Preparation process of hydrodesulfurization catalyst

Abstract

The present invention relates to the technical field of heavy oil hydrodesulfurization, and discloses a hydrodesulfurization catalyst preparation process, which comprises: adding deionized water, a nickel source, a molybdenum source and a dispersant into a reaction container, stirring to obtain a metal solution, pouring into a container filled with gamma-Al2O3, impregnating, drying, and roasting to obtain the hydrodesulfurization catalyst. The dispersing agent contains a large number of nitrogen atoms and a plurality of carboxyl groups and hydroxyl groups, has very strong coordination chelation performance on nickel and molybdenum, improves the dispersity of nickel and molybdenum precursors, enables the nickel and molybdenum precursors to be uniformly impregnated into a gamma-Al2O3 carrier, and nickel oxide and molybdenum oxide are uniformly distributed in the gamma-Al2O3 carrier after calcination, so that the nickel and molybdenum oxide-modified gamma-Al2O3 composite material is prepared. The obtained hydrodesulfurization catalyst can expose more nickel-molybdenum catalytic active centers, effectively catalyzes and removes sulfur-containing substances such as thiophenes in straight-run diesel oil, shows a higher desulfurization rate, and improves the quality of oil products.

Description

Technical Field

[0001] The invention relates to the technical field of heavy oil hydrodesulfurization, in particular to a preparation process of a hydrodesulfurization catalyst. Background Art

[0002] Heavy oil, diesel, and other oil products contain sulfur-containing substances such as thiophene and dibenzothiophene. When burned, these substances produce sulfur dioxide and sulfur trioxide, which can corrode engines, impact performance and service life, and pose significant environmental risks. Using a catalyst to catalyze the reaction of thiophene and other sulfur-containing substances in oil products with tungsten hydrogen to produce gases such as hydrogen sulfide can effectively desulfurize these oil products. Common catalysts include metal catalysts such as nickel, cobalt, and molybdenum, and carriers include alumina, molecular sieves, and activated carbon. Chinese patent CN116196966B discloses a method for preparing an alumina-based desulfurization catalyst. The method blends γ-alumina nanoflowers with a Ni-Mo nitride nanocomposite. The resulting desulfurization catalyst has advantages such as good dispersibility, a high number of catalytic sites, and high hydrodesulfurization efficiency. However, the preparation methods for the products described in this patent, such as the γ-alumina nanoflowers and Ni-Mo nitride nanocomposite, are relatively complex, and the desulfurization rate is relatively low. Summary of the Invention

[0003] In view of the shortcomings of the existing technology, the present invention provides a preparation process of a hydrodesulfurization catalyst, which solves the problem that the existing nickel-molybdenum catalyst has low efficiency in hydrodesulfurization of oil products.

[0004] In order to solve the above technical problems, the technical solution of the present invention is: a preparation process of a hydrodesulfurization catalyst: (1) Deionized water, sodium iminodiacetate, and sodium bicarbonate are added to a reaction vessel, and an acetone solution containing 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine is added dropwise in an ice-water bath. After the reaction, the acetone is removed by vacuum distillation, and a hydrochloric acid solution is added dropwise to adjust the pH to 2-3. After filtration, the precipitate is dissolved in water, heated for evaporation, and cooled for crystallization to obtain a dispersant. The preparation reaction formula is: .

[0005] (2) Deionized water, a nickel source, a molybdenum source, and a dispersant are added to a reaction vessel, and the mixture is stirred and dispersed to obtain a metal solution containing a nickel-molybdenum precursor.

[0006] (3) Pour the metal solution into a container containing γ-Al2O3, perform impregnation, drying, roasting, and cooling to obtain a hydrodesulfurization catalyst.

[0007] Furthermore, the molar ratio of sodium iminodiacetate, sodium bicarbonate, and 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine in (1) is 1:(1-1.1):(1-1.1).

[0008] Furthermore, the reaction temperature in (1) is 90-100°C, and the reaction time is 5-8h.

[0009] Furthermore, the stirring temperature in (2) is 40-60°C and the stirring time is 2-3 hours.

[0010] Furthermore, the mass ratio of nickel source, molybdenum source and dispersant in (2) is (38-64):100:(4-10).

[0011] Furthermore, the nickel source in (2) is nickel nitrate or nickel sulfate.

[0012] Furthermore, the molybdenum source in (2) is ammonium molybdate tetrahydrate.

[0013] Furthermore, the immersion temperature in (3) is 20-35°C and the immersion time is 4-6 hours.

[0014] Furthermore, the drying temperature in (3) is 100-120°C and the drying time is 4-8 hours.

[0015] Furthermore, the calcination temperature in (3) is 500-600°C and the calcination time is 2-3h.

[0016] The above technical solution has the following beneficial technical effects: sodium iminodiacetic acid and 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine are reacted to obtain a dispersant containing a large number of nitrogen atoms, as well as multiple carboxyl and hydroxyl groups. The dispersant has strong coordination and chelating properties for nickel and molybdenum, which is beneficial to improving the dispersibility of nickel and molybdenum precursors, thereby uniformly impregnating the nickel-molybdenum precursors into the γ-Al2O3 carrier. After calcination, the nickel oxide and molybdenum oxide are uniformly distributed in the γ-Al2O3 carrier. The obtained hydrodesulfurization catalyst can expose more nickel-molybdenum catalytic active centers, effectively catalytically remove sulfur-containing substances such as thiophenes in straight-run diesel, exhibit a higher desulfurization rate, and improve the quality of oil products. The catalyst has good practical application in the hydrodesulfurization treatment of heavy oil, diesel, etc. DETAILED DESCRIPTION

[0017] The following γ-Al2O3 model ZTL-AA is from Yangzhou Zhongtianli New Materials Co., Ltd.

[0018] 10 mL of acetone and 10 mmol of cyanuric chloride were added to the reaction vessel, and 10 mL of diethanolamine containing 20 mmol was added dropwise in an ice-water bath. The reaction was stirred until the pH of the solution was about 6.8. After filtering, the solution was washed with water and acetone in sequence and dried to obtain 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine, the structural formula of which is , CAS registration number is 1258-71-5.

[0019] Example 1: (1) Add 8 mL of deionized water, 3 mmol of sodium iminodiacetate, and 3 mmol of sodium bicarbonate to a reaction vessel, and dropwise add 4 mL of an acetone solution containing 3 mmol of 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine in an ice-water bath. Heat to 100 °C, condense and reflux for 5 h, remove acetone by vacuum distillation, add dropwise hydrochloric acid solution to adjust the pH to 2, filter, dissolve the precipitate in water, evaporate by heating, and cool to crystallize to obtain a dispersant.

[0020] (2) Add 30 mL of deionized water, 4.6 g of nickel nitrate, 10 g of ammonium molybdate tetrahydrate, and 0.4 g of a dispersant to a reaction vessel, and stir and disperse at 40° C. for 3 h to obtain a metal solution containing a nickel-molybdenum precursor.

[0021] (3) The metal solution was poured into a container containing 35 g of γ-Al2O3 and immersed in a temperature of 25°C for 6 h; then dried in a drying oven at 110°C for 8 h; finally, placed in a muffle furnace and calcined at 500°C for 3 h, and cooled to obtain a hydrodesulfurization catalyst.

[0022] Example 2: (1) Add 10 mL of deionized water, 3 mmol of sodium iminodiacetate, and 3.3 mmol of sodium bicarbonate to a reaction vessel, and dropwise add 5 mL of an acetone solution containing 3.3 mmol of 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine in an ice-water bath. Heat to 90°C, condense and reflux for 8 h, remove acetone by vacuum distillation, add dropwise hydrochloric acid solution to adjust the pH to 3, filter, dissolve the precipitate in water, evaporate by heating, and cool to crystallize to obtain a dispersant.

[0023] (2) Add 30 mL of deionized water, 3.8 g of nickel sulfate, 10 g of ammonium molybdate tetrahydrate, and 0.6 g of a dispersant to a reaction vessel, and stir and disperse at 50° C. for 2 h to obtain a metal solution containing a nickel-molybdenum precursor.

[0024] (3) The metal solution was poured into a container containing 38 g of γ-Al2O3 and immersed in a temperature of 20°C for 6 h; then dried in a drying oven at 100°C for 8 h; finally, placed in a muffle furnace and calcined at 500°C for 3 h, and cooled to obtain a hydrodesulfurization catalyst.

[0025] Example 3: (1) 40 mL of deionized water, 5.5 g of nickel nitrate, 10 g of ammonium molybdate tetrahydrate, and 0.8 g of a dispersant (prepared according to the method of Example 1) were added to a reaction vessel, and the mixture was stirred and dispersed at 60° C. for 2 h to obtain a metal solution containing a nickel-molybdenum precursor.

[0026] (2) Pour the metal solution into a container filled with 42 γ-Al2O3 and immerse it at 35°C for 4 hours; then dry it in a drying oven at 120°C for 4 hours; finally, place it in a muffle furnace and calcine it at 600°C for 2 hours, and cool it to obtain a hydrodesulfurization catalyst.

[0027] Example 4: (1) 40 mL of deionized water, 6.4 g of nickel nitrate, 10 g of ammonium molybdate tetrahydrate, and 1 g of a dispersant (prepared according to the method of Example 1) were added to a reaction vessel, and the mixture was stirred and dispersed at 60° C. for 2 h to obtain a metal solution containing a nickel-molybdenum precursor.

[0028] (2) The metal solution was poured into a container containing 45 g of γ-Al2O3 and immersed in a temperature of 25°C for 6 h; then dried in a drying oven at 110°C for 7 h; finally, placed in a muffle furnace and calcined at 550°C for 3 h, and cooled to obtain a hydrodesulfurization catalyst.

[0029] Comparative Example 1: (1) Add 30 mL of deionized water, 4.6 g of nickel nitrate, and 10 g of ammonium molybdate tetrahydrate into a reaction vessel, and stir and disperse at 40° C. for 3 h to obtain a metal solution containing a nickel-molybdenum precursor.

[0030] (2) The metal solution was poured into a container containing 35 g of γ-Al2O3 and immersed in a temperature of 25°C for 6 h; then dried in a drying oven at 110°C for 8 h; finally, placed in a muffle furnace and calcined at 500°C for 3 h, and cooled to obtain a hydrodesulfurization catalyst.

[0031] Comparative Example 2: (1) 30 mL of deionized water, 4.6 g of nickel nitrate, 10 g of ammonium molybdate tetrahydrate, and 0.4 g of citric acid as a dispersant were added to a reaction vessel, and the mixture was stirred and dispersed at 40° C. for 3 h to obtain a metal solution containing a nickel-molybdenum precursor.

[0032] (2) The metal solution was poured into a container containing 35 g of γ-Al2O3 and immersed in a temperature of 25°C for 6 h; then dried in a drying oven at 110°C for 8 h; finally, placed in a muffle furnace and calcined at 500°C for 3 h, and cooled to obtain a hydrodesulfurization catalyst.

[0033] Comparative Example 3: (1) Add 30 mL of deionized water, 4.6 g of nickel nitrate, 10 g of ammonium molybdate tetrahydrate, and 0.4 g of ethylenediaminetetraacetic acid as a dispersant to a reaction vessel, stir and disperse at 40° C. for 3 h to obtain a metal solution containing a nickel-molybdenum precursor.

[0034] (2) The metal solution was poured into a container containing 35 g of γ-Al2O3 and immersed in a temperature of 25°C for 6 h; then dried in a drying oven at 110°C for 8 h; finally, placed in a muffle furnace and calcined at 500°C for 3 h, and cooled to obtain a hydrodesulfurization catalyst.

[0035] Comparative Example 4: (1) Add 30 mL of deionized water, 4.6 g of nickel nitrate, 10 g of ammonium molybdate tetrahydrate, and 0.4 g of melamine hexaacetic acid (structural formula: , CAS registration number 1258-71-5) was used as a dispersant, and the mixture was dispersed with stirring at 40° C. for 3 h to obtain a metal solution containing a nickel-molybdenum precursor.

[0036] (2) The metal solution was poured into a container containing 35 g of γ-Al2O3 and immersed in a temperature of 25°C for 6 h; then dried in a drying oven at 110°C for 8 h; finally, placed in a muffle furnace and calcined at 500°C for 3 h, and cooled to obtain a hydrodesulfurization catalyst.

[0037] The desulfurization performance of the catalyst was tested by a fixed-bed microreactor. The raw oil was straight-run diesel, the catalyst loading was controlled to 1.2 g, the hydrogen pressure in the reactor was controlled to 6 MPa, the reaction temperature was 320-360 ° C, and the space velocity was 1 h -1 The sulfur content of straight-run diesel before and after catalytic desulfurization was measured using a microcoulometer, and the desulfurization rate, Q, was calculated as (C0 - C0) / C0 × 100%. C0 represents the sulfur content of the straight-run diesel before catalytic desulfurization. C represents the sulfur content of the straight-run diesel after catalytic desulfurization.

[0038] Table 1 Desulfurization performance of catalysts

[0039] After testing, compared with Comparative Example 1, the hydrodesulfurization catalysts of Examples 1-4 have a desulfurization rate of 85.23-99.38% for straight-run diesel at a reaction temperature of 370°C. This is mainly because the dispersant is added, which contains a large number of nitrogen atoms, as well as multiple carboxyl and hydroxyl groups, and has strong coordination and chelating properties for nickel and molybdenum, which is beneficial to improving the dispersibility of nickel and molybdenum precursors, so that the nickel-molybdenum precursors are evenly impregnated into the γ-Al2O3 carrier. After calcination, the nickel oxide and molybdenum oxide are evenly distributed in the γ-Al2O3 carrier, exposing more nickel-molybdenum catalytic active centers, effectively catalyzing the removal of sulfur-containing substances such as thiophenes in straight-run diesel, and showing a higher desulfurization rate.

[0040] Comparative Example 2 uses conventional citric acid as a dispersant, which has a low hydroxyl and carboxyl content, does not contain nitrogen atoms, and has low coordination and chelating properties with nickel and molybdenum. Comparative Example 3 uses conventional ethylenediaminetetraacetic acid as a dispersant, which does not contain hydroxyl groups, has a low nitrogen atom content, and has low coordination and chelating properties with nickel and molybdenum. As a result, the nickel-molybdenum precursors of the two are difficult to be evenly impregnated into γ-Al2O3, and the nickel-molybdenum catalytic active centers are difficult to be evenly distributed in the γ-Al2O3 carrier after calcination, and the desulfurization rates of the two are low.

[0041] Comparative Example 4 uses melamine hexaacetic acid as a dispersant, which does not contain hydroxyl groups and has lower dispersibility than the dispersant in Example 1, resulting in a desulfurization rate that is significantly lower than that in Example 1.

Claims

1. A process for preparing a hydrodesulfurization catalyst, characterized in that: The preparation process comprises: (1) adding deionized water, a nickel source, a molybdenum source, and a dispersant into a reaction vessel, stirring and dispersing the mixture to obtain a metal solution; The structural formula of the dispersant is: ; (2) Pour the metal solution into a container containing γ-Al2O3, perform impregnation, drying, roasting, and cooling to obtain a hydrodesulfurization catalyst.

2. The process for preparing the hydrodesulfurization catalyst according to claim 1, wherein: The stirring temperature in (1) is 40-60°C and the stirring time is 2-3 hours.

3. The preparation process of the hydrodesulfurization catalyst according to claim 1, characterized in that: The mass ratio of the nickel source, molybdenum source and dispersant in (1) is (38-64):100:(4-10).

4. The process for preparing the hydrodesulfurization catalyst according to claim 3, wherein: The nickel source is nickel nitrate or nickel sulfate; the molybdenum source is ammonium molybdate tetrahydrate.

5. The preparation process of the hydrodesulfurization catalyst according to claim 1, characterized in that: The temperature during the immersion in (2) is 20-35°C and the time is 4-6 hours.

6. The process for preparing the hydrodesulfurization catalyst according to claim 1, wherein: The drying temperature in (2) is 100-120°C and the drying time is 4-8 hours.

7. The process for preparing the hydrodesulfurization catalyst according to claim 1, wherein: The calcination temperature in (2) is 500-600°C and the calcination time is 2-3 hours.

8. The process for preparing the hydrodesulfurization catalyst according to claim 3, wherein: The preparation process of the dispersant comprises the following steps: adding deionized water, sodium iminodiacetate, and sodium bicarbonate into a reaction container, dropwise adding an acetone solution containing 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine in an ice-water bath, heating to 90-100° C., condensing and refluxing for 5-8 hours, removing acetone by distillation under reduced pressure, dropwise adding a hydrochloric acid solution to adjust the pH to 2-3, dissolving the precipitate after filtering in water, heating for evaporation, and cooling for crystallization to obtain the dispersant.

9. The process for preparing the hydrodesulfurization catalyst according to claim 8, wherein: The molar ratio of the sodium iminodiacetate, sodium bicarbonate and 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine is 1:(1-1.1):(1-1.1).

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