Synthesis process of sulfurized isobutylene

Abstract

The invention belongs to the technical field of fine chemical synthesis, and relates to a sulfurized isobutylene synthesis process, which comprises: 1, weighing sulfur, an organic amine catalyst and a balanced catalyst, placing in a reaction kettle, and carrying out nitrogen displacement; 2, hydrogen sulfide is added, and then preheating is conducted; step 3, raising the temperature to a reaction temperature, adding isobutene, and keeping the reaction pressure; 4, after isobutene is added, heat preservation is conducted for 2-5 hours, then cooling is conducted to the room temperature, and a crude product is obtained; 5, the crude product is subjected to alkali washing, water washing, refining and filtering, and sulfurized isobutylene is obtained. According to the present invention, the organic amine catalyst and the balanced catalyst are utilized to easily react the liquid elemental sulfur with the mercaptan to obtain the sulfurized isobutylene product, and the sulfurized isobutylene product is subjected to molecular overlap optimization, such that the selectivity of the synthesis process is improved, and the sulfurized isobutylene with characteristics of high di-tert-butyl trisulfide ratio, low odor and low copper sheet corrosion is obtained.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical synthesis technology and relates to a synthesis process for isobutylene sulfide. Background Technology

[0002] Isobutylene sulfate, as an additive in lubricating oils, is widely used in automotive lubricants and industrial gear oils. As a key component in lubricating oil complexes, isobutylene sulfate plays a crucial role in extreme pressure and anti-wear properties. Traditional atmospheric pressure isobutylene sulfate production has faded from the lubricating oil market, while high-pressure isobutylene sulfate has taken over both domestic and international markets. Because the dosage of high-pressure isobutylene sulfate is lower than that of traditional atmospheric pressure isobutylene sulfate in lubricating oil production, developing low-cost, high-performance, and low-odor isobutylene sulfate production processes remains a pressing issue for isobutylene sulfate manufacturers.

[0003] Current high-pressure isobutylene sulfidation processes utilize hydrogen sulfide, sulfur, and isobutylene to synthesize the product under the action of an alkaline catalyst. The product composition consists of di-tert-butyl disulfide, di-tert-butyl trisulfide, di-tert-butyl tetrasulfide, and di-tert-butyl pentasulfide. The reaction formula is as follows: First, under high temperature and pressure, hydrogen sulfide reacts with isobutylene in the presence of a catalyst to directly generate tert-butyl mercaptan: Secondly, tert-butylthiols (especially polythiols), as intermediate products, will undergo further nucleophilic substitution reactions to generate polysulfides or thioethers, as well as the reactive sulfur byproduct H2S. n (e.g., H2S3);

[0004] The active sulfur byproduct H2S n It will participate in the isobutylene reaction again to form polythiols. Therefore, the selectivity of the existing high-pressure synthesis process is not high, and the product components include di-tert-butyl disulfide, di-tert-butyl trisulfide, di-tert-butyl tetrasulfide, and di-tert-butyl pentasulfide. That is, in terms of component proportion, di-tert-butyl trisulfide is the main product, accounting for about 50%, di-tert-butyl disulfide accounts for about 20%, di-tert-butyl tetrasulfide accounts for about 25%, and di-tert-butyl pentasulfide accounts for 5%-10%. In terms of functional effects, di-tert-butyl disulfide has a significant impact on the odor of the product, and di-tert-butyl tetrasulfide has a significant impact on the corrosion of copper sheets. Therefore, the existing synthesis process tends to produce sulfurized isobutylene products with strong odor and strong corrosion to copper sheets.

[0005] Therefore, there is still a need for a sulfurized isobutylene synthesis process that can reduce the proportion of di-tert-butyl disulfide and di-tert-butyl tetrasulfide and increase the proportion of di-tert-butyl trisulfide, i.e., improve selectivity, in order to obtain sulfurized isobutylene products with low odor and low copper corrosion. Summary of the Invention

[0006] In view of the above-mentioned technical problems, the present invention provides a synthesis process for isobutylene sulfide, thereby solving the technical problems of poor selectivity, strong odor, and strong corrosiveness to copper sheets in the high-pressure isobutylene sulfide synthesis process in the prior art.

[0007] To achieve the above objectives, the present invention adopts the following technical solution.

[0008] A process for synthesizing isobutylene sulfide, comprising the following steps: Step 1: Weigh sulfur, organic amine catalyst, and balanced catalyst into a reaction vessel and purge with nitrogen; Step 2: Add hydrogen sulfide and preheat; Step 3: Heat to the reaction temperature, add isobutylene, and maintain the reaction pressure; Step 4: After the isobutylene is added, keep warm for 2 to 5 hours, then cool to room temperature to obtain a crude product; Step 5: The crude product is washed with alkali, washed with water, purified, and filtered to obtain isobutylene sulfide.

[0009] Further, in steps 1 and 2, by mass ratio, sulfur:isobutylene:hydrogen sulfide:organic amine catalyst:balanced catalyst = (73.7-80):112:34:1.356:0.226.

[0010] Furthermore, in step 2, the preheating temperature is 145℃-155℃.

[0011] Furthermore, in step 3, the reaction temperature is 155℃-185℃; the reaction pressure is ≤6.5Mpa.

[0012] Furthermore, in step 1, the organic amine catalyst is hexamethylenediamine.

[0013] Furthermore, the balanced catalyst is any one or more of copper oxide, aluminum oxide, silicon oxide, calcium oxide, magnesium oxide, sodium oxide, zinc oxide, manganese oxide, iron oxide, or chromium oxide.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a process for synthesizing isobutylene sulfide using sulfur, hydrogen sulfide, and isobutylene as raw materials, with organic amine catalysts and balanced catalysts as catalysts. In this reaction system, due to the presence of a large amount of thiol intermediates, liquid elemental sulfur readily reacts with thiols under the action of the organic amine catalyst to obtain isobutylene sulfide. Furthermore, under the action of the balanced catalyst, the isobutylene sulfide product undergoes molecular overlap optimization, improving the selectivity of the synthesis process and increasing the proportion of di-tert-butyl trisulfide in the product, ultimately yielding isobutylene sulfide with a high proportion of di-tert-butyl trisulfide, low odor, and low copper corrosion resistance. Attached Figure Description

[0015] The present invention is described with reference to the following figures: Figure 1 This is a flowchart of the synthesis process of isobutylene sulfide according to the present invention; Figure 2 The gas chromatogram of the sulfurized isobutylene of the present invention is shown below. Figure 3 This is the gas chromatogram of traditional sulfurized isobutylene. Detailed Implementation

[0016] The technical solutions of this invention will now be clearly and completely described. Obviously, the described embodiments are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0017] In the isobutylene sulfide synthesis process of this invention, sulfur reacts with organic amines to generate ammonium sulfide, which then reacts with isobutylene to generate thiols.

[0018] Thiols, especially polythiols, as reaction intermediates, will undergo further nucleophilic substitution reactions to produce polysulfides or thioethers and reactive sulfur byproducts H₂S. n (For example, H2S3), the reaction formula is as follows:

[0019] Under the action of a balanced catalyst, polysulfide bonds undergo decomposition and rearrangement due to multiple nucleophilic substitutions between polysulfide bonds and thiols, thereby improving selectivity and generating a more stable di-tert-butyl trisulfide target product.

[0020] In the catalytic mechanism described above, both the organic amine catalyst and the equilibrium catalyst coexist. However, sulfur exists as a cyclic S8 molecule (eight-membered ring) at room temperature. Due to the large size and high polarizability of sulfur atoms, they are prone to bond breakage under nucleophilic attack, resulting in weak S–S bonds. Furthermore, the hydrogen atoms within the eight-membered ring repel each other, leading to transring strain and further deteriorating the ring's stability. Therefore, sulfur preferentially undergoes chain opening under the catalytic action of the organic amine catalyst, while the equilibrium catalyst participates in the catalytic reaction later.

[0021] Example 1: Synthesis process for preparing isobutylene sulfide according to the present invention.

[0022] Step 1: Open the lid of the 3L autoclave, add 1.356g of weighed hexamethylenediamine (organic amine catalyst), 0.226g of copper oxide (balanced catalyst) and 75g of sulfur into the autoclave, seal the lid, and then purge the autoclave with nitrogen 3-5 times (each time the nitrogen pressure is 0.3Mpa-0.4Mpa). The specific selection of a balanced catalyst can be based on the cost of raw materials; in this example, copper oxide is selected.

[0023] Step 2: Weigh out 34g of hydrogen sulfide at once, then turn on the electric heating system of the autoclave to preheat the reactor to 145℃-155℃, and check whether the reactor cooling system is normal. Step 3: Add 112g of isobutylene to the metering tank, controlling the inflow rate to 10mL / min-20mL / min. Therefore, the isobutylene should be added to the metering tank slowly. After the metering tank is full, fill the isobutylene feed line to the reactor. Once the reactor temperature reaches the set temperature of 155℃-185℃, adjust the isobutylene feed pump's feed rate to 5mL / min-30mL / min and slowly begin introducing isobutylene, keeping the pressure within the range of 6MPa. Step 4: After the addition of isobutylene is completed, keep warm for 2 hours, cool down to room temperature, open the tail gas absorption system, and systematically discharge the unreacted residual tail gas into the tail gas absorption system. Then open the lid of the autoclave and pour out the solution to obtain the crude product. Step 5: The crude oil obtained from the high-pressure reaction is washed with alkali, water, refined and filtered to obtain the final product 200.32g, which is isobutylene sulfide.

[0024] The above-mentioned alkaline washing, water washing, and refining process is as follows: Under the conditions of 65℃-75℃, the water phase is washed with 15% sodium hydroxide solution for 2 hours, and then the aqueous phase and oil phase are separated (the conventional operation of the existing technology). The oil phase is washed with water twice under the conditions of 80℃. The water-washed oil phase is then purified by vacuum distillation, and then further refined by adding bleaching clay and filtering to obtain the product.

[0025] Combination Figure 2As can be seen, the synthesis process of this invention synthesizes sulfurized isobutylene by using an organic amine catalyst and a balanced catalyst, increasing the di-tert-butyl trisulfide content to over 65%, which greatly increases the selectivity of the synthesis process. Furthermore, through gas chromatography and odor detection analysis, the di-tert-butyl disulfide content in the sulfurized isobutylene is reduced by 5%, resulting in a low-odor sulfurized isobutylene product.

[0026] Comparative Example 1: The reaction conditions were the same as in Example 1, but only an organic amine catalyst was used, specifically 1.356 g of hexamethylenediamine, without the addition of a balanced catalyst, to prepare 199.5 g of sulfide isobutylene. The specific steps are as follows: Step 1: Open the lid of the 3L autoclave, add 1.356g of weighed hexamethylenediamine (organic amine catalyst) and 75g of sulfur into the autoclave, seal the lid, and then purge the autoclave with nitrogen 3-5 times (each time the nitrogen pressure is 0.3Mpa-0.4Mpa). Step 2: Weigh out 34g of hydrogen sulfide at once, then turn on the electric heating system of the autoclave to preheat the reactor to 145℃-155℃, and check whether the reactor cooling system is normal. Step 3: Add 112g of isobutylene to the metering tank, controlling the inflow rate to 10mL / min-20mL / min. Therefore, the isobutylene should be added to the metering tank slowly. After the metering tank is full, fill the isobutylene feed line to the reactor. Once the reactor temperature reaches the set temperature of 155℃-185℃, adjust the isobutylene feed pump's feed rate to 5mL / min-30mL / min and slowly begin introducing isobutylene, keeping the pressure within the range of 6MPa. Step 4: After the addition of isobutylene is completed, keep warm for 2 hours, cool down to room temperature, open the tail gas absorption system, and systematically discharge the unreacted residual tail gas into the tail gas absorption system. Then open the lid of the autoclave and pour out the solution to obtain the crude product. Step 5: The crude oil obtained from the high-pressure reaction is washed with alkali, water, refined and filtered to obtain the final product 199.5g, which is the sulfurized isobutylene product.

[0027] The specific process of alkaline washing, water washing, and refining is as follows: Under the conditions of 65℃-75℃, the water phase and oil phase are washed with 15% sodium hydroxide solution for 2 hours. Then, the water phase and oil phase are separated. The oil phase is washed with water twice under the conditions of 80℃. The water-washed oil phase is then distilled under reduced pressure and further refined and filtered with bleaching clay to obtain the product.

[0028] Furthermore, the sulfurized isobutylene products prepared by conventional sulfurized isobutylene, Example 1, and Comparative Example 1 were compared in terms of sulfur content, kinematic viscosity, copper strip corrosion, flash point, odor, and composition (where S2 represents di-tert-butyl disulfide, S3 represents di-tert-butyl trisulfide, S4 represents di-tert-butyl tetrasulfide, and S5 represents di-tert-butyl pentasulfide). Figure 3 The specific comparison results are shown in Table 1.

[0029] Table 1. Comparison of product indicators for conventional sulfurized isobutylene, isobutylene from Example 1, and isobutylene from Comparative Example 1.

[0030] As shown in Table 1, in multiple data comparisons, the sulfurized isobutylene prepared in Example 1 is consistent with the traditional sulfurized isobutylene in terms of sulfur content, kinematic viscosity, and flash point. However, the composition, odor, and copper strip corrosion of the sulfurized isobutylene are significantly improved compared to the traditional sulfurized isobutylene. Specifically, regarding the odor index, in ppm, Example 1 shows only 1 ppm, significantly better than the 9 ppm of the traditional sulfurized isobutylene and the greater than 10 ppm of Comparative Example 1. As for copper strip corrosion, gas chromatography shows that component S4 in Example 1 is only 15.5, significantly lower than the 23 of the traditional sulfurized isobutylene and the 33.2 of Comparative Example 1. Using GB / T5096-2017 "Test Method for Copper Strip Corrosion of Petroleum Products", the test result of Example 1 is 3b. 3b indicates a better degree of copper strip corrosion than 4a and 4c. The copper strip corrosion levels can be found in Table 2 (GB / T5096-2017, page 9).

[0031] Table 2 Grading and Grade Description of Copper Sheet Etching Standard Color Chart

[0032] To verify the improvement in extrusion performance of this conventional sulfurized isobutylene, Example 1 and Comparative Example 1, a four-ball machine test was conducted to compare the indicators of sintering load (PD value), maximum seizure load (PB value) and comprehensive wear value (ZMZ). The specific comparison results are shown in Table 3.

[0033] Table 3. Comparison of four-ball machine test indicators for traditional sulfurized isobutylene, Example 1, and Comparative Example 1.

[0034] The four-ball test data in Table 3 above show that the sintering load (PD value), maximum non-seize load (PB value), and comprehensive wear value (ZMZ) of sulfurized isobutylene are all superior to those of traditional sulfurized isobutylene. Therefore, in the composite systems of downstream lubricant manufacturers, the amount of sulfurized isobutylene added as a single agent can be greatly reduced, thereby achieving a year-on-year reduction in lubricant costs. It is evident that the extrusion performance of the sulfurized isobutylene obtained in Example 1 is superior to that of traditional sulfurized isobutylene products.

Claims

1. A process for synthesizing isobutylene sulfide, characterized in that, The steps of the synthesis process include: Step 1: Weigh sulfur, organic amine catalyst and balanced catalyst and place them in the reaction vessel, and then purge with nitrogen; Step 2: Add hydrogen sulfide, then preheat; Step 3: Heat to the reaction temperature, add isobutylene, and maintain the reaction pressure; Step 4: After the isobutylene is added, keep warm for 2 to 5 hours, then cool to room temperature to obtain the crude product; Step 5: The crude product is washed with alkali, water, refined and filtered to obtain isobutylene sulfide.

2. The synthesis process of isobutylene sulfide according to claim 1, characterized in that, In steps 1 and 2, the mass ratio of sulfur:isobutylene:hydrogen sulfide:organic amine catalyst:balanced catalyst is (73.7-80):112:34:1.356:0.

226.

3. The synthesis process of isobutylene sulfide according to claim 1, characterized in that, In step 2, the preheating temperature is 145℃-155℃.

4. The synthesis process of isobutylene sulfide according to claim 1, characterized in that, In step 3, the reaction temperature is 155℃-185℃; The reaction pressure is ≤6.5 MPa.

5. The synthesis process of isobutylene sulfide according to claim 1, characterized in that, In step 1, the organic amine catalyst is hexamethylenediamine.

6. The synthesis process of isobutylene sulfide according to claim 1, characterized in that, In step 1, the balanced catalyst is any one or more of copper oxide, aluminum oxide, silicon oxide, calcium oxide, magnesium oxide, sodium oxide, zinc oxide, manganese oxide, iron oxide, or chromium oxide.

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