Catalyst for tartaric acid synthesis and preparation method thereof

Abstract

The invention belongs to the technical field of catalysis, and particularly relates to a catalyst for tartaric acid synthesis and a preparation method thereof. The TS-1 molecular sieve is used as a matrix, vanadium and niobium are doped into the TS-1 molecular sieve, then phosphotungstic acid is adopted for further modification on the surface of the vanadium and niobium doped TS-1 molecular sieve, the prepared catalyst shows excellent catalytic activity in the process of preparing tartaric acid by using maleic anhydride as a raw material, the prepared tartaric acid is high in yield, and the product is easy to separate.

Description

Technical Field

[0001] This invention belongs to the field of catalysis technology, specifically relating to a catalyst for tartaric acid synthesis and its preparation method. Background Technology

[0002] Tartaric acid is commonly used in the preparation of pharmaceuticals, mordants, and tanning agents. It is a relatively expensive and widely used chiral resolving agent. It is also an acidulant in food additives, with a sour taste superior to malic acid and lactic acid. Tartaric acid's greatest use is as a beverage additive, and it is also a raw material in the pharmaceutical industry. In the mirror-making industry, tartaric acid is an important auxiliary agent and reducing agent, which can control the formation rate of silver mirrors and obtain a very uniform coating.

[0003] The existing chemical synthesis of tartaric acid mainly uses maleic anhydride as raw material, hydrogen peroxide as oxidant, and tungstic acid as catalyst to catalyze oxidation to produce epoxy succinic acid, which is then hydrolyzed to obtain tartaric acid. After cooling, crystallization, separation, and drying, the tartaric acid product is obtained. This method is relatively simple, but the yield of tartaric acid is low, which is difficult to meet the needs of large-scale industrial production of tartaric acid. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention provides a catalyst for the synthesis of tartaric acid and a method for preparing the same. The catalyst exhibits excellent catalytic activity in the preparation of tartaric acid from maleic anhydride, and the tartaric acid produced has a high yield and the product is easy to separate.

[0005] The first aspect of this invention provides a method for preparing a catalyst for the synthesis of tartaric acid, comprising the following steps: S1: Mix tetraethyl orthosilicate and an aqueous solution containing tetrapropylammonium hydroxide to form solution A, and mix tetrabutyl titanate and isopropanol to form solution B; S2: Mix ammonium metavanadate, niobium chloride, solution A and solution B, stir thoroughly to form a mixture, add ammonium carbonate to the mixture, perform hydrothermal crystallization treatment, and then calcine in air to obtain vanadium and niobium doped TS-1 molecular sieve; S3: Dissolve phosphotungstic acid in ethanol to obtain a phosphotungstic acid alcohol solution, and uniformly disperse the quaternary ammonium salt in the phosphotungstic acid alcohol solution to obtain a modified solution; S4: Add vanadium- and niobium-doped TS-1 molecular sieves to the modified solution, stir thoroughly, let stand for 2-3 hours, filter, and dry to obtain a catalyst for tartaric acid synthesis.

[0006] Furthermore, the molar ratio of tetrapropylammonium hydroxide to tetraethyl orthosilicate is 0.3~0.5:1, and the mass concentration of the aqueous solution of tetrapropylammonium hydroxide is 20~25%; the molar ratio of isopropanol to tetrabutyl titanate is 60~70:1.

[0007] Furthermore, the molar ratio of ammonium metavanadate, niobium chloride, tetraethyl orthosilicate, tetrabutyl titanate, and ammonium carbonate is 0.03~0.05:0.01~0.02:1:0.03~0.05:0.05~0.2.

[0008] Furthermore, hydrothermal crystallization treatment was carried out at 160~180℃ for 28~32 hours.

[0009] Furthermore, the calcination temperature is 500~550℃, the calcination time is 2~3h, and the heating rate is 2~5℃ / min.

[0010] Furthermore, the quaternary ammonium salt is hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, or octadecyltrimethylammonium bromide.

[0011] Furthermore, in the modified solution, the mass ratio of quaternary ammonium salt to phosphotungstic acid alcohol solution is 1:10.

[0012] Furthermore, the mass concentration of phosphotungstic acid in the phosphotungstic acid alcohol solution is 10%~20%.

[0013] Furthermore, the ratio of vanadium- and niobium-doped TS-1 molecular sieve to modified solution is 1~2g:10mL.

[0014] A second aspect of the present invention provides a catalyst prepared by the above-described method for preparing a catalyst for tartaric acid synthesis.

[0015] A third aspect of this invention provides the application of the above-mentioned catalyst in the preparation of tartaric acid from maleic anhydride. This catalyst can catalyze the reaction in the preparation of tartaric acid from maleic anhydride using hydrogen peroxide as an oxidant. The amount of catalyst used is 2-5% of the mass of maleic anhydride.

[0016] The beneficial effects achieved by one or more technical solutions of the present invention are as follows: 1. This invention uses TS-1 molecular sieve as a matrix and dops vanadium and niobium into the TS-1 molecular sieve. Vanadium and niobium atoms can produce a synergistic effect in the molecular sieve structure, which significantly enhances the catalytic activity of the catalyst. Furthermore, by fixing vanadium and niobium doping in the framework during the preparation of the molecular sieve, the complexation of the product tartaric acid with metallic vanadium and niobium can be effectively avoided, making the catalyst easier to separate from the product and reducing catalyst loss, thus enabling the catalyst to be reused.

[0017] 2. This invention employs phosphotungstic acid to further modify the surface of vanadium and niobium-doped TS-1 molecular sieves, increasing the number of surface proton acid centers, improving the acid strength of the catalyst, and further enhancing the catalyst activity. Detailed Implementation

[0018] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments and comparative examples.

[0019] Example 1 This embodiment provides a catalyst for the synthesis of tartaric acid, and the preparation method is as follows: S1: Mix tetraethyl orthosilicate and a 20% (w / w) aqueous solution of tetrapropylammonium hydroxide to form solution A (molar ratio of tetrapropylammonium hydroxide to tetraethyl orthosilicate is 0.5:1); mix tetrabutyl titanate and isopropanol to form solution B (molar ratio of isopropanol to tetrabutyl titanate is 60:1). S2: Ammonium metavanadate, niobium chloride, solution A, and solution B are mixed and stirred thoroughly to form a mixture. Ammonium carbonate is added to the mixture. The molar ratio of ammonium metavanadate, niobium chloride, tetraethyl orthosilicate, tetrabutyl titanate, and ammonium carbonate is 0.05:0.02:1:0.05:0.1. The mixture is subjected to hydrothermal crystallization treatment at 180℃ for 30h, and then calcined in air at 550℃ for 2h at a heating rate of 5℃ / min to obtain vanadium and niobium-doped TS-1 molecular sieve. S3: Dissolve phosphotungstic acid in ethanol to obtain a phosphotungstic acid alcohol solution with a mass concentration of 20%. Then, uniformly disperse hexadecyltrimethylammonium chloride in the phosphotungstic acid alcohol solution to obtain a modified solution. The mass ratio of hexadecyltrimethylammonium chloride to phosphotungstic acid alcohol solution is 1:10. S4: Add vanadium and niobium-doped TS-1 molecular sieves to the modification solution at a ratio of 1g:10mL. After stirring thoroughly, let stand for 2 hours, filter, and dry to obtain a catalyst for tartaric acid synthesis.

[0020] Example 2 This embodiment provides a catalyst for the synthesis of tartaric acid, and the preparation method is as follows: S1: Mix tetraethyl orthosilicate and a 20% (w / w) aqueous solution of tetrapropylammonium hydroxide to form solution A (molar ratio of tetrapropylammonium hydroxide to tetraethyl orthosilicate is 0.5:1); mix tetrabutyl titanate and isopropanol to form solution B (molar ratio of isopropanol to tetrabutyl titanate is 60:1). S2: Ammonium metavanadate, niobium chloride, solution A, and solution B are mixed and stirred thoroughly to form a mixture. Ammonium carbonate is added to the mixture. The molar ratio of ammonium metavanadate, niobium chloride, tetraethyl orthosilicate, tetrabutyl titanate, and ammonium carbonate is 0.03:0.02:1:0.05:0.2. The mixture is subjected to hydrothermal crystallization treatment at 180℃ for 28 hours, and then calcined in air at 500℃ for 3 hours at a heating rate of 5℃ / min to obtain vanadium and niobium-doped TS-1 molecular sieve. S3: Dissolve phosphotungstic acid in ethanol to obtain a phosphotungstic acid alcohol solution with a mass concentration of 20%. Then, uniformly disperse hexadecyltrimethylammonium chloride in the phosphotungstic acid alcohol solution to obtain a modified solution. The mass ratio of hexadecyltrimethylammonium chloride to phosphotungstic acid alcohol solution is 1:10. S4: Add vanadium and niobium-doped TS-1 molecular sieves to the modification solution at a ratio of 1g:10mL. After stirring thoroughly, let stand for 3 hours, filter, and dry to obtain a catalyst for tartaric acid synthesis.

[0021] Example 3 This embodiment provides a catalyst for the synthesis of tartaric acid, and the preparation method is as follows: S1: Mix tetraethyl orthosilicate and a 25% (w / w) aqueous solution of tetrapropylammonium hydroxide to form solution A (molar ratio of tetrapropylammonium hydroxide to tetraethyl orthosilicate is 0.3:1); mix tetrabutyl titanate and isopropanol to form solution B (molar ratio of isopropanol to tetrabutyl titanate is 70:1). S2: Ammonium metavanadate, niobium chloride, solution A, and solution B are mixed and stirred thoroughly to form a mixture. Ammonium carbonate is added to the mixture. The molar ratio of ammonium metavanadate, niobium chloride, tetraethyl orthosilicate, tetrabutyl titanate, and ammonium carbonate is 0.05:0.02:1:0.03:0.2. The mixture is subjected to hydrothermal crystallization treatment at 160℃ for 32 hours, and then calcined in air at 500℃ for 3 hours at a heating rate of 2℃ / min to obtain vanadium and niobium-doped TS-1 molecular sieve. S3: Dissolve phosphotungstic acid in ethanol to obtain a 10% phosphotungstic acid alcohol solution. Then, uniformly disperse hexadecyltrimethylammonium bromide in the phosphotungstic acid alcohol solution to obtain a modified solution. The mass ratio of hexadecyltrimethylammonium bromide to phosphotungstic acid alcohol solution is 1:10. S4: Add vanadium and niobium-doped TS-1 molecular sieves to the modification solution at a ratio of 1g:5mL. After stirring thoroughly, let stand for 3 hours, filter, and dry to obtain a catalyst for tartaric acid synthesis.

[0022] Example 4 This embodiment provides a catalyst for the synthesis of tartaric acid, and the preparation method is as follows: S1: Mix tetraethyl orthosilicate and a 20% (w / w) aqueous solution of tetrapropylammonium hydroxide to form solution A (molar ratio of tetrapropylammonium hydroxide to tetraethyl orthosilicate is 0.5:1); mix tetrabutyl titanate and isopropanol to form solution B (molar ratio of isopropanol to tetrabutyl titanate is 60:1). S2: Ammonium metavanadate, niobium chloride, solution A, and solution B are mixed and stirred thoroughly to form a mixture. Ammonium carbonate is added to the mixture. The molar ratio of ammonium metavanadate, niobium chloride, tetraethyl orthosilicate, tetrabutyl titanate, and ammonium carbonate is 0.03:0.01:1:0.03:0.05. The mixture is subjected to hydrothermal crystallization treatment at 160℃ for 32 hours, and then calcined in air at 550℃ for 2 hours at a heating rate of 5℃ / min to obtain vanadium and niobium-doped TS-1 molecular sieve. S3: Dissolve phosphotungstic acid in ethanol to obtain a phosphotungstic acid alcohol solution with a mass concentration of 15%. Then, uniformly disperse hexadecyltrimethylammonium chloride in the phosphotungstic acid alcohol solution to obtain a modified solution. The mass ratio of hexadecyltrimethylammonium chloride to phosphotungstic acid alcohol solution is 1:10. S4: Add vanadium and niobium-doped TS-1 molecular sieves to the modification solution at a ratio of 1g:10mL. After stirring thoroughly, let stand for 3 hours, filter, and dry to obtain a catalyst for tartaric acid synthesis.

[0023] Comparative Example 1 This comparative example provides a catalyst for the synthesis of tartaric acid, and the preparation method is as follows: S1: Mix tetraethyl orthosilicate and a 20% (w / w) aqueous solution of tetrapropylammonium hydroxide to form solution A (molar ratio of tetrapropylammonium hydroxide to tetraethyl orthosilicate is 0.5:1); mix tetrabutyl titanate and isopropanol to form solution B (molar ratio of isopropanol to tetrabutyl titanate is 60:1). S2: Ammonium metavanadate, niobium chloride, solution A, and solution B are mixed and stirred thoroughly to form a mixture. Ammonium carbonate is added to the mixture. The molar ratio of ammonium metavanadate, niobium chloride, tetraethyl orthosilicate, tetrabutyl titanate, and ammonium carbonate is 0.05:0.02:1:0.05:0.1. Hydrothermal crystallization is performed at 180℃ for 30h, and then calcined in air at 550℃ for 2h at a heating rate of 5℃ / min to obtain vanadium- and niobium-doped TS-1 molecular sieve catalyst.

[0024] Comparative Example 2 This comparative example provides a catalyst for the synthesis of tartaric acid, and the preparation method is as follows: S1: Mix tetraethyl orthosilicate and a 20% (w / w) aqueous solution of tetrapropylammonium hydroxide to form solution A (molar ratio of tetrapropylammonium hydroxide to tetraethyl orthosilicate is 0.5:1); mix tetrabutyl titanate and isopropanol to form solution B (molar ratio of isopropanol to tetrabutyl titanate is 60:1). S2: Mix ammonium metavanadate, solution A, and solution B, and stir thoroughly to form a mixture. Add ammonium carbonate to the mixture. The molar ratio of ammonium metavanadate, tetraethyl orthosilicate, tetrabutyl titanate, and ammonium carbonate is 0.05:1:0.05:0.1. Perform hydrothermal crystallization treatment at 180℃ for 30h, and then calcine in air at 550℃ for 2h at a heating rate of 5℃ / min to obtain vanadium-doped TS-1 molecular sieve catalyst.

[0025] Performance testing: 49.0g maleic anhydride, 2g catalyst, 130g 30% hydrogen peroxide and 50ml water were mixed evenly and reacted at 70℃ for 8h. The mixture was then heated under reflux for 1h. After cooling, the catalyst was removed by filtration. 5ml concentrated sulfuric acid was added and the mixture was heated to boiling for 1h. After cooling, crystals were precipitated, filtered, washed with water and dried to obtain tartaric acid.

[0026] Table 1 shows the yield (%) of tartaric acid obtained by reacting with the catalysts prepared in Examples 1-4 and Comparative Examples 1-2.

[0027] Table 1

[0028] As shown in Table 1, the tartaric acid yield using the catalysts prepared in Examples 1-4 is above 97%, which is significantly higher than that of Comparative Example 1 and Comparative Example 2. This indicates that the catalysts provided by the present invention have excellent catalytic activity and can efficiently prepare tartaric acid.

Claims

1. A method for preparing a catalyst for the synthesis of tartaric acid, characterized in that: Includes the following steps: S1: Mix tetraethyl orthosilicate and an aqueous solution containing tetrapropylammonium hydroxide to form solution A, and mix tetrabutyl titanate and isopropanol to form solution B; S2: Mix ammonium metavanadate, niobium chloride, solution A and solution B, stir thoroughly to form a mixture, add ammonium carbonate to the mixture, perform hydrothermal crystallization treatment, and then calcine in air to obtain vanadium and niobium doped TS-1 molecular sieve; S3: Dissolve phosphotungstic acid in ethanol to obtain a phosphotungstic acid alcohol solution, and uniformly disperse the quaternary ammonium salt in the phosphotungstic acid alcohol solution to obtain a modified solution; S4: Add vanadium- and niobium-doped TS-1 molecular sieves to the modified solution, stir thoroughly, let stand for 2-3 hours, filter, and dry to obtain a catalyst for tartaric acid synthesis.

2. The method for preparing the catalyst for tartaric acid synthesis as described in claim 1, characterized in that: The molar ratio of tetrapropylammonium hydroxide to tetraethyl orthosilicate is 0.3~0.5:1, and the mass concentration of the aqueous solution of tetrapropylammonium hydroxide is 20~25%; the molar ratio of isopropanol to tetrabutyl titanate is 60~70:

1.

3. The method for preparing the catalyst for tartaric acid synthesis as described in claim 1, characterized in that: The molar ratio of ammonium metavanadate, niobium chloride, tetraethyl orthosilicate, tetrabutyl titanate, and ammonium carbonate is 0.03~0.05:0.01~0.02:1:0.03~0.05:0.05~0.

2.

4. The method for preparing the catalyst for tartaric acid synthesis as described in claim 1, characterized in that: Perform hydrothermal crystallization treatment at 160~180℃ for 28~32h.

5. The method for preparing the catalyst for tartaric acid synthesis as described in claim 1, characterized in that: The calcination temperature is 500~550℃, the calcination time is 2~3h, and the heating rate is 2~5℃ / min.

6. The method for preparing the catalyst for tartaric acid synthesis as described in claim 1, characterized in that: The quaternary ammonium salt is hexadecyltrimethylammonium chloride, hexadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, or octadecyltrimethylammonium bromide.

7. The method for preparing the catalyst for tartaric acid synthesis as described in claim 1, characterized in that: In the modified solution, the mass ratio of quaternary ammonium salt to phosphotungstic acid alcohol solution is 1:

10.

8. The method for preparing the catalyst for tartaric acid synthesis as described in claim 1, characterized in that: The mass concentration of phosphotungstic acid in the phosphotungstic acid alcohol solution is 10%~20%; The addition ratio of vanadium- and niobium-doped TS-1 molecular sieve to the modified solution is 1~2g:10mL.

9. The catalyst prepared by the method for preparing the catalyst for tartaric acid synthesis according to any one of claims 1 to 8.

10. The application of the catalyst according to claim 9 in the preparation of tartaric acid from maleic anhydride.

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