Method for preparing organic polysulfide

Abstract

The invention discloses a method for preparing organic polysulfide, which comprises the following steps: adding mercaptan, sulfur and a basic catalyst into a reactor with an outlet connected with a gas separation device to carry out vulcanization reaction so as to obtain the organic polysulfide, the gas separation device comprises a membrane separation unit, a condensation unit and a pressure regulation unit, wherein a membrane component for separating mercaptan and gas is arranged in the membrane separation unit. According to the method, the organic polysulfide is prepared from the mercaptan and the sulfur, and a gas separation device is additionally arranged aiming at the problem that the mercaptan loss amount is large in the reaction process. By utilizing the method disclosed by the invention, inorganic gases such as H2S and the like in the reaction process can be efficiently separated out, mercaptan and thioether obtained by synthesis are reserved to the maximum extent, the loss of mercaptan is reduced, the cost is reduced, and meanwhile, the reaction efficiency and the product purity are improved.

Description

Technical Field

[0001] This invention belongs to the field of chemical production technology, and specifically relates to a method for preparing organic polysulfides. Background Technology

[0002] Organic polysulfides, as important extreme pressure anti-wear agents, have wide applications in industrial lubrication. Organic polysulfides such as trisulfides possess both optimal sulfur content and low copper corrosion resistance, making them ideal lubricant additives that simultaneously meet the requirements of extreme pressure anti-wear and copper corrosion resistance. Currently, the products obtained by synthesizing organic polysulfides from thiols and sulfur are relatively pure, but thiols are expensive, and a large amount of thiols are lost during the reaction process when hydrogen sulfide gas is emitted, leading to an increase in the amount of thiols used.

[0003] CN115477601A discloses a method for preparing organic polysulfides. This patent first reacts a metal hydroxide with sulfur to generate a metal sulfide, which then undergoes a substitution reaction with an alkyl chain containing halogen atoms. Finally, the organic polysulfide is obtained through extraction, washing, and distillation. However, this method generates a large amount of metal salt byproducts during the reaction, and the subsequent separation and purification processes are complex, increasing costs and potentially causing environmental pollution.

[0004] US5442123A discloses a method for preparing organic polysulfides. Using thiols and sulfur as raw materials, organic trisulfides are selectively prepared under the action of an alkali metal catalyst. During the reaction, H2S needs to be removed promptly by high-temperature reflux to drive the reaction. However, during the removal of H2S, a large amount of thiols is carried out of the reaction system, resulting in thiols loss and ultimately increasing costs.

[0005] Therefore, it is of great significance to develop an efficient, low-cost, and environmentally friendly method for preparing organic polysulfides based on the reaction of thiols with sulfur. Summary of the Invention

[0006] To address the aforementioned technical problems, the present invention aims to provide a method for preparing organic polysulfides, the method comprising:

[0007] Thiols, sulfur, and a basic catalyst are added to a reactor with a gas separation device connected to the outlet to carry out a sulfidation reaction, thereby obtaining organic polysulfides.

[0008] The gas separation device includes a membrane separation unit, a condensation unit, and a pressure regulating unit, wherein the membrane separation unit contains a membrane module for separating thiols and H2S.

[0009] Preferably, the membrane module is a hollow fiber membrane or flat sheet membrane module made of microporous membrane material, wherein the microporous membrane material is selected from any one of polytetrafluoroethylene (PTEE), polyimide (PI), and polyethersulfone (PES), preferably polytetrafluoroethylene; and the pore size range of the microporous membrane material is 0.01μm-5μm, preferably 0.3μm-0.5μm, and more preferably 0.1μm-0.5μm.

[0010] Preferably, the operating temperature within the membrane separation unit is 20-60℃, the operating pressure is 0.1-0.3MPa, and the gas flow rate is 100-200m / s. 3 / h.

[0011] The present invention has at least the following beneficial effects:

[0012] The method of this invention yields a product with high conversion rate and simple operation. It also separates inorganic gases such as H2S from the reaction process, retaining thiols and the synthesized thioethers. This method offers high thiols recovery, reducing costs. Furthermore, the efficient separation of H2S by the gas separation device simplifies the purification process, reduces H2S corrosion of equipment, and extends equipment lifespan. Detailed Implementation

[0013] To provide a clearer understanding of the technical features, objectives, and beneficial effects of the present invention, the present invention will now be described in detail below, but this should not be construed as limiting the scope of the invention.

[0014] It should be noted that, unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0015] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0016] It should be understood that the terms “comprising,” “including,” and / or “containing” as used herein specify the presence of the stated features, integers, steps, components, or combinations thereof, but do not exclude the presence or addition of one or more other features, integers, steps, components, or combinations thereof.

[0017] Unless otherwise specified, when referring to content or proportion in the following text, it is based on weight.

[0018] The endpoints and any values ​​of the ranges disclosed in this invention are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this invention.

[0019] This invention uses thiols and sulfur as raw materials to prepare polysulfides in the presence of a catalyst. The overall reaction process is represented by the following formula (1):

[0020] 2RSH + (n-1)S → RS n -R + H2S (1)

[0021] Where R represents an alkyl chain with 1 to 18 carbon atoms; n is an integer greater than or equal to 3.

[0022] This method yields a high product conversion rate and is simple to operate, but it results in significant thiol loss during the reaction. To address this issue, gas membrane separation technology is introduced in this invention. Gas membrane separation technology follows the "dissolution-diffusion" mass transfer mechanism of membrane materials. Driven by external energy or chemical potential difference, it utilizes the different permeability of different components to a polymer membrane material to ultimately separate different substances in a mixture. The pressure difference between the gases on both sides of the gas separation membrane induces the gases to reach the membrane. Whether separation occurs ultimately depends primarily on the permeability of the molecules, i.e., the different gases in the raw material mixture have different permeabilities to the membrane material itself. The permeable side yields a material enriched with gases of high permeability, while the non-permeable side yields a separated gas enriched with gases of low permeability, thus achieving gas separation.

[0023] Specifically, the present invention provides a method for preparing organic polysulfides, the method comprising:

[0024] Thiols, sulfur, and a basic catalyst are added to a reactor with a gas separation device connected to the outlet to carry out a sulfidation reaction, thereby obtaining organic polysulfides.

[0025] The gas separation device includes a membrane separation unit, a condensation unit, and a pressure regulating unit, wherein the membrane separation unit contains a membrane module for separating thiols and H2S.

[0026] In this invention, the membrane module in the gas separation device is a hollow fiber membrane or flat sheet membrane module made of a microporous membrane material with selective permeability. During the reaction process, when the reactant gas passes through the membrane module in the gas separation device, H2S molecules, due to their small size and high polarity, are preferentially separated through the membrane pores; while thiols, due to their larger molecular weight, are effectively retained by the membrane and refluxed back into the reaction system, thereby achieving efficient recovery of thiols. The acid and alkali resistance of the gas separation membrane varies depending on the material type. Common materials such as ceramic membranes, polysulfone membranes, and polyolefin membranes have different characteristics. Furthermore, the pore size of the gas separation membrane directly affects its separation effect. The smaller the pore size, the stronger the retention capacity for small molecules, but it may reduce the permeate flux; the larger the pore size, the higher the flux but the lower the selectivity. To select a membrane material suitable for separating thiols and H2S, the inventors compared different types of membrane materials, and the results are shown in Table 1 below:

[0027] Table 1. Different types of membrane materials

[0028]

[0029] As can be seen from the table above, based on the comparison of filter membrane pore size and acid and alkali resistance, the microporous membrane material in this invention is preferably selected from any one of polytetrafluoroethylene (PTEE), polyimide (PI), and polyethersulfone (PES), with polytetrafluoroethylene being more preferred; and its pore size range is 0.01 μm-5 μm, preferably 0.3 μm-0.5 μm, and more preferably 0.1 μm-0.5 μm. This membrane material has high permeability to small molecule acidic gases such as H2S, while exhibiting good retention performance for larger molecule organic compounds such as thiols.

[0030] In some embodiments, the operating temperature within the membrane separation unit can be 20-60°C, the operating pressure can be 0.1-0.3 MPa, and the gas flow rate can be 100-200 m / s. 3 / h. Alternatively, other suitable membrane materials and pore size ranges can be selected, and the reaction conditions can be adjusted within the above temperature, pressure, and gas flow rate ranges, as long as the desired H2S and thiol separation effect can be achieved.

[0031] In some embodiments, the molar ratio of the added thiol to the added sulfur can be 1:(1-4), preferably 1:(1-2), more preferably 1:1; and the amount of the added alkaline additive relative to 100 parts by mass of the total of the thiol and the sulfur can be 1-10 parts by mass, preferably 1-5 parts by mass, more preferably 1-3 parts by mass.

[0032] In some embodiments, the reaction can be carried out at a temperature of 40°C-90°C for 2-10 hours, preferably 4-10 hours, and more preferably 5-8 hours.

[0033] In some embodiments, the thiol may be a straight-chain or branched thiol having 1-18 carbon atoms, preferably a straight-chain or branched thiol having 1-10 carbon atoms, more preferably one or more selected from isopropyl thiol, tert-butyl thiol, neopentyl thiol, tert-octyl thiol and n-hexyl thiol, but not limited thereto.

[0034] In some embodiments, the purity of the sulfur can be ≥90%, preferably ≥95%, and more preferably ≥98%.

[0035] In some embodiments, the alkaline catalyst may be selected from any one of alumina, zinc oxide, and zirconium oxide, but is not limited thereto.

[0036] In some embodiments, the membrane separation unit further includes a housing, an inlet, an outlet, and a permeate outlet, wherein the housing houses the membrane assembly, the inlet is connected to the gas outlet of the reactor, the outlet is connected to a downstream processing unit or recycled back to the reactor, and the permeate outlet discharges the gas.

[0037] In some embodiments, the membrane module is arranged in a multi-stage series or parallel configuration, and the membrane area of ​​each stage is not less than 3m². 2 Under these conditions, the residual amount of H2S is no higher than 150 ppm, while the rejection rate of thiols can even reach over 99.5%.

[0038] The aforementioned gas separation device can separate inorganic gases such as H2S during the reaction process, while retaining thiols and the synthesized sulfides. This not only reduces the loss of thiols and lowers costs, but also reduces the corrosion of equipment by H2S (especially the metal packing of the distillation column), thereby extending the service life of the equipment.

[0039] The technical solutions of the present invention are specifically illustrated below through embodiments, but the present invention is not limited to these embodiments. Of course, various modifications can be made within the scope of the key points of the present invention.

[0040] Unless otherwise stated, all reagents and instruments used are commercially available or can be prepared by methods known in the art.

[0041] Example 1

[0042] This embodiment provides a method for preparing sulfurized isobutylene. Specifically, a four-necked flask equipped with a gas separation device is selected. This gas separation device contains a hollow fiber membrane module made of polytetrafluoroethylene (PTFE) material, wherein the membrane pore size is 0.01 μm. The gas separation device is turned on, with the gas inlet temperature controlled at 40°C, the operating pressure at 0.1 MPa, and the gas flow rate at 150 m / s². 3 / h. At this point, 100g of tert-butyl mercaptan, 35.48g of sulfur, and 1.63g of alumina were added to the four-necked flask, and the mixture was refluxed at 60°C for 5 hours. The isobutylene sulfide product and the gas permeating through the separation membrane were collected by condensation. After the reaction was completed, 116.64g of isobutylene sulfide was obtained.

[0043] Example 2

[0044] This embodiment was carried out under the same operations and conditions as Example 1, except that the membrane module was made of a polyimide material and the membrane pore size was 0.5 μm. After the reaction was completed, 112.75 g of sulfurized isobutylene was obtained.

[0045] Comparative Example 1

[0046] This comparative example was carried out under the same operation and conditions as Example 1, except that the gas separation device was removed. After the reaction was completed, 101.09 g of sulfurized isobutylene was obtained.

[0047] Comparative Example 2

[0048] This comparative example was conducted under the same operation and conditions as Example 1, except that a condenser reflux device was added at the outlet, the condensation temperature was set to -2℃ to 10℃, and the gas at the tail gas outlet was condensed and collected. After the reaction was completed, 114.17 g of sulfurized isobutylene was obtained.

[0049] The H2S and thiol content and polysulfide composition in the products and recovered gases obtained in Examples 1-2 and Comparative Examples 1-2 were analyzed using a gas chromatograph equipped with an FID detector (model: GC-2010PRO, SHIMADZU). The results are shown in Tables 2 to 4 below.

[0050] Table 2. Gas phase composition of recovered gas (through the separation membrane side and at the tail gas outlet)

[0051]

[0052] Table 3. Thiol loss and conversion rates in Examples 1-2 and Comparative Examples 1-2

[0053]

[0054] Table 4. Product composition of Examples 1-2 and Comparative Examples 1-2

[0055]

[0056] As shown in Tables 2 and 3 above, compared to Comparative Examples 1 and 2, the loss of thiols in Examples 1 and 2 was significantly reduced by using a gas separation device, and the conversion rate of thiols during the reaction process exceeded 95%, demonstrating a high recovery rate of thiols. Meanwhile, as shown in Table 4 above, compared to Comparative Example 1 (which did not use a separation membrane) and Comparative Example 2 (which only used a reflux condenser), the H2S content in the products obtained from Examples 1 and 2 was significantly reduced.

[0057] Example 3

[0058] This embodiment provides a method for preparing isooctene sulfide. Specifically, a four-necked flask equipped with a gas separation device is selected. This gas separation device contains a hollow fiber membrane module made of polytetrafluoroethylene (PTFE) material, wherein the membrane pore size is 0.03 μm. The gas separation device is turned on, with the gas inlet temperature controlled at 55°C, the operating pressure at 0.15 MPa, and the gas flow rate at 180 m / s². 3 / h. At this point, 200 g of tert-octyl mercaptan, 65.62 g of sulfur, and 7.97 g of aluminum oxide were added to the four-necked flask, and the mixture was heated at 80 °C for 7 h. The isooctene sulfide product and the gas permeating through the separation membrane were collected by condensation. After the reaction was complete, 240.33 g of isooctene sulfide was obtained.

[0059] Comparative Example 3

[0060] This comparative example was carried out under the same operation and conditions as Example 3, except that the gas separation device was removed. After the reaction was completed, 205.83 g of sulfurized isobutylene was obtained.

[0061] The H2S and thiol contents in the products obtained in Example 3 and Comparative Example 3 were analyzed using a gas chromatograph equipped with an FID detector (model: GC-2010PRO, SHIMADZU). The results are shown in Tables 5 and 6 below.

[0062] Table 5. Thiol loss and conversion rates in Example 3 and Comparative Example 3

[0063]

[0064] Table 6. Product composition of Example 3 and Comparative Example 3

[0065]

[0066] As shown in Table 5 above, compared to Comparative Example 3, the loss of thiols in Example 3 was significantly reduced by using a gas separation device, and the conversion rate of thiols during the reaction process reached over 99%, demonstrating a high recovery rate of thiols. Meanwhile, as shown in Table 6 above, compared to Comparative Example 3 which did not use a separation membrane, the H2S content in the product obtained in Example 3 was significantly reduced.

[0067] The results from the above examples and comparative studies demonstrate that adding a gas separation device can both reduce mercaptan loss and improve mercaptan conversion rate. Simultaneously, the residual amounts of H2S and mercaptan in the crude product are significantly reduced, post-processing time is shortened, and costs are saved. The efficient separation of mercaptan and H2S not only reduces the load on the subsequent desulfurization process in refining but also reduces H2S corrosion of the equipment, extending its service life.

[0068] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for preparing organic polysulfides, the method comprising: Thiols, sulfur, and a basic catalyst are added to a reactor with a gas separation device connected to the outlet to carry out a sulfidation reaction, thereby obtaining organic polysulfides. The gas separation device includes a membrane separation unit, a condensation unit, and a pressure regulating unit, wherein the membrane separation unit contains a membrane module for separating thiols and H2S.

2. The method according to claim 1, wherein the membrane assembly is a hollow fiber membrane or flat sheet membrane assembly made of a microporous membrane material, wherein the microporous membrane material is selected from any one of polytetrafluoroethylene (PTEE), polyimide (PI), and polyethersulfone (PES), preferably polytetrafluoroethylene; and the pore size of the microporous membrane material is in the range of 0.01 μm-5 μm, preferably 0.3 μm-0.5 μm, more preferably 0.1 μm-0.5 μm.

3. The method according to claim 1 or 2, wherein the operating temperature within the membrane separation unit is 20-60°C, the operating pressure is 0.1-0.3 MPa, and the gas flow rate is 100-200 m / s. 3 / h.

4. The method according to any one of claims 1 to 3, wherein the molar ratio of the added thiol to the sulfur is 1:(1-4), preferably 1:(1-2), more preferably 1:1; and the amount of the added alkaline additive is 1-10 parts by mass, preferably 1-5 parts by mass, more preferably 1-3 parts by mass, relative to the total of 100 parts by mass of the thiol and the sulfur.

5. The method according to any one of claims 1 to 4, wherein the reaction is carried out at a temperature of 40°C to 90°C for 2 h to 10 h, preferably 4 h to 10 h, more preferably 5 h to 8 h.

6. The method according to any one of claims 1 to 5, wherein the thiol is a straight-chain or branched thiol having 1-18 carbon atoms, preferably a straight-chain or branched thiol having 1-10 carbon atoms, more preferably one or more selected from isopropyl thiol, tert-butyl thiol, neopentyl thiol, tert-octyl thiol and n-hexyl thiol; and the sulfur has a purity of ≥90%, preferably ≥95%, more preferably ≥98%.

7. The method according to any one of claims 1 to 6, wherein the alkaline catalyst is selected from any one of alumina, zinc oxide, and zirconium oxide.

8. The method according to any one of claims 1 to 7, wherein the membrane separation unit further comprises a housing, an inlet, an outlet, and a permeate outlet, wherein the housing houses the membrane assembly, the inlet is connected to the gas outlet of the reactor, the outlet is connected to a downstream processing device or recycled back to the reactor, and the permeate outlet discharges the gas.

9. The method according to any one of claims 1 to 8, wherein the membrane module is arranged in a multi-stage series or parallel configuration, and the membrane area of ​​each stage is not less than 3m². 2 .

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