A methanethiol synthesis apparatus

Abstract

The utility model provides a kind of methyl mercaptan synthesis device, using self-made catalyst in fixed bed reactor catalysis hydrogen sulfide and methanol reaction to obtain methyl mercaptan. After methanol is vaporized, it is mixed with hydrogen sulfide and enters preheater to preheat, then enters reactor, and mixed gas passes through the reactor filled with catalyst from top to bottom, and methyl mercaptan is obtained under certain temperature and pressure. The reaction principle of the device is simple, has raw material price advantage, and the catalyst obtained can be used to catalyze the reaction of methanol and hydrogen sulfide to generate methyl mercaptan, with the advantages of high selectivity and stability, and the device can realize continuous production.

Description

Technical Field

[0001] This utility model relates to an apparatus for synthesizing methanethiol in chemical production, specifically a new apparatus for catalytically synthesizing methanethiol by reacting methanol with hydrogen sulfide. Background Technology

[0002] Methanethiol, a high-value-added sulfur-containing organic chemical intermediate, is widely used in downstream industries such as pesticides, pharmaceuticals, dyes, rubber, food, and feed additives. In the pesticide sector, methanethiol is a core intermediate in the synthesis of herbicides such as atrazine and insecticides such as fenthion. In the dye sector, methanethiol can be synthesized into methanesulfonyl chloride (MSC) through wet chlorination. MSC, as an important organic synthesis raw material, has been widely used as an intermediate in pesticide and pharmaceutical synthesis. In the rubber sector, methanethiol is mainly used as a vulcanizing agent. In the production of food and feed additives, methanethiol is an important intermediate in the industrial synthesis of feed-grade methionine.

[0003] Currently, based on raw materials and production routes, methanethiol synthesis methods can be categorized into: thiourea-dimethyl sulfate method, high-sulfur syngas one-step method, methanol-carbon disulfide method, and sodium methanethiol-sulfuric acid method. These methods easily generate waste and require expensive raw materials, and therefore cannot currently meet the needs of large-scale industrial production. Currently, the industrial method generally uses methanol-hydrogen sulfide to prepare methanethiol. The catalyst is the key factor limiting the high selectivity of methanethiol synthesis in this method. This invention patent uses a self-made catalyst to catalyze the reaction of hydrogen sulfide and methanol to produce methanethiol. This method produces fewer byproducts, has a simple reaction principle, possesses a raw material price advantage, and can achieve continuous production; therefore, it is a reasonable synthesis route. Summary of the Invention

[0004] The purpose of this invention is to address existing technical challenges by developing a new methanethiol synthesis device, which includes a synthesis unit, a gas phase acquisition unit, a liquid phase condensation and collection unit, and a tail gas treatment unit.

[0005] In the synthesis unit, the upper end of the reactor is connected to the preheater, the preheater is connected to the vaporizer, and the vaporizer is connected to the liquid feed system. The liquid feed system specifically includes: a raw material tank, a filter, and a liquid feed pump, which are connected in series. The hydrogen sulfide pipeline is connected to the vaporizer via a three-way valve and then to the inlet of the preheater.

[0006] In the gas phase acquisition unit, the reactor outlet is connected to a gas chromatograph.

[0007] In the liquid condensation and collection unit, the lower end of the reactor is connected to a condenser, which is connected to a sealed sampler and a gas-liquid separator respectively. The gas-liquid separator is connected to the collection tank through a gas-liquid separator liquid phase pneumatic valve.

[0008] In the exhaust gas treatment unit, the reactor outlet and the gas phase outlet of the gas-liquid separator are connected to the anti-backflow tank. The anti-backflow tank is connected to the alkaline absorption tank A and the alkaline absorption tank B, respectively. The alkaline absorption tank A is connected to the potassium permanganate absorption bottle A, and the alkaline absorption tank B is connected to the potassium permanganate absorption bottle B.

[0009] The entire device is made of 316L material and can withstand atmospheric pressure to 10MPa; safety valves are installed at the lower end of the reactor and the collection tank; a filter is installed at the outlet of the raw material tank; there are two sets of tail gas treatment units, A and B, with one in use and one on standby; the pipeline between the vaporizer outlet and the tail gas treatment unit is fully insulated, with an insulation temperature of 25℃~250℃ to ensure that the raw material gas and synthesis gas do not condense.

[0010] The reactor is equipped with a sieve plate, and the catalyst is packed on the sieve plate. The raw material gas passes through the catalyst packed in the pipe from top to bottom.

[0011] In the liquid phase condensation and collection unit, the upper and lower ends of the sealed sampler are equipped with detachable ball valves. Before sampling, the lower end of the condenser is opened to connect with the sealed sampler. The collection of liquid phase analysis samples is controlled by the opening and closing of the ball valves at the upper and lower ends of the sealed sampler.

[0012] Another objective of this invention is to explore the various process parameters of the self-made catalyst in the methanethiol synthesis reaction, in order to obtain a higher methanethiol yield, thereby reducing raw material costs and waste treatment volume. Therefore, this invention provides a methanethiol synthesis process, comprising the following steps:

[0013] S1: Liquid methanol is metered by the liquid feed pump and then fed into the vaporizer for vaporization.

[0014] S2: The vaporized methanol and hydrogen sulfide are mixed and then fed into the preheater for preheating.

[0015] S3: The preheated mixed raw material gas is introduced into a reactor containing a catalyst, and the reaction begins under the set pressure and temperature;

[0016] S4: After the reaction is completed, the mixed gas enters the gas chromatograph in one direction and the gas enters the gas-liquid separator after being condensed by the condenser. The condensed methanethiol liquid is temporarily stored in the gas-liquid separator. The liquid level is automatically controlled by the liquid phase pneumatic valve of the gas-liquid separator. The portion of the methanethiol liquid above the set liquid level is discharged into the collection tank. The tail gas enters the tail gas treatment unit through the back pressure valve.

[0017] The liquid feed rate described in S1 is 0.05~5mL, the methanol liquid purity is 99.5%~99.9%, the vaporization temperature is 70~400℃, and the vaporization time is 0.1~0.5min.

[0018] The preheating temperature described in S2 is 100~450℃, and the preheating time is 0.1~0.5min; the molar ratio of hydrogen sulfide to methanol in the feed is 1~5, and the purity of hydrogen sulfide gas is 95%~99.95%.

[0019] The reaction temperature described in S3 is 300℃~450℃, and the space velocity is 50~3000h. -1 The reaction system pressure is 0.2~2.5MPa, and the heating method is one or more of the following: electric heating, hot water heating, steam heating, heat transfer oil heating or molten salt heating.

[0020] The catalyst described in S3 is prepared by loading one or more combined oxides of cobalt, tungsten, and potassium onto an alumina support or molecular sieve. The particle size of the catalyst is 1.0 to 5 mm, and the loading of the active component is 5% to 30%.

[0021] The condenser described in S4 uses a propylene glycol / water mixture at -25~0℃ or a chilled brine solution at -15~-10℃.

[0022] The gas-liquid separator described in S4 uses an air compressor to supply compressed gas to the liquid phase pneumatic valve, and the pneumatic valve controls the liquid level height to be between 20 and 200 mm.

[0023] The exhaust gas described in S4 is sequentially introduced into an alkaline absorption tank and an acidic potassium permanganate absorption bottle; the alkaline solution is a sodium hydroxide solution with a concentration of 10% to 30%, and the acidic potassium permanganate solution has a concentration of 1% to 10%.

[0024] In this invention, methanol and hydrogen sulfide are reacted under certain temperature, pressure and catalyst conditions to produce methanethiol, which may be accompanied by the formation of dimethyl sulfide as a byproduct.

[0025] The beneficial technical effects of this utility model are as follows: the device of this application improves the conversion rate of methanol and the selectivity of methanethiol, reduces the generation of by-products, the self-made catalyst preparation method is simple and has a long service life, and reduces the cost of raw materials while facilitating the subsequent product purification process. Attached Figure Description

[0026] Figure 1This is a simplified structural diagram of a methanethiol synthesis apparatus according to this utility model. In the diagram: 1. Raw material tank; 2. Filter; 3. Liquid feed pump; 4. Hydrogen sulfide pressure reducing valve; 5. Hydrogen sulfide flow meter; 6. Hydrogen sulfide check valve; 7. Vaporizer; 8. Three-way valve; 9. Preheater; 10. Reactor; 11. Condenser; 12. Sealed sampler; 13. Gas-liquid separator; 14. Gas-liquid separator liquid phase pneumatic valve; 15. Back pressure valve; 16. Gas chromatograph; 17. Collection tank; 18. Anti-backflow tank; 19. Alkali absorption tank A; 20. Potassium permanganate absorption tank A; 21. Alkali absorption tank B; 22. Potassium permanganate absorption tank B. Detailed Implementation

[0027] The present invention will be further illustrated below through embodiments. It is worth noting that the given embodiments should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by those skilled in the art based on the content of the present invention should still fall within the scope of protection of the present invention. In the embodiments, the methanethiol synthesis reaction adopts a fixed-bed reactor, and the analytical instruments in the embodiments include a Shimadzu gas chromatograph, a gas chromatograph column, and a TCD detector.

[0028] Example 1

[0029] A methanethiol synthesis apparatus, with the following structure: Figure 1 As shown, the device includes a synthesis unit, a gas phase acquisition unit, a liquid phase condensation and collection unit, and a tail gas treatment unit:

[0030] In the synthesis unit, the upper end of the reactor 10 is connected to the preheater 9, the preheater 9 is connected to the vaporizer 7, and the vaporizer 7 is connected to the liquid feed system. The liquid feed system specifically includes: raw material tank 1, filter 2, and liquid feed pump 3, which are connected in series. The hydrogen sulfide pipeline is connected to the vaporizer 7 via a three-way valve 8 and then connected to the inlet of the preheater 9.

[0031] In the gas phase acquisition unit, the outlet of reactor 10 is connected to gas chromatograph 16;

[0032] In the liquid condensation and collection unit, the lower end of the reactor 10 is connected to the condenser 11, the condenser 11 is connected to the sealed sampler 12 and the gas-liquid separator 13 respectively, and the gas-liquid separator 13 is connected to the collection tank 17 through the gas-liquid separator liquid phase pneumatic valve 14.

[0033] In the exhaust gas treatment unit, the outlet of reactor 10 and the gas phase outlet of gas-liquid separator 13 are connected to anti-backflow tank 18. Anti-backflow tank 18 is connected to alkaline absorption tank A 19 and alkaline absorption tank B 21 respectively. Alkaline absorption tank A 19 is connected to potassium permanganate absorption bottle A 20, and alkaline absorption tank B 21 is connected to potassium permanganate absorption bottle B 22.

[0034] 2. The entire device is made of 316L material and can withstand atmospheric pressure to 10MPa; safety valves are installed at the lower end of the reactor 10 and the collection tank 17; a filter is installed at the outlet of the raw material tank 1; there are two sets of tail gas treatment units, A and B, one in use and one on standby; the pipeline from the outlet of the vaporizer 7 to the tail gas treatment unit is fully insulated, with an insulation temperature of 25℃~250℃ to ensure that the raw material gas and synthesis gas do not condense.

[0035] 3. The reactor 10 is equipped with a sieve plate, and the catalyst is packed on the sieve plate. The raw material gas passes through the catalyst packed in the pipe from top to bottom.

[0036] 4. In the liquid phase condensation and collection unit, the upper and lower ends of the sealed sampler 12 are equipped with detachable ball valves. Before sampling, the lower end of the condenser 11 is opened to connect with the sealed sampler 12. The collection of liquid phase analysis samples is controlled by the opening and closing of the ball valves at the upper and lower ends of the sealed sampler 12.

[0037] 5. The implementation process of the methanethiol synthesis apparatus is as follows:

[0038] Raw material vaporization stage: Liquid methanol is filtered through filter 2 to remove impurities and then enters liquid feed pump 3. After being metered by the liquid feed pump, it is fed into vaporizer 7 for vaporization. A one-way valve is installed between the liquid feed pump and the vaporizer.

[0039] Preheating stage: After the hydrogen sulfide gas is adjusted by the hydrogen sulfide pressure reducing valve 4 to be slightly higher than the reaction pressure by 0.2 MPa, it is then adjusted and measured by the hydrogen sulfide flow meter 5 to the set flow rate. After being mixed with the vaporized methanol in the three-way valve 8, it enters the preheater 9 for preheating. A one-way valve is installed between the hydrogen sulfide flow meter 5 and the three-way valve.

[0040] Synthesis stage: The preheated mixed raw material gas enters the reactor from the top of reactor 10 and continues to be heated to the reaction temperature. The mixed raw material gas passes from top to bottom through the reactor containing catalyst and packing material, and the reaction begins under the set pressure and temperature.

[0041] Condensate collection stage: After the reaction is completed, the mixed gas enters the gas chromatograph 16 in one direction and the condenser 11 in the other. After condensation, the gas-liquid mixture enters the gas-liquid separator 13 for gas-liquid separation. The condensed methanethiol liquid is temporarily stored in the gas-liquid separator. The liquid level is automatically controlled by the liquid phase pneumatic valve 14 of the gas-liquid separator. The methanethiol liquid above the set liquid level is discharged into the collection tank 17. The gas phase enters the tail gas treatment unit through the tail gas control valve and the back pressure valve 15.

[0042] Gas phase analysis: In order to keep track of the reaction in a timely manner, the synthesis gas is continuously sampled online. The synthesis gas comes out from the bottom of the reactor and enters the gas chromatograph 16 for online analysis after passing through the inlet control valve of the gas chromatograph.

[0043] Tail gas treatment stage: The tail gas coming out of the back pressure valve and some of the volatilized methanethiol gas phase in the collection tank enter the anti-backflow tank 18, and then enter the alkaline absorption tank A 19 and the potassium permanganate absorption bottle A 20. The entire tail gas treatment unit is divided into two sets, A and B, one open and one standby, controlled by valves.

[0044] Example 2

[0045] The methanethiol synthesis apparatus of Example 1 was used. 30 mL of W-1 type catalyst (W-1 type catalyst: 15% potassium tungstate, granular, supported on alumina) was packed into reactor 10. The reactor temperature was controlled at 360°C, and the back pressure valve 15 was adjusted to achieve a reaction pressure of 0.8 MPa. The feed molar ratio of hydrogen sulfide to methanol was 1.8:1. After 12 h of reaction, chromatographic analysis was performed. The tested and calculated methanol conversion rate was 98.78%, the methanethiol selectivity was 85.43%, and the methanethiol yield was 84.38%.

Claims

1. A methanethiol synthesis apparatus, characterized in that, The hydrogen sulfide pipeline and the vaporizer (7) are connected to the inlet of the preheater (9) via a three-way valve (8). The outlet of the preheater (9) is connected to the inlet of the reactor (10). The lower end of the reactor (10) is connected to the condenser (11). The outlet of the condenser (11) is connected to the sealed sampler (12).

2. The methanethiol synthesis apparatus according to claim 1, characterized in that, The hydrogen sulfide pipeline is equipped with a hydrogen sulfide pressure reducing valve (4), a hydrogen sulfide flow meter (5), and a hydrogen sulfide check valve (6).

3. The methanethiol synthesis apparatus according to claim 1, characterized in that, The vaporizer (7) is connected to the liquid feeding system, which includes: raw material tank (1), filter (2), and liquid feed pump (3), which are connected in series.

4. The methanethiol synthesis apparatus according to claim 1, characterized in that, The other outlet of the reactor (10) is connected to a gas chromatograph (16) to form a gas phase acquisition unit to realize the detection of the gas phase.

5. The methanethiol synthesis apparatus according to claim 4, characterized in that, The outlet of the condenser (11) is also connected to the gas-liquid separator (13), which is connected to the collection tank (17) through the gas-liquid separator liquid phase pneumatic valve (14).

6. The methanethiol synthesis apparatus according to claim 1, characterized in that, The reactor (10) outlet and the gas phase outlet of the gas-liquid separator (13) are connected to the anti-backflow tank (18). The anti-backflow tank (18) is connected to the alkaline absorption tank A (19) and the alkaline absorption tank B (21) respectively. The alkaline absorption tank A (19) is connected to the potassium permanganate absorption bottle A (20), and the alkaline absorption tank B (21) is connected to the potassium permanganate absorption bottle B (22).

7. The methanethiol synthesis apparatus according to claim 1, characterized in that, Safety valves are installed at the lower end of the reactor (10) and the collection tank (17).

8. The methanethiol synthesis apparatus according to claim 1, characterized in that, The reactor (10) is equipped with a sieve plate, and the catalyst is packed on the sieve plate. The raw material gas passes through the catalyst packed in the pipe from top to bottom.

9. The methanethiol synthesis apparatus according to claim 1, characterized in that, The sealed sampler (12) is equipped with detachable ball valves at the upper and lower ends. Before sampling, the lower end of the condenser (11) is opened and connected to the sealed sampler (12). The collection of liquid phase analysis samples is controlled by the ball valves at the upper and lower ends of the sealed sampler (12).

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