A molecular sieve hydrodesulfurization catalyst and its preparation method

Abstract

This invention relates to the field of hydrodesulfurization catalyst technology, and discloses a molecular sieve hydrodesulfurization catalyst and its preparation method. The invention utilizes the active Si-Cl bond of maleate methyl dichlorosilane to react with the hydroxyl groups in MCM-41 molecular sieves, followed by hydrolysis with sodium hydroxide, thereby grafting a large number of carboxyl groups into the molecular sieve. These carboxyl groups can form strong coordination interactions with metal ions such as nickel, thus uniformly adsorbing nickel and molybdenum into the molecular sieve matrix. After high-temperature calcination, nickel-molybdenum oxide catalytic active centers are uniformly generated in the molecular sieve. These catalytic sites are not prone to aggregation and have good dispersibility, effectively enabling the hydrodesulfurization reaction of sulfur-containing substances such as thiophenes in straight-run diesel fuel, resulting in a higher desulfurization rate. It has excellent practical applications in oil hydrodesulfurization catalysis.

Description

Technical Field

[0001] This invention relates to the field of hydrodesulfurization catalyst technology, specifically to a molecular sieve hydrodesulfurization catalyst and its preparation method. Background Technology

[0002] Gasoline, diesel, kerosene and other petroleum products contain sulfur compounds such as thiophene and mercaptans. When these compounds burn, they produce sulfur dioxide gas, which, when released into the atmosphere, causes sulfuric acid mist, acid rain, and other pollution problems, including soil acidification and vegetation damage. At the same time, excessive sulfur content in petroleum products reduces their combustion performance and stability. Currently, hydrodesulfurization is an effective method to reduce the sulfur content in petroleum products.

[0003] Catalysts used in hydrodesulfurization mainly consist of metal oxides such as nickel, molybdenum, and cobalt, while catalyst supports primarily include molecular sieves and alumina. Molecular sieves, in particular, have a large specific surface area and high chemical stability, making them widely used. Patent CN119955541B discloses a gradation method for a deep hydrodesulfurization catalyst for diesel fuel, using phosphorus-aluminum molecular sieves and alumina as catalyst supports, and oxides such as nickel, molybdenum, and cobalt as active catalyst components. This method can effectively reduce the sulfur content in diesel fuel. However, when molecular sieve supports are used to load the active catalyst components, problems such as poor dispersion of the active catalyst components can occur, severely affecting the hydrodesulfurization performance of the catalyst. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a molecular sieve hydrodesulfurization catalyst and its preparation method, which solves the problem of low efficiency of nickel-molybdenum molecular sieve catalysts in the hydrodesulfurization of oil products.

[0005] To solve the above-mentioned technical problems, the technical solution of the present invention is: a method for preparing a molecular sieve hydrodesulfurization catalyst.

[0006] (1) Toluene, methyldichlorosilane, and maleate monomer were added to a reaction vessel, followed by an isopropanol solution of chloroplatinic acid. The mixture was stirred and reacted. After filtration, the filtrate was distilled under reduced pressure, the product was washed with petroleum ether, and dried to obtain maleate-based methyldichlorosilane. The reaction formula is:

[0007] .

[0008] (2) The molecular sieve is placed in a vacuum sintering furnace, vacuumed, subjected to high-temperature heat treatment, and cooled to obtain activated molecular sieve.

[0009] (3) Add toluene and activated molecular sieve to the reaction vessel, stir and add maleate methyl dichlorosilane, stir to modify, use the Si-Cl bond of maleate methyl dichlorosilane to react with the hydroxyl group of molecular sieve, filter and wash the product with toluene and ethanol, then add to sodium hydroxide aqueous solution, stir to hydrolyze, hydrolyze the ester group to carboxyl group, filter and wash with water, dry to obtain modified molecular sieve.

[0010] (4) Add water, modified molecular sieve, nickel source and molybdenum source to the container, stir and disperse, and uniformly adsorb the nickel source and molybdenum source into the molecular sieve matrix through the coordination of carboxyl groups, etc., dry, calcine and cool to obtain molecular sieve hydrodesulfurization catalyst.

[0011] Furthermore, in (1), the mass ratio of methyl dichlorosilane to maleate monomer is 100:(126-150).

[0012] Furthermore, in (1), the maleate monomer is dimethyl maleate or diethyl maleate.

[0013] Furthermore, in (1), the reaction temperature is 80-90℃ and the reaction time is 2-3h.

[0014] Furthermore, (2) the medium-high temperature heat treatment is carried out at a heating rate of 3-5℃ / min, raising the temperature to 400-450℃ and holding it for 10-16h.

[0015] Furthermore, in (3), the temperature during modification is 65-80℃ and the modification time is 12-18h.

[0016] Furthermore, in (3), the hydrolysis temperature is 80-90℃ and the hydrolysis time is 3-6h.

[0017] Furthermore, in (3), the mass fraction of the sodium hydroxide aqueous solution is 10-15%.

[0018] Furthermore, in (3), the mass ratio of activated molecular sieve to maleate methyl dichlorosilane is 100:(80-250).

[0019] Furthermore, in (4), the mass ratio of modified molecular sieve, nickel source, and molybdenum source is 100:(12-18):(25-32).

[0020] Furthermore, in (4), the nickel source is nickel nitrate or nickel sulfate.

[0021] Furthermore, in (4), the molybdenum source is ammonium molybdate tetrahydrate.

[0022] Furthermore, in (4), the stirring temperature is 20-50℃ and the stirring time is 3-5h.

[0023] Furthermore, in (4), the drying temperature is 100-120℃ and the time is 5-8h.

[0024] Furthermore, in (4), the roasting temperature is 500-550℃ and the time is 2-3h.

[0025] (III) Beneficial Technical Effects of the Invention: The active Si-Cl bond of maleate methyl dichlorosilane reacts with the hydroxyl groups in the MCM-41 molecular sieve. The ester group is then hydrolyzed with sodium hydroxide to generate carboxyl groups, resulting in a large number of carboxyl groups grafted into the molecular sieve. These carboxyl groups form strong coordination interactions with metal ions such as nickel, uniformly adsorbing nickel and molybdenum into the molecular sieve matrix. After high-temperature calcination, nickel-molybdenum oxide catalytic active centers are uniformly generated within the molecular sieve. These catalytic sites are not prone to aggregation, exhibiting good dispersibility and exposing a large number of catalytic sites. This allows for effective hydrogenation of sulfur-containing substances such as thiophenes in straight-run diesel fuel, achieving a higher desulfurization rate. It has excellent practical applications in oil hydrodesulfurization catalysis and the lightening of heavy aromatics. Detailed Implementation

[0026] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0027] Example 1:

[0028] (1) Add 200 mL of toluene, 20 g of methyl dichlorosilane, and 25.2 g of dimethyl maleate to the reaction vessel, add 80 μL of isopropanol solution containing 1.6 mg of chloroplatinic acid, heat to 80 °C, stir and react for 3 h, filter, distill the filtrate under reduced pressure, wash the product with petroleum ether, dry, and obtain maleate methyl dichlorosilane.

[0029] (2) Place the MCM-41 molecular sieve in a vacuum sintering furnace, evacuate the vacuum, raise the temperature to 450°C at a heating rate of 5°C / min, hold for 10 hours, and cool to obtain the activated molecular sieve.

[0030] (3) Add 1.5L toluene and 30g activated molecular sieve to the reaction vessel, stir, add 24g maleate methyl dichlorosilane, heat to 70℃, stir for 12h, filter, wash the product with toluene and ethanol, then add to a 10% sodium hydroxide aqueous solution, heat to 70℃, stir for 4h, filter, wash with water, and dry to obtain modified molecular sieve.

[0031] (4) Add 200 mL of water, 50 g of modified molecular sieve, 6 g of nickel nitrate and 16 g of ammonium molybdate tetrahydrate to the container, stir and disperse at 30 °C for 3 h, dry at 110 °C for 5 h, place in a muffle furnace, calcine at 500 °C for 3 h, and cool to obtain molecular sieve hydrodesulfurization catalyst.

[0032] Example 2:

[0033] (1) Add 250 mL of toluene, 20 g of methyl dichlorosilane, and 30 g of diethyl maleate to the reaction vessel, add 60 μL of isopropanol solution containing 1.2 mg of chloroplatinic acid, heat to 90 °C, stir and react for 2 h, filter, distill the filtrate under reduced pressure, wash the product with petroleum ether, dry, and obtain maleate methyl dichlorosilane.

[0034] (2) Place the MCM-41 molecular sieve in a vacuum sintering furnace, evacuate the vacuum, raise the temperature to 400°C at a rate of 3°C / min, hold for 16 hours, and cool to obtain the activated molecular sieve.

[0035] (3) Add 2L of toluene and 30g of activated molecular sieve to the reaction vessel, stir, add 55g of maleic acid methyl dichlorosilane, heat to 65℃, stir for 18h, filter, wash the product with toluene and ethanol, then add to a 10% sodium hydroxide aqueous solution, heat to 90℃, stir for 3h, filter, wash with water, and dry to obtain the modified molecular sieve.

[0036] (4) Add 300 mL of water, 50 g of modified molecular sieve, 7.7 g of nickel nitrate and 14.8 g of ammonium molybdate tetrahydrate to the container, stir and disperse at 50 °C for 3 h, dry at 100 °C for 8 h, place in a muffle furnace, calcine at 550 °C for 2 h, and cool to obtain molecular sieve hydrodesulfurization catalyst.

[0037] Example 3:

[0038] (1) Place the MCM-41 molecular sieve in a vacuum sintering furnace, evacuate the vacuum, raise the temperature to 450°C at a heating rate of 5°C / min, hold for 12 hours, and cool to obtain the activated molecular sieve.

[0039] (2) Add 2L of toluene and 30g of activated molecular sieve to the reaction vessel, stir, add 75g of maleate methyl dichlorosilane (prepared from Example 1), heat to 80°C, stir and modify for 12h, filter and wash the product with toluene and ethanol, then add to a 15% sodium hydroxide aqueous solution, heat to 80°C, stir and hydrolyze for 6h, filter, wash with water, and dry to obtain the modified molecular sieve.

[0040] (3) Add 300 mL of water, 50 g of modified molecular sieve, 9 g of nickel sulfate and 12.5 g of ammonium molybdate tetrahydrate to the container, stir and disperse at 20 °C for 5 h, dry at 120 °C for 5 h, place in a muffle furnace, calcine at 550 °C for 2 h, and cool to obtain molecular sieve hydrodesulfurization catalyst.

[0041] Comparative Example 1:

[0042] (1) Add 200 mL of water, 50 g of activated molecular sieve (prepared according to the method of Example 1), 6 g of nickel nitrate and 16 g of ammonium molybdate tetrahydrate to a container, stir and disperse at 30 °C for 3 h, dry at 110 °C for 5 h, place in a muffle furnace, calcine at 500 °C for 3 h, and cool to obtain molecular sieve hydrodesulfurization catalyst.

[0043] Comparative Example 2:

[0044] (1) Add 1.5L toluene and 30g activated molecular sieve (prepared according to the method of Example 1) to the reaction vessel, stir, add 24g methyldichlorosilane, heat to 70°C, stir for 12h to modify, filter, wash the product with toluene and ethanol, then add to a 10% sodium hydroxide aqueous solution, heat to 70°C, stir for 4h to hydrolyze, filter, wash with water, and dry to obtain modified molecular sieve.

[0045] (2) Add 200mL of water, 50g of modified molecular sieve, 6g of nickel nitrate and 16g of ammonium molybdate tetrahydrate to the container, stir and disperse at 30℃ for 3h, dry at 110℃ for 5h, place in a muffle furnace, calcine at 500℃ for 3h and cool to obtain molecular sieve hydrodesulfurization catalyst.

[0046] Comparative Example 3:

[0047] (1) Add 200 mL of toluene, 20 g of methyldichlorosilane, and 17.5 g of methyl methacrylate to a reaction vessel, add 40 μL of isopropanol solution containing 1.2 mg of chloroplatinic acid, heat to 80 °C, stir and react for 3 h, filter, distill under reduced pressure, wash the product with petroleum ether, and dry to obtain methyl methacrylate-based methyldichlorosilane, with the structural formula: .

[0048] (2) Add 1.5L toluene and 30g activated molecular sieve to the reaction vessel, stir, add 24g methyl methylpropionate dichlorosilane, heat to 70℃, stir for 12h, filter, wash the product with toluene and ethanol, then add to a 10% sodium hydroxide aqueous solution, heat to 70℃, stir for 4h, filter, wash with water, and dry to obtain modified molecular sieve.

[0049] (3) Add 200mL of water, 50g of modified molecular sieve, 6g of nickel nitrate and 16g of ammonium molybdate tetrahydrate to the container, stir and disperse at 30℃ for 3h, dry at 110℃ for 5h, place in a muffle furnace, calcine at 500℃ for 3h, and cool to obtain molecular sieve hydrodesulfurization catalyst.

[0050] Comparative Example 4:

[0051] (1) Add 1.5L toluene and 30g activated molecular sieve to the reaction vessel, stir and add 24g maleic acid, heat to 70℃, stir and modify for 12h, filter and wash the product with toluene and ethanol, dry to obtain modified molecular sieve.

[0052] (2) Add 200mL of water, 50g of modified molecular sieve, 6g of nickel nitrate and 16g of ammonium molybdate tetrahydrate to the container, stir and disperse at 30℃ for 3h, dry at 110℃ for 5h, place in a muffle furnace, calcine at 500℃ for 3h and cool to obtain molecular sieve hydrodesulfurization catalyst.

[0053] The desulfurization performance of the catalyst was tested using a fixed-bed microreactor. The feedstock was straight-run diesel oil, the catalyst loading was 1.5 g, the hydrogen pressure in the reactor was 5 MPa, the reaction temperature was 300-360 °C, and the space velocity was 1.2 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.

[0054] Table 1. Hydrodesulfurization test results using sulfur catalysts.

[0055]

[0056] The low desulfurization rate of the molecular sieve hydrodesulfurization catalyst in Comparative Example 1 is mainly due to the poor dispersion of the nickel-molybdenum oxide catalytic active centers within the molecular sieve, which affects the catalytic hydrodesulfurization performance. The modified molecular sieves in Examples 1-3 contain a large number of carboxyl groups, which can form strong coordination interactions with metal ions such as nickel, thereby uniformly adsorbing nickel and molybdenum into the molecular sieve matrix. After high-temperature calcination, nickel-molybdenum oxide catalytic active centers are uniformly generated within the molecular sieve. These catalytic sites are less prone to aggregation and exhibit good dispersion, effectively enabling the hydrodesulfurization reaction of sulfur-containing substances such as thiophenes in straight-run diesel fuel, resulting in a higher desulfurization rate.

[0057] Compared with Example 1, Comparative Example 2 uses methyldichlorosilane to modify the molecular sieve. The modified molecular sieve does not contain carboxyl groups, making it difficult to form coordination with metal ions such as nickel. Nickel and molybdenum cannot be uniformly adsorbed into the molecular sieve matrix. The dispersion of the catalytic active centers of nickel and molybdenum oxides in the molecular sieve is poor, resulting in a lower desulfurization rate of the catalyst than in Example 1.

[0058] The molecular sieve modified with methyl methylpropionate in Comparative Example 3 has a lower carboxyl content and weaker coordination effect of metal ions such as nickel. The dispersion of the catalytic active center of nickel-molybdenum oxide in the molecular sieve is lower than that in Example 1, resulting in a lower desulfurization rate of the catalyst than in Example 1.

[0059] Maleic acid in Comparative Example 4 does not contain Si-Cl and cannot react with the hydroxyl groups of the molecular sieve. After washing, maleic acid in the molecular sieve is easily removed, resulting in the modified molecular sieve containing almost no carboxyl groups. The molecular sieve is difficult to coordinate with metal ions such as nickel, and nickel and molybdenum cannot be uniformly adsorbed into the matrix of the molecular sieve. The catalytic active centers of nickel and molybdenum oxides are poorly dispersed in the molecular sieve, resulting in a lower desulfurization rate of the catalyst than in Example 1.

[0060] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing a molecular sieve hydrodesulfurization catalyst, characterized in that, The preparation method includes: (1) The molecular sieve is placed in a vacuum sintering furnace, vacuumed, subjected to high-temperature heat treatment, and cooled to obtain activated molecular sieve; (2) Add toluene and activated molecular sieve to the reaction vessel, stir and then add maleate methyl dichlorosilane, stir to modify, filter and wash the product, then add to sodium hydroxide aqueous solution, stir to hydrolyze, filter and wash, dry to obtain modified molecular sieve. (3) Add water, modified molecular sieve, nickel source and molybdenum source to the container, stir and disperse, dry, calcine and cool to obtain molecular sieve hydrodesulfurization catalyst; The preparation method of the maleate methyl dichlorosilane includes: adding toluene, methyl dichlorosilane in a mass ratio of 100:(126-150), maleate monomer to a reaction vessel, adding isopropanol solution of chloroplatinic acid, heating to 80-90℃, stirring and reacting for 2-3 hours, filtering, distilling the filtrate under reduced pressure, washing the product, drying, and obtaining maleate methyl dichlorosilane; The maleate monomer is dimethyl maleate or diethyl maleate.

2. The method for preparing the molecular sieve hydrodesulfurization catalyst according to claim 1, characterized in that, The high-temperature heat treatment in (1) is to raise the temperature to 400-450℃ at a heating rate of 3-5℃ / min and hold it for 10-16 hours.

3. The method for preparing the molecular sieve hydrodesulfurization catalyst according to claim 1, characterized in that, The temperature during modification in (2) is 65-80℃ and the modification time is 12-18h; the temperature during hydrolysis is 80-90℃ and the hydrolysis time is 3-6h.

4. The method for preparing the molecular sieve hydrodesulfurization catalyst according to claim 1, characterized in that, The mass fraction of sodium hydroxide aqueous solution in (2) is 10-15%.

5. The method for preparing the molecular sieve hydrodesulfurization catalyst according to claim 1, characterized in that, The mass ratio of activated molecular sieve to maleate methyl dichlorosilane in (2) is 100:(80-250).

6. The method for preparing the molecular sieve hydrodesulfurization catalyst according to claim 1, characterized in that, In step (3), the mass ratio of the modified molecular sieve, nickel source, and molybdenum source is 100:(12-18):(25-32); the nickel source is nickel nitrate or nickel sulfate; and the molybdenum source is ammonium molybdate tetrahydrate.

7. The method for preparing the molecular sieve hydrodesulfurization catalyst according to claim 1, characterized in that, The stirring temperature in (3) is 20-50℃ and the time is 3-5h; the drying temperature is 100-120℃ and the time is 5-8h; the calcination temperature is 500-550℃ and the time is 2-3h.

8. A molecular sieve hydrodesulfurization catalyst obtained by the preparation method according to any one of claims 1-7.

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