Heteropolyacid-loaded titanium silicalite molecular sieve catalyst as well as preparation method and application thereof
By load mixed acid on the titanium silicon molecule sieve, a dual -active position is formed, solving the problem of existing titanium silicon molecular sieving catalyst activity limit and an olefin one -step legal diol separation energy consumption. Dibol synthesis.
Patent Information
- Application Number
- CN202411626504.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-14
- Publication Date
- 2025-01-28
AI Technical Summary
The existing titanium silicon molecular sieve catalysts have limitations in improving catalytic activity, and the separation energy consumption of diols is high in one-step process for olefin preparation.
Through load mixed acid (such as phosphate and/or chromium phosphate) on titanium silicon molecular sieves, a dual -active position is formed, promoting the oxide process of olefin, and using acidic conditions to promote the hydrolysis of epoxide oxides to achieve a one -step method Synthetic diol.
Improve the catalytic activity of the catalyst, reduce the separation energy consumption, the conversion rate of the olefin is more than 10%, and the diol selectivity is more than 60%.
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Abstract
Description
Technical Field
[0001] The invention belongs to the field of molecular sieve preparation, and specifically relates to a titanium silicon molecular sieve catalyst loaded with heteropoly acid, and a preparation method and application thereof. Background Art
[0002] At present, the epoxidation catalytic system composed of titanium silicalite represented by TS-1 and hydrogen peroxide has been widely used in reactions such as olefin epoxidation due to its green and environmentally friendly characteristics. The epoxidation catalytic system has a simple reaction process, strong operability, mild reaction conditions, the reaction temperature is generally not higher than 100°C, the reaction pressure is mostly normal pressure, and the safety performance is greatly improved. In the above system, the active site of titanium silicalite is an isolated four-coordinated Ti species, and its catalytic activity can generally be enhanced by increasing the titanium content of the framework, but the atomic radius of titanium is larger than that of silicon and aluminum, so it is more difficult to enter the framework. It is theoretically proposed that it is difficult to break through the threshold of silicon-titanium ratio of 40 during the synthesis of titanium silicalite, so there is a great limitation to enhancing the catalytic activity of titanium silicalite by increasing the titanium content of the framework.
[0003] In addition, when diols are prepared from olefins as raw materials, olefins are generally epoxidized to prepare epoxides, which are then hydrolyzed to prepare diols, which results in high separation energy consumption.
[0004] Therefore, it is urgent to find other methods to improve the catalytic activity of titanium silicalite. Summary of the invention
[0005] In view of this, the purpose of the present invention is to provide a titanium silicon molecular sieve catalyst loaded with heteropoly acid and its preparation method and application. The titanium silicon molecular sieve catalyst loaded with heteropoly acid has dual active sites, which jointly promote the epoxidation process of olefins and improve the catalytic activity of the catalyst.
[0006] To achieve this object, the present invention adopts the following technical solutions:
[0007] In a first aspect, the present invention provides a titanium silicate molecular sieve catalyst loaded with a heteropoly acid, comprising a titanium silicate molecular sieve and a heteropoly acid loaded on the titanium silicate molecular sieve;
[0008] The heteropoly acid comprises phosphomolybdic acid and / or phosphochromic acid;
[0009] The mass ratio or molar ratio of the titanium silicate molecular sieve and the heteropoly acid is (0.5-7.5):1.
[0010] In a second aspect, the present invention provides a method for preparing the above-mentioned titanium silicon molecular sieve catalyst loaded with heteropoly acid, comprising the following steps:
[0011] The titanium silicon molecular sieve is impregnated with an aqueous solution of a heteropoly acid, and a titanium silicon molecular sieve catalyst loaded with a heteropoly acid is obtained after drying.
[0012] Preferably, in the aqueous solution of heteropolyacid, the concentration of heteropolyacid is 0.01-0.1 mol / L, and the volume of the aqueous solution of heteropolyacid is 20-30 mL.
[0013] Preferably, the immersion treatment is carried out at a temperature of 10 to 30° C. and for a time of 6 to 18 h.
[0014] Preferably, the drying temperature is 60-120° C. and the drying time is 4-20 h.
[0015] Preferably, the titanium silicate molecular sieve is prepared according to the following method:
[0016] S1: Mixing a silicon source and a template to obtain a solution A; mixing an alcohol, a titanium source, and a template to obtain a solution B; mixing solution A and solution B, removing alcohol, and adding water to obtain a solution C;
[0017] S2: After the solution C is crystallized, it is centrifuged to obtain a solid; after the solid is dried and calcined, a titanium silicon molecular sieve is obtained.
[0018] Preferably, the silicon source is selected from tetraethyl orthosilicate.
[0019] Preferably, the template is selected from tetrapropylammonium hydroxide and / or tetrabutylammonium hydroxide.
[0020] Preferably, the alcohol is selected from any one or more of ethanol, isopropanol or butanol.
[0021] Preferably, the titanium source is selected from tetrabutyl titanate and / or tetraethyl titanate.
[0022] Preferably, the volume ratio of the silicon source to the template is 1:(1-1.8).
[0023] Preferably, the volume ratio of the titanium source, alcohol and template is 1:(1.5-6):(6-12).
[0024] Preferably, in the process of obtaining solution A, the mixing temperature is 30-60° C., the mixing time is 2-6 h, and the mixing is performed under stirring conditions.
[0025] Preferably, in the process of obtaining solution B, the mixing temperature is 10-30° C., the mixing time is 0.5-2 h, and the mixing is performed under stirring conditions.
[0026] Preferably, the temperature for removing alcohol is 75-100°C.
[0027] Preferably, the crystallization treatment is performed at a temperature of 150-240° C. and for a time of 24-96 h.
[0028] Preferably, the centrifugal separation speed is 3500-4500 rpm and the time is 30-120 min.
[0029] Preferably, the drying temperature is 60-130° C. and the drying time is 4-12 h.
[0030] Preferably, the calcination temperature is 400-600° C. and the calcination time is 2-8 h.
[0031] Preferably, the heating rate during the calcination process is 1-10° C. / min.
[0032] In a third aspect, the present invention provides an application of the above-mentioned titanium silicalite catalyst loaded with heteropoly acid in catalyzing the one-step preparation of glycols from olefins.
[0033] In a fourth aspect, the present invention provides a method for preparing diols by epoxidation of olefins, comprising the following steps:
[0034] After the catalyst, olefin, solvent and hydrogen peroxide are mixed and reacted, diol is obtained;
[0035] The catalyst is the titanium silicon molecular sieve catalyst loaded with heteropoly acid involved in the above technical solution.
[0036] Preferably, the olefin is selected from any one or more of 1-pentene, 1-hexene, 1-heptene, 1-octene, cyclopentene or styrene.
[0037] Preferably, the solvent is selected from any one or more of methanol, acetonitrile or acetone.
[0038] Preferably, the mass ratio of the olefin to the solvent is 1:(3-9).
[0039] Preferably, the amount of the catalyst added is 0.5-8% of the mass of the olefin.
[0040] Preferably, the molar ratio of hydrogen peroxide to olefin is 1:(2-3.5).
[0041] Preferably, the reaction temperature is 40-100° C. and the reaction time is 1-5 h.
[0042] Preferably, the reaction is carried out under stirring conditions, and the stirring rate is 100-800 rpm.
[0043] Compared with the prior art, the present invention has the following beneficial effects:
[0044] The present invention provides a titanium silicalite catalyst loaded with heteropolyacids, which comprises a titanium silicalite and a heteropolyacid loaded on the titanium silicalite. The heteropolyacid comprises phosphomolybdic acid and / or phosphochromic acid, which are introduced into the titanium silicalite in the present invention, and it is found that the molybdenum in the phosphomolybdic acid and the chromium in the phosphochromic acid can be used as active sites for olefin epoxidation, and form dual active sites with the titanium sites in the titanium silicalite, jointly promoting the olefin epoxidation process and improving the catalytic activity of the catalyst; on the other hand, the acidity of the heteropolyacid is conducive to the hydrolysis of epoxides into the final target product diols.
[0045] The heteropolyacid-loaded titanium silicon molecular sieve catalyst provided by the present invention can realize the one-step synthesis of diols from olefins and reduce separation energy consumption. According to tests, the selectivity of diols prepared by olefin epoxidation is above 60%, and the olefin conversion rate is above 10%. DETAILED DESCRIPTION
[0046] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0047] When preparing diols from olefins as raw materials, olefins are generally first epoxidized to prepare epoxides, and then hydrolyzed to prepare diols, which consumes a lot of separation energy. Studies have shown that acidic conditions are conducive to the hydrolysis of epoxides, so it is possible to consider using acidity to promote the hydrolysis of epoxides, thereby achieving a one-step synthesis of diols from olefins and reducing separation energy consumption.
[0048] Based on this, the present invention provides a titanium silicon molecular sieve catalyst loaded with heteropoly acid, comprising a titanium silicon molecular sieve and a heteropoly acid loaded on the titanium silicon molecular sieve. The mass ratio or molar ratio of the titanium silicon molecular sieve and the heteropoly acid is (0.5-7.5):1, preferably (1.0-7.5):1.
[0049] In the present invention, the heteropoly acid includes phosphomolybdic acid and / or phosphochromic acid.
[0050] The present invention introduces heteropoly acid into titanium silicalite. On the one hand, the metal in the heteropoly acid can serve as an active site for olefin epoxidation, and constitutes a dual active site with the titanium site in the titanium silicalite, jointly promoting the olefin epoxidation process to improve the catalytic activity of the catalyst; on the other hand, the acidity of the heteropoly acid is conducive to the hydrolysis of epoxides into the final target product diol.
[0051] The present invention also provides a method for preparing the above-mentioned heteropolyacid-loaded titanium silicon molecular sieve catalyst, comprising the following steps:
[0052] The titanium silicon molecular sieve is impregnated with an aqueous solution of a heteropoly acid, and a titanium silicon molecular sieve catalyst loaded with a heteropoly acid is obtained after drying.
[0053] In the present invention, the titanium silicon molecular sieve can be prepared by a hydrothermal method.
[0054] In some embodiments of the present invention, the titanium silicate molecular sieve is prepared according to the following method:
[0055] S1: Mixing a silicon source and a template to obtain a solution A; mixing an alcohol, a titanium source, and a template to obtain a solution B; mixing solution A and solution B, removing alcohol, and adding water to obtain a solution C;
[0056] S2: After the solution C is crystallized, it is centrifuged to obtain a solid; after the solid is dried and calcined, a titanium silicon molecular sieve is obtained.
[0057] It should be noted that the hydrolysis rates of the silicon source and the titanium source are different. If the silicon source, the titanium source and the template are directly mixed, it is very likely that the hydrolysis rates of the silicon source and the titanium source will not match, which may cause the Si / Ti ratio of the synthesized molecular sieve to be unpredictable.
[0058] Therefore, according to the present invention, firstly, a silicon source and a template are mixed to obtain a solution A. The silicon source is selected from tetraethyl orthosilicate (TEOS for short); the template is selected from tetrapropylammonium hydroxide (TPAOH for short) and / or tetrabutylammonium hydroxide (TBAOH for short). In the present invention, the silicon source and the template are preferably mixed in a volume ratio of 1:(1~1.8), preferably 1:(1.1~1.2), and hydrolyzed to form a solution A. The mixing is carried out under heating and stirring conditions, and the heating and stirring temperature is 30~60°C, preferably 35~55°C; the time is 2~6 h, preferably 3~5 h. It should be noted that the mixing process is constant temperature.
[0059] Then, according to the present invention, alcohol, titanium source and template are mixed to obtain solution B. Wherein, the alcohol is selected from any one or more of ethanol, isopropanol or butanol; the template is selected from tetrapropylammonium hydroxide (abbreviated as: TPAOH) and / or tetrabutylammonium hydroxide (abbreviated as: TBAOH); the titanium source is selected from tetrabutyl titanate (abbreviated as: TBOT) and / or tetraethyl titanate (abbreviated as: TET). In the present invention, it is preferred to mix the titanium source, alcohol and template in a volume ratio of 1:(1.5~6):(6~12), preferably 1:(2~4):(8~10), and hydrolyze to form solution B. The mixing is carried out at a constant temperature under stirring conditions, and the mixing temperature is room temperature, specifically 10~30°C, preferably 15~25°C; the time is 0.5~2 h, preferably 0.5~1.5 h.
[0060] Then, according to the present invention, solution A and solution B are mixed, and solution C is obtained after removing alcohol and replenishing water. In the present invention, the above mixing can be carried out at room temperature, specifically 10~30°C, preferably 15~25°C. The time of the mixing is not specifically limited, and the mixing is uniform. In the present invention, since alcohols are produced during the hydrolysis of silicon source and titanium source, especially the hydrolysis of silicon source, a large amount of alcohols will be produced, these alcohols may affect the crystallization process of molecular sieves, affect the structure of synthetic molecular sieves, and cause the performance of molecular sieves to deteriorate, so it is necessary to remove alcohol after the mixing is completed. The temperature of the alcohol removal is 75~100°C, preferably 85~95°C. After the alcohol is removed, the volume of the entire system is reduced, so it is necessary to replenish water, and the purpose of replenishing water is to restore the volume of the system to the volume before the alcohol is removed. That is, the water replenishment standard is: replenish the system volume to the same volume as before the alcohol is removed.
[0061] Then, according to the present invention, solution C is subjected to a crystallization treatment to obtain a crystallized product. The purpose of the crystallization treatment is to form an MFI structure of silicon and titanium under the action of a template agent, while simultaneously growing a molecular sieve, and finally forming a desired molecular sieve structure, and the temperature is 150-240° C., preferably 180-210° C.; the time is 24-96 h, preferably 48-72 h.
[0062] Then, the crystallized product is centrifuged to obtain a solid. The centrifugal separation speed is 3500-4500 rpm, preferably 4000-4500 rpm, and the time is 30-120 min, preferably 40-90 min.
[0063] Finally, the solid is dried and calcined to obtain a titanium silicon molecular sieve. The drying temperature is 60-130°C, preferably 80-100°C; the time is 4-12 h, preferably 6-10 h. The calcination is used to remove the template, and the temperature is 400-600°C, preferably 450-550°C; the time is 2-8 h, preferably 4-6 h. In the present invention, heating too fast during the calcination process may destroy the structure of the titanium silicon molecular sieve, so a smaller heating rate is used when synthesizing the titanium silicon molecular sieve. The present invention preferably uses a heating rate of 1-10°C / min during the calcination process, preferably 2-5°C / min.
[0064] The present invention utilizes a hydrothermal method to prepare a titanium silicalite, and uses tetrapropylammonium hydroxide and / or tetrabutylammonium hydroxide as a template agent, which is beneficial to the formation of an MFI topological structure of the titanium silicalite; in the process of preparing the titanium silicalite, the addition amount of raw materials (such as a silicon source, a titanium source, a template agent and water) and the conditions during preparation (such as the temperature and time of hydrolysis of the silicon source and the titanium source) are well controlled, so that the degree of hydrolysis of the silicon source and the titanium source can be avoided, and more active species can be formed.
[0065] According to the present invention, after the titanium silicon molecular sieve is obtained, the titanium silicon molecular sieve is impregnated with an aqueous solution of a heteropoly acid, and after drying, a titanium silicon molecular sieve catalyst loaded with a heteropoly acid is obtained.
[0066] In the present invention, in the aqueous solution of heteropolyacid, the concentration of heteropolyacid is 0.01-0.1 mol / L, preferably 0.04-0.08 mol / L; the volume of the aqueous solution of heteropolyacid is 20-30 mL, preferably 25-30 mL.
[0067] In the present invention, the immersion treatment is carried out at a temperature of 10 to 30° C., preferably 15 to 25° C., and for a time of 6 to 18 h, preferably 8 to 16 h.
[0068] In the present invention, the drying temperature is 60-120° C., preferably 80-100° C.; the drying time is 4-20 h, preferably 10-18 h.
[0069] In some embodiments of the present invention, 3 g of titanium silicalite is preferably dispersed in 30-40 mL of a heteropolyacid aqueous solution having a concentration of 0.01-0.1 mol / L, stirred at room temperature for 6-18 h, and then dried at 60-120° C. for 4-20 h to obtain a titanium silicalite loaded with heteropolyacid.
[0070] The present invention also provides an application of the titanium silicon molecular sieve catalyst loaded with heteropoly acid in catalyzing olefins to prepare glycols in a one-step process.
[0071] Specifically, the present invention also provides a method for preparing diols by epoxidation of olefins, comprising the following steps:
[0072] After the catalyst, olefin, solvent and hydrogen peroxide are mixed and reacted, diol is obtained;
[0073] The catalyst is the titanium silicon molecular sieve catalyst loaded with heteropoly acid.
[0074] In the present invention, the olefin is selected from any one or more of 1-pentene, 1-hexene, 1-heptene, 1-octene, cyclopentene or styrene; and the solvent is selected from any one or more of methanol, acetonitrile or acetone.
[0075] In the present invention, the mass ratio of the olefin to the solvent is 1:(3-9), preferably 1:(5-8); the amount of the catalyst added is 0.5-8% of the mass of the olefin, preferably 2-6%; the molar ratio of the hydrogen peroxide to the olefin is 1:(2-3.5), preferably 1:(2.5-3.5).
[0076] In the present invention, the reaction temperature is 40-100°C, preferably 40-70°C; the reaction time is 1-5 h, preferably 2-4 h. The reaction is preferably carried out under stirring, and the stirring rate is 100-800 rpm, preferably 300-600 rpm.
[0077] In some embodiments of the present invention, after the above reaction is completed, the catalyst is separated. At the same time, the obtained product is quantitatively analyzed, and it is found that the olefin conversion rate is above 10%, and the selectivity of the final product diol is above 60%.
[0078] In summary, the use of the heteropolyacid-loaded titanium silicalite catalyst provided by the present invention can realize the one-step synthesis of diols from olefins, reduce separation energy consumption, and simultaneously obtain higher olefin conversion rate and diol selectivity.
[0079] In order to further illustrate the present invention, the following examples are used to explain it in detail. The experimental raw materials used in the following examples of the present invention are all common commercial products. The room temperature involved in the following is 25°C.
[0080] The amount of alcohol removed in the following description is: 1 / 4 of the total volume of the system when the alcohol is not removed; the amount of water added is: added to the same total volume as the system when the alcohol is not removed.
[0081] Example 1
[0082] Preparation of titanium silicon molecular sieve: 20.0 mL of tetraethyl orthosilicate and 22.0 mL of tetrapropylammonium hydroxide were mixed evenly, stirred at 35°C for 3 h to form solution ①. 1.0 mL of tetrabutyl titanate, 2 mL of ethanol and 8.0 mL of tetrapropylammonium hydroxide were mixed evenly, stirred at room temperature for 0.5 h to form solution ②. Solution ① was mixed with solution ② to form solution ③. After the alcohol was removed at 90°C and water was added, solution ④ was formed. Solution ④ was transferred to a crystallization kettle and crystallized at 180°C for 48 h. After crystallization, the molecular sieve was separated by centrifugation, dried at 80°C for 6 h, and then placed in a muffle furnace and calcined at a heating rate of 2°C / min to 450°C for 4 h to obtain titanium silicon molecular sieve TS.
[0083] Titanium silicate molecular sieve doped with heteropoly acid: 3 g of molecular sieve was dispersed in 30 mL of 0.04 mol / L aqueous phosphochromic acid solution, stirred at room temperature for 8 h, and then dried at 80 °C for 18 h to obtain titanium silicate molecular sieve loaded with heteropoly acid, recorded as TS-load 1.
[0084] Example 2
[0085] Preparation of titanium silicate molecular sieve: 20.0 mL of tetraethyl orthosilicate and 24.0 mL of tetrapropylammonium hydroxide were mixed evenly, stirred at 55°C for 5 h, and solution ① was formed. 1.0 mL of tetrabutyl titanate, 4 mL of isopropanol and 10.0 mL of tetrapropylammonium hydroxide were mixed evenly, stirred at room temperature for 1.5 h, and solution ② was formed. Solution ① was mixed with solution ② to form solution ③. After the alcohol was removed at 90°C and water was added, solution ④ was formed. Solution ④ was transferred to a crystallization kettle and crystallized at 210°C for 72 h. After crystallization, the molecular sieve was separated by centrifugation, dried at 100°C for 10 h, and then placed in a muffle furnace and calcined at a heating rate of 5°C / min to 550°C for 6 h to obtain titanium silicate molecular sieve TS.
[0086] Titanium silicate molecular sieve doped with heteropoly acid: 3 g of molecular sieve was dispersed in 30 mL of phosphomolybdic acid aqueous solution with a concentration of 0.04 mol / L, stirred at room temperature for 8 h, and then dried at 80°C for 18 h to obtain titanium silicate molecular sieve loaded with heteropoly acid, recorded as TS-load 2.
[0087] Example 3
[0088] Preparation of titanium silicon molecular sieve: 20.0 mL of tetraethyl orthosilicate and 22.0 mL of tetrapropylammonium hydroxide were mixed evenly, stirred at 55°C for 3 h to form solution ①. 1.0 mL of tetrabutyl titanate, 4 mL of isopropanol and 8.0 mL of tetrapropylammonium hydroxide were mixed evenly, stirred at room temperature for 1.5 h to form solution ②. Solution ① was mixed with solution ② to form solution ③. After the alcohol was removed at 90°C and water was added, solution ④ was formed. Solution ④ was transferred to a crystallization kettle and crystallized at 180°C for 72 h. After crystallization, the molecular sieve was separated by centrifugation, dried at 100°C for 10 h, and then placed in a muffle furnace and calcined at a heating rate of 2°C / min to 550°C for 6 h to obtain titanium silicon molecular sieve TS.
[0089] Titanium silicate molecular sieve doped with heteropoly acid: 3 g of molecular sieve was dispersed in 30 mL of 0.08 mol / L aqueous phosphochromic acid solution, stirred at room temperature for 16 h, and then dried at 100 °C for 10 h to obtain titanium silicate molecular sieve loaded with heteropoly acid, recorded as TS-loaded 3.
[0090] Example 4
[0091] Preparation of titanium silicon molecular sieve: 20.0 mL of tetraethyl orthosilicate and 22.0 mL of tetrapropylammonium hydroxide were mixed evenly, stirred at 50°C for 4 h to form solution ①. 1.0 mL of tetrabutyl titanate, 4 mL of butanol and 8.0 mL of tetrapropylammonium hydroxide were mixed evenly, stirred at room temperature for 0.5 h to form solution ②. Solution ① was mixed with solution ② to form solution ③. After the alcohol was removed at 90°C and water was added, solution ④ was formed. Solution ④ was transferred to a crystallization kettle and crystallized at 180°C for 48 h. After crystallization, the molecular sieve was separated by centrifugation, dried at 100°C for 10 h, and then placed in a muffle furnace and calcined at a heating rate of 5°C / min to 550°C for 6 h to obtain titanium silicon molecular sieve TS.
[0092] Titanium silicate molecular sieve doped with heteropoly acid: 3 g of molecular sieve was dispersed in 30 mL of phosphomolybdic acid aqueous solution with a concentration of 0.08 mol / L, stirred at room temperature for 16 h, and then dried at 100 °C for 10 h to obtain titanium silicate molecular sieve loaded with heteropoly acid, recorded as TS-loaded 4.
[0093] Example 5
[0094] Preparation of titanium silicon molecular sieve: 20.0 mL of tetraethyl orthosilicate and 24.0 mL of tetrapropylammonium hydroxide were mixed evenly, stirred at 45°C for 4 h to form solution ①. 1.0 mL of tetrabutyl titanate, 3 mL of isopropanol and 8.0 mL of tetrapropylammonium hydroxide were mixed evenly, stirred at room temperature for 0.5 h to form solution ②. Solution ① was mixed with solution ② to form solution ③. After the alcohol was removed at 90°C and water was added, solution ④ was formed. Solution ④ was transferred to a crystallization kettle and crystallized at 210°C for 48 h. After crystallization, the molecular sieve was separated by centrifugation, dried at 100°C for 10 h, and then placed in a muffle furnace and calcined at a heating rate of 5°C / min to 500°C for 6 h to obtain titanium silicon molecular sieve TS.
[0095] Titanium silicate molecular sieve doped with heteropoly acid: 3 g of molecular sieve was dispersed in 30 mL of 0.06 mol / L aqueous phosphochromic acid solution, stirred at room temperature for 12 h, and then dried at 100 °C for 10 h to obtain titanium silicate molecular sieve loaded with heteropoly acid, recorded as TS-loaded 5.
[0096] Example 6
[0097] Preparation of titanium silicon molecular sieve: 20.0 mL of tetraethyl orthosilicate and 24.0 mL of tetrapropylammonium hydroxide were mixed evenly, stirred at 50°C for 3 h to form solution ①. 1.0 mL of tetrabutyl titanate, 4 mL of butanol solution and 8.0 mL of tetrapropylammonium hydroxide were mixed evenly, stirred at room temperature for 1.5 h to form solution ②. Solution ① was mixed with solution ② to form solution ③. After the alcohol was removed at 90°C and water was added, solution ④ was formed. Solution ④ was transferred to a crystallization kettle and crystallized at 180°C for 72 h. After crystallization, the molecular sieve was separated by centrifugation, dried at 100°C for 10 h, and then placed in a muffle furnace and calcined at a heating rate of 5°C / min to 550°C for 6 h to obtain titanium silicon molecular sieve TS.
[0098] Titanium silicate molecular sieve doped with heteropoly acid: 3 g of molecular sieve was dispersed in 30 mL of phosphomolybdic acid aqueous solution with a concentration of 0.06 mol / L, stirred at room temperature for 12 h, and then dried at 100 °C for 10 h to obtain titanium silicate molecular sieve loaded with heteropoly acid, recorded as TS-loaded 6.
[0099] Example 7
[0100] Preparation of titanium silicon molecular sieve: 20.0 mL of tetraethyl orthosilicate and 24.0 mL of tetrapropylammonium hydroxide were mixed evenly, stirred at 50°C for 5 h, and solution ① was formed. 1.0 mL of tetrabutyl titanate, 2 mL of isopropanol and 8.0 mL of tetrapropylammonium hydroxide were mixed evenly, stirred at room temperature for 0.5 h, and solution ② was formed. Solution ① was mixed with solution ② to form solution ③. After the alcohol was removed at 90°C and water was added, solution ④ was formed. Solution ④ was transferred to a crystallization kettle and crystallized at 180°C for 48 h. After crystallization, the molecular sieve was separated by centrifugation, dried at 100°C for 10 h, and then placed in a muffle furnace and calcined at a heating rate of 4°C / min to 550°C for 6 h to obtain titanium silicon molecular sieve TS.
[0101] Titanium silicate molecular sieve doped with heteropoly acid: 3 g of molecular sieve was dispersed in 30 mL of 0.06 mol / L aqueous phosphochromic acid solution, stirred at room temperature for 10 h, and then dried at 100 °C for 16 h to obtain titanium silicate molecular sieve loaded with heteropoly acid, recorded as TS-loaded 7.
[0102] Example 8
[0103] Preparation of titanium silicon molecular sieve: 20.0 mL of tetraethyl orthosilicate and 24.0 mL of tetrapropylammonium hydroxide were mixed evenly, stirred at 50°C for 5 h, and solution ① was formed. 1.0 mL of tetrabutyl titanate, 2 mL of isopropanol and 8.0 mL of tetrapropylammonium hydroxide were mixed evenly, stirred at room temperature for 0.5 h, and solution ② was formed. Solution ① was mixed with solution ② to form solution ③. After the alcohol was removed at 90°C and water was added, solution ④ was formed. Solution ④ was transferred to a crystallization kettle and crystallized at 180°C for 48 h. After crystallization, the molecular sieve was separated by centrifugation, dried at 100°C for 10 h, and then placed in a muffle furnace and calcined at a heating rate of 4°C / min to 550°C for 6 h to obtain titanium silicon molecular sieve TS.
[0104] Titanium silicate molecular sieve doped with heteropoly acid: 3 g of molecular sieve was dispersed in 30 mL of phosphomolybdic acid aqueous solution with a concentration of 0.06 mol / L, stirred at room temperature for 10 h, and then dried at 100 °C for 16 h to obtain titanium silicate molecular sieve loaded with heteropoly acid, recorded as TS-loaded 8.
[0105] Application Example 1
[0106] In a 250 mL reactor, 6.4 g of pentene, 16.8 g of methanol, 15.2 g of acetonitrile, 4.52 g of 27.5% aqueous hydrogen peroxide solution, and 0.128 g of TS-supported 1 catalyst were added, and the stirring rate was 300 rpm. The reaction was carried out at 50°C for 2 h. After centrifugation and quantitative analysis, the olefin conversion rate was 15%, and the selectivity of the final product diol was 60%.
[0107] Application Example 2
[0108] In a 250 mL reactor, 6.4 g of pentene, 32 g of methanol, 3.23 g of 27.5% aqueous hydrogen peroxide solution, and 0.384 g of TS-supported 2 catalyst were added, and the stirring rate was 600 rpm. The reaction was carried out at 50°C for 2 h. After centrifugation and quantitative analysis, the olefin conversion rate was 18%, and the selectivity of the final product diol was 75%.
[0109] Application Example 3
[0110] In a 250 mL reactor, 6.4 g hexene, 32.8 g methanol, 18.4 g acetonitrile, 3.76 g 27.5% aqueous hydrogen peroxide solution, and 0.256 g TS-supported 3 catalyst were added, and the stirring rate was 400 rpm. The reaction was carried out at 60°C for 3 h. After centrifugation and quantitative analysis, the olefin conversion rate was 20%, and the selectivity of the final product diol was 83%.
[0111] Application Example 4
[0112] In a 250 mL reactor, 6.4 g of pentene, 32 g of acetone, 4.52 g of 27.5% aqueous hydrogen peroxide solution, and 0.32 g of TS-supported 4 catalyst were added, and the stirring rate was 500 rpm. The reaction was carried out at 70°C for 2 h. After centrifugation and quantitative analysis, the olefin conversion rate was 25%, and the selectivity of the final product diol was 86%.
[0113] Application Example 5
[0114] In a 250 mL reactor, 6.4 g of pentene, 32 g of acetone, 4.52 g of 27.5% aqueous hydrogen peroxide solution, and 0.32 g of TS-supported 5 catalyst were added, and the stirring rate was 300 rpm. The reaction was carried out at 70°C for 4 h. After centrifugation and quantitative analysis, the olefin conversion rate was 23%, and the selectivity of the final product diol was 94%.
[0115] Application Example 6
[0116] In a 100 mL reactor, 6.4 g of heptene, 32 g of methanol, 3.23 g of 27.5% aqueous hydrogen peroxide solution, and 0.32 g of TS-supported 6 catalyst were added, and the stirring rate was 300 rpm. The reaction was carried out at 60°C for 2 h. After centrifugation and quantitative analysis, the olefin conversion rate was 13%, and the selectivity of the final product diol was 81%.
[0117] Application Example 7
[0118] In a 100 mL reactor, 6.4 g octene, 32 g acetone, 2.82 g 27.5% aqueous hydrogen peroxide solution, and 0.32 g TS-supported 7 catalyst were added, and the stirring rate was 300 rpm. The reaction was carried out at 70°C for 2 h. After centrifugation and quantitative analysis, the olefin conversion rate was 11%, and the selectivity of the final product diol was 70%.
[0119] Application Example 8
[0120] In a 250 mL reactor, 6.4 g of cyclopentene, 32 g of methanol, 4.65 g of 27.5% aqueous hydrogen peroxide solution, and 0.32 g of TS-supported 8 catalyst were added, and the stirring rate was 300 rpm. The reaction was carried out at 70°C for 2 h. After centrifugation and quantitative analysis, the olefin conversion rate was 10%, and the selectivity of the final product diol was 89%.
[0121] Comparative application example 1
[0122] In a 250 mL reactor, 6.4 g of pentene, 32 g of acetone, 4.52 g of 27.5% aqueous hydrogen peroxide solution, and 0.32 g of the TS catalyst prepared in Example 5 were added, and the stirring rate was 300 rpm, and the reaction was carried out at 70° C. for 4 h. After centrifugal separation and quantitative analysis, the olefin conversion rate was 15%, and the selectivity of the final product diol was 5%.
[0123] Comparative Application Example 2
[0124] In a 250 mL reactor, 6.4 g of heptene, 32 g of methanol, 3.23 g of 27.5% aqueous hydrogen peroxide solution, and 0.32 g of the TS catalyst prepared in Example 6 were added, and the stirring rate was 300 rpm, and the reaction was carried out at 60° C. for 2 h. After centrifugal separation and quantitative analysis, the olefin conversion rate was 10%, and the selectivity of the final product diol was 10%.
[0125] Comparative Application Example 3
[0126] 6.4 g of octene, 32 g of acetone, 2.82 g of 27.5% aqueous hydrogen peroxide solution, and 0.32 g of the TS catalyst prepared in Example 7 were added to a 250 mL reactor, and the stirring rate was 300 rpm, and the reaction was carried out at 70° C. for 2 h. After centrifugal separation and quantitative analysis, the olefin conversion rate was 8%, and the selectivity of the final product diol was 3%.
[0127] Comparative Application Example 4
[0128] 6.4 g of cyclopentene, 32 g of methanol, 4.65 g of 27.5% aqueous hydrogen peroxide solution, and 0.32 g of the TS catalyst prepared in Example 8 were added to a 250 mL reactor, and the stirring rate was 300 rpm, and the reaction was carried out at 70° C. for 2 h. After centrifugal separation and quantitative analysis, the olefin conversion rate was 6%, and the selectivity of the final product diol was 11%.
[0129] The experimental conditions and results of the above application examples and comparative application examples are summarized in Table 1 (wherein the catalyst dosage is the ratio of the added amount of the catalyst to the mass of the olefin, the solvent ratio is the mass ratio of the solvent to the olefin, and the H2O2 ratio is the molar ratio of H2O2 to the olefin):
[0130] Table 1
[0131]
[0132] As can be seen from the data in Table 1, compared with the comparative application examples 1 to 4 using a single TS catalyst without heteropoly acid for olefin epoxidation, the selectivity of the obtained diol is very low, while the application examples 1 to 8 using the TS catalyst loaded with heteropoly acid provided by the present invention for olefin epoxidation, the obtained diol selectivity is higher, above 60%, up to 94%, and the olefin conversion rate is higher, above 10%, up to 25%. The above results show that the acidity of heteropoly acid can promote the conversion of intermediate product alkylene oxide into diol; in addition, the molybdenum metal and chromium metal in the heteropoly acid have the performance of catalyzing olefin epoxidation, so that they can form dual active sites with the titanium site, jointly promote olefin epoxidation, and improve catalytic activity.
[0133] The above description of the disclosed embodiments enables those skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention. Therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A titanium silicon molecular sieve catalyst loaded with heteropoly acid, characterized in that: It comprises a titanium silicate molecular sieve and a heteropoly acid supported on the titanium silicate molecular sieve; The heteropoly acid comprises phosphomolybdic acid and / or phosphochromic acid; The mass ratio of the titanium silicon molecular sieve and the heteropoly acid is (0.5~7.5):
1.
2. A method for preparing the heteropolyacid-loaded titanium silicon molecular sieve catalyst according to claim 1, characterized in that: The following steps are involved: The titanium silicon molecular sieve is impregnated with an aqueous solution of a heteropoly acid, and a titanium silicon molecular sieve catalyst loaded with a heteropoly acid is obtained after drying.
3. The preparation method according to claim 2, characterized in that: In the aqueous solution of the heteropoly acid, the concentration of the heteropoly acid is 0.01-0.1 mol / L, and the volume of the aqueous solution of the heteropoly acid is 20-30 mL.
4. The preparation method according to claim 2 or 3, characterized in that: The immersion treatment temperature is 10-30°C and the time is 6-18 hours; The drying temperature is 60-120° C. and the drying time is 4-20 h.
5. The preparation method according to any one of claims 2 to 4, characterized in that The titanium silicate molecular sieve is prepared according to the following method: S1: Mixing a silicon source and a template to obtain a solution A; mixing an alcohol, a titanium source, and a template to obtain a solution B; mixing solution A and solution B, removing alcohol, and adding water to obtain a solution C; S2: After the solution C is crystallized, it is centrifuged to obtain a solid; after the solid is dried and calcined, a titanium silicon molecular sieve is obtained.
6. The preparation method according to claim 5, characterized in that: The silicon source is selected from tetraethyl orthosilicate; The template agent is selected from tetrapropylammonium hydroxide and / or tetrabutylammonium hydroxide; The alcohol is selected from any one or more of ethanol, isopropanol or butanol; The titanium source is selected from tetrabutyl titanate and / or tetraethyl titanate; The volume ratio of the silicon source to the template is 1:(1-1.8); The volume ratio of the titanium source, alcohol and template is 1:(1.5-6):(6-12).
7. The preparation method according to claim 5 or 6, characterized in that: In the process of obtaining solution A, the mixing temperature is 30-60°C, the time is 2-6 h, and the mixing is performed under stirring conditions; In the process of obtaining solution B, the mixing temperature is 10-30°C, the time is 0.5-2 h, and the mixing is performed under stirring conditions; The temperature of the alcohol removal is 75-100°C; The crystallization treatment temperature is 150-240°C and the time is 24-96 h; The centrifugal separation speed is 3500-4500 rpm, and the time is 30-120 min; The drying temperature is 60-130°C and the drying time is 4-12 hours; The calcination temperature is 400-600°C and the calcination time is 2-8 h; The heating rate during the calcination process is 1-10°C / min.
8. Use of the heteropolyacid-loaded titanium silicon molecular sieve catalyst according to claim 1 or the heteropolyacid-loaded titanium silicon molecular sieve catalyst prepared by the preparation method according to any one of claims 2 to 7 in catalyzing the one-step preparation of diols from olefins.
9. A method for preparing diols by epoxidation of olefins, characterized in that: The following steps are involved: After the catalyst, olefin, solvent and hydrogen peroxide are mixed and reacted, diol is obtained; The catalyst is the heteropolyacid-loaded titanium silicon molecular sieve catalyst according to claim 1 or the heteropolyacid-loaded titanium silicon molecular sieve catalyst prepared by the preparation method according to any one of claims 2 to 7.
10. The method according to claim 9, characterized in that The olefin is selected from any one or more of 1-pentene, 1-hexene, 1-heptene, 1-octene, cyclopentene or styrene; The solvent is selected from any one or more of methanol, acetonitrile or acetone; The mass ratio of the olefin to the solvent is 1:(3-9); The amount of the catalyst added is 0.5-8% of the mass of the olefin; The molar ratio of hydrogen peroxide to olefin is 1:(2-3.5); The reaction temperature is 40-100°C and the reaction time is 1-5 h; The reaction is carried out under stirring conditions, and the stirring rate is 100-800 rpm.