A hydrophobic catalyst for the synthesis of tetrahydrothiophene, its preparation method and application

Abstract

This invention discloses a hydrophobic catalyst for the synthesis of tetrahydrothiophene, its preparation method, and its application. The preparation method includes the following steps: (1) firstly, alkyl phosphoric acid, γ-Al2O3, and solvent are weighed and mechanically stirred to prepare hydrophobic γ-Al2O3; (2) a hydrophobic catalyst is prepared using a heteropolyacid active component, hydrophobic γ-Al2O3, and solvent; the obtained catalyst is used to catalyze the reaction of tetrahydrofuran, carbon disulfide, and water to produce tetrahydrothiophene. In the tetrahydrofuran catalytic reaction, the catalyst provided by this invention achieves a maximum tetrahydrofuran conversion rate of 99.5% and a maximum tetrahydrothiophene selectivity of 99.7%.

Description

Technical Field

[0001] This invention belongs to the technical field of chemical catalysts, and particularly relates to a hydrophobic catalyst for the synthesis of tetrahydrothiophene, its preparation method and application. Background Technology

[0002] Tetrahydrothiophene (THT) is an important sulfur-containing saturated heterocyclic compound widely used as an odorant and warning agent in natural gas due to its distinctive odor. Natural gas itself is colorless and odorless, making leaks undetectable and highly prone to causing accidents. Currently, international standards require the use of tetrahydrothiophene as an odorant for city gas, natural gas, and other gases, replacing previously used odorants such as ethanethiol. Tetrahydrothiophene can also be used as an intermediate in the production of novel pharmaceuticals, pesticides, and polymer synthesis materials, and in the formulation of dental and pharmaceutical primers. With technological advancements, many applications and functions of tetrahydrothiophene are being developed, and domestic demand is gradually increasing.

[0003] Currently, the traditional process for the direct sulfidation synthesis of tetrahydrofuran to tetrahydrothiophene uses heteropolyacid catalysts. The main drawback of this existing process is that tetrahydrofuran reacts directly with hydrogen sulfide to produce water, directly affecting catalyst selectivity (unreacted tetrahydrofuran and water easily form an azeotrope), increasing the difficulty of subsequent tetrahydrofuran distillation and the cost of separation and recovery. Furthermore, hydrogen sulfide is a gaseous reactant, posing a significant transportation safety risk. However, in the catalytic reaction of tetrahydrofuran, carbon disulfide, and water to produce tetrahydrothiophene, the reaction steps are as follows: (1) Carbon disulfide reacts with a small amount of water to produce hydrogen sulfide and carbon dioxide; (2) Tetrahydrofuran reacts with hydrogen sulfide to produce tetrahydrothiophene and water; (3) The water in step (2) reacts with carbon disulfide to produce hydrogen sulfide. This process can overcome the shortcomings of the traditional direct sulfidation process for tetrahydrofuran to a limited extent. Summary of the Invention

[0004] To address the problems existing in the prior art, the present invention provides a hydrophobic catalyst for the synthesis of tetrahydrothiophene, a preparation method, and an application. The catalyst provided by the present invention achieves a maximum tetrahydrofuran conversion rate of 99.5% and a maximum tetrahydrothiophene selectivity of 99.7% in the tetrahydrofuran catalytic reaction.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0006] A method for preparing a hydrophobic catalyst for the synthesis of tetrahydrothiophene includes the following steps:

[0007] (1) First, weigh out alkyl phosphoric acid, γ-Al2O3 and solvent and mechanically stir to prepare hydrophobic γ-Al2O3;

[0008] (2) Prepare a hydrophobic catalyst precursor by stirring and reacting heteropolyacid active components, hydrophobic γ-Al2O3 and solvent;

[0009] (3) The catalyst precursor obtained in step (2) is dried to obtain the catalyst.

[0010] Furthermore, in step (1), the mass ratio of alkyl phosphoric acid to solvent is (1-3):7, the mass ratio of γ-Al2O3 to solvent is (1-4):6; the stirring temperature is 100-130℃, the stirring speed is 400-1000r / min, and the stirring time is 60-120min.

[0011] Furthermore, the alkyl phosphoric acid is one of octadecyl phosphoric acid, hexadecyl phosphoric acid, tetradecyl phosphoric acid, dodecyl phosphoric acid, undecyl phosphoric acid, and decadecyl phosphoric acid; the solvent is one of methanol, ethanol, diethyl ether, tetrahydrothiophene, and acetone; and the γ-Al2O3 has the following shape: spherical, rod-shaped, cubic, octahedral, flower-shaped, or nanosheet.

[0012] Furthermore, in step (2), the mass ratio of the heteropolyacid active component to the hydrophobic γ-Al2O3 is (1-3):7, and the mass ratio of the hydrophobic γ-Al2O3 to the solvent is (1-4):6; the stirring reaction temperature is 10-30℃, the stirring speed is 100-1000r / min, and the stirring time is 5-100min.

[0013] Furthermore, in step (2), the heteropolyacid active component is one of phosphomolybdic acid, phosphotungstic acid, molybdic acid, tungstic acid, vanadic acid, chromic acid, and manganic acid; and the solvent is one of methanol, ethanol, diethyl ether, and acetone.

[0014] Furthermore, in step (3), the drying temperature is 100-120℃ and the drying time is 10-120min.

[0015] The present invention also provides a hydrophobic catalyst for the synthesis of tetrahydrothiophene prepared by the aforementioned preparation method.

[0016] The present invention also provides the application of the catalyst in the catalytic synthesis of tetrahydrothiophene: tetrahydrofuran, carbon disulfide, water and the catalyst are added to a high-pressure catalytic reactor to react and generate tetrahydrothiophene.

[0017] Furthermore, the reaction temperature is 200-280℃, the reaction pressure is 0.2-0.8 MPa, and the reaction time is 60-240 min. The mass ratio of catalyst to tetrahydrofuran is (1-3):10, and the mass ratio of tetrahydrofuran, carbon disulfide, and water is (1-3):1:1.

[0018] The beneficial effects of the present invention: In the tetrahydrofuran catalytic reaction, the catalyst provided by the present invention has a maximum tetrahydrofuran conversion rate of 99.5% and a maximum tetrahydrothiophene selectivity of 99.7%. This is because the catalyst of the present invention achieves a closed-loop reaction during the preparation process, and the steps are as follows: (1) First, carbon disulfide reacts with a small amount of water to generate hydrogen sulfide and carbon dioxide (product); (2) Tetrahydrofuran reacts with hydrogen sulfide to generate tetrahydrothiophene (product) and water; (3) Water in step (2) reacts with carbon disulfide to generate hydrogen sulfide, which significantly improves the catalyst activity and selectivity, and significantly reduces the difficulty of subsequent tetrahydrofuran, tetrahydrothiophene and carbon dioxide distillation processes and the separation and recovery costs. Detailed Implementation

[0019] The present invention will be further described below with reference to specific embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Those skilled in the art can make some non-essential improvements and adjustments based on the above-described invention.

[0020] Example 1

[0021] The catalyst preparation method in this embodiment is as follows:

[0022] (1) First, weigh 10g of alkyl phosphoric acid, 70g of rod-shaped γ-Al2O3 and 164g of tetrahydrothiophene solvent and mechanically stir for 60min at 100℃ and 400r / min to prepare hydrophobic γ-Al2O3.

[0023] (2) Prepare a hydrophobic catalyst precursor by mechanically stirring 10g of phosphomolybdic acid, 70g of hydrophobic γ-Al2O3 and 164g of ethanol solvent at 20℃ and 200r / min for 5min.

[0024] (3) The catalyst precursor obtained in step (2) is dried at 100°C for 60 min to obtain catalyst 1.

[0025] Application of Catalyst 1 in the catalytic synthesis of tetrahydrothiophene:

[0026] Tetrahydrofuran, carbon disulfide, water, and catalyst 1 were mixed and placed in a catalytic reactor. The reaction temperature was 270℃, the reaction pressure was 1.0 MPa, and the reaction time was 60 min. The mass ratio of catalyst to tetrahydrofuran was 1:10, and the mass ratio of tetrahydrofuran, carbon disulfide, and water was 1:1:1. The initial conversion rate of tetrahydrofuran was 99.5%, and the selectivity of tetrahydrothiophene was 99.1%.

[0027] Example 2

[0028] The catalyst preparation method in this embodiment is as follows:

[0029] (1) First, weigh 10g of undecyl phosphoric acid, 70g of cubic γ-Al2O3 and 200g of diethyl ether solvent and mechanically stir for 60min at 130℃ and 1000r / min to prepare hydrophobic γ-Al2O3;

[0030] (2) Prepare a hydrophobic catalyst precursor by mechanically stirring 10g of phosphomolybdic acid, 70g of hydrophobic γ-Al2O3 and 200g of ethanol solvent at 30℃ and 100r / min for 5min.

[0031] (3) The catalyst precursor obtained in step (2) is dried at 100°C for 60 min to obtain catalyst 2.

[0032] Application of Catalyst 2 in the catalytic synthesis of tetrahydrothiophene:

[0033] Tetrahydrofuran, carbon disulfide, water, and catalyst 2 were mixed and placed in a catalytic reactor. The reaction temperature was 270℃, the reaction pressure was 1.0 MPa, and the reaction time was 60 min. The mass ratio of catalyst to tetrahydrofuran was 1:10, and the mass ratio of tetrahydrofuran, carbon disulfide, and water was 1:1:1. The initial conversion rate of tetrahydrofuran was 99.4%, and the selectivity of tetrahydrothiophene was 99.5%.

[0034] Example 3

[0035] The catalyst preparation method in this embodiment is as follows:

[0036] (1) First, weigh 30g tetradecyl phosphoric acid, 70g octahedral γ-Al2O3 and 420g diethyl ether solvent and mechanically stir for 60min at 130℃ and 500r / min to prepare hydrophobic γ-Al2O3;

[0037] (2) Prepare a hydrophobic catalyst precursor by mechanically stirring 30g molybdic acid, 70g hydrophobic γ-Al2O3 and 420g ethanol solvent at 30℃ and 100r / min for 5min.

[0038] (3) The catalyst precursor obtained in step (2) is dried at 120°C for 60 min to obtain catalyst 3.

[0039] Application of Catalyst 3 in the catalytic synthesis of tetrahydrothiophene:

[0040] Tetrahydrofuran, carbon disulfide, water, and catalyst 3 were mixed and placed in a catalytic reactor. The reaction temperature was 280℃, the reaction pressure was 1.0 MPa, and the reaction time was 60 min. The mass ratio of catalyst to tetrahydrofuran was 1:10, and the mass ratio of tetrahydrofuran, carbon disulfide, and water was 1:1:1. The initial conversion rate of tetrahydrofuran was 99.3%, and the selectivity of tetrahydrothiophene was 99.6%.

[0041] Example 4

[0042] The catalyst preparation method in this embodiment is as follows:

[0043] (1) First, weigh 10g of tridecyl phosphoric acid, 70g of nanosheet γ-Al2O3 and 200g of diethyl ether solvent and mechanically stir for 60min at 130℃ and 1000r / min to prepare hydrophobic γ-Al2O3;

[0044] (2) Prepare a hydrophobic catalyst precursor by mechanically stirring 10g of phosphomolybdic acid, 70g of hydrophobic γ-Al2O3 and 200g of ethanol solvent at 30℃ and 100r / min for 5min.

[0045] (3) The catalyst precursor obtained in step (2) is dried at 120°C for 120 min to obtain catalyst 4.

[0046] Application of Catalyst 4 in the catalytic synthesis of tetrahydrothiophene:

[0047] Tetrahydrofuran, carbon disulfide, water, and catalyst 4 were mixed and placed in a catalytic reactor. The reaction temperature was 290℃, the reaction pressure was 1.0 MPa, and the reaction time was 60 min. The mass ratio of catalyst to tetrahydrofuran was 3:10, and the mass ratio of tetrahydrofuran, carbon disulfide, and water was 1:1:1. The initial conversion rate of tetrahydrofuran was 99.5%, and the selectivity of tetrahydrothiophene was 99.6%.

[0048] Example 5

[0049] The catalyst preparation method in this embodiment is as follows:

[0050] (1) First, weigh 10g of undecyl phosphoric acid, 70g of spherical γ-Al2O3 and 200g of diethyl ether solvent and mechanically stir for 60min at 130℃ and 1000r / min to prepare hydrophobic γ-Al2O3;

[0051] (2) Prepare a hydrophobic catalyst precursor by mechanically stirring 10g of phosphomolybdic acid, 70g of hydrophobic γ-Al2O3 and 200g of ethanol solvent at 30℃ and 1000r / min for 100min.

[0052] (3) The catalyst precursor obtained in step (2) is dried at 100°C for 60 min to obtain catalyst 5.

[0053] Application of Catalyst 5 in the catalytic synthesis of tetrahydrothiophene:

[0054] Tetrahydrofuran, carbon disulfide, water, and catalyst 5 were mixed and placed in a catalytic reactor. The reaction temperature was 280℃, the reaction pressure was 1.0 MPa, and the reaction time was 240 min. The mass ratio of catalyst to tetrahydrofuran was 1:10, and the mass ratio of tetrahydrofuran, carbon disulfide, and water was 1:1:1. The initial conversion rate of tetrahydrofuran was 99.3%, and the selectivity of tetrahydrothiophene was 99.7%.

[0055] Example 6

[0056] The catalyst preparation method in this embodiment is as follows:

[0057] (1) First, weigh 10g tetradecyl phosphoric acid, 70g spherical γ-Al2O3 and 200g diethyl ether solvent and mechanically stir for 60min at 130℃ and 1000r / min to prepare hydrophobic γ-Al2O3;

[0058] (2) Prepare a hydrophobic catalyst precursor by mechanically stirring 10g of phosphomolybdic acid, 70g of hydrophobic γ-Al2O3 and 200g of ethanol solvent at 30℃ and 1000r / min for 100min.

[0059] (3) The catalyst precursor obtained in step (2) is dried at 100°C for 60 min to obtain catalyst 6.

[0060] Application of Catalyst 6 in the catalytic synthesis of tetrahydrothiophene:

[0061] Tetrahydrofuran, carbon disulfide, water, and catalyst 6 were mixed and placed in a catalytic reactor. The reaction temperature was 280℃, the reaction pressure was 1.0 MPa, and the reaction time was 240 min. The mass ratio of catalyst to tetrahydrofuran was 1:10, and the mass ratio of tetrahydrofuran, carbon disulfide, and water was 1:1:1. The initial conversion rate of tetrahydrofuran was 99.0%, and the selectivity of tetrahydrothiophene was 99.2%.

[0062] Comparative Example 1

[0063] The preparation method of this comparative catalyst is as follows:

[0064] (1) First, 70g of spherical γ-Al2O3 and 200g of diethyl ether solvent were weighed and mechanically stirred for 60min at 130℃ and 1000r / min to prepare hydrophobic γ-Al2O3;

[0065] (2) Prepare a hydrophobic catalyst precursor by mechanically stirring 10g of phosphomolybdic acid, 70g of hydrophobic γ-Al2O3 and 200g of ethanol solvent at 30℃ and 1000r / min for 100min.

[0066] (3) The catalyst precursor obtained in step (2) was dried at 100°C for 60 min to obtain comparative catalyst 1.

[0067] Compare the application of catalyst 1 in the catalytic synthesis of tetrahydrothiophene:

[0068] Tetrahydrofuran, carbon disulfide, water, and comparative catalyst 1 were mixed and placed in a catalytic reactor. The reaction temperature was 280℃, the reaction pressure was 1.0 MPa, and the reaction time was 240 min. The mass ratio of catalyst to tetrahydrofuran was 1:10, and the mass ratio of tetrahydrofuran, carbon disulfide, and water was 1:1:1. The initial conversion of tetrahydrofuran was 53.8%, and the selectivity of tetrahydrothiophene was 88.1%.

[0069] Comparative Example 2

[0070] The preparation method of this comparative catalyst is as follows:

[0071] (1) First, weigh 10g tetradecyl phosphoric acid, 70g spherical γ-Al2O3 and 200g diethyl ether solvent and mechanically stir for 60min at 130℃ and 1000r / min to prepare hydrophobic γ-Al2O3;

[0072] (2) Prepare a hydrophobic catalyst precursor by mechanically stirring 70g of hydrophobic γ-Al2O3 and 200g of ethanol solvent at 30℃ and 1000r / min for 100min.

[0073] (3) The catalyst precursor obtained in step (2) is dried at 100°C for 60 min to obtain the comparative catalyst 2.

[0074] Compare the application of catalyst 2 in the catalytic synthesis of tetrahydrothiophene:

[0075] Tetrahydrofuran, carbon disulfide, water, and comparative catalyst 2 were mixed and placed in a catalytic reactor. The reaction temperature was 280℃, the reaction pressure was 1.0 MPa, and the reaction time was 240 min. The mass ratio of catalyst to tetrahydrofuran was 1:10, and the mass ratio of tetrahydrofuran, carbon disulfide, and water was 1:1:1. The initial conversion rate of tetrahydrofuran was 31.6%, and the selectivity of tetrahydrothiophene was 93.7%.

[0076] Comparative Example 3

[0077] The preparation method of this comparative catalyst is as follows:

[0078] (1) First, weigh 10g of phosphomolybdic acid, 70g of γ-Al2O3 and 200g of diethyl ether solvent and mechanically stir for 100min at 30℃ and 1000r / min to prepare hydrophobic γ-Al2O3;

[0079] (2) The catalyst precursor obtained in step (1) was dried to obtain the comparative catalyst 3; the drying temperature was 100℃ and the drying time was 60min.

[0080] Compare the application of catalyst 3 in the catalytic synthesis of tetrahydrothiophene:

[0081] Tetrahydrofuran, carbon disulfide, water, and comparative catalyst 3 were mixed and placed in a catalytic reactor. The reaction temperature was 280℃, the reaction pressure was 1.0 MPa, and the reaction time was 240 min. The mass ratio of catalyst to tetrahydrofuran was 1:10, and the mass ratio of tetrahydrofuran, carbon disulfide, and water was 1:1:1. The initial conversion of tetrahydrofuran was 78.4%, and the selectivity of tetrahydrothiophene was 95.6%.

[0082] Comparative Example 4

[0083] The preparation method of this comparative catalyst is as follows:

[0084] (1) First, weigh 10g of undecyl phosphoric acid, 70g of spherical γ-Al2O3 and 200g of diethyl ether solvent and mechanically stir for 60min at 130℃ and 1000r / min to prepare hydrophobic γ-Al2O3;

[0085] (2) Prepare a hydrophobic catalyst precursor by mechanically stirring 10g of phosphomolybdic acid, 70g of hydrophobic γ-Al2O3 and 200g of ethanol solvent at 30℃ and 1000r / min for 100min.

[0086] (3) The catalyst precursor obtained in step (2) was dried at 100°C for 60 min to obtain the comparative catalyst 4.

[0087] Compare the application of catalyst 4 in the catalytic synthesis of tetrahydrothiophene:

[0088] Tetrahydrofuran, carbon disulfide, and comparative catalyst 4 were mixed and placed in a catalytic reactor. The reaction temperature was 280℃, the reaction pressure was 1.0 MPa, and the reaction time was 240 min. The mass ratio of catalyst to tetrahydrofuran was 1:10, and the mass ratio of tetrahydrofuran to carbon disulfide was 1:1. The initial conversion rate of tetrahydrofuran was 21.2%, and the selectivity of tetrahydrothiophene was 33.7%.

[0089] Table 1 Catalyst performance

[0090]

[0091]

[0092] As shown in Table 1, the catalysts prepared in this invention achieve a conversion rate of over 99.5% for tetrahydrofuran and up to 99.7% for tetrahydrothiophene, demonstrating simultaneous improvement in both conversion rate and selectivity, and exhibiting high catalytic activity. A comparison of Example 6 with Comparative Examples 1-3 shows that the catalytic activity of γ-Al₂O₃ without alkyl phosphoric acid chemical treatment, hydrophobic γ-Al₂O₃ without supporting heteropolyacid active components, or heteropolyacid active components not supported on hydrophobic γ-Al₂O₃, is lower than that of this invention. This further demonstrates the synergistic effect between hydrophobic γ-Al₂O₃ and heteropolyacid active components. By grafting phosphorus atoms of alkyl phosphoric acid onto the aluminum atom surface, and through the synergistic effect between phosphorus-aluminum and heteropolyacid atoms, the acidity of the catalyst is further enhanced. Utilizing this synergistic effect, the catalyst activity can be effectively improved. Simultaneously, the alkyl grafting of alkyl phosphoric acid onto the aluminum atom surface effectively enhances the hydrophobicity of the catalyst surface, gradually achieving a three-step closed-loop catalytic reaction, resulting in improved catalyst selectivity. As can be seen from the comparison between Example 6 and Comparative Example 4, the addition of trace amounts of water as reactants and initiators to the reaction can effectively improve the overall catalytic activity of the hydrophobic catalyst.

[0093] The foregoing has shown and described the basic principles and main features of the present invention, as well as its advantages. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. The application of a catalyst in the catalytic synthesis of tetrahydrothiophene, characterized in that, Tetrahydrofuran, carbon disulfide, water and catalyst are added to a high-pressure catalytic reactor to react and generate tetrahydrothiophene; the reaction temperature is 270-280℃, the reaction pressure is 1MPa, and the reaction time is 60-240 min, wherein the mass ratio of catalyst to tetrahydrofuran is 1:10, and the mass ratio of tetrahydrofuran, carbon disulfide and water is 1:1:

1. The catalyst preparation method includes the following steps: (1) First, weigh alkyl phosphoric acid, γ-Al2O3 and solvent and mechanically stir to prepare hydrophobic γ-Al2O3; (2) Prepare a hydrophobic catalyst precursor by stirring and reacting heteropolyacid active components, hydrophobic γ-Al2O3 and solvent; (3) The catalyst precursor obtained in step (2) is dried to obtain the catalyst.

2. The application according to claim 1, characterized in that: In step (1), the mass ratio of alkyl phosphoric acid to solvent is (1-3):7, and the mass ratio of γ-Al2O3 to solvent is (1-4):6; the stirring temperature is 100-130℃, the stirring speed is 400-1000r / min, and the stirring time is 60-120min.

3. The application according to claim 1, characterized in that: The alkyl phosphoric acid is one of octadecyl phosphoric acid, hexadecyl phosphoric acid, tetradecyl phosphoric acid, dodecyl phosphoric acid, and decadecyl phosphoric acid; the solvent is one of methanol, ethanol, diethyl ether, and acetone; the γ-Al2O3 has the following shape: spherical, rod-shaped, cubic, octahedral, flower-shaped, or nanosheet.

4. The application according to claim 1, characterized in that: In step (2), the mass ratio of heteropolyacid active component to hydrophobic γ-Al2O3 is (1-3):7, and the mass ratio of hydrophobic γ-Al2O3 to solvent is (1-4):6; the stirring reaction temperature is 10-30℃, the stirring speed is 100-1000r / min, and the stirring time is 5-100min.

5. The application according to claim 1, characterized in that: In step (2), the heteropolyacid active component is one of phosphomolybdic acid and phosphotungstic acid; the solvent is one of methanol, ethanol, diethyl ether, and acetone.

6. The application according to claim 1, characterized in that: In step (3), the drying temperature is 100-120℃ and the drying time is 10-120min.

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