Process for the preparation of a hydrodesulfurization catalyst

Abstract

The present application relates to heavy oil hydrodesulfurization technical field, and disclose a kind of preparation process of hydrodesulfurization catalyst, the present application is added to reaction vessel deionized water, nickel source, molybdenum source, dispersing agent, stirring to obtain metal solution, pour into the container with γ-Al2O3, impregnation, drying, calcination, obtain hydrodesulfurization catalyst.The dispersing agent contains a large number of nitrogen atom, multiple carboxyl and hydroxyl, with very strong coordination chelation performance to nickel, molybdenum, improve the dispersibility of nickel, molybdenum precursor, make nickel molybdenum precursor evenly impregnated into γ-Al2O3 carrier, calcined nickel oxide, molybdenum oxide is evenly distributed in γ-Al2O3 carrier, the obtained hydrodesulfurization catalyst can expose more nickel molybdenum catalytic active center, effectively catalyze removed in straight-run diesel oil thiophene and other sulfur-containing substances, show higher desulfurization rate, improve the quality of oil.

Description

Technical Field

[0001] This invention relates to the field of heavy oil hydrodesulfurization technology, specifically to a preparation process for a hydrodesulfurization catalyst. Background Technology

[0002] Heavy oil and diesel fuel contain sulfur-containing substances such as thiophene and dibenzothiophene. When burned, these substances produce sulfur dioxide and sulfur trioxide, which corrode engines, affecting performance and lifespan, and posing significant environmental hazards. Using a catalyst to react the sulfur-containing substances like thiophene in oil products with tungsten hydrogen gas to generate hydrogen sulfide can effectively achieve desulfurization of oil products. Common catalysts include metal catalysts such as nickel, cobalt, and molybdenum, and supports include alumina, molecular sieves, and activated carbon. Chinese patent CN116196966B discloses a method for preparing an alumina-based desulfurization catalyst by blending γ-alumina nanoflowers with Ni-Mo nitride nanocomposites. The resulting desulfurization catalyst has advantages such as good dispersibility, numerous catalytic sites, and high hydrodesulfurization efficiency. However, the preparation method of the γ-alumina nanoflowers and Ni-Mo nitride nanocomposites in this patent is relatively complex, and the desulfurization rate is low. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention provides a preparation process for a hydrodesulfurization catalyst, which solves the problem of low efficiency of existing nickel-molybdenum catalysts in the hydrodesulfurization of oil products.

[0004] To solve the above-mentioned technical problems, the technical solution of the present invention is: a preparation process for a hydrodesulfurization catalyst:

[0005] (1) Add deionized water, sodium iminodiacetic acid, and sodium bicarbonate to the reaction vessel. In an ice-water bath, add dropwise an acetone solution containing 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine. After the reaction, remove the acetone by vacuum distillation. Adjust the pH to 2-3 by adding hydrochloric acid solution. After filtration, dissolve the precipitate in water, heat to evaporate, and cool to crystallize to obtain the dispersant. The preparation reaction formula is:

[0006] .

[0007] (2) Add deionized water, nickel source, molybdenum source and dispersant to the reaction vessel, stir to disperse, and obtain a metal solution containing nickel-molybdenum precursor.

[0008] (3) Pour the metal solution into a container containing γ-Al2O3, impregnate, dry, calcine, and cool to obtain a hydrodesulfurization catalyst.

[0009] Furthermore, in (1), the molar ratio of 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).

[0010] Furthermore, in (1), the reaction temperature is 90-100℃ and the reaction time is 5-8h.

[0011] Furthermore, in (2), the stirring temperature is 40-60℃ and the stirring time is 2-3h.

[0012] Furthermore, in (2), the mass ratio of nickel source, molybdenum source and dispersant is (38-64):100:(4-10).

[0013] Furthermore, in (2), the nickel source is nickel nitrate or nickel sulfate.

[0014] Furthermore, in (2), the molybdenum source is ammonium molybdate tetrahydrate.

[0015] Furthermore, in (3), the immersion temperature is 20-35℃ and the time is 4-6h.

[0016] Furthermore, in (3), the drying temperature is 100-120℃ and the time is 4-8h.

[0017] Furthermore, in (3), the roasting temperature is 500-600℃ and the time is 2-3h.

[0018] The beneficial technical effects of adopting the above technical solution are as follows: Reaction of sodium iminodiacetic acid and 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine yields a dispersant containing a large number of nitrogen atoms, as well as multiple carboxyl and hydroxyl groups. This dispersant exhibits strong coordination and chelation properties for nickel and molybdenum, which is beneficial for improving the dispersibility of nickel and molybdenum precursors. This allows the nickel and molybdenum precursors to be uniformly impregnated into the γ-Al₂O₃ support. After calcination, nickel oxide and molybdenum oxide are uniformly distributed within the γ-Al₂O₃ support. The resulting hydrodesulfurization catalyst exposes more nickel and molybdenum catalytic active centers, effectively catalyzing the removal of sulfur-containing substances such as thiophenes from straight-run diesel, exhibiting a higher desulfurization rate and improving oil quality. This catalyst has excellent practical applications in the hydrodesulfurization treatment of heavy oil and diesel. Detailed Implementation

[0019] The following γ-Al2O3 model ZTL-AA is from Yangzhou Zhongtianli New Material Co., Ltd.

[0020] Add 10 mL of acetone and 10 mmol of cyanuric chloride to a reaction vessel. Then, add 10 mL of diethanolamine containing 20 mmol in an ice-water bath. Stir the reaction until the pH of the solution reaches approximately 6.8. Filter the solution, wash with water and acetone successively, and dry to obtain 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine, with the structural formula [insert structural formula here]. The CAS accession number is 1258-71-5.

[0021] Example 1:

[0022] (1) Add 8 mL of deionized water, 3 mmol of sodium iminodiacetate and 3 mmol of sodium bicarbonate to the reaction vessel. Add 4 mL of acetone solution containing 3 mmol of 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine dropwise in an ice-water bath. Heat to 100°C and reflux for 5 h. Remove acetone by vacuum distillation. Adjust the pH to 2 by adding hydrochloric acid solution. After filtration, dissolve the precipitate in water, heat to evaporate, and cool to crystallize to obtain the dispersant.

[0023] (2) Add 30 mL of deionized water, 4.6 g of nickel nitrate, 10 g of ammonium molybdate tetrahydrate and 0.4 g of dispersant to the reaction vessel, and stir at 40 °C for 3 h to obtain a metal solution containing nickel-molybdenum precursor.

[0024] (3) Pour the metal solution into a container containing 35g γ-Al2O3 and immerse it in 25℃ for 6h; then dry it in a drying oven at 110℃ for 8h; finally place it in a muffle furnace and calcine it at 500℃ for 3h, and cool it to obtain the hydrodesulfurization catalyst.

[0025] Example 2:

[0026] (1) Add 10 mL of deionized water, 3 mmol of sodium iminodiacetate and 3.3 mmol of sodium bicarbonate to the reaction vessel. Add 5 mL of acetone solution containing 3.3 mmol of 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine dropwise in an ice-water bath. Heat to 90 °C and reflux for 8 h. Remove acetone by vacuum distillation. Adjust the pH to 3 by adding hydrochloric acid solution. After filtration, dissolve the precipitate in water, heat to evaporate, and cool to crystallize to obtain the dispersant.

[0027] (2) Add 30 mL of deionized water, 3.8 g of nickel sulfate, 10 g of ammonium molybdate tetrahydrate and 0.6 g of dispersant to the reaction vessel, and stir at 50 °C for 2 h to obtain a metal solution containing nickel-molybdenum precursor.

[0028] (3) Pour the metal solution into a container containing 38g γ-Al2O3 and immerse it in 20℃ for 6h; then dry it in a drying oven at 100℃ for 8h; finally place it in a muffle furnace and calcine it at 500℃ for 3h, and cool it to obtain the hydrodesulfurization catalyst.

[0029] Example 3:

[0030] (1) Add 40 mL of deionized water, 5.5 g of nickel nitrate, 10 g of ammonium molybdate tetrahydrate and 0.8 g of dispersant (prepared according to the method of Example 1) to the reaction vessel and stir at 60 °C for 2 h to obtain a metal solution containing nickel-molybdenum precursor.

[0031] (2) Pour the metal solution into a container containing 42 γ-Al2O3 and immerse it in 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 the hydrodesulfurization catalyst.

[0032] Example 4:

[0033] (1) Add 40 mL of deionized water, 6.4 g of nickel nitrate, 10 g of ammonium molybdate tetrahydrate and 1 g of dispersant (prepared according to the method of Example 1) to the reaction vessel and stir at 60 °C for 2 h to obtain a metal solution containing nickel-molybdenum precursor.

[0034] (2) Pour the metal solution into a container containing 45g γ-Al2O3 and immerse it in 25℃ for 6h; then dry it in a drying oven at 110℃ for 7h; finally place it in a muffle furnace and calcine it at 550℃ for 3h, and cool it to obtain the hydrodesulfurization catalyst.

[0035] Comparative Example 1:

[0036] (1) Add 30 mL of deionized water, 4.6 g of nickel nitrate and 10 g of ammonium molybdate tetrahydrate to the reaction vessel and stir at 40 °C for 3 h to obtain a metal solution containing nickel-molybdenum precursor.

[0037] (2) Pour the metal solution into a container containing 35g γ-Al2O3 and immerse it in 25℃ for 6h; then dry it in a drying oven at 110℃ for 8h; finally place it in a muffle furnace and calcine it at 500℃ for 3h, and cool it to obtain the hydrodesulfurization catalyst.

[0038] Comparative Example 2:

[0039] (1) Add 30 mL of deionized water, 4.6 g of nickel nitrate, 10 g of ammonium molybdate tetrahydrate and 0.4 g of citric acid to the reaction vessel as a dispersant, and stir at 40 °C for 3 h to obtain a metal solution containing nickel-molybdenum precursor.

[0040] (2) Pour the metal solution into a container containing 35g γ-Al2O3 and immerse it in 25℃ for 6h; then dry it in a drying oven at 110℃ for 8h; finally place it in a muffle furnace and calcine it at 500℃ for 3h, and cool it to obtain the hydrodesulfurization catalyst.

[0041] Comparative Example 3:

[0042] (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 to the reaction vessel as a dispersant, and stir at 40 °C for 3 h to obtain a metal solution containing nickel-molybdenum precursor.

[0043] (2) Pour the metal solution into a container containing 35g γ-Al2O3 and immerse it in 25℃ for 6h; then dry it in a drying oven at 110℃ for 8h; finally place it in a muffle furnace and calcine it at 500℃ for 3h, and cool it to obtain the hydrodesulfurization catalyst.

[0044] Comparative Example 4:

[0045] (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: Using a dispersant (CAS Registry No. 1258-71-5), the mixture was stirred at 40°C for 3 hours to obtain a metal solution containing nickel-molybdenum precursors.

[0046] (2) Pour the metal solution into a container containing 35g γ-Al2O3 and immerse it in 25℃ for 6h; then dry it in a drying oven at 110℃ for 8h; finally place it in a muffle furnace and calcine it at 500℃ for 3h, and cool it to obtain the hydrodesulfurization catalyst.

[0047] The desulfurization performance of the catalyst was tested using a fixed-bed microreactor. The feedstock was straight-run diesel oil. The catalyst loading was controlled at 1.2 g, the hydrogen pressure in the reactor was controlled at 6 MPa, the reaction temperature was 320-360 °C, and the space velocity was 1 h⁻¹. -1 The sulfur content in straight-run diesel fuel before and after the catalytic desulfurization reaction was measured using a microcoulometric analyzer, and the desulfurization rate Q was calculated as follows: Q = (C0 - C) / C0 × 100%. C0 is the sulfur content in the straight-run diesel fuel before the catalytic desulfurization reaction, and C is the sulfur content in the straight-run diesel fuel after the catalytic desulfurization reaction.

[0048] Table 1 Desulfurization performance of the catalyst

[0049]

[0050] After testing, compared with Comparative Example 1, the hydrodesulfurization catalysts of Examples 1-4 achieved a desulfurization rate of 85.23-99.38% for straight-run diesel at a reverse temperature of 370°C. This was mainly due to the addition of a dispersant containing a large number of nitrogen atoms, as well as multiple carboxyl and hydroxyl groups, which has strong coordination and chelation properties for nickel and molybdenum. This is beneficial to improving the dispersibility of nickel and molybdenum precursors, allowing the nickel and molybdenum precursors to be uniformly impregnated into the γ-Al2O3 support. After calcination, the nickel oxide and molybdenum oxide are uniformly distributed in the γ-Al2O3 support, exposing more nickel and molybdenum catalytic active centers, effectively catalyzing the removal of sulfur-containing substances such as thiophenes from straight-run diesel, and exhibiting a higher desulfurization rate.

[0051] Comparative Example 2 used conventional citric acid as a dispersant, which has low hydroxyl and carboxyl content and no nitrogen atoms, resulting in low coordination and chelation performance with nickel and molybdenum. Comparative Example 3 used conventional ethylenediaminetetraacetic acid as a dispersant, which also has low hydroxyl content and low nitrogen atom content, resulting in low coordination and chelation performance with nickel and molybdenum. As a result, the nickel and molybdenum precursors of both examples were difficult to impregnate uniformly into γ-Al2O3. After calcination, the catalytic active centers of nickel and molybdenum were difficult to distribute uniformly in the γ-Al2O3 support, resulting in low desulfurization rates for both examples.

[0052] Comparative Example 4 used melamine hexaacetic acid as a dispersant, which does not contain hydroxyl groups and has lower dispersing performance than the dispersant in Example 1, resulting in a significantly lower desulfurization rate than in Example 1.

Claims

1. A preparation process for a hydrodesulfurization catalyst, characterized in that, The preparation process includes: (1) Add deionized water, nickel source, molybdenum source and dispersant to the reaction vessel, stir to disperse and obtain metal solution; The structural formula of the dispersant is: ; (2) Pour the metal solution into a container containing γ-Al2O3, impregnate, dry, calcine, and cool to obtain a hydrodesulfurization catalyst.

2. The preparation process of the hydrodesulfurization catalyst according to claim 1, characterized in that, The temperature during stirring in (1) is 40-60℃ and the time is 2-3h.

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

4. The preparation process of the hydrodesulfurization catalyst according to claim 3, characterized in that, 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 immersion in (2) is 20-35℃ and the time is 4-6h.

6. The preparation process of the hydrodesulfurization catalyst according to claim 1, characterized in that, The drying temperature in (2) is 100-120℃ and the drying time is 4-8h.

7. The preparation process of the hydrodesulfurization catalyst according to claim 1, characterized in that, The roasting temperature in (2) is 500-600℃ and the time is 2-3h.

8. The preparation process of the hydrodesulfurization catalyst according to claim 3, characterized in that, The dispersant is prepared as follows: deionized water, sodium iminodiacetic acid, and sodium bicarbonate are added to a reaction vessel. An acetone solution containing 6-(N,N-dihydroxyethyl)amino-2,4-dichloro-1,3,5-triazine is added dropwise in an ice-water bath. The mixture is heated to 90-100°C and refluxed for 5-8 hours. The acetone is removed by vacuum distillation. The pH is adjusted to 2-3 by adding hydrochloric acid solution. After filtration, the precipitate is dissolved in water, heated to evaporate, and cooled to crystallize, thus obtaining the dispersant.

9. The preparation process of the hydrodesulfurization catalyst according to claim 8, characterized in that, The molar ratio of 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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