Method for synthesizing and refining DMS and DMSO embedded into methanol plant

Abstract

The invention relates to the technical field of organic sulfide preparation, in particular to a method for synthesizing and refining dimethyl sulfide (DMS) and dimethyl sulfoxide (DMSO) embedded into a methanol plant, which mainly utilizes high-purity oxygen of an air separation unit of the methanol plant, a high-concentration hydrogen sulfide product of low-temperature methanol washing and part of top gas-phase refined methanol of a pressurizing tower of a methanol rectification device. The production cost of the product is reduced, the added value of the product is improved, and the hydrogen sulfide product of a methanol plant is effectively utilized.

Description

Technical Field

[0001] This invention relates to the field of organosulfur compound preparation technology, specifically a method for the synthesis and purification of dimethyl sulfide (DMS) and dimethyl sulfoxide (DMSO) embedded in a methanol plant. It utilizes high-purity oxygen from the methanol plant's air separation unit, high-concentration hydrogen sulfide products from low-temperature methanol washing, a portion of the top gaseous refined methanol from the pressurized column of the methanol distillation unit, and low-pressure steam as a byproduct of the methanol synthesis unit, thereby reducing production costs and increasing product added value. Background Technology

[0002] In existing chemical production, dimethyl sulfide (DMS) and dimethyl sulfoxide (DMSO) are important organosulfur compounds, widely used in pharmaceuticals, pesticides, dyes, and fragrances. However, traditional processes have the following problems:

[0003] 1. Low utilization rate of raw materials, especially low utilization rate of sulfur atoms.

[0004] 2. The production process has high energy consumption, with significant consumption of steam, circulating water, liquid ammonia, and electricity.

[0005] 3. The separation and purification process is complex, and the purity of the product is difficult to guarantee.

[0006] 4. Exhaust gas treatment is difficult and has a certain impact on the environment. Summary of the Invention

[0007] To address the problems existing in the prior art, this invention provides a method for the synthesis and purification of DMS and DMSO embedded in a methanol plant. By optimizing the process flow, it improves the utilization rate of raw materials, reduces energy consumption, simplifies the separation and purification process, and effectively treats the exhaust gas, thereby achieving green production.

[0008] The main processing steps of this invention are as follows:

[0009] 1. Raw material pretreatment

[0010] Gas mixture compression: Hydrogen sulfide (H2S), carbon dioxide (CO2), and methanol (MeOH) are mixed and compressed to ensure uniform distribution of the raw materials in subsequent reactions.

[0011] Cryogenic purification of H2S: Cryogenic purification of H2S removes impurities, especially carbon dioxide (CO2), and improves its purity, providing high-purity raw materials for subsequent reactions.

[0012] Multi-stage preheating: The mixed gas is preheated in multiple stages to reach the temperature conditions required for the reaction, while simultaneously recovering and utilizing heat to improve energy efficiency.

[0013] 2. DMS Synthesis

[0014] DMS Synthesis Reaction: Preheated feed gas is introduced into the DMS synthesis reactor, and dimethyl sulfide (DMS) is synthesized under specific temperature, pressure and catalyst conditions.

[0015] Multi-stage cooling: The DMS gas generated during the reaction is cooled by a multi-stage cooling device to recover the heat of reaction, save heat for multi-stage preheating, and ensure that the temperature of the reaction products is suitable to avoid the impact of high temperature on subsequent equipment.

[0016] 3. DMS Refined

[0017] Methanol removal tower: The product from the DMS synthesis reactor is introduced into the methanol removal tower to separate excess methanol and initially improve the purity of DMS.

[0018] Demethyl mercaptan: The methanol-free DMS is introduced into the demethyl mercaptan to remove impurities such as methanethiol, thereby further improving the purity of the DMS.

[0019] PSD Alcohol-Ether Separation: The impurity-removed DMS is introduced into the PSD alcohol-ether separation unit. Through acid-aldehyde separation technology, the alcohol and ether components in the product are separated, ensuring the purity of the DMS. The methanol gas generated during the separation process, along with refined methanol gas from the methanol distillation pressurization tower, is recycled as feedstock.

[0020] 4.DMSO synthesis

[0021] DMSO synthesis reaction: The purified DMS gas is introduced into the DMSO synthesis reactor, and under the action of a one-time purging of circulating nitrogen dioxide (NO2) and oxygen (O2), the DMS is further oxidized to dimethyl sulfoxide (DMSO).

[0022] Multi-stage cooling: The reaction products are cooled by a multi-stage cooling device to ensure the smooth progress of the reaction and improve the yield of DMSO.

[0023] 5. DMSO Refined

[0024] Vacuum flash evaporation: The product from the DMSO synthesis reactor is introduced into a vacuum flash evaporation unit, where it is flashed using vacuum technology to further purify the DMSO.

[0025] Vacuum distillation: DMSO is further purified using techniques such as vacuum distillation to ensure that the product quality meets the standards.

[0026] 6. Waste gas recovery and treatment

[0027] Alkaline washing and evaporation: The waste liquid and exhaust gas generated in the mercaptan removal tower are passed into an alkaline washing and evaporation unit, where a 10% NaOH solution is used for alkaline washing to remove acidic gases and other impurities. The treated exhaust gas is then further purified through evaporation.

[0028] Recycling: DMSO is recycled as a reaction solvent, improving resource utilization.

[0029] After the methanol removal tower, the methanol gas is processed by a distillation and pressurization tower, with part of it being recycled and part being output as a product.

[0030] The treated tail gas after alkaline washing and evaporation is used for methanol distillation to further recover the methanol.

[0031] The refined methanol produced in the PSD alcohol-ether separation process, together with the refined methanol gas from the methanol distillation pressurization tower, is recycled as a raw material.

[0032] The technical solution of this invention is a method for the synthesis and purification of DMS and DMSO embedded in a methanol plant, comprising the following steps:

[0033] 1) Raw material pretreatment: The hydrogen sulfide, carbon dioxide and methanol raw materials are mixed and compressed, the hydrogen sulfide is cryogenically purified, and the mixed gas is preheated in multiple stages.

[0034] 2) DMS Synthesis: The preheated feed gas is introduced into the DMS synthesis reactor. Under the action of the catalyst, the mass ratio of catalyst to methanol is 10-18:1 to synthesize dimethyl sulfide (DMS). The heat of reaction is recovered by cooling the DMS gas through a multi-stage cooling device.

[0035] The reaction temperature for DMS synthesis is 350°C to 390°C, and the reaction pressure is 1.5 to 2.5 MPa.

[0036] 3) DMS purification: The product from the DMS synthesis reactor is introduced into a methanol removal tower to separate excess methanol. The methanol-removed DMS is then introduced into a mercaptan to remove impurities. The impurity-removed DMS is then introduced into a PSD alcohol-ether separation unit, where the alcohol and ether components in the product are separated using acid-aldehyde separation technology.

[0037] 4) DMSO synthesis: The purified DMS gas is introduced into the DMSO synthesis reactor. Under the action of circulating nitrogen dioxide and oxygen introduced in one go, the DMS is further oxidized to dimethyl sulfoxide DMSO, and then cooled.

[0038] The reaction temperature for DMSO synthesis is 100°C to 150°C, and the reaction pressure is 0.5 to 1.0 MPa.

[0039] 5) DMSO purification: The product from the DMSO synthesis reactor is introduced into a vacuum flash evaporation unit for flash purification, and then further purified by vacuum distillation.

[0040] In the aforementioned reduced pressure flash evaporation, the flash temperature is 50°C to 70°C, and the flash pressure is 0.1 to 0.3 MPa;

[0041] In the vacuum distillation, the distillation temperature is 60℃ to 80℃ and the distillation pressure is 0.05 to 0.15MPa; 6) Waste gas recovery and treatment: The waste liquid generated in the demethyl mercaptan and the external tail gas are subjected to alkaline washing and evaporation.

[0042] Furthermore, an alkaline washing treatment is performed using NaOH solution, and the treated exhaust gas is then evaporated.

[0043] Furthermore, the DMSO is recycled as a reaction solvent.

[0044] Furthermore, the methanol gas after the methanol removal tower is processed by a distillation and pressurization tower, with part of it being recycled and part being output as a product.

[0045] Furthermore, in the multi-stage preheating process, the heat generated by the DMS synthesis reaction is used to recover heat through heat exchange and is then used to preheat the raw material gas.

[0046] Furthermore, in the multi-stage cooling process, the reaction products are cooled by a multi-stage cooling device, and the recovered heat is used for the multi-stage preheating step, saving external heat input.

[0047] Furthermore, in the PSD alcohol-ether separation process, the generated methanol gas is directly returned to the raw material pretreatment step via pipeline as a recycled raw material.

[0048] Furthermore, in the alkaline washing and evaporation process, the treated tail gas is returned to the methanol distillation unit through a pipeline for further recovery of methanol.

[0049] Furthermore, in the DMSO synthesis, the ratio of nitrogen dioxide to oxygen is 1:1 to 1:3.

[0050] Furthermore, the treated tail gas after alkaline washing and evaporation is used for methanol distillation to further recover the methanol.

[0051] Among them, the refined methanol produced in the PSD alcohol-ether separation process, together with the refined methanol gas from the methanol distillation pressurization tower, is recycled as raw material.

[0052] The present invention provides a method for the synthesis and purification of DMS and DMSO in a methanol plant, which has the following significant advantages:

[0053] 1. Make full use of existing resources: Utilize the high-purity oxygen from the air separation unit of the methanol plant, the high-concentration hydrogen sulfide products from the low-temperature methanol wash, and part of the top gas phase refined methanol from the pressurized tower of the methanol distillation unit, as well as the low-pressure steam by-product from the methanol synthesis unit, thereby reducing additional raw material procurement and processing costs.

[0054] 2. Reduced production costs: By integrating the existing equipment and resources of the methanol plant, investment in building new independent production units is reduced, while transportation and storage costs are also lowered.

[0055] 3. Improve production efficiency: By utilizing the existing processes and infrastructure of the methanol plant, efficient synthesis and purification of DMS and DMSO can be achieved, shortening the production cycle and improving production efficiency.

[0056] 4. Increase product added value: By embedding the product into the methanol plant's production process, high-purity DMS and DMSO can be produced, thereby enhancing the product's market competitiveness and added value.

[0057] Innovation

[0058] Full-process optimization: This invention optimizes the synthesis and refining process of DMS and DMSO. From raw material pretreatment to product refining, each link is closely connected, realizing a highly efficient and energy-saving production process.

[0059] High sulfur atom utilization rate: By optimizing reaction conditions and process flow, this invention significantly improves sulfur atom utilization rate by 91.4%, reduces raw material waste, and lowers production costs.

[0060] Energy saving and consumption reduction: In the synthesis and refining process, multi-stage preheating, cooling and recycling technologies effectively reduce the consumption of steam, circulating water, liquid ammonia and electricity, thus achieving green production.

[0061] Highly efficient separation and purification: By adopting PSD alcohol-ether separation technology and vacuum distillation technology, the purity and quality of the product are improved. The purity of this invention can reach 99.9%, and the separation and purification process is simplified.

[0062] Environmentally friendly exhaust gas treatment: Through alkaline washing evaporation and recycling technology, we ensure that the exhaust gas and waste liquid discharged from the outside meet environmental protection requirements, thus reducing the impact on the environment.

[0063] Resource recycling: By recycling DMSO as a solvent and using methanol gas generated during PSD alcohol-ether separation and tail gas from alkaline washing and evaporation for methanol distillation, the maximum utilization of resources is achieved. Attached Figure Description

[0064] Figure 1 This is a process flow diagram of the present invention. Detailed Implementation

[0065] The present invention will be further described below with reference to the accompanying drawings.

[0066] like Figure 1 As shown, a method for the synthesis and purification of DMS and DMSO in a methanol plant includes the following steps:

[0067] 1) Raw material pretreatment: The hydrogen sulfide, carbon dioxide and methanol raw materials are mixed and compressed, the hydrogen sulfide is cryogenically purified, and the mixed gas is preheated in multiple stages. The heat generated by the DMS synthesis reaction is used to reduce the input of external heat and improve energy utilization efficiency.

[0068] 2) DMS Synthesis: The preheated raw material gas is introduced into the DMS synthesis reactor, and dimethyl sulfide is synthesized under the action of a catalyst. The DMS gas is cooled by a multi-stage cooling device to recover the heat of reaction and save heat for multi-stage preheating.

[0069] 3) DMS purification: The product from the DMS synthesis reactor is introduced into a methanol removal tower to separate excess methanol. The methanol-removed DMS is then introduced into a mercaptan to remove impurities. The impurity-removed DMS is then introduced into a PSD alcohol-ether separation unit, where the alcohol and ether components in the product are separated using acid-aldehyde separation technology.

[0070] The methanol gas generated during the separation process, together with the refined methanol gas from the methanol distillation pressurization tower, is recycled as a raw material.

[0071] 4) DMSO synthesis: The purified DMS gas is introduced into the DMSO synthesis reactor. Under the action of circulating nitrogen dioxide and oxygen, DMS is further oxidized to dimethyl sulfoxide (DMSO). The reaction products are cooled by a multi-stage cooling device to ensure the smooth progress of the reaction and improve the yield of DMSO.

[0072] 5) DMSO purification: The product from the DMSO synthesis reactor is introduced into a vacuum flash evaporation unit for flash evaporation using vacuum technology to further purify the DMSO; the DMSO is further purified using vacuum distillation and other technologies to ensure that the product quality meets the standards.

[0073] Waste gas recovery and treatment: The waste liquid and exhaust gas generated in the mercaptan removal tower are passed into an alkaline washing and evaporation unit, where a 10±5% NaOH solution is used for alkaline washing to remove acidic gases and other impurities. The treated exhaust gas is further purified by evaporation. DMSO is recycled as a reaction solvent to improve resource utilization. The methanol gas after the methanol removal tower is processed by a distillation pressurization tower, with part of it recycled and part of it output as a product. The treated exhaust gas after alkaline washing and evaporation is used for methanol distillation to further recover methanol. The refined methanol generated in the PSD alcohol-ether separation and the refined methanol gas from the methanol distillation pressurization tower are recycled as raw materials.

[0074] In the multi-stage preheating step, the heat generated by the DMS synthesis reaction is recovered through a heat exchanger and used to preheat the raw material gas.

[0075] In the multi-stage cooling step, the reaction products are cooled by a multi-stage cooling device, and the recovered heat is used for the multi-stage preheating step, saving external heat input.

[0076] In the PSD alcohol-ether separation step, the generated methanol gas is directly returned to the raw material pretreatment step through a pipeline as a recycled raw material.

[0077] In the alkaline washing and evaporation step, the treated tail gas is returned to the methanol distillation unit through a pipeline for further recovery of methanol.

[0078] In the DMSO synthesis reactor, the ratio of nitrogen dioxide (NO2) to oxygen (O2) is 1:1 to 1:3.

[0079] In the reduced pressure flash evaporation step, the flash evaporation temperature is 50°C to 70°C, and the flash evaporation pressure is 0.1 to 0.3 MPa.

[0080] In the vacuum distillation step, the distillation temperature is 60°C to 80°C, and the distillation pressure is 0.05 to 0.15 MPa.

[0081] In the DMS synthesis stage, the preheated feed gas enters the DMS synthesis reactor. The reactor is packed with γ-Al2O3 catalyst, and the mass ratio of catalyst to methanol is 10-18:1, preferably 15:1.

[0082] Hydrogen sulfide reacts with methanol in the presence of a catalyst at temperatures ranging from 350°C to 390°C and pressures ranging from 1.5 to 2.5 MPa to produce dimethyl sulfide (DMS).

[0083] The heat generated during the reaction is recovered and reused in multi-stage preheating steps, thereby saving external heat input and improving energy utilization efficiency.

[0084] In the DMSO synthesis stage, purified DMS gas enters the DMSO synthesis reactor. The reactor is packed with a titanium silicate molecular sieve (TS-1) catalyst, which has an MFI structure, a titanium oxide content of 2.5 to 4.5% by weight, and a surface silicon-to-titanium ratio to bulk silicon-to-titanium ratio of 2.0 to 3.0. Under conditions of 100°C to 150°C and 0.5 to 1.0 MPa pressure, DMS reacts with an oxidant (such as hydrogen peroxide or tert-butyl hydrogen peroxide) in the presence of the catalyst to produce dimethyl sulfoxide (DMSO).

[0085] During the reaction, the reaction products are cooled by a multi-stage cooling device to ensure the smooth progress of the reaction and improve the yield of DMSO.

[0086]

[0087]

[0088] The energy consumption of this invention is significantly lower than that of the other two devices. The sulfur atom utilization rate is 0.914; the DMSO steam consumption is 0.975; the DMSO circulating water consumption is 57.90; the DMSO circulating liquid ammonia consumption is 0.299; and the DMSO power consumption (kW) is 216.4.

Claims

1. A method for the synthesis and purification of DMS and DMSO embedded in a methanol plant, characterized in that, Includes the following steps: 1) Raw material pretreatment: The hydrogen sulfide, carbon dioxide and methanol raw materials are mixed and compressed, the hydrogen sulfide is cryogenically purified, and the mixed gas is preheated in multiple stages. 2) DMS Synthesis: The preheated feed gas is introduced into the DMS synthesis reactor. Under the action of the catalyst, the mass ratio of catalyst to methanol is 10-18:1 to synthesize dimethyl sulfide (DMS). The heat of reaction is recovered by cooling the DMS gas through a multi-stage cooling device. The reaction temperature for DMS synthesis is 350°C to 390°C, and the reaction pressure is 1.5 to 2.5 MPa. 3) DMS purification: The product from the DMS synthesis reactor is introduced into a methanol removal tower to separate excess methanol. The methanol-removed DMS is then introduced into a mercaptan to remove impurities. The impurity-removed DMS is then introduced into a PSD alcohol-ether separation unit, where the alcohol and ether components in the product are separated using acid-aldehyde separation technology. 4) DMSO synthesis: The purified DMS gas is introduced into the DMSO synthesis reactor. Under the action of circulating nitrogen dioxide and oxygen introduced in one go, the DMS is further oxidized to dimethyl sulfoxide DMSO, and then cooled. The reaction temperature for DMSO synthesis is 100°C to 150°C, and the reaction pressure is 0.5 to 1.0 MPa. 5) DMSO purification: The product from the DMSO synthesis reactor is introduced into a vacuum flash evaporation unit for flash purification, and then further purified by vacuum distillation. In the aforementioned reduced pressure flash evaporation, the flash temperature is 50°C to 70°C, and the flash pressure is 0.1 to 0.3 MPa; In the aforementioned vacuum distillation, the distillation temperature is 60°C to 80°C, and the distillation pressure is 0.05 to 0.15 MPa; 6) Waste gas recovery and treatment: The waste liquid generated in the mercaptan removal tower and the external tail gas are subjected to alkaline washing and evaporation.

2. The method for synthesizing and purifying DMS and DMSO in a methanol plant according to claim 1, characterized in that, The exhaust gas is then subjected to alkaline washing with NaOH solution and subsequently evaporated.

3. The method for synthesizing and purifying DMS and DMSO in a methanol plant according to claim 1, characterized in that, The DMSO is recycled as a reaction solvent.

4. The method for synthesizing and purifying DMS and DMSO in a methanol plant according to claim 1, characterized in that, After the methanol removal tower, the methanol gas is processed by a distillation and pressurization tower, with part of it being recycled and part being output as a product.

5. The method for synthesizing and purifying DMS and DMSO in a methanol plant according to claim 1, characterized in that, In the multi-stage preheating process, the heat generated by the DMS synthesis reaction is used to recover heat through heat exchange and is then used to preheat the raw material gas.

6. The method for synthesizing and purifying DMS and DMSO in a methanol plant according to claim 1, characterized in that, In the multi-stage cooling process, the reaction products are cooled by a multi-stage cooling device, and the recovered heat is used for multi-stage preheating steps, saving external heat input.

7. The method for synthesizing and purifying DMS and DMSO in a methanol plant according to claim 1, characterized in that, In the PSD alcohol-ether separation process, the generated methanol gas is directly returned to the raw material pretreatment step via pipeline as a recycled raw material.

8. The method for synthesizing and purifying DMS and DMSO in a methanol plant according to claim 1, characterized in that, In the alkaline washing and evaporation process, the treated tail gas is returned to the methanol distillation unit through a pipeline for further recovery of methanol.

9. The method for synthesizing and purifying DMS and DMSO in a methanol plant according to claim 1, characterized in that, In the DMSO synthesis, the ratio of nitrogen dioxide to oxygen is 1:1 to 1:

3.

10. The method for synthesizing and purifying DMS and DMSO in a methanol plant according to claim 1, characterized in that, The treated tail gas after alkaline washing and evaporation is used for methanol distillation to further recover methanol. The refined methanol produced in the PSD alcohol-ether separation process, together with the refined methanol gas from the methanol distillation pressurization tower, is recycled as a raw material.

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