A method for synthesizing tetrahydrothiophene

Abstract

The present invention provides a method for synthesizing tetrahydrothiophene, which belongs to the technical field of fine chemicals and is used to solve the technical problem that water is produced during the tetrahydrofuran method for preparing tetrahydrothiophene, resulting in low product separation efficiency and high energy consumption. The present invention heats and vaporizes the reaction raw materials carbon disulfide and tetrahydrofuran, and then passes them into a fixed-bed catalytic reactor. The fixed-bed catalytic reactor is equipped with a catalyst. The reaction raw materials contact the catalyst to produce a catalytic reaction, and the product is distilled to obtain tetrahydrothiophene. The present invention uses carbon disulfide and tetrahydrofuran as raw materials to produce tetrahydrothiophene, and the byproduct is non-toxic and harmless carbon dioxide gas. Compared with the preparation of tetrahydrothiophene by reacting tetrahydrofuran with hydrogen sulfide, no water is produced, so the separation and purification of the reaction products is simpler. At the same time, the conversion rate of tetrahydrofuran and the selectivity of tetrahydrothiophene in this reaction both reach 99.5%.

Description

Technical Field

[0001] The invention belongs to the technical field of fine chemicals, and in particular relates to a method for synthesizing tetrahydrothiophene. Background Art

[0002] Tetrahydrothiophene is an important sulfur-containing saturated heterocyclic compound used as a fuel gas odorant due to its unique odor. It is also widely used in pharmaceuticals, pesticides, and as a material additive intermediate.

[0003] There are three main methods for producing tetrahydrothiophene: (1) Thiophene catalytic hydrogenation method, which uses thiophene as raw material and synthesizes tetrahydrothiophene through catalytic hydrogenation reduction reaction. This process has problems such as high thiophene raw material price, high catalyst price, complex process conditions, high production cost, and no obvious market advantage; (2) 1,4-dichlorobutane direct thiolation method, which uses 1,4-dichlorobutane and sodium sulfide containing crystal water as raw materials and ethanol as solvent to generate tetrahydrothiophene under the action of iodine catalyst. Water is produced during this reaction, which is difficult to separate from the product. (3) Furan direct thiolation method, which directly reacts tetrahydrofuran with hydrogen sulfide under the action of solid acid catalyst to generate tetrahydrothiophene. For example, patent publication number CN113135890A discloses a method for preparing tetrahydrothiophene using a two-component catalyst. 1,4-Butanediol undergoes intramolecular dehydration to form tetrahydrofuran (THF) under heating conditions, catalyzed by heteropolyacid 1. The THF then reacts with hydrogen sulfide under the same conditions, catalyzed by heteropolyacid 2, to produce the target product, THT. However, water is produced as a byproduct during the reaction, which directly affects product separation efficiency. Summary of the Invention

[0004] In response to the technical problem that water is produced during the preparation of tetrahydrothiophene by the tetrahydrofuran method, resulting in low product separation efficiency and high energy consumption, the present invention proposes a method for synthesizing tetrahydrothiophene, which uses tetrahydrofuran and carbon disulfide as raw materials to produce tetrahydrothiophene. This method overcomes the problems of high energy consumption and wastewater by-production in the production process, and also has the characteristics of high raw material conversion rate and product selectivity.

[0005] In order to achieve the above object, the technical solution of the present invention is achieved as follows:

[0006] A method for synthesizing tetrahydrothiophene comprises heating and gasifying carbon disulfide and tetrahydrofuran as reaction raw materials and then introducing them into a fixed-bed catalytic reactor provided with a catalyst. The reaction raw materials and the catalyst come into contact with each other to produce a catalytic reaction, and the product is distilled to obtain tetrahydrothiophene.

[0007] The specific steps include:

[0008] (1) Carbon disulfide and furan raw materials are pumped into a shell-and-tube heat exchanger, heated to 66-150°C to gasify, and then enter a premixing device. They then enter a fixed-bed catalytic reactor where they come into contact with the catalyst to produce a catalytic reaction that produces crude tetrahydrofuran.

[0009] (2) The crude tetrahydrofuran product enters the first distillation tower to separate out the unreacted carbon disulfide, which is recycled. The bottom product of the first distillation tower enters the second distillation tower to separate out furan and tetrahydrothiophene. The former is recycled as a reaction raw material, and the latter is sent to the storage tank as the finished tetrahydrothiophene.

[0010] Wherein, the catalyst is a supported rare earth-based catalyst.

[0011] The catalyst preparation method is as follows: first, a γ-Al2O3 carrier, a sulfate aqueous solution containing a rare earth element and a heteropoly acid are mixed and stirred, evaporated to dryness, and then further dried. Finally, the catalyst precursor is high-temperature calcined and activated under an activation temperature of 400-550°C and a nitrogen atmosphere to finally obtain a rare earth-based catalyst.

[0012] The mass ratio of tetrahydrofuran to carbon disulfide is 1:1.5-7.

[0013] The catalytic reaction is carried out in a tubular fixed bed reactor. The bed temperature is heated to 150-280°C using thermal oil. That is, the reaction temperature is 150-280°C and the carbon disulfide space velocity is 15-100h -1 .

[0014] The solute in the rare earth element-containing sulfate solution contains a sulfate of the rare earth element, which is one of lanthanum sulfate, cerium sulfate, praseodymium sulfate, neodymium sulfate, samarium sulfate, europium sulfate, gadolinium sulfate, terbium sulfate, holmium sulfate, and lutetium sulfate; the mass ratio of the γ-Al2O3 carrier to the sulfate containing the rare earth element is 4-200:1; and the solute content in the rare earth element-containing sulfate aqueous solution is 1-20wt%.

[0015] The heteropoly acid is one of phosphotungstic acid and phosphotungstomolybdic acid; the mass ratio of the γ-Al2O3 carrier to the heteropoly acid is 4-100:1.

[0016] The mixing and stirring is carried out at a stirring speed of 500-1000 r / min and a stirring temperature of 100-120° C.; and the drying temperature is 110-120° C.

[0017] The present invention has the beneficial effects of producing tetrahydrothiophene using carbon disulfide and tetrahydrofuran as raw materials, with non-toxic and harmless carbon dioxide gas as a byproduct. Compared to the production of tetrahydrothiophene by reacting tetrahydrofuran with hydrogen sulfide, no water is produced, making the separation and purification of the reaction product much simpler. Furthermore, the conversion rate of tetrahydrofuran and the selectivity for tetrahydrothiophene in this reaction both reach 99.5%. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 The synthetic process flow chart of tetrahydrothiophene.

[0020] Figure 2 H of tetrahydrothiophene 1 -NMR nuclear magnetic spectrum.

[0021] In the figure, 1. Heat exchanger I; 2. Heat exchanger II; 3. Premixer; 4. Catalytic reactor; 5. Crude product tank; 6. Distillation tower I; 7. Condenser I; 8. Distillation tower II; 9. Condenser II. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0023] Example 1

[0024] A method for synthesizing tetrahydrothiophene, the process flow is as follows Figure 1 As shown, the following steps are included:

[0025] (1) Catalyst Preparation: 20 g of γ-Al2O3, 4 g of an aqueous solution containing 4 wt% cerium sulfate, and 5 g of phosphotungstomolybdic acid were placed in a beaker and gently stirred at 100°C and 800 rpm until the aqueous solvent in the beaker evaporated. The mixture was then dried at 110°C for 1 hour to prepare a catalyst precursor. Finally, the catalyst precursor was calcined at 400°C in a nitrogen atmosphere to obtain rare earth-based catalyst A.

[0026] (2) Preparation of tetrahydrothiophene: First, carbon disulfide and tetrahydrofuran in the storage tank are pumped into heat exchanger II2 (80°C) and heat exchanger I1 (100°C) respectively for preheating, and then merged into premixer 3. The mixed raw materials (the mass ratio of tetrahydrofuran to carbon disulfide is 1:1.5) are then sent to catalytic reactor 4 (catalyst A) for reaction. The carbon disulfide space velocity is 15h -1 The catalytic reaction temperature is maintained at 230°C. Heat from the catalytic reaction is recovered and used to preheat the feedstock. The crude product enters crude product tank 5, and then enters distillation tower I 6. Carbon disulfide (47.2°C) is separated at the top of the tower and recycled after passing through condenser I 7. The bottom liquid is then sent to distillation tower II 8 (65.2°C), where tetrahydrothiophene (118.2°C) is separated at the bottom of the tower. Tetrahydrofuran is separated at the top of the tower after passing through condenser II 9 and recycled.

[0027] (3) Performance of Catalyst A: The conversion of tetrahydrofuran was 98.0%, the selectivity of tetrahydrothiophene was 98.5%, and the yield of tetrahydrothiophene was 96.53%.

[0028] The nuclear magnetic resonance hydrogen spectrum of tetrahydrothiophene purified from the bottom of the tower is as follows Figure 2 As shown, the single peaks at chemical shifts 2.823 and 1.936 correspond to methylene hydrogen at positions A and B, respectively, which are consistent with the H NMR spectrum of tetrahydrothiophene.

[0029] Example 2

[0030] A method for synthesizing tetrahydrothiophene, the process flow is as follows Figure 1 As shown, the following steps are included:

[0031] (1) Catalyst Preparation: 20 g of γ-Al2O3, an aqueous solution containing 4 g of neodymium sulfate (6 wt%), and 2 g of phosphotungstomolybdic acid were placed in a beaker and gently stirred at 110°C and 900 rpm until the aqueous solvent in the beaker evaporated. The mixture was then dried at 110°C for 1 hour to obtain a catalyst precursor. Finally, the catalyst precursor was calcined at an activation temperature of 450°C in a nitrogen atmosphere to obtain rare earth-based catalyst B.

[0032] (2) Preparation of tetrahydrothiophene: First, carbon disulfide and tetrahydrofuran in the storage tank are pumped into heat exchanger II2 (85°C) and heat exchanger I1 (95°C) respectively for preheating, and then merged into premixer 3. The mixed raw materials (the mass ratio of tetrahydrofuran to carbon disulfide is 1:7) are then sent to catalytic reactor 4 (catalyst B) for reaction. The carbon disulfide space velocity is 20h -1The catalytic reaction temperature is maintained at 230°C. Heat from the catalytic reaction is recovered and used to preheat the feedstock. The crude product enters crude product tank 5, and then enters distillation tower I 6. Carbon disulfide (48.5°C) is separated at the top of the tower and recycled after passing through condenser I 7. The bottom liquid is then sent to distillation tower II 8 (65.2°C), where tetrahydrothiophene (115.2°C) is separated at the bottom. Refined tetrahydrofuran is separated at the top of the tower through condenser II 9 and recycled.

[0033] (3) Performance of Catalyst B: The conversion of tetrahydrofuran was 99.0%, the selectivity of tetrahydrothiophene was 98.9%, and the yield of tetrahydrothiophene was 97.91%.

[0034] Example 3

[0035] A method for synthesizing tetrahydrothiophene, the process flow is as follows Figure 1 As shown, the following steps are included:

[0036] (1) Catalyst Preparation: 20 g of γ-Al2O3, an aqueous solution containing 3 g of cerium sulfate (6 wt%), and 3 g of phosphotungstic acid were slowly placed in a beaker and gently stirred at 110°C and 600 rpm until the aqueous solvent in the beaker evaporated. The catalyst precursor was then dried at 110°C for 1 hour to obtain a catalyst precursor. Finally, the catalyst precursor was calcined at an activation temperature of 550°C in a nitrogen atmosphere to obtain rare earth-based catalyst C.

[0037] (2) Preparation of tetrahydrothiophene: First, carbon disulfide and tetrahydrofuran in the storage tank are pumped into heat exchanger II2 (70°C) and heat exchanger I1 (120°C) respectively for preheating, and then merged into premixer 3. The mixed raw materials (the mass ratio of tetrahydrofuran to carbon disulfide is 1:3) are then sent to catalytic reactor 4 (catalyst C) for reaction. The carbon disulfide space velocity is 80h -1 The catalytic reaction temperature is maintained at 260°C. Heat from the catalytic reaction is recovered and used to preheat the feedstock. The crude product enters crude product tank 5, and then enters distillation tower I 6. Carbon disulfide (47.5°C) is separated at the top of the tower and recycled after passing through condenser I 7. The bottom liquid is then sent to distillation tower II 8 (64.9°C), where tetrahydrothiophene (117.3°C) is separated at the bottom of the tower. Refined tetrahydrofuran is separated at the top of the tower through condenser II 9 and recycled.

[0038] (3) Performance of Catalyst C: The conversion of tetrahydrofuran was 99.5%, the selectivity of tetrahydrothiophene was 98.9%, and the yield of tetrahydrothiophene was 98.41%.

[0039] Example 4

[0040] A method for synthesizing tetrahydrothiophene, the process flow is as follows Figure 1As shown, the following steps are included:

[0041] (1) Catalyst Preparation: 20 g of γ-Al2O3, 5 g of an aqueous solution containing 10 wt% cerium sulfate, and 5 g of phosphotungstomolybdic acid were placed in a beaker and gently stirred at 100°C and 1000 rpm until the aqueous solvent in the beaker evaporated. The mixture was then dried at 110°C for 1 hour to obtain a catalyst precursor. Finally, the catalyst precursor was calcined at 500°C in a nitrogen atmosphere to obtain rare earth-based catalyst D.

[0042] (2) Preparation of tetrahydrothiophene: First, carbon disulfide and tetrahydrofuran in the storage tank are pumped into heat exchanger II2 (66°C) and heat exchanger I1 (110°C) respectively for preheating, and then merged into premixer 3. The mixed raw materials (the mass ratio of tetrahydrofuran to carbon disulfide is 1:4) are then sent to catalytic reactor 4 (catalyst D) for reaction. The carbon disulfide space velocity is 45h -1 The catalytic reaction temperature is maintained at 220°C. Heat from the catalytic reaction is recovered and used to preheat the feedstock. The crude product enters crude product tank 5, and then enters distillation tower I 6. Carbon disulfide (47.2°C) is separated at the top of the tower and recycled after passing through condenser I 7. The bottom liquid is then sent to distillation tower II 8 (64.7°C), where tetrahydrothiophene (117.5°C) is separated at the bottom of the tower. Tetrahydrofuran is separated at the top of the tower after passing through condenser II 9 and recycled.

[0043] (3) Performance of Catalyst D: The conversion of tetrahydrofuran was 97.0%, the selectivity of tetrahydrothiophene was 99.5%, and the yield of tetrahydrothiophene was 96.52%.

[0044] Example 5

[0045] A method for synthesizing tetrahydrothiophene, the process flow is as follows Figure 1 As shown, the following steps are included:

[0046] (1) Catalyst Preparation: 20 g of γ-Al2O3, an aqueous solution containing 5 g of samarium sulfate (11 wt%), and 5 g of phosphotungstomolybdic acid were slowly placed in a beaker and stirred gently at 110°C and 800 rpm until the aqueous solvent in the beaker evaporated. The mixture was then dried at 110°C for 1 hour to obtain a catalyst precursor. Finally, the catalyst precursor was calcined at 400°C in a nitrogen atmosphere to obtain rare earth-based catalyst E.

[0047] (2) Preparation of tetrahydrothiophene: First, carbon disulfide and tetrahydrofuran in the storage tank are pumped into heat exchanger II2 (66°C) and heat exchanger I1 (105°C) respectively for preheating, and then merged into premixer 3. The mixed raw materials (the mass ratio of tetrahydrofuran to carbon disulfide is 1:3) are then sent to catalytic reactor 4 (catalyst E) for reaction. The carbon disulfide space velocity is 40h -1 The catalytic reaction temperature is maintained at 260°C. Heat from the catalytic reaction is recovered and used to preheat the feedstock. The crude product enters crude product tank 5, and then enters distillation tower I 6. Carbon disulfide (47.0°C) is separated at the top of the tower and recycled after passing through condenser I 7. The bottom liquid is then sent to distillation tower II 8 (64.2°C), where tetrahydrothiophene (118.1°C) is separated at the bottom of the tower. Tetrahydrofuran product is separated at the top of the tower after passing through condenser II 9 and recycled.

[0048] (3) Performance of Catalyst E: The conversion of tetrahydrofuran was 99.5%, the selectivity of tetrahydrothiophene was 97.9%, and the yield of tetrahydrothiophene was 97.41%.

[0049] Example 6

[0050] A method for synthesizing tetrahydrothiophene, the process flow is as follows Figure 1 As shown, the following steps are included:

[0051] (1) Catalyst Preparation: 20 g of γ-Al2O3, an aqueous solution containing 0.1 g of samarium sulfate (11 wt%), and 5 g of phosphotungstomolybdic acid were slowly placed in a beaker and stirred gently at 110°C and 800 rpm until the aqueous solvent in the beaker evaporated. The mixture was then dried at 110°C for 1 hour to obtain a catalyst precursor. Finally, the catalyst precursor was calcined at 400°C in a nitrogen atmosphere to obtain rare earth-based catalyst F.

[0052] (2) Preparation of tetrahydrothiophene: First, carbon disulfide and tetrahydrofuran in the storage tank are pumped into heat exchanger II2 (66°C) and heat exchanger I1 (105°C) respectively for preheating, and then merged into premixer 3. The mixed raw materials (the mass ratio of tetrahydrofuran to carbon disulfide is 1:3) are then sent to catalytic reactor 4 (catalyst F) for reaction. The carbon disulfide space velocity is 40h -1 The catalytic reaction temperature is maintained at 260°C. Heat from the catalytic reaction is recovered and used to preheat the feedstock. The crude product enters crude product tank 5, and then enters distillation tower I 6. Carbon disulfide (47.0°C) is separated at the top of the tower and recycled after passing through condenser I 7. The bottom liquid is then sent to distillation tower II 8 (64.2°C), where tetrahydrothiophene (118.1°C) is separated at the bottom. Refined tetrahydrofuran is separated at the top of the tower through condenser II 9 and recycled.

[0053] (3) Performance of Catalyst F: The conversion of tetrahydrofuran was 67.1%, the selectivity of tetrahydrothiophene was 98.9%, and the yield of tetrahydrothiophene was 66.36%.

[0054] Example 7

[0055] A method for synthesizing tetrahydrothiophene, the process flow is as follows Figure 1 As shown, the following steps are included:

[0056] (1) Catalyst Preparation: 20 g of γ-Al2O3, an aqueous solution containing 5 g of samarium sulfate (11 wt%), and 5 g of phosphotungstomolybdic acid were slowly placed in a beaker and stirred gently at 110°C and 800 rpm until the aqueous solvent in the beaker evaporated. The mixture was then dried at 110°C for 1 hour to obtain a catalyst precursor. Finally, the catalyst precursor was calcined at 400°C in a nitrogen atmosphere to obtain rare earth-based catalyst G.

[0057] (2) Preparation of tetrahydrothiophene: First, carbon disulfide and tetrahydrofuran in the storage tank are pumped into heat exchanger II2 (66°C) and heat exchanger I1 (105°C) respectively for preheating, and then merged into premixer 3. The mixed raw materials (the mass ratio of tetrahydrofuran to carbon disulfide is 1:3) are then sent to catalytic reactor 4 (catalyst G) for reaction. The carbon disulfide space velocity is 40h -1 The catalytic reaction temperature is maintained at 280°C. Heat from the catalytic reaction is recovered and used to preheat the feedstock. The crude product enters crude product tank 5, and then enters distillation tower I 6. Carbon disulfide (47.0°C) is separated at the top of the tower and recycled after passing through condenser I 7. The bottom liquid is then sent to distillation tower II 8 (64.2°C), where tetrahydrothiophene (118.1°C) is separated at the bottom of the tower. Tetrahydrofuran is separated at the top of the tower after passing through condenser II 9 and recycled.

[0058] (3) Performance of Catalyst G: The conversion of tetrahydrofuran was 99.5%, the selectivity of tetrahydrothiophene was 99.2%, and the yield of tetrahydrothiophene was 98.7%.

[0059] Example 8

[0060] A method for synthesizing tetrahydrothiophene, the process flow is as follows Figure 1 As shown, the following steps are included:

[0061] (1) Catalyst Preparation: 20 g of γ-Al2O3, an aqueous solution containing 5 g of samarium sulfate (11 wt%), and 5 g of phosphotungstomolybdic acid were slowly placed in a beaker and stirred gently at 110°C and 800 rpm until the aqueous solvent in the beaker evaporated. The mixture was then dried at 110°C for 1 hour to obtain a catalyst precursor. Finally, the catalyst precursor was calcined at 550°C in a nitrogen atmosphere to obtain the rare earth-based catalyst H.

[0062] (2) Preparation of tetrahydrothiophene: First, carbon disulfide and tetrahydrofuran in the storage tank are pumped into heat exchanger 1 (66°C) and heat exchanger 2 (105°C) respectively for preheating, and then merged into premixer 3. The mixed raw materials (the mass ratio of tetrahydrofuran to carbon disulfide is 1:3) are then sent to catalytic reactor 4 (catalyst H) for reaction. The carbon disulfide space velocity is 40h -1 The catalytic reaction temperature is maintained at 280°C. Heat from the catalytic reaction is recovered and used to preheat the feedstock. The crude product enters crude product tank 5, and then enters distillation tower I 6. Carbon disulfide (47.0°C) is separated at the top of the tower and recycled after passing through condenser I 7. The bottom liquid is then sent to distillation tower II 8 (64.2°C), where tetrahydrothiophene (118.1°C) is separated at the bottom of the tower. Tetrahydrofuran is separated at the top of the tower after passing through condenser II 9 and recycled.

[0063] (3) Performance of Catalyst H: The conversion of tetrahydrofuran was 99.5%, the selectivity of tetrahydrothiophene was 99.7%, and the yield of tetrahydrothiophene was 99.2%.

[0064] Example 9

[0065] A method for synthesizing tetrahydrothiophene, the process flow is as follows Figure 1 As shown, the following steps are included:

[0066] (1) Catalyst Preparation: 20 g of γ-Al2O3, an aqueous solution containing 4 g of samarium sulfate (11 wt%), and 5 g of phosphotungstomolybdic acid were slowly placed in a beaker and gently stirred at 110°C and 800 rpm until the aqueous solvent in the beaker evaporated. The mixture was then dried at 110°C for 1 hour to obtain a catalyst precursor. Finally, the catalyst precursor was calcined at 450°C in a nitrogen atmosphere to obtain rare earth-based catalyst I.

[0067] (2) Preparation of tetrahydrothiophene: First, carbon disulfide and tetrahydrofuran in the storage tank were pumped into heat exchanger 1 (66°C) and heat exchanger 2 (105°C) respectively for preheating, and then merged into premixer 3. The mixed raw materials (the mass ratio of tetrahydrofuran to carbon disulfide was 1:3) were then sent to catalytic reactor 4 (catalyst I) for reaction. The carbon disulfide space velocity was 40h -1The catalytic reaction temperature is maintained at 280°C. Heat from the catalytic reaction is recovered and used to preheat the feedstock. The crude product enters crude product tank 5, and then enters distillation tower I 6. Carbon disulfide (47.0°C) is separated at the top of the tower and recycled after passing through condenser I 7. The bottom liquid is then sent to distillation tower II 8 (64.2°C), where tetrahydrothiophene (118.1°C) is separated at the bottom of the tower. Tetrahydrofuran is separated at the top of the tower after passing through condenser II 9 and recycled.

[0068] (3) Performance of Catalyst I: The conversion of tetrahydrofuran was 99.5%, the selectivity of tetrahydrothiophene was 99.4%, and the yield of tetrahydrothiophene was 98.9%.

[0069] Example 10

[0070] A method for synthesizing tetrahydrothiophene, the process flow is as follows Figure 1 As shown, the following steps are included:

[0071] (1) Catalyst Preparation: 20 g of γ-Al2O3, an aqueous solution containing 4 g of samarium sulfate (11 wt%), and 5 g of phosphotungstomolybdic acid were slowly placed in a beaker and stirred gently at 110°C and 800 rpm until the aqueous solvent in the beaker evaporated. The mixture was then dried at 110°C for 1 hour to obtain a catalyst precursor. Finally, the catalyst precursor was calcined at 400°C in a nitrogen atmosphere to obtain rare earth-based catalyst J.

[0072] (2) Preparation of tetrahydrothiophene: First, carbon disulfide and tetrahydrofuran in the storage tank are pumped into heat exchanger II2 (66°C) and heat exchanger I1 (105°C) respectively for preheating, and then merged into premixer 3. The mixed raw materials (the mass ratio of tetrahydrofuran to carbon disulfide is 1:3) are then sent to catalytic reactor 4 (catalyst J) for reaction. The carbon disulfide space velocity is 40h -1 The catalytic reaction temperature is maintained at 270°C. Heat from the catalytic reaction is recovered and used to preheat the feedstock. The crude product enters crude product tank 5, and then enters distillation tower I 6. Carbon disulfide (47.0°C) is separated at the top of the tower and recycled after passing through condenser I 7. The bottom liquid is then sent to distillation tower II 8 (64.2°C), where tetrahydrothiophene (118.1°C) is separated at the bottom of the tower. Tetrahydrofuran is separated at the top of the tower after passing through condenser II 9 and recycled.

[0073] (3) Performance of Catalyst J: The conversion of tetrahydrofuran was 99.5%, the selectivity of tetrahydrothiophene was 99.0%, and the yield of tetrahydrothiophene was 98.50%.

[0074] Example 11

[0075] A method for synthesizing tetrahydrothiophene, the process flow is as follows Figure 1As shown, the following steps are included:

[0076] (1) Catalyst Preparation: 20 g of γ-Al2O3, 1 g of an aqueous solution containing holmium sulfate (20 wt%), and 0.2 g of phosphotungstic acid were slowly placed in a beaker and gently stirred at 120°C and 800 rpm until the aqueous solvent in the beaker evaporated. The mixture was then dried at 120°C for 1 hour to obtain a catalyst precursor. Finally, the catalyst precursor was calcined at 400°C in a nitrogen atmosphere to obtain rare earth-based catalyst K.

[0077] (2) Preparation of tetrahydrothiophene: First, carbon disulfide and tetrahydrofuran in the storage tank are pumped into heat exchanger II2 (150°C) and heat exchanger I1 (150°C) respectively for preheating, and then merged into premixer 3. The mixed raw materials (the mass ratio of tetrahydrofuran to carbon disulfide is 1:3) are then sent to catalytic reactor 4 (catalyst K) for reaction. The carbon disulfide space velocity is 100h -1 The catalytic reaction temperature is maintained at 150°C. Heat from the catalytic reaction is recovered and used to preheat the feedstock. The crude product enters crude product tank 5, and then enters distillation tower I 6. Carbon disulfide (47.0°C) is separated at the top of the tower and recycled after passing through condenser I 7. The bottom liquid is then sent to distillation tower II 8 (64.2°C), where tetrahydrothiophene (118.1°C) is separated at the bottom. Refined tetrahydrofuran is separated at the top of the tower through condenser II 9 and recycled.

[0078] (3) Performance of Catalyst K: The conversion of tetrahydrofuran was 99.8%, the selectivity of tetrahydrothiophene was 99.5%, and the yield of tetrahydrothiophene was 99.5%.

[0079] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for synthesizing tetrahydrothiophene, characterized in that: The reaction raw materials carbon disulfide and tetrahydrofuran are heated and gasified and then introduced into a fixed-bed catalytic reactor, which is equipped with a catalyst. The reaction raw materials and the catalyst come into contact with each other to cause a catalytic reaction, and the product is distilled to obtain tetrahydrothiophene; The mass ratio of tetrahydrofuran to carbon disulfide is 1:(1.5-7); The temperature of the carbon disulfide and tetrahydrofuran after heating and gasification is 66-150° C.; The catalytic reaction temperature in the fixed bed catalytic reactor is 150-280°C, and the carbon disulfide space velocity is 15-100 h -1 ; The catalyst is a supported rare earth-based catalyst; The catalyst preparation method comprises: mixing and stirring a γ-Al2O3 carrier, a sulfate aqueous solution containing a rare earth element, and a heteropoly acid, evaporating and drying the mixture to obtain a catalyst precursor, and calcining the catalyst precursor at a high temperature in an inert gas atmosphere to activate the catalyst; wherein the sulfate containing the rare earth element in the sulfate aqueous solution containing the rare earth element is one of lanthanum sulfate, cerium sulfate, praseodymium sulfate, neodymium sulfate, samarium sulfate, europium sulfate, gadolinium sulfate, terbium sulfate, holmium sulfate, or lutetium sulfate; The heteropoly acid is one of phosphotungstic acid and phosphotungstomolybdic acid.

2. The method for synthesizing tetrahydrothiophene according to claim 1, wherein The mass ratio of the γ-Al2O3 carrier and the sulfate containing rare earth elements is (4-200):1; the solute content in the sulfate aqueous solution containing rare earth elements is 1-20wt%.

3. The method for synthesizing tetrahydrothiophene according to claim 2, wherein The mass ratio of the γ-Al2O3 carrier to the heteropoly acid is (4-100):

1.

4. The method for synthesizing tetrahydrothiophene according to claim 3, wherein The high temperature calcination activation atmosphere is nitrogen, and the temperature is 400-550°C.

5. The method for synthesizing tetrahydrothiophene according to claim 4, wherein The mixing and stirring is carried out at a speed of 500-1000 r / min and a temperature of 100-120° C.; the drying temperature is 110-120° C.

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