A method for continuous preparation of diisopropyl xanthogen disulfide based on a micro-packed bed reactor

Abstract

A method for preparing diisopropyl xanthate, a solid base catalyst is filled into a fixed bed reactor after being immobilized with molybdenum disulfide, a mixed solution of isopropyl alcohol, carbon disulfide and an organic solvent is injected into a micro-mixer through a feeding pump at the same time with oxygen or air, the gas-liquid mixture is fully mixed and then enters the fixed bed for heterogeneous catalytic oxidation reaction. The solid base-immobilized composite catalyst has long service life and good stability; the composite base catalyst can provide an alkaline environment to promote the formation of intermediates and avoid the generation of high-salt wastewater; a micro-mixer is added at the front end of the fixed bed reactor to realize the full mixing of gas-liquid, so that the gas-liquid heterogeneous catalytic oxidation reaction can be continuously carried out with high efficiency and high selectivity; oxygen or air which is cheap and easy to obtain is used as the oxidant, and the by-product is water, basically without three wastes.

Description

Technical Field

[0001] This invention belongs to the field of fine chemicals, specifically relating to a method for the continuous preparation of diisopropyl disulfide xanthate based on a micro-packed bed reactor. Background Technology

[0002] Diisopropyl xanthate disulfide (DIP) is primarily used as a molecular weight regulator in the synthesis of low molecular weight xanthate-terminated polymers. It can also serve as a super-accelerator for natural and synthetic rubber, a lubricant additive, an ore flotation agent, a fungicide, and a herbicide. Furthermore, DIP is an important intermediate in the production of high-performance, environmentally friendly rubber vulcanizing agents, specifically diisopropyl xanthate polysulfides.

[0003] The synthesis of diisopropyl xanthate disulfide generally involves two reaction stages: 1. Isopropanol, carbon disulfide, and an alkali (such as sodium hydroxide) react under certain conditions to obtain isopropyl xanthate; 2. Isopropyl xanthate is oxidized by an oxidizing agent (such as sodium hypochlorite, hydrogen peroxide, chlorine, or potassium persulfate) to generate diisopropyl xanthate disulfide.

[0004] Chinese Patent CN 114920677 A discloses a method for synthesizing diisopropyl disulfide xanthate using cyclohexane as a solvent and adding a highly efficient water-binding agent to the system. This synthesis method has high yield and good quality. Its drawbacks are: to promote the deep conversion of the raw material isopropanol, an alkali is added to shift the equilibrium to the right; however, during the oxidation reaction, acid must be added to protonate sodium xanthate before it can react with the oxidant, which generates a large amount of high-salt wastewater; since cyclohexane is used as a solvent in the intermediate synthesis process, the intermediate must be separated and dissolved in water before subsequent oxidation steps can be carried out, making the production process relatively complex and inefficient.

[0005] Chinese patent CN 106380436 B discloses a method for synthesizing diisopropyl disulfide xanthate using isopropanol as a reaction solvent and chlorine as an oxidant. This method achieves a product yield of up to 90-95% and a purity of up to 99%. However, its drawbacks include: while achieving a one-step process, it still generates a large amount of high-salt wastewater; the use of highly toxic chlorine as an oxidant poses significant safety risks; and because isopropanol is used as a solvent, the post-processing requires distillation to recover the isopropanol to reduce material costs, which undoubtedly increases energy consumption. Furthermore, isopropanol and water have an azeotropic composition (87.4% / 12.6%), requiring dehydration before reuse, making the production process relatively complex.

[0006] The two processes described above are currently the two mainstream processes used in production, each with its own advantages and disadvantages. Because both employ batch reactor processes, compared to continuous processes, they have lower production efficiency and more complex processes, which does not align with the development direction of continuous, automated, intelligent, and green chemical production. Summary of the Invention

[0007] To address the shortcomings of the above-mentioned processes, this invention provides a method for the continuous preparation of diisopropyl disulfide xanthate based on a micro-packed bed reactor. The specific process is as follows: molybdenum disulfide and a solid alkaline catalyst are immobilized in a specific manner and then packed into a specific fixed-bed reactor. A mixed solution of isopropanol, carbon disulfide, and an organic solvent, along with oxygen or air, is simultaneously injected into a micro-mixer under certain process conditions via a feed pump. This ensures thorough gas-liquid mixing before the mixture enters the fixed bed for a heterogeneous catalytic oxidation reaction. After the solvent is evaporated from the reaction solution, other solvents are added for recrystallization to obtain high-purity diisopropyl disulfide xanthate.

[0008]

[0009] The catalyst of the present invention is prepared by mixing powdered molybdenum disulfide and solid alkaline catalyst in a certain proportion and grinding them thoroughly; adding a certain proportion of hydroxyethyl cellulose colloid to the above mixed powder and mixing them evenly; filling the mixed paste into a specific mold and drying it to obtain spherical catalyst particles or spreading it on a tray, drying it, and then cutting it to obtain sheet catalyst.

[0010] The solid alkaline catalyst of the present invention is sodium hydroxide, potassium hydroxide, copper hydroxide, or calcium hydroxide, preferably calcium hydroxide; the hydroxyethyl cellulose colloid is a 1-10 wt% aqueous solution, preferably 4-6 wt%.

[0011] The mass ratio of molybdenum disulfide, calcium hydroxide, and hydroxyethyl cellulose colloid in this invention is 1:(0.02-1):(30-60), preferably 1:0.04:45.

[0012] The particle size of the catalyst described in this invention should be controlled within 1 mm, preferably 0.2 to 0.6 mm.

[0013] The micro-filled bed selected in this invention should have a micron-sized T-shaped gas-liquid mixer and a fixed-bed reactor with a length-to-diameter ratio of (15-30):1.

[0014] The molar ratio of isopropanol, carbon disulfide, and oxygen in this invention is 1:(1-1.03):(0.5-1), preferably 1:1.01:0.7.

[0015] The process conditions described in this invention are a reaction temperature of 20–80°C, a reaction pressure of 0.1–1.0 MPa, and a residence time of 1–30 min, preferably a reaction temperature of 45–48°C, a reaction pressure of 0.2–0.3 MPa, and a residence time of 3–4 min.

[0016] The reaction solvent of the present invention is one of cyclohexane, toluene, and petroleum ether, preferably cyclohexane; the crystallization solvent is one of water, methanol, and ethanol, preferably water.

[0017] This invention also claims a micro-filled bed reaction system for the continuous preparation of diisopropyl xanthate disulfide, comprising a micro-mixer and a fixed-bed reactor. Molybdenum disulfide and a solid alkaline catalyst are immobilized and filled into the fixed-bed reactor. The feed liquid and oxygen or air enter the micro-mixer through their respective channels for gas-liquid mixing, and then flow through the fixed-bed reactor for heterogeneous catalytic oxidation reaction. After the reaction, the product is continuously separated into gas and liquid in a gas-liquid separator, and the oxygen or air and the product liquid are discharged separately.

[0018] Furthermore, oxygen or air is discharged through a back pressure valve; the micro mixer is a T-shaped gas-liquid mixer with micron-sized channels, and the length-to-diameter ratio of the fixed-bed reactor is (15-30):1.

[0019] The innovativeness and beneficial effects of this invention are as follows: 1. Preparation of supported catalysts: Powdered catalysts are uniformly supported on a support, giving the catalyst good plasticity and physical strength. The catalyst has good reactivity and selectivity, resulting in a high conversion rate and selectivity, achieving good process effects. The overall yield can reach over 99%, the purity is >99%, and the melting point is >54℃.

[0020] 2. The construction of a high-efficiency reaction device achieves efficient mixing of gas and liquid flow through a micro mixer. After mixing, a micron-sized bubble flow can be formed, which can carry out efficient catalytic reaction in a fixed-bed reactor. The shorter residence time not only helps to improve efficiency, but also avoids the occurrence of peroxidation side reactions.

[0021] 3. Economic and environmentally friendly: By using an immobilized alkaline catalyst, an alkaline environment is provided to promote the formation of intermediates, which can avoid the generation of large amounts of high-salt wastewater; oxygen or air is used as an oxidant, which is inexpensive, readily available, non-toxic and harmless.

[0022] 4. High efficiency, stability and continuous process: This process can be used to achieve continuous synthesis of DIP, reducing the reaction time from several to tens of hours to 1 to 10 minutes, and there is no batch-to-batch quality difference in the product. Compared with the traditional batch reaction, it can effectively improve the reaction efficiency and product quality stability. Attached Figure Description

[0023] Figure 1This is a flowchart illustrating the continuous preparation of diisopropyl disulfide xanthate based on a micro-packed bed reactor according to the present invention. 1 is a micro mixer, 2 is a fixed-bed reactor, 3 is a gas-liquid separator, and 4 is a back pressure valve. Detailed Implementation

[0024] This section discloses detailed embodiments of the present invention. The embodiments disclosed herein are examples of the invention and may be embodied in different forms. Therefore, the detailed disclosure, including specific structural and functional details, is not intended to limit the invention but merely to form the basis of the claims. The invention will now be described with reference to embodiments and comparative examples. Example 1

[0025] ① Preparation of mixed catalyst: Mix molybdenum disulfide and calcium hydroxide in a mortar until homogeneous; ② Preparation of hydroxyethyl cellulose colloid: Slowly add hydroxyethyl cellulose (CAS 9004-62-0, 2600~3300mPa·s, 25℃) to pure water to prepare a 5wt% hydroxyethyl cellulose aqueous solution. Stir vigorously while adding hydroxyethyl cellulose. After the addition is complete, continue stirring at room temperature until a colorless, transparent, viscous solution is obtained. After dissolution, sonicate the hydroxyethyl cellulose colloid until no more bubbles emerge. Sonicate for at least 2 hours. ③ Catalyst loading operation: Thoroughly mix the hydroxyethyl cellulose colloid with the mixed catalyst, pour the mixed catalyst colloid into a trough-shaped or spherical mold, and use ultrasonic vibration to fill the mold cavity. Then, place the mold in a 70℃ oven to dry, and obtain a fixed catalyst film or spherical catalyst particles after drying. The fixed catalyst film needs to be cut into small fragments with a size of less than 1 mm using scissors. The spherical catalyst particles can be directly used for loading into a fixed bed reactor. ④ Based on the above steps, adjust the proportions of different materials and the shape and particle size of the catalyst to obtain the following catalyst:

[0026] The continuous preparation methods of diisopropyl disulfide xanthate in Examples 2-10 below, based on a fixed-bed reactor, all require adherence to the following steps: ①Isopropanol and carbon disulfide are used as raw materials and dissolved in cyclohexane to form the substrate solution to be oxidized; ② The substrate solution obtained in step ① is simultaneously introduced into the micro mixer 1 by a feed pump and oxygen to form a good gas-liquid micro-dispersion state; ③ The gas-liquid mixture formed in step ② enters a fixed-bed reactor 2 containing supported catalyst particles, and the pressure, temperature and material residence time of the reaction process are controlled to complete the oxidation process; ④ After the reaction in step ③ is completed, the product obtained is subjected to continuous gas-liquid separation in gas-liquid separator 3. The gas enters the tail gas treatment system and is discharged through back pressure valve 4. The liquid product undergoes solvent evaporation and recrystallization. The recovered solvent is recycled for the preparation of the substrate solution in step ①. After recrystallization, the solid is filtered and dried to obtain the finished product. A continuous catalytic oxidation reaction was carried out in an 8×120 (6ml) fixed-bed reactor. CHJ-1 to CHJ-8 from the examples were respectively packed into the above fixed-bed reactor for experiments. The following experiments were conducted under different process conditions. Example 2

[0027] The experiment was conducted according to the above method. A cyclohexane solution of isopropanol and carbon disulfide with a mass concentration of 10% (calculated as xanthic acid) was prepared. The molar ratio of isopropanol, carbon disulfide, and oxygen was 1:1:0.5. The solution and oxygen were mixed in an inlet T-type micro-mixer to form a well-dispersed gas-liquid state. The mixture flowed through a micro-packed bed containing CHJ-1. The reaction temperature was controlled at 40℃, the reaction pressure at 0.2 MPa, and the residence time at 1 min. After separation by a gas-liquid separator, the liquid product was collected after 2 h of stable conditions. The cyclohexane was removed by vacuum distillation at -0.09 MPa and 40℃. 100 g of water was added for recrystallization of the product. After filtration, the product was dried at 40℃ to obtain off-white crystals. The product yield was 90.3%, the melting point was 54.5℃, and the purity was 99.1%. Example 3

[0028] The experiment was conducted according to the above method. A cyclohexane solution of isopropanol and carbon disulfide with a mass concentration of 20% (based on xanthic acid) was prepared. The molar ratio of isopropanol, carbon disulfide, and oxygen was 1:1.01:0.55. The solution and oxygen were mixed in an inlet T-type micro-mixer to form a well-dispersed gas-liquid state. The mixture flowed through a micro-packed bed containing CHJ-2. The reaction temperature was controlled at 45℃, the reaction pressure at 0.2 MPa, and the residence time at 1 min. After separation by a gas-liquid separator, the liquid product was collected after 2 h of stable conditions. Cyclohexane was removed by vacuum distillation at -0.09 MPa and 40℃. 100 g of water was added for recrystallization of the product. After filtration, the product was dried at 40℃ to obtain off-white crystals. The product yield was 90.1%, the melting point was 54.3℃, and the purity was 99%. Example 4

[0029] The experiment was conducted according to the above method. A cyclohexane solution of isopropanol and carbon disulfide with a mass concentration of 30% (based on xanthic acid) was prepared. The molar ratio of isopropanol, carbon disulfide, and oxygen was 1:1.01:0.6. The solution and oxygen were mixed in an inlet T-type micro-mixer to form a well-dispersed gas-liquid state. The mixture flowed through a micro-packed bed containing CHJ-3. The reaction temperature was controlled at 45℃, the reaction pressure at 0.25 MPa, and the residence time at 2 min. After separation by a gas-liquid separator, the liquid product was collected after 2 h of stable conditions. Cyclohexane was removed by vacuum distillation at -0.09 MPa and 40℃. 100 g of water was added for recrystallization of the product. After filtration, the product was dried at 40℃ to obtain off-white crystals. The product yield was 92.7%, the melting point was 54.7℃, and the purity was 99.3%. Example 5

[0030] The experiment was conducted according to the above method. A cyclohexane solution of isopropanol and carbon disulfide with a mass concentration of 30% (based on xanthic acid) was prepared. The molar ratio of isopropanol, carbon disulfide, and oxygen was 1:1.01:0.65. The solution and oxygen were mixed in an inlet T-type micro-mixer to form a well-dispersed gas-liquid state. The mixture flowed through a micro-packed bed containing CHJ-4. The reaction temperature was controlled at 50℃, the reaction pressure at 0.25 MPa, and the residence time at 3 min. After separation by a gas-liquid separator, the liquid product was collected after 2 h of stable conditions. Cyclohexane was removed by vacuum distillation at -0.09 MPa and 40℃. 100 g of water was added for recrystallization of the product. After filtration, the product was dried at 40℃ to obtain off-white crystals. The product yield was 94.9%, the melting point was 54.7℃, and the purity was 99.2%. Example 6

[0031] The experiment was conducted according to the above method. A cyclohexane solution of isopropanol and carbon disulfide with a mass concentration of 35% (based on xanthic acid) was prepared. The molar ratio of isopropanol, carbon disulfide, and oxygen was 1:1.01:0.7. The solution and oxygen were mixed in an inlet T-type micro-mixer to form a well-dispersed gas-liquid state. The mixture flowed through a micro-packed bed containing CHJ-5. The reaction temperature was controlled at 50℃, the reaction pressure at 0.25 MPa, and the residence time at 3 min. After separation by a gas-liquid separator, the liquid product was collected after 2 h of stable conditions. Cyclohexane was removed by vacuum distillation at -0.09 MPa and 40℃. 100 g of water was added for recrystallization of the product. After filtration, the product was dried at 40℃ to obtain off-white crystals. The product yield was 95.2%, the melting point was 54.9℃, and the purity was 99.2%. Example 7

[0032] The experiment was conducted according to the above method. A cyclohexane solution of isopropanol and carbon disulfide with a mass concentration of 35% (based on xanthic acid) was prepared. The molar ratio of isopropanol, carbon disulfide, and oxygen was 1:1.01:0.7. The solution and oxygen were mixed in an inlet T-type micro-mixer to form a well-dispersed gas-liquid state. The mixture flowed through a micro-packed bed containing CHJ-6. The reaction temperature was controlled at 50℃, the reaction pressure at 0.25 MPa, and the residence time at 3.5 min. After separation by a gas-liquid separator, the liquid product was collected after 2 h of stable conditions. Cyclohexane was removed by vacuum distillation at -0.09 MPa and 40℃. 100 g of water was added for recrystallization of the product. After filtration, the product was dried at 40℃ to obtain off-white crystals. The product yield was 95.6%, the melting point was 54.8℃, and the purity was 99.1%. Example 8

[0033] The experiment was conducted according to the above method. A cyclohexane solution of isopropanol and carbon disulfide with a mass concentration of 35% (based on xanthic acid) was prepared. The molar ratio of isopropanol, carbon disulfide, and oxygen was 1:1.01:0.7. The solution and oxygen were mixed in an inlet T-type micro-mixer to form a well-dispersed gas-liquid state. The mixture flowed through a micro-packed bed containing CHJ-7. The reaction temperature was controlled at 48℃, the reaction pressure at 0.25 MPa, and the residence time at 3.5 min. After separation by a gas-liquid separator, the liquid product was collected after 2 h of stable conditions. Cyclohexane was removed by vacuum distillation at -0.09 MPa and 40℃. 100 g of water was added for recrystallization of the product. After filtration, the product was dried at 40℃ to obtain off-white crystals. The product yield was 96.2%, the melting point was 54.9℃, and the purity was 99.3%. Example 9

[0034] The experiment was conducted according to the above method. A cyclohexane solution of isopropanol and carbon disulfide with a mass concentration of 35% (based on xanthic acid) was prepared. The molar ratio of isopropanol, carbon disulfide, and oxygen was 1:1.01:0.7. The solution and oxygen were mixed in an inlet T-type micro-mixer to form a well-dispersed gas-liquid state. The mixture flowed through a micro-packed bed containing CHJ-8. The reaction temperature was controlled at 48℃, the reaction pressure at 0.25 MPa, and the residence time at 3.5 min. After separation by a gas-liquid separator, the liquid product was collected after 2 h of stable conditions. Cyclohexane was removed by vacuum distillation at -0.09 MPa and 40℃. 100 g of water was added for recrystallization of the product. After filtration, the product was dried at 40℃ to obtain off-white crystals. The product yield was 95.2%, the melting point was 54.6℃, and the purity was 99%. Example 10

[0035] The experiment was conducted according to the above method. A cyclohexane solution of isopropanol and carbon disulfide was prepared using the mother liquor from Example 8, with a mass concentration of 35% (based on xanthic acid). The molar ratio of isopropanol, carbon disulfide, and oxygen was 1:1.01:0.7. The solution and oxygen were mixed in an inlet T-type micro-mixer to form a well-dispersed gas-liquid state. The mixture flowed through a micro-packed bed containing CHJ-7. The reaction temperature was controlled at 48℃, the reaction pressure at 0.25 MPa, and the residence time at 3.5 min. The experiment was run continuously for over 500 hours. Every 50 hours, the liquid product separated by the gas-liquid separator underwent vacuum distillation to remove cyclohexane and recrystallization with water. After filtration, the product was dried at 40℃ to obtain off-white crystals. After the experiment, the calculated overall product yield was 99.3%, the melting point was 54.7–55.2℃, and the purity was 99.3–99.6%. The recovered cyclohexane was recycled 10 times.

[0036] Comparative Example 1 At room temperature, towards 1m 3 200 kg of cyclohexane, 50 kg of solid sodium hydroxide, and 8 kg of sodium sulfate were added to a reactor, and stirring was started. At 20–25 °C, 20 kg of isopropanol was pumped in sequentially, followed by the slow addition of 30 kg of carbon disulfide. This process was repeated 3 times for a total of 4 times, and the mixture was kept at this temperature for 3 hours. The intermediate product was filtered, and water was added and stirred to form a solution. Then, 260 kg of 8% hydrogen peroxide solution was slowly added at 20–30 °C, and the reaction was continued for 3 hours until completion. Separation yielded a pale yellow diisopropyl xanthate disulfide. The yield was 99.2%, and the purity was 99.6%.

[0037] Comparative Example 2 300g (5.0 mol) of isopropanol and 49g (1.2 mol) of sodium hydroxide (98% purity) were added to a 1000ml four-necked glass flask equipped with a high-speed disperser (model: IKA T25 digital ULTRA-TURRAX® disperser, disperser head S25 N-25G-ST), condenser, thermometer, and dropping funnel. The mixture was pulverized at 8000 RPM for 5 minutes until the particle size of the material was reduced to below 100μm. The speed of the high-speed disperser was then adjusted to 3000 RPM. The temperature of the reactants was controlled within the range of 35-40℃ using a water bath. 76g (1.0 mol) of carbon disulfide was added dropwise over 50 minutes. After 20 minutes of carbon disulfide addition, chlorine gas was introduced. The chlorine gas flow rate was controlled, and 44.5g (0.63 mol) of chlorine gas was introduced over 100 minutes. Then, at this temperature, the speed of the high-speed disperser was adjusted to 500 RPM, and the reaction was continued for 10 minutes (the particle size of the material remained below 100 μm throughout the reaction). After the reaction, insoluble matter was removed by filtration. The filter cake was washed twice with 100 g of isopropanol each time. The filtrate was transferred to a distillation flask, and 400 g of water and 1.0 g of emulsifier OP-10 were added. Isopropanol was recovered by distillation. When the temperature reached 85°C, the distillation was stopped. The mixture was stirred and cooled to room temperature. Finally, it was filtered and dried at 50°C under vacuum. Diisopropyl disulfide xanthate solid was obtained, with a product yield (calculated based on carbon disulfide) of 94.2% and a product purity (HPLC purity) of 98.8%.

[0038] The results of Examples 2-10 and Comparative Examples 1-2 are summarized below:

[0039] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for the continuous preparation of diisopropyl disulfide xanthate based on a micro-packed bed reactor, comprising the following steps: (1) Molybdenum disulfide and solid alkaline catalyst are immobilized and then packed into a fixed-bed reactor. (2) A mixed solution of isopropanol, carbon disulfide, and organic solvent is injected simultaneously into the micro mixer along with oxygen or air as the raw material solution. (3) After the raw material liquid is fully mixed with the oxygen or air in the micro mixer, it enters the fixed bed reactor for heterogeneous catalytic oxidation reaction to prepare diisopropyl disulfide xanthate.

2. The method for continuous preparation of diisopropyl disulfide xanthate based on a micro-packed bed reactor according to claim 1, characterized in that, The method for immobilizing molybdenum disulfide and solid alkaline catalyst is as follows: mix powdered molybdenum disulfide with solid alkaline catalyst and grind thoroughly to obtain mixed powder; add hydroxyethyl cellulose colloid to the above mixed powder and mix evenly to obtain paste; fill the paste into a mold and dry to obtain spherical catalyst particles or spread it on a tray, dry it, and then cut it to obtain sheet catalyst.

3. The method for continuous preparation of diisopropyl disulfide xanthate based on a micro-packed bed reactor according to claim 2, characterized in that, The solid alkaline catalyst is any one of sodium hydroxide, potassium hydroxide, copper hydroxide, and calcium hydroxide, and the hydroxyethyl cellulose colloid is a 1-10 wt% aqueous solution.

4. The method for continuous preparation of diisopropyl disulfide xanthate based on a micro-packed bed reactor according to claim 3, characterized in that, The solid alkaline catalyst is calcium hydroxide, and the hydroxyethyl cellulose colloid is a 4-6 wt% aqueous solution.

5. The method for continuous preparation of diisopropyl disulfide xanthate based on a micro-packed bed reactor according to claim 4, characterized in that, The mass ratio of molybdenum disulfide, calcium hydroxide, and hydroxyethyl cellulose colloid is 1:(0.02-1):(30-60); the particle size of the spherical or sheet-like catalyst is controlled within 1 mm.

6. The method for continuous preparation of diisopropyl disulfide xanthate based on a micro-packed bed reactor according to claim 1, characterized in that, The micro-filled bed reactor includes a micro-mixer and a fixed bed reactor. The micro-mixer is a T-shaped gas-liquid mixer with micron-sized channels, and the fixed bed reactor has an aspect ratio of (15-30):

1.

7. The method for continuous preparation of diisopropyl disulfide xanthate based on a micro-packed bed reactor according to claim 1, characterized in that, The molar ratio of isopropanol, carbon disulfide, and oxygen is 1:(1-1.03):(0.5-1).

8. The method for continuous preparation of diisopropyl disulfide xanthate based on a micro-packed bed reactor according to claim 1, characterized in that, The reaction temperature is 20–80℃, the reaction pressure is 0.1–1.0 MPa, and the residence time is 1–30 min, preferably 45–48℃, 0.2–0.3 MPa, and 3–4 min.

9. The method for continuous preparation of diisopropyl disulfide xanthate based on a micro-packed bed reactor according to claim 1, characterized in that, It also includes step (4), where the solvent is evaporated from the reaction solution and then a crystallization solvent is added for recrystallization to obtain high-purity diisopropyl disulfide xanthate.

10. A micro-packed bed reaction system for the continuous preparation of diisopropyl disulfide xanthate, characterized in that, It includes a micro mixer and a fixed-bed reactor. Molybdenum disulfide and a solid alkaline catalyst are immobilized and filled into the fixed-bed reactor. The feed liquid and oxygen or air enter the micro mixer through their respective channels for gas-liquid mixing. Then, the mixture flows through the fixed-bed reactor for heterogeneous catalytic oxidation. After the reaction, the product is continuously separated into gas and liquid in a gas-liquid separator. The oxygen or air and the product liquid are discharged separately.

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