A system and method for continuous production of n-octanethiol

Abstract

The application relates to a system and a method for continuously producing n-octyl mercaptan, the system comprising a first reaction unit (1) and a second reaction unit (2); the first reaction unit (1) comprises a first reactor (11) and a first phase separator (12), the input end of the first reactor (11) is connected with a n-octanol conveying pipeline and a hydrobromic acid conveying pipeline, and the output end is connected with the first phase separator (12); the second reaction unit (2) comprises a second reactor (21) and a second phase separator (22), the input end of the second reactor (21) is connected with the first phase separator (12) and a sodium hydrosulfide conveying pipeline, and the output end is connected with the second phase separator (22). Compared with the prior art, the application has the advantages of realizing efficient, safe and low-energy-consumption industrial production and the like.

Description

Technical Field

[0001] This invention relates to the field of organosulfur compound synthesis technology, and in particular to a system and method for the continuous production of n-octylthiol. Background Technology

[0002] n-Octamethasone (C8H) 18 Octyl mercaptan (n-octyl mercaptan) is an important organic intermediate widely used in pesticide synthesis (such as insecticides and herbicides), pharmaceuticals (such as antiviral drug precursors), rubber additives (to promote vulcanization reactions), and polymer modification (such as polypropylene antioxidants). With the development of the global fine chemical industry, the market demand for high-purity n-octyl mercaptan has been increasing year by year. According to industry statistics, the average annual growth rate is 8%. Traditional production methods mostly employ batch processes, using octanol (or octyl halides) with thiourea or hydrogen sulfide (H2S) as raw materials, reacting under high temperature and high pressure conditions to generate the target product. However, due to its low efficiency and significant safety hazards, it is difficult to meet the needs of industrial production. Existing technologies have the following drawbacks:

[0003] Batch processes are inefficient: reaction times can be as long as 6-12 hours, resulting in high equipment downtime and making it difficult to meet the demands of large-scale production. For example, when using a batch reactor to produce n-octyl mercaptan, the single batch capacity is only 500 kg, with an annual capacity of less than 300 tons. Moreover, the repeated heating and cooling processes increase energy consumption, with energy costs per ton of product being approximately 30% higher than that of continuous processes.

[0004] Significant safety risks exist: Hydrogen sulfide (H2S) is a highly toxic, flammable, and explosive gas. Intermittent operation requires frequent opening and closing of the reactor for feeding, which easily leads to leakage risks. According to statistics, in 2019, a chemical plant suffered three people poisoned due to a hydrogen sulfide (H2S) leak, resulting in direct economic losses exceeding 5 million yuan.

[0005] Complex byproducts: During the reaction, byproducts such as n-octyl disulfide and n-octyl sulfide are easily generated, and the purity of the product is only 85%-90%. Multi-stage distillation (3-4 times) is required to reach the industrial grade standard (≥98%), and the post-processing cost accounts for 40% of the total cost.

[0006] High energy consumption: The reaction requires high temperature and high pressure conditions, and the intermittent process of repeated heating and cooling leads to energy waste.

[0007] Significant environmental pressure: Traditional catalysts using concentrated sulfuric acid generate large amounts of acidic wastewater (pH < 2), which is difficult to treat. Approximately 2 tons of wastewater are generated per ton of product, resulting in significant environmental pressure and making large-scale industrial continuous production difficult.

[0008] Existing Chinese patent CN113372248A discloses a method for preparing octylthiol. Although it improves the thiol synthesis route, it still employs a batch reaction and does not solve the problems of hydrogen sulfide leakage and waste acid water. Existing international patent WO2019055560A1 proposes a continuous reactor design, but it suffers from short catalyst lifetime (only 200 hours), numerous byproducts, and ineffective recovery, failing to address the industry's key challenges and bottlenecks. Therefore, there is an urgent need to develop an efficient, safe, and continuously operating process system and method. Summary of the Invention

[0009] The purpose of this invention is to provide a system and method for the continuous production of n-octylthiol, which achieves efficient, safe, and low-energy-consumption industrial production through continuous reaction technology and continuous separation process.

[0010] The objective of this invention can be achieved through the following technical solution: a system for continuous production of n-octylthiol, comprising a primary reaction unit and a secondary reaction unit;

[0011] The primary reaction unit includes a primary reactor and a primary phase separator. The input end of the primary reactor is connected to the n-octanol delivery pipeline and the hydrobromic acid delivery pipeline, and the output end is connected to the primary phase separator.

[0012] The secondary reaction unit includes a secondary reactor and a secondary phase separator. The input end of the secondary reactor is connected to the primary phase separator and the sodium hydrosulfide delivery pipeline, and the output end is connected to the secondary phase separator.

[0013] Preferably, the primary reactor is a tubular fixed-bed reactor.

[0014] Preferably, the primary reactor is filled with a catalyst for catalyzing the reaction of n-octanol and hydrobromic acid to produce n-octane.

[0015] More preferably, the catalyst is a solid superacid catalyst.

[0016] More preferably, the solid superacid catalyst has a particle size of 0.5 to 1.0 mm.

[0017] More preferably, the solid superacid catalyst comprises a superacid containing halogen, fluorosulfonic acid resin or sulfuric acid system.

[0018] Preferably, the primary reactor is made of Hastelloy C276.

[0019] Preferably, the secondary reactor is a tubular reactor.

[0020] Preferably, the secondary reactor is filled with a catalyst for catalyzing the reaction of n-octane bromide with sodium hydrosulfide to produce n-octane mercaptan.

[0021] More preferably, the catalyst comprises a super-strong solid acid containing halogen, fluorosulfonic acid resin, or sulfuric acid system.

[0022] Preferably, the n-octanol delivery pipeline is equipped with a primary heater, the hydrobromic acid delivery pipeline is equipped with a primary heat exchanger, and the output end of the primary reactor is connected to the input end of the primary phase separator through the primary heat exchanger.

[0023] Preferably, the hydrobromic acid delivery pipeline is connected to the n-octanol delivery pipeline, and the hydrobromic acid delivery pipeline is connected to the primary reactor through the n-octanol delivery pipeline.

[0024] Preferably, an extraction unit is provided between the primary reaction unit and the secondary reaction unit;

[0025] The extraction unit includes an extraction tower, the input end of which is connected to the aqueous phase outlet of the primary phase separator, and the top of the extraction tower is connected to the input end of the secondary reactor.

[0026] More preferably, the extractant in the extraction tower is a synthetic extractant.

[0027] More preferably, the synthetic extractant is a halogenated alkane extractant.

[0028] More preferably, the extraction tower is made of 316L stainless steel.

[0029] More preferably, the extraction unit further includes an extractant recovery tower and a first feed pump;

[0030] The bottom of the extraction tower is connected to the input end of the extractant recovery tower via a first feed pump, and the bottom of the extractant recovery tower is connected back to the extraction tower.

[0031] More preferably, the extraction tower is a packed tower with a theoretical plate number of 10 to 30.

[0032] More preferably, the top of the extraction tower is connected to the input end of the secondary reactor via a secondary cooler;

[0033] The sodium hydrosulfide delivery pipeline is equipped with a secondary heat exchanger, and the output end of the secondary reactor is connected to the input end of the secondary phase separator through the secondary heat exchanger.

[0034] More preferably, the input end of the secondary reactor is connected to the oil phase outlet of the primary phase separator via a secondary cooler.

[0035] Preferably, the output of the secondary reaction unit is connected to a purification unit.

[0036] More preferably, the refining unit includes a refining tower and a recovery tower, the input end of the refining tower is connected to the oil phase outlet of the secondary phase separator, and the top of the refining tower is connected to the product tank;

[0037] The bottom of the refining tower is connected to a recovery tower via a recovery tank and a second feed pump, and the top of the recovery tower is connected to a product tank.

[0038] More preferably, the recovery tank is connected to a reducing agent delivery pipeline.

[0039] A method for continuous production of n-octylthiol, using the above-described system, includes the following steps:

[0040] Octyl alcohol and hydrobromic acid are transported to the input end of the primary reactor via octyl alcohol and hydrobromic acid pipelines, respectively. After mixing, they enter the primary reactor and undergo catalytic synthesis to obtain n-octyl bromide. The reacted material enters the primary phase separator to separate the oil phase and the aqueous phase. The oil phase enters the secondary reactor and is mixed with sodium hydrosulfide transported via a sodium hydrosulfide pipeline. Under the catalytic action of the catalyst, n-octyl bromide reacts with sodium hydrosulfide to generate the target product n-octyl mercaptan (1-octyl mercaptan). The aqueous phase is then separated by the secondary phase separator and removed.

[0041] Preferably, the hydrobromic acid is an aqueous solution of hydrobromic acid with a concentration of 35-45 wt%.

[0042] Preferably, the primary reactor has a reaction temperature range of 100–180°C, a reaction pressure range of 0.2–1.2 MPa, and a mass hourly space velocity of 0.1–2 h⁻¹. -1 .

[0043] Preferably, the sodium hydrosulfide is an aqueous solution of sodium hydrosulfide with a concentration of 65-75 wt%.

[0044] Preferably, the reaction temperature range of the secondary reactor is 70–140°C, the reaction pressure range is 0.2–1.2 MPa, and the mass hourly space velocity is 0.1–2 h⁻¹. -1 .

[0045] Preferably, after the primary phase separator separates the oil phase and the aqueous phase, the aqueous phase enters the extraction unit. The aqueous phase first enters the extraction tower to extract the oil phase from the aqueous phase. It is then discharged from the top of the tower and enters the secondary reaction unit. The mixture of aqueous phase and extractant is discharged from the bottom of the tower. After being pressurized by the first feed pump, it enters the extractant recovery tower to separate the aqueous phase and extractant. The aqueous phase is discharged from the top of the tower, and the extractant is discharged from the bottom of the tower. The separated extractant is then returned to the extraction tower to achieve the recovery and utilization of the extractant.

[0046] Preferably, after separation by the secondary phase separator, the oil phase first enters the purification tower, where the by-products in the material are separated from the target product n-octyl mercaptan. The by-products n-octyl ether, n-octyl sulfide, and n-octyl disulfide are discharged from the bottom of the tower and enter the recovery tank. A reducing agent is added to the recovery tank to reduce the by-product n-octyl disulfide to the target product n-octyl mercaptan. The material is then pumped to the recovery tower via a second feed pump to separate the n-octyl mercaptan and the remaining by-products in the material. The n-octyl mercaptan is discharged from the top of the tower and sent to the product tank, while the by-products are discharged from the bottom of the tower and sent to the by-product tank.

[0047] More preferably, the reducing agent comprises a fourth-period metallic element.

[0048] More preferably, the refining tower operates at a pressure range of less than or equal to 10 kPa, a temperature range of 60–160 °C, and a reflux ratio range of 0.1–5.0.

[0049] More preferably, the operating pressure range of the recovery tower is less than or equal to 10 kPa, the temperature range is 60 to 160°C, and the reflux ratio range is 0.1 to 5.0.

[0050] In this invention, the system comprises a primary reaction unit, an extraction unit, a secondary reaction unit, and a purification unit. The primary reaction unit uses a solid superacid catalyst to catalyze the synthesis of n-octane from n-octanol and hydrobromic acid; the extraction unit separates the oil and aqueous phases; the secondary reaction unit reacts n-octane with sodium hydrosulfide under the action of a catalyst to produce n-octane mercaptan; the purification unit purifies the crude n-octane mercaptan to a purity ≥98.5% through vacuum distillation, and uses a reducing agent to reduce the byproduct n-octyl disulfide to n-octane mercaptan, maximizing product yield.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] 1. This invention provides a system and method for the continuous industrial production of n-octylthiol, which achieves efficient, safe, and low-energy-consumption industrial production through continuous reaction technology and continuous separation process;

[0053] 2. This invention adopts a continuous production process, which shortens the reaction time of the traditional process from 6-12 hours to less than 10 minutes, reduces the unit energy consumption by 40%, and solves the problems of low efficiency, large amount of waste acid water and great safety hazards of the traditional process, greatly reducing the industrial production cost and making it suitable for large-scale industrial production.

[0054] 3. This invention uses a solid superacid catalyst to replace traditional concentrated sulfuric acid in the generation of the intermediate product n-octane bromide, thus avoiding the environmental pollution caused by the large amount of waste acid water generated by traditional concentrated sulfuric acid.

[0055] 4. The crude thiol of the present invention is subjected to vacuum distillation to obtain n-octyl thiol with a purity of over 98.5%, which meets the requirements for industrial production.

[0056] 5. The yields of the intermediate product n-octane bromide and the product n-octanethiol generated by this invention are significantly improved;

[0057] 6. This invention uses n-octanol and hydrobromic acid as raw materials to first generate n-octane bromide, and then reacts n-octane bromide with sodium hydrosulfide to generate n-octane mercaptan. Compared with the traditional method that uses H2S gas as raw material, it will not cause H2S gas leakage and poisoning, and the safety risk is small.

[0058] 7. By controlling the stable temperature and pressure in the continuous primary and secondary reactors, this invention can avoid energy waste caused by repeated heating and cooling processes. At the same time, stable temperature and pressure can provide a stable reaction system, thereby reducing the occurrence of side reactions and improving the selectivity of the target product. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0060] Figure 2 This is a schematic diagram of the structure of the first-stage reaction unit of the present invention;

[0061] Figure 3 This is a schematic diagram of the extraction unit of the present invention;

[0062] Figure 4 This is a schematic diagram of the structure of the secondary reaction unit of the present invention;

[0063] Figure 5 This is a schematic diagram of the refining unit of the present invention;

[0064] In the diagram: 1-First-stage reaction unit, 11-First-stage reactor, 12-First-stage phase separator, 13-First-stage heater, 14-First-stage heat exchanger, 2-Second-stage reaction unit, 21-Second-stage reactor, 22-Second-stage phase separator, 23-Second-stage cooler, 24-Second-stage heat exchanger, 3-Extraction unit, 31-Extraction tower, 32-Extractant recovery tower, 33-First feed pump, 4-Refining unit, 41-Refining tower, 42-Recovery tower, 43-Product tank, 44-Recovery tank, 45-Second feed pump. Detailed Implementation

[0065] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0066] A system for the continuous industrial production of n-octylthiol, such as Figure 1 As shown, it includes: primary reaction unit 1, extraction unit 3, secondary reaction unit 2, and purification unit 4.

[0067] Specifically, such as Figure 2 As shown, the primary reaction unit 1 includes a primary reactor 11, a primary phase separator 12, a primary heater 13, and a primary heat exchanger 14. The input end of the primary reactor 11 is connected to the n-octanol delivery pipeline, and the hydrobromic acid delivery pipeline is connected to the input end of the primary reactor 11 through the n-octanol delivery pipeline. The n-octanol delivery pipeline is equipped with the primary heater 13, and the hydrobromic acid delivery pipeline is equipped with the primary heat exchanger 14. The output end of the primary reactor 11 is connected to the input end of the primary phase separator 12 through the primary heat exchanger 14.

[0068] like Figure 3 As shown, the extraction unit 3 includes an extraction tower 31, an extractant recovery tower 32, and a first feed pump 33. The input end of the extraction tower 31 is connected to the aqueous phase outlet of the primary phase separator 12. The top of the extraction tower 31 is connected to the secondary reaction unit 2. The bottom of the extraction tower 31 is connected to the input end of the extractant recovery tower 32 through the first feed pump 33. The bottom of the extractant recovery tower 32 is connected back to the extraction tower 31. The aqueous phase is discharged from the top of the extractant recovery tower 32.

[0069] like Figure 4 As shown, the secondary reaction unit 2 includes a secondary reactor 21, a secondary phase separator 22, a secondary cooler 23, and a secondary heat exchanger 24. The top of the extraction tower 31 is connected to the input end of the secondary reactor 21 via the secondary cooler 23. The input end of the secondary reactor 21 is also connected to the oil phase outlet of the primary phase separator 12 and the sodium hydrosulfide delivery pipeline. The sodium hydrosulfide delivery pipeline is equipped with a secondary heat exchanger 24. The output end of the secondary reactor 21 is connected to the input end of the secondary phase separator 22 via the secondary heat exchanger 24.

[0070] like Figure 5 As shown, the refining unit 4 includes a refining tower 41, a recovery tower 42, a product tank 43, a recovery tank 44, and a second feed pump 45. The input end of the refining tower 41 is connected to the oil phase outlet of the secondary phase separator 22. The top of the refining tower 41 is connected to the product tank 43. The bottom of the refining tower 41 is connected to the recovery tower 42 via the recovery tank 44 and the second feed pump 45. The top of the recovery tower 42 is connected to the product tank 43. The recovery tank 44 is connected to the reducing agent delivery pipeline.

[0071] A method for the continuous industrial production of n-octylthiol includes the following steps:

[0072] (a) The raw material, n-octanol, is heated in the primary heater 13, and then mixed with a heated 40% hydrobromic acid solution before entering the primary reactor 11. The reaction temperature range is 100–180 °C, the reaction pressure range is 0.2–1.2 MPa, and the mass hourly space velocity is 0.1–2 h⁻¹.-1 This reactor is a tubular fixed-bed reactor, preferably made of Hastelloy C276, and filled with a solid superacid catalyst (particle size 0.5–1.0 mm). Octanol and hydrobromic acid are synthesized into n-octane under the catalysis of the solid superacid catalyst. The yield of n-octane is approximately 72%, and the feed conversion rate is approximately 70%. The reactants then enter a primary phase separator 12 to separate the oil and aqueous phases. The aqueous phase enters an extraction unit 3 to extract the remaining oil phase.

[0073] (b) Extraction unit 3 consists of one extraction tower 31, one feed pump (first feed pump 33), and one extractant recovery tower 32. The aqueous phase first enters the extraction tower 31, where the oil phase is extracted and discharged from the top of the tower into the secondary reaction unit 2. The mixture of aqueous phase and extractant is discharged from the bottom of the tower, then pressurized by the feed pump and enters the extractant recovery tower 32 to separate the aqueous phase and extractant. The aqueous phase is discharged from the top of the tower, and the extractant is discharged from the bottom. The separated extractant is then returned to the extraction tower 31, achieving extractant recovery. The extraction tower 31 is a packed tower, and the extractant is a formulated synthetic extractant, made of 316L stainless steel. The theoretical number of plates is between 10 and 30, preferably 20 theoretical plates, with an extraction efficiency ≥98% and an extractant recovery rate of approximately 99.5%.

[0074] (c) Secondary reaction unit 2 involves mixing the oil phase obtained from initial separation and extraction, then cooling it to 70–140°C in a cooler (secondary cooler 23). The mixture is then mixed with a 70% sodium hydrosulfide solution heated to 70–140°C and introduced into secondary reactor 21. This reactor is a tubular reactor, packed with catalyst. The reaction temperature range is 70–140°C, the reaction pressure range is 0.2–1.2 MPa, and the mass hourly space velocity (WHSV) is 0.1–2 h⁻¹. -1 Under the catalysis of a catalyst, n-octane bromide reacts with sodium hydrosulfide to produce the target product, n-octanethiol. The yield of n-octanethiol synthesized in the second-order reaction unit is approximately 94%.

[0075] (d) Crude mercaptan enters purification unit 4, where it is distilled under reduced pressure to obtain high-purity n-octyl mercaptan. The purification unit comprises two columns, one pump, and three tanks. The two columns are purification column 41 and recovery column 44, the pump is the feed pump (second feed pump 45), and the three tanks are product tank 43, recovery tank 44, and by-product tank. The material first enters purification column 41. The operating pressure control range of purification column 41 is ≤10 kPa, the operating temperature control range is 60–160℃, and the reflux ratio control range is 0.1–5.0. Purification column 41 separates the by-products from the target product, n-octyl mercaptan. The by-products n-octyl ether, n-octyl sulfide, and n-octyl disulfide are discharged from the bottom of the column and enter the recovery tank. The n-octyl mercaptan (purity ≥98.5%) is discharged from the top of the column and enters product tank 43. A reducing agent is added to recovery tank 44 to reduce the byproduct n-octyl disulfide to the target product n-octyl mercaptan. The material is pumped to recovery tower 42 for further vacuum distillation. The operating pressure range of recovery tower 42 is ≤10 kPa, the operating temperature range is 60–160℃, and the reflux ratio range is 0.1–5.0. This process separates the n-octyl mercaptan from the remaining byproducts. The n-octyl mercaptan is discharged from the top of the tower and sent to product tank 43. The byproducts are discharged from the bottom of the tower and sent to the byproduct tank.

[0076] The following detailed description is based on specific embodiments.

[0077] Unless otherwise specified, the reagents, methods, instruments, and equipment used in this invention are conventional in the art. Unless otherwise specified, the reagents and materials used in the following examples are all commercially available.

[0078] Example 1

[0079] A 1000-ton / year continuous production unit for n-octyl mercaptan (based on n-octyl alcohol feed rate) (based on 8000 hours of operation per year).

[0080] The n-octyl mercaptan production unit is divided into a primary reaction unit, a secondary reaction unit, an extraction unit, and a purification unit.

[0081] The 1000-ton / year continuous production unit for n-octyl mercaptan uses one primary reactor in its first-stage reaction unit. The reactor has a volume of approximately 5 m³. 3 The zinc sulfate oxide super solid acid catalyst has a loading of approximately 2.5 tons and a mass hourly space velocity (MHSV) of 0.5 h⁻¹. -1 The reaction temperature was 150℃, and the reaction pressure was 0.8MPa. The hydrobromic acid feed rate was 37.5 kg / h, producing 111 kg / h of the intermediate product n-octane bromide, with a yield of approximately 72.23% and a feed conversion rate of approximately 68.45%.

[0082] The separated oil phase, after cooling, is mixed with sodium hydrosulfide and then fed into a two-stage reactor. The reactor has a volume of approximately 5 m³. 3The fluorinated mesoporous SiO2 catalyst was loaded with approximately 2.5 tons, with a mass hourly space velocity (HWV) of 0.5 h⁻¹. -1 The reaction temperature was 120℃, and the reaction pressure was 1.0 MPa. The sodium hydrosulfide feed rate was 137.5 kg / h. 232 kg / h of crude n-octyl mercaptan was produced, with a yield of approximately 94% and a feed conversion rate of approximately 93.39%.

[0083] The extraction unit employs two extraction towers and one pump. The extraction towers use chloroform as the extractant to separate the aqueous and oil phases from the material generated in the primary reaction unit. The aqueous phase and extractant are then separated in an extractant recovery tower to recover the extractant. The extracted oil phase contains approximately 5% aqueous phase. This extraction tower is a packed tower with an extraction efficiency ≥98% and an extractant recovery rate of approximately 99.5%.

[0084] The refining unit consists of two towers, one pump, and three tanks. The refining towers operate at a pressure of 7–10 kPa, a temperature of 60–100 °C, a bottom temperature of 110 °C, and a reflux ratio of 2.0. The oil phase generated in the secondary reaction unit enters the refining tower to separate byproducts and n-octyl mercaptan. The byproducts are sent to the recovery tank. In the recovery tank, zinc reducing agent is added to reduce n-octyl disulfide to n-octyl mercaptan. This is then sent back to the recovery tower to separate n-octyl mercaptan and other byproducts. The recovery tower operates at a pressure of 7–10 kPa, a temperature of 60–100 °C, a bottom temperature of 130 °C, and a reflux ratio of 1.5.

[0085] This unit has an annual processing capacity of 1,000 tons of n-octanol and an annual production of 1,856 tons of n-octanthiol, with a comprehensive yield of 67.90%, a comprehensive conversion rate of 63.92%, and a n-octanthiol product purity of ≥98.5%.

[0086] Example 2

[0087] A 1500-ton / year continuous production unit for n-octyl mercaptan (based on n-octyl alcohol feed rate) (based on 8000 hours of operation per year).

[0088] The n-octyl mercaptan production unit is divided into a primary reaction unit, a secondary reaction unit, an extraction unit, and a purification unit.

[0089] The 1500-ton / year continuous production unit for n-octyl mercaptan uses one primary reactor in its first-stage reaction unit. The reactor volume is approximately 7.5 m³. 3 The zinc sulfate oxide super solid acid catalyst has a loading of approximately 3.8 tons and a mass hourly space velocity (HWV) of 0.5 h⁻¹. -1 The reaction temperature was 150℃, and the reaction pressure was 0.8 MPa. The hydrobromic acid feed rate was 56.25 kg / h. The intermediate product n-octane was produced at a rate of 169.04 kg / h, with a yield of approximately 72.01% and a feed conversion rate of approximately 69.35%.

[0090] The separated oil phase, after cooling, is mixed with sodium hydrosulfide and then fed into a two-stage reactor. The reactor has a volume of approximately 7.5 m³. 3 The fluorinated mesoporous SiO2 catalyst was loaded with approximately 3.8 tons, with a mass hourly space velocity (HWV) of 0.5 h⁻¹. -1 The reaction temperature was 120℃, and the reaction pressure was 1.0 MPa. The sodium hydrosulfide feed rate was 206.25 kg / h, and the crude n-octyl mercaptan product was produced at a rate of 357.35 kg / h, with a yield of approximately 94% and a raw material conversion rate of approximately 95.22%.

[0091] The extraction unit employs two extraction towers and one pump. The extraction towers use chloroform as the extractant to extract the oil phase from the aqueous phase of the material generated in the primary reaction unit. The aqueous phase and extractant are then separated by a distillation tower, recovering the extractant. The extracted oil phase contains approximately 7% aqueous phase. This extraction tower is a packed tower with an extraction efficiency ≥98% and an extractant recovery rate of approximately 99.5%.

[0092] The refining unit consists of two towers, one pump, and three tanks. The refining towers operate at a pressure of 5–6 kPa, a temperature of 110–160 °C, a bottom temperature of 130 °C, and a reflux ratio of 1.5. The oil phase generated in the secondary reaction unit enters the refining tower to separate byproducts and n-octyl mercaptan. The byproducts are sent to the recovery tank. In the recovery tank, zinc reducing agent is added to reduce n-octyl disulfide to n-octyl mercaptan. This is then sent back to the recovery tower to separate n-octyl mercaptan and other byproducts. The recovery tower operates at a pressure of 5–6 kPa, a temperature of 110–160 °C, a bottom temperature of 140 °C, and a reflux ratio of 1.2.

[0093] This unit has an annual processing capacity of 1,500 tons of n-octanol and an annual production of 2,859 tons of n-octanthiol, with a comprehensive yield of 67.69%, a comprehensive conversion rate of 66.04%, and a n-octanthiol product purity of ≥98.5%.

[0094] This invention provides a system and method for the continuous industrial production of n-octyl mercaptan, which solves the problems of low efficiency, large amount of waste acid water, and great safety hazards of traditional processes, and is suitable for large-scale industrial production.

[0095] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. A system for continuous production of n-octylthiol, characterized in that, It includes a primary reaction unit (1) and a secondary reaction unit (2); The primary reaction unit (1) includes a primary reactor (11) and a primary phase separator (12). The input end of the primary reactor (11) is connected to the n-octanol delivery pipeline and the hydrobromic acid delivery pipeline, and the output end is connected to the primary phase separator (12). The secondary reaction unit (2) includes a secondary reactor (21) and a secondary phase separator (22). The input end of the secondary reactor (21) is connected to the primary phase separator (12) and the sodium hydrosulfide delivery pipeline, and the output end is connected to the secondary phase separator (22).

2. The system for continuous production of n-octylthiol according to claim 1, characterized in that, The primary reactor (11) is a tubular fixed-bed reactor filled with a solid superacid catalyst for catalyzing the reaction of n-octanol and hydrobromic acid to produce n-bromooctane. The particle size of the solid superacid catalyst is 0.5-1.0 mm. The solid superacid catalyst includes superacids containing halogens, fluorosulfonic acid resins, or sulfuric acid systems.

3. The system for continuous production of n-octylthiol according to claim 1, characterized in that, The secondary reactor (21) is a tubular reactor, and the secondary reactor (21) is filled with a catalyst for catalyzing the reaction of n-octane bromide with sodium hydrosulfide to produce n-octane mercaptan. The catalyst comprises a super-strong solid acid containing halogens, fluorosulfonic acid resins, or sulfuric acid systems.

4. The system for continuous production of n-octylthiol according to claim 1, characterized in that, The n-octanol delivery pipeline is equipped with a primary heater (13), the hydrobromic acid delivery pipeline is equipped with a primary heat exchanger (14), and the output end of the primary reactor (11) is connected to the input end of the primary phase separator (12) through the primary heat exchanger (14).

5. The system for continuous production of n-octylthiol according to claim 1, characterized in that, An extraction unit (3) is provided between the primary reaction unit (1) and the secondary reaction unit (2); The extraction unit (3) includes an extraction tower (31), the input end of which is connected to the aqueous phase outlet of the primary phase separator (12), and the top of the extraction tower (31) is connected to the input end of the secondary reactor (21).

6. The system for continuous production of n-octylthiol according to claim 5, characterized in that, The extraction unit (3) also includes an extractant recovery tower (32) and a first feed pump (33); The bottom of the extraction tower (31) is connected to the input end of the extractant recovery tower (32) via the first feed pump (33), and the bottom of the extractant recovery tower (32) is connected back to the extraction tower (31). The extraction tower (31) is a packed tower with a theoretical number of plates of 10 to 30.

7. The system for continuous production of n-octylthiol according to claim 5, characterized in that, The top of the extraction tower (31) is connected to the input end of the secondary reactor (21) via a secondary cooler (23); A secondary heat exchanger (24) is provided on the sodium hydrosulfide delivery pipeline, and the output end of the secondary reactor (21) is connected to the input end of the secondary phase separator (22) through the secondary heat exchanger (24).

8. The system for continuous production of n-octylthiol according to claim 1, characterized in that, The output of the secondary reaction unit (2) is connected to the purification unit (4); The refining unit (4) includes a refining tower (41) and a recovery tower (42). The input end of the refining tower (41) is connected to the oil phase outlet of the secondary phase separator (22), and the top of the refining tower (41) is connected to the product tank (43). The bottom of the refining tower (41) is connected to the recovery tower (42) via the recovery tank (44) and the second feed pump (45), and the top of the recovery tower (42) is connected to the product tank (43).

9. A method for continuous production of n-octylthiol, characterized in that, Using the system according to any one of claims 1 to 8, the process includes the following steps: Octanol and hydrobromic acid are transported to the input end of the primary reactor (11) via the octanol and hydrobromic acid transport pipelines. After mixing, they enter the primary reactor (11) and are synthesized by catalysis to obtain n-octane. The reacted material enters the primary phase separator (12) to separate the oil phase and the water phase. The oil phase enters the secondary reactor (21) and is mixed with sodium hydrosulfide transported via the sodium hydrosulfide transport pipeline. Under the catalytic action of the catalyst, n-octane reacts with sodium hydrosulfide to generate the target product n-octane mercaptan. The water phase is separated by the secondary phase separator (22).

10. The method for continuous production of n-octylthiol according to claim 9, characterized in that, The hydrobromic acid is an aqueous solution with a concentration of 35-45 wt%. The reaction temperature range of the primary reactor (11) is 100-180℃, the reaction pressure range is 0.2-1.2 MPa, and the mass hourly space velocity is 0.1-2 h⁻¹. -1 ; The sodium hydrosulfide is an aqueous solution of sodium hydrosulfide with a concentration of 65-75 wt%. The reaction temperature range of the secondary reactor (21) is 70-140℃, the reaction pressure range is 0.2-1.2 MPa, and the mass hourly space velocity is 0.1-2 h⁻¹. -1 .

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