Process method and process device for producing triethylamine

Abstract

The invention discloses a process method and a process device for producing triethylamine, and the process method comprises the following steps: carrying out hydrogenation reaction on a raw material containing hydrogen and acetonitrile in a hydrogenation reactor to obtain a hydrogenation reaction product, and condensing and separating the hydrogenation reaction product to obtain a gas phase and a liquid phase; after the liquid phase is rectified and separated through an ammonia removal tower, ammonia gas and waste liquid are separated at the tower top, a deamination product is obtained at the tower bottom, and after the deamination product is rectified through a product tower, a circulating raw material is obtained at the tower top, and a triethylamine product is obtained at the tower bottom; the gas phase is recovered by a hydrogen recovery unit to obtain circulating hydrogen; the raw materials also comprise the circulating raw material and circulating hydrogen. The method can be used for continuous production of a process for preparing triethylamine through acetonitrile hydrogenation, is convenient to operate and is suitable for industrial large-scale production.

Description

TECHNICAL FIELD

[0001] The application relates to a process and a device for producing triethylamine, and belongs to the technical field of chemical industry. BACKGROUND

[0002] Ethylamine compounds are important organic chemical raw materials, which are widely used in solvents, pesticides, pharmaceuticals, fine chemicals, high-energy fuels, surfactants and intermediate synthesis. At present, the synthesis process of ethylamine compounds is mainly ammonia alcoholization, but the product of the process is limited by reaction equilibrium, resulting in a mixture of monoethylamine, diethylamine and triethylamine, and the yield of single target product is not high. Based on the defects of the prior art, researchers have explored the reaction path of acetonitrile hydrogenation to produce triethylamine, and developed various related catalysts, which realize the catalytic hydrogenation reaction of acetonitrile with high conversion rate and high triethylamine selectivity, but the corresponding process research has not been reported yet, and further research is needed. SUMMARY

[0003] The application provides a process and a method for producing triethylamine product from acetonitrile and hydrogen, which realizes triethylamine product refining and hydrogen recovery through the cycle operation of "raw material preheating-reaction-pressurized condensation-sequential rectification-low-temperature hydrogen recovery-decompression cooling heat exchange", and is simple in process, convenient in operation and suitable for industrial scale production.

[0004] According to one aspect of the application, a process for producing triethylamine is provided, specifically a process and a method for producing unsaturated nitrogen-containing monomers. The method is to hydrogenate acetonitrile under mild conditions, and then obtain triethylamine product and by-product crude ammonia through pressurized condensation, sequential rectification, low-temperature hydrogen recovery and decompression cooling heat exchange, while recycling the unreacted hydrogen.

[0005] Optionally, the process method comprises: hydrogen and acetonitrile raw materials are subjected to hydrogenation reaction in a hydrogenation reactor to obtain a hydrogenation reaction product, and the hydrogenation reaction product is subjected to condensation separation to obtain a gas phase and a liquid phase;

[0006] The liquid phase is subjected to rectification separation in an ammonia removal tower to separate ammonia gas and waste liquid at the top, and to obtain a deamination product at the bottom, and the deamination product is subjected to rectification in a product tower to obtain a circulating raw material at the top and a triethylamine product at the bottom;

[0007] The gas phase is recycled in a hydrogen recovery unit to obtain circulating hydrogen;

[0008] The raw material further comprises the circulating raw material and the circulating hydrogen.

[0009] Optionally, the process method further comprises raw material preheating.

[0010] The preheating temperature of the raw material is 40-200 DEG C.

[0011] Optionally, the temperature for preheating the raw materials is independently selected from any value of 40°C, 80°C, 120°C, 135°C, 159°C, 180°C, 200°C, or a range between any two of the above.

[0012] Optionally, the raw material preheating specifically refers to mixing fresh hydrogen with recycled hydrogen and heating it to a higher temperature in a hydrogen preheater; or mixing fresh acetonitrile with recycled acetonitrile and heating it to a higher temperature in an acetonitrile preheater.

[0013] Optionally, the temperature of the hydrogenation reaction is 110–200°C;

[0014] The operating pressure for the hydrogenation reaction is 0.1–12 bar (A).

[0015] Optionally, the temperature of the hydrogenation reaction is independently selected from any value of 110°C, 135°C, 150°C, 175°C, 200°C, or a range between any two of the above.

[0016] Optionally, the operating pressure of the hydrogenation reaction is independently selected from any value of 0.1 bar (A), 1 bar (A), 3 bar (A), 5 bar (A), 7 bar (A), 10 bar (A), 12 bar (A) or a range between any two of the above.

[0017] Optionally, the heated hydrogen is mixed with acetonitrile to reach the reaction temperature and sent to the hydrogenation reactor to react and obtain the hydrogenation reaction product; a raw material heater can be installed before the inlet of the hydrogenation reactor to ensure the inlet temperature.

[0018] Optionally, the condensation separation includes:

[0019] After being cooled by a cooler, the hydrogenation product is pressurized, condensed by a condenser, and then sent to a gas-liquid separator for gas-liquid separation.

[0020] The cooling temperature of the cooler is 60–110°C;

[0021] The condenser has a condensation temperature of -40 to 20°C.

[0022] The operating pressure of the gas-liquid separator is 5–40 bar (A).

[0023] Optionally, the cooling temperature of the cooler is independently selected from any value of 60°C, 85°C, 100°C, 110°C, or a range between any two of the above.

[0024] Optionally, the condensing temperature of the condenser is independently selected from any value among -40°C, -20°C, 0°C, 20°C, or a range between any two of the above.

[0025] Optionally, the operating pressure of the gas-liquid separator is independently selected from any value of 5 bar (A), 10 bar (A), 15 bar (A), 20 bar (A), 30 bar (A), 40 bar (A) or a range between any two of the above.

[0026] Optionally, the top temperature of the ammonia removal tower is -30 to 40°C, and the top pressure is 0.1 to 10 bar (A).

[0027] The theoretical number of plates in the ammonia removal tower is 10 to 60, and the reflux ratio is 0.1 to 8.

[0028] Optionally, the top temperature of the ammonia removal tower is independently selected from any value among -30℃, -20℃, -8℃, 0℃, 20℃, and 40℃, or a range between any two of the above.

[0029] Optionally, the top pressure of the ammonia removal tower is independently selected from any value among 0.1 bar (A), 1 bar (A), 3 bar (A), 5 bar (A), 8 bar (A), 10 bar (A) or a range between any two of the above.

[0030] Optionally, the theoretical plate number of the ammonia removal tower is independently selected from any value among 10, 25, 45, and 60, or a range between any two of the above.

[0031] Optionally, the reflux ratio of the ammonia removal tower is independently selected from any value of 0.1, 1, 3, 5, 8 or a range between any two of the above.

[0032] Optionally, the top temperature of the product column is 40–140°C, and the top pressure is 0.1–5 bar (A).

[0033] The product tower has a theoretical plate count of 10 to 60 and a reflux ratio of 1 to 25.

[0034] Optionally, the top temperature of the product tower is independently selected from any value of 40°C, 69°C, 90°C, 120°C, 140°C, or a range between any two of the above.

[0035] Optionally, the top pressure of the product tower is independently selected from any value of 0.1 bar (A), 1.3 bar (A), 4 bar (A), 8 bar (A), 10 bar (A) or a range between any two of the above.

[0036] Optionally, the theoretical plate number of the product tower is independently selected from any value of 10, 18, 32, 48, 60 or a range between any two of the above.

[0037] Optionally, the reflux ratio of the product tower is independently selected from any value of 1, 5, 10, 13.6, 15, 20, 25 or a range between any two of the above.

[0038] Optionally, the recovery includes sequential compression, cryogenic cooling, adiabatic decompression, and heat exchange;

[0039] The cryogenic temperature is -20 to -70°C;

[0040] The adiabatic pressure reduction is carried out in an expander, the outlet pressure of which is 0.1 to 12 bar (A).

[0041] Optionally, the temperature of the cryogenic treatment is independently selected from any value among -70°C, -50°C, -30°C, and -20°C, or a range between any two of the above.

[0042] Optionally, the outlet pressure of the expander is independently selected from any value of 0.1 bar (A), 1 bar (A), 3 bar (A), 5 bar (A), 7 bar (A), 10 bar (A), 12 bar (A) or a range between any two of the above.

[0043] Optionally, the cryogenic process further includes: removing condensate from the mixture obtained after cryogenic treatment via a liquid removal tank;

[0044] The operating pressure of the liquid removal tank 10 is 10 to 60 bar (A).

[0045] Another aspect of this application provides a process apparatus used in the above-described process for producing triethylamine, the process apparatus comprising: a reaction unit and a condensation separation unit connected in sequence;

[0046] The reaction unit includes a hydrogenation reactor;

[0047] The condensation separation unit is provided with a liquid phase outlet and a gas phase outlet;

[0048] The liquid phase outlet is connected to the distillation unit;

[0049] The gas phase outlet is connected to the hydrogen recovery unit;

[0050] The distillation unit includes an ammonia removal column and a product column connected in sequence. The ammonia removal column has a liquid phase inlet on its side wall, and a liquid phase outlet connected to the liquid phase inlet. The top of the column has an ammonia gas outlet and a waste liquid outlet, and the bottom of the column has a deammoniation product outlet. The product column has a deammoniation product inlet on its side wall, and a deammoniation product outlet connected to the deammoniation product inlet. The top of the column has a circulating feed outlet connected to the hydrogenation reactor, and the bottom of the column has a triethylamine outlet.

[0051] The hydrogen recovery unit is equipped with a circulating hydrogen outlet, which is connected to the hydrogenation reactor.

[0052] Optionally, the reaction unit further includes a hydrogen preheater and an acetonitrile preheater;

[0053] The condensation separation unit includes a cooler, a compressor I, a condenser, and a gas-liquid separator connected in sequence; the gas-liquid separator is provided with a liquid phase outlet and a gas phase outlet;

[0054] The hydrogen recovery unit includes a hydrogen compressor II, a cryogenic heat exchanger, a liquid removal tank, an expander, and a buffer tank connected in sequence; the buffer tank is provided with a circulating hydrogen outlet, and the circulating hydrogen outlet, the cryogenic heat exchanger, the hydrogen preheater, and the hydrogenation reactor are connected in sequence.

[0055] The acetonitrile preheater is located on the pipeline connecting the circulating feed outlet and the hydrogenation reactor.

[0056] As a specific implementation, the production process and method described in this application uses acetonitrile and hydrogen as raw materials. The apparatus includes the following components: a hydrogen preheater, an acetonitrile preheater, a hydrogenation reactor, a cooler, a No. 1 hydrogen compressor, a condenser, a gas-liquid separator, a No. 2 hydrogen compressor, a cryogenic heat exchanger, a liquid removal tank, an expander, a buffer tank, an ammonia removal tower, and a product tower. Specifically, it includes the following steps: Hydrogen is mixed with circulating hydrogen and preheated to a higher temperature by the hydrogen preheater. Acetonitrile and circulating raw materials are mixed and preheated to a higher temperature by the acetonitrile preheater. After the mixture reaches the reaction temperature, it is fed into the hydrogenation reactor to undergo a hydrogenation reaction, yielding a hydrogenation reaction product. The hydrogenation reaction product is cooled to a lower temperature but above the dew point by the cooler, then pressurized by the No. 1 hydrogen compressor and condensed in the condenser. It is then fed into the gas-liquid separator, and the resulting liquid phase enters the ammonia removal tower. Ammonia and waste liquid are separated at the top of the tower, and the deammoniation product is obtained at the bottom and sent to the product tower. The product column obtains recycled feedstock at the top and triethylamine at the bottom through distillation. The gas phase from the gas-liquid separator is pressurized to a higher pressure by the No. 2 hydrogen compressor, then cryogenically cooled by cryogenic circulating hydrogen / cryogenic condensate in a cryogenic heat exchanger. The condensate generated during cryogenic cooling is removed in a condensate separator. The gas phase is then adiabatically depressurized to a cryogenic temperature by an expander and sent to a buffer tank. The gas phase from the buffer tank is then mixed with fresh hydrogen and recycled after exchanging heat with the high-temperature gas phase in the cryogenic heat exchanger. The cryogenic liquid flowing from the buffer tank and condensate separator can be discharged directly as waste liquid, or it can be discharged as waste gas after exchanging heat with the high-temperature gas from the No. 2 hydrogen compressor.

[0057] In the specific reaction process, the hydrogenation reaction products are cooled and then pressurized by hydrogen compressor #1. The pressurized reaction products are condensed in a condenser and then separated into gas and liquid phases in a gas-liquid separator. The gas phase flowing out of the gas-liquid separator is further pressurized by hydrogen compressor #2. The further pressurized gas phase is cryogenically cooled by low-temperature circulating hydrogen / low-temperature condensate in a cryogenic heat exchanger to form a gas-liquid two-phase system. The condensate generated during cryogenic cooling is removed in a liquid removal tank. The liquid phase obtained from the liquid removal tank is discharged as waste liquid. The gas phase from the liquid removal tank is adiabatically depressurized to low temperature by an expander and then sent to a buffer tank. After depressurization and expansion, the gas phase serves as a cold source for the cryogenic heat exchanger, is heated, and then recycled. The liquid phase flowing out of the gas-liquid separator is distilled in an ammonia removal tower to separate non-condensable gas and liquid ammonia. The bottom material of the ammonia removal tower is distilled in a product tower to obtain triethylamine product and unreacted raw materials, of which the unreacted raw materials are recycled. The cryogenic liquid flowing out of the buffer tank and the liquid removal tank can be discharged directly as waste liquid, or it can be discharged as waste gas after exchanging heat with the high-temperature gas from the No. 2 hydrogen compressor.

[0058] Optionally, the material at the inlet of each device is pressurized and fed by each pressurized pump.

[0059] Alternatively, the expander may take the form of a pressure reducing valve, an expansion turbine, or other adiabatic pressure reducing equipment.

[0060] The beneficial effects that this application can produce include:

[0061] The process and apparatus provided in this application employ a cyclical operation process of "raw material preheating - reaction - pressurized condensation - sequential distillation - low-temperature hydrogen recovery - reduced pressure cooling and heat exchange," in which acetonitrile is hydrogenated to produce a hydrogenation product containing triethylamine. The product is then purified to obtain triethylamine. Unreacted hydrogen is purified and recycled, and the generated ammonia is used as a byproduct. The unreacted hydrogen is separated by pressurized, staged, and low-temperature flash evaporation and then recycled. This process can be used for the continuous production of triethylamine from acetonitrile hydrogenation, is convenient to operate, and is suitable for industrial-scale production. Attached Figure Description

[0062] Figure 1 This is a process diagram for the production of triethylamine in one embodiment of this application.

[0063] List of components and reference numerals:

[0064] 1. Hydrogen preheater; 2. Acetonitrile preheater; 3. Hydrogenation reactor; 4. Cooler; 5. Hydrogen compressor #1; 6. Condenser; 7. Gas-liquid separator; 8. Hydrogen compressor #2; 9. Cryogenic heat exchanger; 10. Liquid removal tank; 11. Expander; 12. Buffer tank; 13. Ammonia removal tower; 14. Product tower. Detailed Implementation

[0065] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0066] Unless otherwise specified, the raw materials and catalysts used in the embodiments of this application were all purchased commercially.

[0067] like Figure 1 As shown, the process apparatus used in this embodiment includes a hydrogen preheater 1, an acetonitrile preheater 2, a hydrogenation reactor 3, a cooler 4, a hydrogen compressor 1# 5, a condenser 6, a gas-liquid separator 7, a hydrogen compressor 2# 8, a cryogenic heat exchanger 9, a liquid removal tank 10, an expander 11, a buffer tank 12, an ammonia removal tower 13, and a product tower 14.

[0068] Hydrogen preheater 1 and acetonitrile preheater 2 are respectively connected to the raw material inlet of hydrogenation reactor 3. Hydrogenation reactor 3, cooler 4, No. 1 hydrogen compressor 5, condenser 6, and gas-liquid separator 7 are connected in sequence. Gas-liquid separator 7 is provided with liquid phase outlet and gas phase outlet.

[0069] The side wall of the ammonia removal tower 13 is provided with a liquid phase inlet, and the liquid phase outlet is connected to the liquid phase inlet. The top of the tower is provided with an ammonia gas outlet and a waste liquid outlet, and the bottom of the tower is provided with a deammoniation product outlet. The side wall of the product tower 14 is provided with a deammoniation product inlet, and the deammoniation product outlet is connected to the deammoniation product inlet. The top of the tower is provided with a circulating raw material outlet, which is connected to the acetonitrile preheater 2, and the bottom of the tower is provided with a triethylamine outlet.

[0070] The gas phase outlet is connected to the inlet of hydrogen compressor #2 8. Hydrogen compressor #2 8, cryogenic heat exchanger 9, liquid removal tank 10, expander 11, and buffer tank 12 are connected in sequence. Buffer tank 12 has a circulating hydrogen outlet, and the circulating hydrogen outlet, the cryogenic heat exchanger 9, hydrogen preheater 1, and hydrogenation reactor 3 are connected in sequence. The bottom of buffer tank 12 and liquid removal tank 10 are respectively provided with liquid outlets for the discharge of cryogenic liquid as waste liquid.

[0071] Example 1

[0072] Adopting such Figure 1The process unit shown in the diagram involves mixing hydrogen with recycled hydrogen and preheating the mixture to 129°C via hydrogen preheater 1. Acetonitrile, the raw material, is mixed with recycled raw material and preheated to 159°C via acetonitrile preheater 2. The mixture reaches a temperature of 135°C and is then fed into hydrogenation reactor 3 for hydrogenation reaction, yielding hydrogenation reaction products. The reaction temperature is 135°C, and the reaction pressure is 7 bar (A). The hydrogenation reaction products are cooled to 85°C by cooler 4 and then sent to hydrogen compressor 5 (No. 1) for pressurization to 20 bar (A). They are then condensed to -20°C in condenser 6 and sent to gas-liquid separator 7, where gas-liquid phase separation occurs at 20 bar (A). The resulting liquid phase enters ammonia removal tower 13. The top pressure of ammonia removal tower 13 is 3 bar (A), the top temperature is -8°C, and it has 45 theoretical plates with a reflux ratio of 1. Ammonia and waste liquid are separated at the top of the tower, and the deammoniation product is obtained at the bottom and sent to product tower 14. The product column 14 has a top pressure of 1.3 bar (A) and a top temperature of 69°C. It has 32 theoretical plates and a reflux ratio of 13.6. Recycled feedstock is obtained at the top of the column through distillation, and triethylamine is obtained at the bottom. The gas phase from the gas-liquid separator 7 is pressurized to 40 bar (A) by hydrogen compressor 8 (No. 2). It is then cryogenically cooled to -50°C in cryogenic heat exchanger 9 by cryogenic circulating hydrogen / cryogenic condensate. The condensate generated during cryogenic cooling is removed in condensate separator 10, which operates at a pressure of 39.5 bar (A). The gas phase is then adiabatically depressurized to 7 bar (A) by expander 11 and sent to buffer tank 12. The -106°C gas phase from buffer tank 12 exchanges heat with the high-temperature gas phase in cryogenic heat exchanger 9 and is then mixed with fresh hydrogen for recycling. The cryogenic liquid flowing from buffer tank 12 and condensate separator 10 is mixed and discharged as waste liquid.

[0073] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and all fall within the scope of the technical solution.

Claims

1. A process for producing triethylamine, characterized in that, The process includes: a hydrogen and acetonitrile feedstock undergoing a hydrogenation reaction in a hydrogenation reactor to obtain a hydrogenation reaction product, and the hydrogenation reaction product being condensed and separated to obtain a gas phase and a liquid phase. After the liquid phase is separated by distillation in the ammonia removal tower, ammonia gas and waste liquid are separated at the top of the tower, and ammonia removal product is obtained at the bottom of the tower. After distillation in the product tower, the deammoniation product is used to obtain recycled raw material at the top of the tower and triethylamine product at the bottom of the tower. The gas phase is recovered by a hydrogen recovery unit to obtain recycled hydrogen; The raw materials also include the recycled raw materials and recycled hydrogen.

2. The process method according to claim 1, characterized in that, The process method also includes raw material preheating; The raw materials are preheated at a temperature of 40–200°C.

3. The process method according to claim 1, characterized in that, The temperature of the hydrogenation reaction is 110–200°C; The operating pressure for the hydrogenation reaction is 0.1–12 bar (A).

4. The process method according to claim 1, characterized in that, The condensation separation includes: After being cooled by a cooler, the hydrogenation product is pressurized, condensed by a condenser, and then sent to a gas-liquid separator for gas-liquid separation. The cooling temperature of the cooler is 60–110°C; The condenser has a condensation temperature of -40 to 20°C. The operating pressure of the gas-liquid separator is 5–40 bar (A).

5. The process method according to claim 1, characterized in that, The temperature at the top of the ammonia removal tower is -30 to 40°C, and the pressure at the top of the tower is 0.1 to 10 bar (A). The theoretical number of plates in the ammonia removal tower is 10 to 60, and the reflux ratio is 0.1 to 8.

6. The process method according to claim 1, characterized in that, The product tower has a top temperature of 40–140°C and a top pressure of 0.1–5 bar (A). The product tower has a theoretical plate count of 10 to 60 and a reflux ratio of 1 to 25.

7. The process method according to claim 1, characterized in that, The recovery process includes sequential compression, cryogenic cooling, adiabatic decompression, and heat exchange. The cryogenic temperature is -20 to -70°C; The adiabatic pressure reduction is carried out in an expander, the outlet pressure of which is 0.1 to 12 bar (A).

8. The process method according to claim 7, characterized in that, The cryogenic process also includes: removing condensate from the mixture obtained after cryogenic treatment via a liquid removal tank; The operating pressure of the liquid removal tank is 10–60 bar (A).

9. A process apparatus used in the process for producing triethylamine according to any one of claims 1 to 8, characterized in that, The process apparatus includes: The reaction unit and the condensation separation unit are connected in sequence. The reaction unit includes a hydrogenation reactor; The condensation separation unit is provided with a liquid phase outlet and a gas phase outlet; The liquid phase outlet is connected to the distillation unit; The gas phase outlet is connected to the hydrogen recovery unit; The distillation unit includes an ammonia removal column and a product column connected in sequence. The ammonia removal column has a liquid phase inlet on its side wall, and a liquid phase outlet connected to the liquid phase inlet. The top of the column has an ammonia gas outlet and a waste liquid outlet, and the bottom of the column has a deammoniation product outlet. The product column has a deammoniation product inlet on its side wall, and a deammoniation product outlet connected to the deammoniation product inlet. The top of the column has a circulating feed outlet connected to the hydrogenation reactor, and the bottom of the column has a triethylamine outlet. The hydrogen recovery unit is equipped with a circulating hydrogen outlet, which is connected to the hydrogenation reactor.

10. The process apparatus according to claim 9, characterized in that, The reaction unit also includes a hydrogen preheater and an acetonitrile preheater; The condensation separation unit includes a cooler, a compressor I, a condenser, and a gas-liquid separator connected in sequence; the gas-liquid separator is provided with a liquid phase outlet and a gas phase outlet; The hydrogen recovery unit includes a hydrogen compressor II, a cryogenic heat exchanger, a liquid removal tank, an expander, and a buffer tank connected in sequence; the buffer tank is provided with a circulating hydrogen outlet, and the circulating hydrogen outlet, the cryogenic heat exchanger, the hydrogen preheater, and the hydrogenation reactor are connected in sequence. The acetonitrile preheater is located on the pipeline connecting the circulating feed outlet and the hydrogenation reactor.

Images