant temperature for 8 h; then slowly add an appropriate amount of KOH to adjust the system pH = 10 to form a gel, and age for 3 h; wash with deionized water until neutral, and then suction filter to obtain a wet filter cake; add 4.4 g of diatomite and 4 g of sesbania powder to the wet filter cake, mix evenly, and then extrude into a shape; freeze dry at 20 KPa and -30°C for 8 h, and then calcine at 520°C for 3 h to obtain a carrier; prepare an impregnation solution by using basic nickel carbonate and molybdenum trioxide, and then impregnate to prepare a nickel-molybdenum supported catalyst, wherein the loadings of MoO3 and NiO are 26 wt% and 4 wt%, respectively. The main properties are listed in Table 1.

[0033] Example 4

[0034] To a container containing 3000 ml of deionized water, add 100 g of pseudoboehmite (dry basis 70 wt%), 48 g of potassium dititanate, stir evenly, seal and stand for 12 h to obtain a sample; under stirring, add 28 g of 35% hydrochloric acid to the above sample dropwise, heat to 70°C and keep constant temperature for 12 h; then slowly add an appropriate amount of KOH to adjust the system pH = 9 to form a gel, and age for 2 h; wash with deionized water until neutral, and then suction filter to obtain a wet filter cake; add 11.8 g of diatomite and 4 g of sesbania powder to the wet filter cake, mix evenly, and then extrude into a shape; freeze dry at 30 KPa and -25°C for 24 h, and then calcine at 600°C for 2 h to obtain a carrier; prepare an impregnation solution by using basic nickel carbonate and molybdenum trioxide, and then impregnate to prepare a nickel-molybdenum supported catalyst, wherein the loadings of MoO3 and NiO are 26 wt% and 4 wt%, respectively. The main properties are listed in Table 1.

[0035] Comparative Example 1

[0036] According to the description in Example 1 of patent CN110725005B, add deionized water to potassium dititanate dropwise, with a mass ratio of 1.5:1, stir evenly, seal and stand for 7 days to obtain a sample; disperse the above sample into excess water, so that the mass ratio of potassium dititanate to water is 1:300, add 35% hydrochloric acid dropwise, adjust the solution pH = 2, and stir for 24 h for ion exchange; suction filter and dry the exchanged emulsion to obtain dititanic acid; immerse the dititanic acid in a 15 wt% KOH aqueous solution for secondary ion exchange, stand for 12 h, and then suction filter and dry to obtain mesoporous TiO2 whiskers.

[0037] The mass ratio of pseudoboehmite (dry basis 70wt%) and mesoporous TiO2 whisker is 6:1, and deionized water is added at a solid-liquid ratio of 1:30, stirred and mixed uniformly, placed in an oil bath and heated to 60°C and kept constant temperature; slowly add 65% mass concentration HNO3 to adjust the system pH=1, acidolysis 6h; then slowly add appropriate amount of ammonia to adjust the system pH=9.5 to form a gel, aging 2h; finally, wash with deionized water to pH=7, suction filtration, drying, calcination at 550°C for 2h, to obtain mesoporous TiO2 whisker / γ-Al2O3 composite material. The above composite material is used as the base material, and a shaping aid (nitric acid, citric acid, deionized water) is added to obtain the carrier by extrusion molding.

[0038] On the basis of completing the preparation of the carrier, the impregnation solution is prepared by using basic nickel carbonate and molybdenum trioxide, and the nickel-molybdenum supported catalyst is prepared by equal-volume impregnation method. The loadings of MoO3 and NiO are 28wt% and 3.5wt% respectively. Comparative example 1 is obtained.

[0039] Comparative example 2

[0040] Pseudoboehmite (dry basis 70wt%) 107g and potassium dititanate 40g are added to a container containing 2200ml of deionized water, stirred uniformly, sealed and placed for 20h to obtain a sample; under stirring, 18.6g of 35% mass concentration hydrochloric acid is added to the above sample, heated to 90°C and kept constant temperature for 10h; then slowly add appropriate amount of KOH to adjust the system pH=9.5 to form a gel, aging 2h; wash with deionized water to neutral, suction filtration, drying to obtain titanium-aluminum composite material; after grinding and sieving the above titanium-aluminum composite material, add diatomite 8.8g, sesbania powder 4g, acetic acid 6g, and deionized water, mix uniformly and extrude; freeze-drying at 15KPa, -30°C for 18h, calcination at 450°C for 3h to obtain the carrier; the impregnation solution is prepared by using basic nickel carbonate and molybdenum trioxide, and the nickel-molybdenum supported catalyst is prepared by equal-volume impregnation method, wherein the loadings of MoO3 and NiO are 26wt% and 4wt% respectively. The main properties are listed in Table 1.

[0041] Test example 1

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

[0043] Table 1 shows the structural characteristics and strength properties of the catalysts obtained in examples 1-4 and comparative example 1.

[0044] Table 1 Catalyst properties

[0045]

[0046] Table 2 Properties of raw oil

[0047] Item Mixed diesel Density (20°C), kg / m 3 ]] 840 Nitrogen content, ppm 81 Sulfur content, ppm 11900 Polycyclic aromatic hydrocarbons, wt% 11.3

[0048] Table 3 Catalyst hydrogenation evaluation results

[0049]

[0050] As can be seen from Table 3, the hydrogenation desulfurization activity and aromatic saturation performance of the catalysts provided by Examples 1-4 are higher than that of the catalyst of Comparative Example 1. 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 application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications to the present application without departing from the spirit and essence of the present application, but these corresponding changes and modifications shall all belong to the protection scope of the claims of the present application.

Claims

1. A method for producing a titanium-aluminum composite material, characterized by, Comprise the following steps: S1, add pseudo-boehmite and potassium dititanate into water, disperse and then seal and stand; the mass ratio of pseudo-boehmite and potassium dititanate is (2-6):1; S2, under stirring, add hydrochloric acid into the material after standing in step S1, then heat and keep constant temperature to acidify, to form titanium-aluminum sol; S3, adjust the pH of titanium-aluminum sol to 9-10 to form gel, then wash with water after aging, filter to obtain titanium-aluminum composite material wet filter cake; S4, add diatomite, acetic acid and lubricant into the wet filter cake, mix uniformly, then extrude and shape, then vacuum freeze dry, and then bake to obtain titanium-aluminum composite material; the temperature of vacuum freeze drying is -30--20℃, and the pressure is 15-30KPa.

2. The method of producing a titanium-aluminum composite material according to claim 1, characterized by, In step S1, the mass ratio of total mass of pseudo-boehmite and potassium dititanate to water is 1:(8-20).

3. The method of producing a titanium-aluminum composite material according to claim 1, characterized by, The sealing standing time in step S1 is 12-24h.

4. The method of producing a titanium-aluminum composite material according to claim 1, characterized by, The acid-aluminum ratio in step S2 is 0.2-0.4mol / mol.

5. The method of producing a titanium-aluminum composite material according to claim 1, characterized by, The heating temperature in step S2 is 60-90℃, and the acidolysis time is 8-12h.

6. The method of producing a titanium-aluminum composite material according to claim 1, characterized by, The aging time in step S3 is 2-4h.

7. The method of producing a titanium-aluminum composite material according to claim 1, wherein In step S4, the diatomite is added in an amount of 3-8% of the total mass of potassium dititanate and pseudo-boehmite, the acetic acid is added in an amount of 2-5% of the total mass of potassium dititanate and pseudo-boehmite, the lubricant is one or more of sesbania powder, dry starch and graphite, and the lubricant is added in an amount of 2-3% of the total mass of potassium dititanate and pseudo-boehmite.

8. The method of producing a titanium-aluminum composite material according to claim 1, characterized by, The freeze drying time in step S4 is 8-24h.

9. The method of producing a titanium-aluminum composite material according to claim 1, characterized by, The baking temperature in step S4 is 420-600℃, and the baking time is 2-5h.

10. A middle distillate hydrofmishing catalyst characterized by, The titanium-aluminum composite material carrier prepared by the preparation method of any one of claims 1-9, and active components MoO3 and NiO.

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