Continuous production process of dimethyl glycine nitrile

Abstract

The invention relates to the technical field of chemical synthesis, and particularly discloses a continuous production process of dimethyl glycine nitrile. According to the invention, hydrocyanic acid, formaldehyde and dimethylamine are taken as raw materials, hydroxynitrile lyase is taken as a catalyst, and the reaction is efficiently catalyzed by a specific biological enzyme, so that the selectivity of the reaction and the conversion rate of the raw materials of hydrocyanic acid and formaldehyde are effectively improved, and the excess ratio of dimethylamine is remarkably reduced; the molar excess ratio of the dimethylamine relative to the formaldehyde is only 0-1% (the feeding molar weight of the dimethylamine in the prior art is at least 1.1 times of the molar weight of the formaldehyde), and meanwhile, by controlling the molar excess ratio of the hydrocyanic acid, the product quality of the dimethyl glycine nitrile is further improved, and the yield of the dimethyl glycine nitrile product is improved; the dimethyl glycine nitrile reaction liquid obtained through catalysis is subsequently subjected to simple multi-stage continuous countercurrent extraction, desolvation and rectification to obtain a dimethyl glycine nitrile product with the purity of 99.5% or above, and the product yield reaches up to 98% or above.

Description

Technical Field

[0001] The invention relates to the technical field of chemical synthesis, and in particular to a continuous production process of dimethylglycine nitrile. Background Art

[0002] Dimethylglycine nitrile, also known as N,N-dimethylaminoacetonitrile (DMAC for short), CAS No.: 926-64-7, EINECS No.: 213-140-4, has been widely used in the chemical, dye and plastic industries. Dimethylglycine nitrile is an important solvent for synthetic man-made fibers, such as polyamide fibers and polyamide synthetic fibers. It also plays an important role in the preparation of high-performance polyurethane, polyester, polyamide, polyamic acid and other polymer materials. It can also be used as a solvent in the textile industry, a dissolving agent for dyes, and a medium for polymer catalytic reactions, and has a large market demand.

[0003] In industrial production, the synthesis of dimethylglycine nitrile mainly depends on chemical synthesis. The traditional synthesis method is to synthesize dimethylglycine nitrile with hydroxyacetonitrile and dimethylamine as raw materials. Since it is necessary to add inorganic acid such as sulfuric acid, phosphoric acid and other stabilizers in the hydroxyacetonitrile aqueous solution, the wastewater produced by dimethylglycine nitrile contains substances such as sulfate or phosphate, and the wastewater treatment is difficult. And the reaction rate of hydroxyacetonitrile and dimethylamine is slow, the raw material hydroxyacetonitrile dripping time and the insulation time after the addition are long, the production efficiency is low, and it is difficult to realize the continuous production of the process. The production efficiency of the intermittent production process is low, the number of equipment required is large, and therefore the number of operators required is also large, resulting in the high production cost of dimethylglycine nitrile. With the continuous growth of the market demand for dimethylglycine nitrile, the development of efficient and continuous dimethylglycine nitrile production technology has become a problem to be solved at present. Summary of the invention

[0004] Aiming at the problems of long production cycle, low production efficiency and high production cost in the existing process for producing dimethylglycine nitrile, the present invention provides a continuous production process for dimethylglycine nitrile. The process mainly uses hydrocyanic acid, formaldehyde and dimethylamine as raw materials, uses cyanocyanide lyase as catalyst, prepares dimethylglycine nitrile reaction liquid through enzyme catalysis reaction, and subjecting the obtained dimethylglycine nitrile reaction liquid to multi-stage countercurrent continuous extraction, removes the extraction solvent, and performs rectification to obtain a high-purity dimethylglycine nitrile product. The present invention not only effectively improves production efficiency and reduces production cost, but also significantly improves the yield and purity of the dimethylglycine nitrile product, and has high industrial application prospect.

[0005] In order to solve the above technical problems, the technical solution provided by the present invention is:

[0006] A continuous production process of dimethylglycine nitrile comprises the following steps:

[0007] Step a, continuously introducing formaldehyde aqueous solution, hydrocyanic acid, dimethylamine aqueous solution and cyanocyanate lyase aqueous solution into a reactor for reaction at 10° C. to 40° C., and cooling to obtain a dimethylglycine nitrile reaction solution;

[0008] Step b, continuously passing the dimethylglycine nitrile into a multi-stage countercurrent extraction device to obtain an oil phase mixture and an aqueous phase;

[0009] Step c, continuously passing the oil phase mixture into a desolventizing tower for desolventizing to obtain a crude dimethylglycine nitrile product;

[0010] Step d, distilling the crude dimethylglycine nitrile to obtain a dimethylglycine nitrile product;

[0011] The aqueous solution of hydroxynitrile lyase is an aqueous solution of aliphatic (R)-hydroxynitrile lyas; the molar ratio of formaldehyde, hydrocyanic acid and dimethylamine is (1-1.01):1:(1-1.01).

[0012] Compared with the prior art, the continuous production process of dimethylglycine nitrile provided by the present invention uses hydrocyanic acid, formaldehyde and dimethylamine as raw materials, uses cyanocyanide lyase as a catalyst, and carries out the reaction by high-efficiency catalysis through specific biological enzymes, thereby effectively improving the selectivity of the reaction and the raw material conversion rate of hydrocyanic acid and formaldehyde, thereby significantly reducing the excess ratio of dimethylamine, and the molar excess ratio of dimethylamine relative to formaldehyde is only 0% to 1% (in the prior art, the feed molar amount of dimethylamine is at least 1.1 times the molar amount of formaldehyde). At the same time, by controlling the molar excess ratio of hydrocyanic acid, the product quality of dimethylglycine nitrile is further improved, and the yield of the dimethylglycine nitrile product is increased; the dimethylglycine nitrile reaction liquid obtained by catalysis can be subsequently subjected to simple multi-stage continuous countercurrent extraction, desolventization and distillation to obtain a dimethylglycine nitrile product with a purity of more than 99.5%, and the product yield is as high as more than 98%.

[0013] The invention realizes the continuous production of dimethylglycine nitrile, completely solves the problems of long production cycle, low production efficiency and high production cost of dimethylglycine nitrile products, is suitable for industrial promotion and application, and is of great significance for expanding the application of dimethylglycine nitrile.

[0014] Furthermore, the continuous production process of dimethylglycine nitrile specifically comprises the following steps:

[0015] A formaldehyde aqueous solution, hydrocyanic acid, a dimethylamine aqueous solution and a hydroxynitrile lyase aqueous solution are continuously introduced into a tubular reactor at a temperature of 10°C to 40°C; the dimethylglycine nitrile reaction liquid coming out of the tubular reactor is cooled in a cooler and then continuously introduced into a multi-stage countercurrent extraction device for extraction; the oil phase mixture obtained by extraction is continuously introduced into a desolventizing tower to remove the solvent; the crude dimethylglycine nitrile obtained in the bottom of the tower is continuously introduced into a distillation tower, and the dimethylglycine nitrile product is collected from the top of the tower.

[0016] Furthermore, the mass concentration of the formaldehyde aqueous solution is 35% to 50%.

[0017] Furthermore, the mass concentration of the dimethylamine aqueous solution is 40% to 45%.

[0018] Furthermore, the flow rate of the hydrocyanic acid is 500kg / h to 1000kg / h.

[0019] The preferred concentration and flow rate of the reaction raw materials can improve the conversion rate of the reaction raw materials and reduce the occurrence of side reactions, thereby facilitating the improvement of the yield and purity of the dimethylglycine nitrile product.

[0020] It should be noted that the hydrocyanic acid used in the present invention is liquid hydrocyanic acid, and the hydrocyanic acid content is ≥99%.

[0021] Furthermore, the concentration of the cyanohydrin lyase aqueous solution is 1×10 9 U / L~2×10 9 U / L.

[0022] Specifically, the cyanohydrin lyase is numbered as EC 4.1.2.46.

[0023] Furthermore, the flow rate of the cyanolyase aqueous solution is 40 kg / h to 60 kg / h.

[0024] The preferred biological enzyme can efficiently catalyze the reaction of hydroxyacetonitrile, dimethylamine and formaldehyde, and improve the selectivity of the reaction. At the same time, with the preferred biological enzyme as a catalyst, the reaction conditions are milder, and there is no need to add inorganic salts such as sulfuric acid or phosphoric acid as a stabilizer for the hydroxyacetonitrile aqueous solution during the reaction process, the wastewater treatment is less difficult, and the environmental friendliness is higher.

[0025] Furthermore, the amount of the cyanohydrin lyase aqueous solution added is 0.5% to 2% of the total mass of the formaldehyde aqueous solution, hydrocyanic acid and dimethylamine aqueous solution.

[0026] Preferably, the amount of the cyanohydrin lyase aqueous solution added is 0.9% to 1.2% of the total mass of the formaldehyde aqueous solution, hydrocyanic acid and dimethylamine aqueous solution.

[0027] The amount of the hydroxylase added is small, and the impact on the environment during use is small, which effectively improves the environmental protection of the process and reduces the process cost.

[0028] Furthermore, the extractant of the multi-stage countercurrent extraction device is at least one of dichloromethane, dichloroethane or chloroform.

[0029] Furthermore, the multi-stage countercurrent extraction device is a six-stage countercurrent extraction device.

[0030] Specifically, the multi-stage countercurrent extraction device is a six-stage countercurrent extraction centrifuge.

[0031] Furthermore, the mass ratio of the extractant to the dimethylglycine nitrile reaction liquid in each stage of the extraction device is 0.8:1 to 2:1.

[0032] The preferred extraction stages, extractant and amount of the extractant added can fully separate dimethylglycine nitrile from impurities, thereby improving the yield and purity of dimethylglycine nitrile.

[0033] It should be noted that after the water phase obtained after extraction is simply evaporated to remove a small amount of extractant in the water phase, the remaining wastewater containing cyanohydrin lyase directly enters the biochemical wastewater treatment system.

[0034] Furthermore, the pressure in the desolventizing tower is normal pressure, the temperature of the tower bottom is controlled at 100° C. to 115° C., and the temperature of the tower top is controlled at the boiling point of the extractant under normal pressure.

[0035] Furthermore, the top temperature of the distillation tower is 77°C to 86°C, the bottom temperature is 100°C to 105°C, and the vacuum degree is 10KPa to 15KPa.

[0036] It should be noted that the dimethylglycine nitrile collected from the top of the distillation tower is condensed to 20℃~30℃ through a condenser and enters the finished product packaging; the kettle residue collected from the bottom of the tower is cooled to 30℃~40℃ and enters the kettle residue storage tank.

[0037] The production method of dimethylglycine nitrile provided by the invention has the advantages of simple process operation, significantly reduced amount of dimethyl as a raw material, fast reaction rate, purity of the prepared dimethylglycine nitrile product reaching more than 99.8%, yield reaching more than 98%, high product quality consistency, and completely solving the problems of long production cycle and low production efficiency of traditional n-butyl glycolate. Moreover, the generated wastewater does not contain inorganic salts, is easier to process, and has extremely high industrial application prospects. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention.

[0039] In order to better illustrate the present invention, further examples are given below.

[0040] The hydroxylase used in the following examples is aliphatic (R)-hydroxynitrile lyas, numbered as EC4.1.2.46.

[0041] Example 1

[0042] This embodiment provides a continuous production process of dimethylglycine nitrile, comprising the following steps:

[0043] A 37.1% formaldehyde aqueous solution, a 99.5% hydrocyanic acid solution, and a 41.1% dimethylamine aqueous solution were added at a molar ratio of 1.0:1.0:1.0, and the flow rate was automatically controlled by a regulating valve and a mass flow meter. The flow rate of hydrocyanic acid was set to 500.0 kg / h, the flow rate of formaldehyde aqueous solution was set to 1489.8 kg / h, the flow rate of dimethylamine aqueous solution was set to 2018.8 kg / h, and the concentration of hydroxynitrile lyase aqueous solution was set to 1.5×10 9 U / L, and the flow rate of the cyanolyase aqueous solution was 40 kg / h.

[0044] The formaldehyde aqueous solution, hydrocyanic acid, dimethylamine aqueous solution and cyanocyanate lyase aqueous solution are simultaneously and continuously introduced into the tubular reactor, the temperature of the materials in the tubular reactor is controlled to be 20°C, the reaction liquid of the tubular reactor is introduced into a condenser for cooling, the material temperature at the discharge port of the condenser is 5°C, the materials coming out of the condenser are continuously introduced into a storage tank, and then continuously introduced into a six-stage countercurrent extraction centrifuge at a flow rate of 4048.6kg / h for continuous extraction from the storage tank, the flow rate of the extractant dichloromethane is 4000kg / h, the water phase coming out of the six-stage countercurrent extraction centrifuge is simply evaporated to remove a small amount of the extractant in the water phase, and the remaining water phase enters the biochemical wastewater treatment system, the oil phase mixture obtained by extraction enters the storage tank, and then is continuously extracted at a flow rate of 5540kg / h. The solvent is put into the desolventizing tower for desolventizing. The bottom temperature of the desolventizing tower is controlled to be 100°C, the top temperature is 39.5-40°C, the extraction amount of the condensed solvent at the top of the tower is 3990kg / h, and it directly enters the solvent tank for recycling. The crude dimethylglycine nitrile extracted from the bottom of the tower is continuously introduced into the distillation tower at a flow rate of 1550kg / h. The vacuum degree of the distillation tower is controlled to be 14.5KPa, the top temperature is 84-85°C, and the bottom temperature is 102°C. The dimethylglycine nitrile product continuously extracted from the top of the tower is extracted into the finished product tank at a rate of 1530kg / h after cooling. The content of the extracted product is 99.92%, and the pure yield is 98.76%. The high-boiling substances in the bottom of the tower are extracted at a rate of 20kg / h, placed in a special storage tank, and regularly handed over to relevant departments for processing.

[0045] Example 2

[0046] This embodiment provides a continuous production process of dimethylglycine nitrile, comprising the following steps:

[0047] A 41.9% formaldehyde aqueous solution, a 99.6% hydrocyanic acid solution, and a 42.5% dimethylamine aqueous solution were added at a molar ratio of 1.005:1.0:1.01 and automatically controlled by a regulating valve and a mass flow meter. The flow rate of hydrocyanic acid was set to 600.0 kg / h, the flow rate of formaldehyde aqueous solution was set to 1592.5 kg / h, the flow rate of dimethylamine aqueous solution was set to 2368.5 kg / h, and the concentration of hydroxynitrile lyase aqueous solution was set to 2×10 9 U / L, and the flow rate of the cyanolyase aqueous solution was 40 kg / h.

[0048] A formaldehyde aqueous solution, hydrocyanic acid, a dimethylamine aqueous solution and a cyanolyase aqueous solution are simultaneously and continuously introduced into a tubular reactor, the temperature of the materials in the tubular reactor is controlled to be 30°C, the reaction liquid of the tubular reactor is introduced into a condenser for cooling, the material temperature at the discharge port of the condenser is 5°C, the materials coming out of the condenser are continuously introduced into a storage tank, and then continuously introduced into a six-stage countercurrent extraction centrifuge at a flow rate of 4601.0kg / h for continuous extraction from the storage tank, the flow rate of the extractant dichloroethane is 5000kg / h, the water phase coming out of the six-stage countercurrent extraction centrifuge is simply evaporated to remove a small amount of the extractant in the water phase, and the remaining water phase enters the biochemical wastewater treatment system, the oil phase mixture obtained by extraction enters the storage tank, and then is continuously extracted at a flow rate of 6850kg / h. The solvent is then put into a desolventizing tower for desolventizing. The bottom temperature of the desolventizing tower is controlled at 114°C, the top temperature is 83.5-84°C, the top condensed solvent is produced at 4990 kg / h, and directly enters the solvent tank for recycling. The crude dimethylglycine nitrile produced from the bottom of the tower is continuously introduced into the distillation tower at a flow rate of 1860 kg / h. The vacuum degree of the distillation tower is controlled at 10.0 KPa, the top temperature is 77-78°C, and the bottom temperature is 100°C. The dimethylglycine nitrile product produced continuously from the top of the tower is cooled and then produced into a finished product tank at a rate of 1833 kg / h. The content of the produced product is 99.90%, and the pure yield is 98.48%. The high-boiling substances in the bottom of the tower are produced at a rate of 27 kg / h, placed in a special storage tank, and regularly handed over to relevant departments for processing.

[0049] Example 3

[0050] This embodiment provides a continuous production process of dimethylglycine nitrile, comprising the following steps:

[0051] A 47.3% formaldehyde aqueous solution, a 99.5% hydrocyanic acid solution, and a 44.3% dimethylamine aqueous solution were added at a molar ratio of 1.001:1.000:1.005, and the flow rate was automatically controlled by a regulating valve and a mass flow meter. The flow rate of hydrocyanic acid was set to 801.0 kg / h, the flow rate of formaldehyde aqueous solution was set to 1873.9 kg / h, the flow rate of dimethylamine aqueous solution was set to 3015.5 kg / h, and the concentration of hydroxynitrile lyase aqueous solution was set to 1×10 9 U / L, and the flow rate of the cyanolyase aqueous solution was 60 kg / h.

[0052] A formaldehyde aqueous solution, hydrocyanic acid, a dimethylamine aqueous solution and a cyanolyase aqueous solution are simultaneously and continuously introduced into a tubular reactor, the temperature of the materials in the tubular reactor is controlled to be 40° C. The reaction liquid of the tubular reactor is introduced into a condenser for cooling, the material temperature at the discharge port of the condenser is 8° C. The materials coming out of the condenser are continuously introduced into a storage tank, and then continuously introduced into a six-stage countercurrent extraction centrifuge at a flow rate of 5750.4 kg / h for continuous extraction from the storage tank, the flow rate of the extractant chloroform is 10000 kg / h, and the water phase coming out of the six-stage countercurrent extraction centrifuge is simply evaporated to remove a small amount of the extractant in the water phase, and the remaining water phase enters a biochemical wastewater treatment system, and the oil phase mixture obtained by extraction enters a storage tank and then is continuously extracted at a flow rate of 12470 kg / h. The crude dimethylglycine nitrile produced from the tower bottom is continuously introduced into the distillation tower at a flow rate of 2480 kg / h, and the vacuum degree of the distillation tower is controlled to be 12.0 KPa, the tower top temperature is 80-81 ° C, and the tower bottom temperature is 103 ° C. The dimethylglycine nitrile product continuously produced from the tower top is produced into the finished product tank at a rate of 2440 kg / h after cooling. The content of the produced product is 99.85%, and the pure yield is 98.25%. The high-boiling substances produced from the tower bottom material are produced at a rate of 40 kg / h, placed in a special storage tank, and regularly handed over to relevant departments for processing.

[0053] Comparative Example 1

[0054] This comparative example provides a continuous production process of dimethylglycine nitrile, which is different from Example 1 only in that hydroxynitrile lyase is not added, and specifically comprises the following steps:

[0055] A 37.1% formaldehyde aqueous solution, a 99.5% hydrocyanic acid solution and a 41.1% dimethylamine aqueous solution were added at a molar ratio of 1.0:1.0:1.0, and the mixture was automatically controlled by a regulating valve and a mass flow meter. The flow rate of hydrocyanic acid was set to 500 kg / h, the flow rate of formaldehyde aqueous solution was set to 1489.8 kg / h, and the flow rate of dimethylamine aqueous solution was set to 2018.8 kg / h.

[0056] The formaldehyde aqueous solution, hydrocyanic acid and dimethylamine aqueous solution are continuously introduced into the tubular reactor at the same time, and the temperature of the materials in the tubular reactor is controlled to be 20°C. The reaction liquid of the tubular reactor is introduced into a condenser for cooling. The temperature of the material liquid at the outlet of the condenser is 5°C. The material coming out of the condenser is continuously introduced into a storage tank, and then continuously introduced into a six-stage countercurrent extraction centrifuge at a flow rate of 4008.6kg / h for continuous extraction from the storage tank. The flow rate of the extractant dichloromethane is 4000kg / h. After a small amount of the extractant in the water phase is removed by simple evaporation, the remaining water phase enters the biochemical wastewater treatment system. The oil phase mixture obtained by extraction enters the storage tank and then enters the desolventizing system at a flow rate of 5080kg / h. Desolventizing is carried out in the tower, the bottom temperature of the desolventizing tower is controlled to be 100°C, the top temperature is 39.5-40°C, the extraction amount of the condensed solvent at the top of the tower is 3990kg / h, and it directly enters the solvent tank for recycling. The crude dimethylglycine nitrile extracted from the bottom of the tower is continuously introduced into the distillation tower at a flow rate of 1090kg / h, the vacuum degree of the distillation tower is controlled to be 14.5KPa, the top temperature is 84-85°C, and the bottom temperature is 102°C. The dimethylglycine nitrile product continuously extracted from the top of the tower is extracted into the finished product tank at a rate of 1060kg / h after cooling. The content of the extracted product is 99.3%, and the pure yield is 68.00%. The high-boiling substances in the bottom of the tower are extracted at a rate of 30kg / h, placed in a special storage tank, and regularly handed over to relevant departments for processing.

[0057] During the test, it was found that the amount of oil phase coming out of the six-stage countercurrent extraction centrifuge was small, the amount of water phase increased significantly, and the color of the water phase was dark red.

[0058] Comparative Example 2

[0059] This comparative example provides a continuous production process of dimethylglycine nitrile, which is different from Example 1 only in that the hydroxynitrile lyase is replaced by (S)-hydroxynitrile of the same concentration, and comprises the following steps:

[0060] A 37.1% formaldehyde aqueous solution, a 99.5% hydrocyanic acid solution, and a 41.1% dimethylamine aqueous solution were added at a molar ratio of 1.0:1.0:1.0, and the flow rate was automatically controlled by a regulating valve and a mass flow meter. The flow rate of hydrocyanic acid was set to 500 kg / h, the flow rate of formaldehyde aqueous solution was set to 1489.8 kg / h, the flow rate of dimethylamine aqueous solution was set to 2018.8 kg / h, and the concentration of (S)-hydroxynitrile aqueous solution was set to 1.5×10 9 U / L, the flow rate of (S)-hydroxynitrile aqueous solution is 40 kg / h.

[0061] A formaldehyde aqueous solution, hydrocyanic acid, a dimethylamine aqueous solution and a cyanolyase aqueous solution are continuously introduced into a tubular reactor at the same time, the temperature of the materials in the tubular reactor is controlled to be 20°C, the reaction liquid of the tubular reactor is introduced into a condenser for cooling, the material temperature at the discharge port of the condenser is 5°C, the materials coming out of the condenser are continuously introduced into a storage tank, and then continuously introduced into a six-stage countercurrent extraction centrifuge at a flow rate of 4048.6kg / h for continuous extraction from the storage tank, the flow rate of the extractant dichloromethane is 4000kg / h, the water phase coming out of the six-stage countercurrent extraction centrifuge is simply evaporated to remove a small amount of the extractant in the water phase, and the remaining water phase enters the biochemical wastewater treatment system, and the oil phase mixture obtained by extraction enters the storage tank and is then continuously extracted at a flow rate of 5200kg / h. The crude dimethylglycine nitrile produced from the tower bottom is continuously introduced into the distillation tower at a flow rate of 1210 kg / h, and the vacuum degree of the distillation tower is controlled to be 14.5 KPa, the tower top temperature is 84-85 ° C, and the tower bottom temperature is 102 ° C. The dimethylglycine nitrile product continuously produced from the tower top is produced into the finished product tank at a rate of 1180 kg / h after cooling. The content of the produced product is 99.1%, and the pure yield is 75.55%. The high-boiling substances in the tower bottom material are produced at a rate of 30 kg / h, placed in a special storage tank, and regularly handed over to relevant departments for treatment.

[0062] Comparative Example 3

[0063] This comparative example provides a continuous production process of dimethylglycine nitrile, which is different from Example 1 only in that the feed ratio of hydrocyanic acid is increased, and specifically comprises the following steps:

[0064] A 37.1% formaldehyde aqueous solution, a 99.5% hydrocyanic acid solution, and a 41.1% dimethylamine aqueous solution were added at a molar ratio of 1.00:1.05:1.00 and automatically controlled by a regulating valve and a mass flow meter. The flow rate of hydrocyanic acid was set to 1500 kg / h, the flow rate of formaldehyde aqueous solution was set to 4256.6 kg / h, the flow rate of dimethylamine aqueous solution was set to 5767.9 kg / h, and the concentration of hydroxynitrile lyase aqueous solution was set to 1.5×10 9 U / L, and the flow rate of the cyanolyase aqueous solution was 40 kg / h.

[0065] A formaldehyde aqueous solution, hydrocyanic acid, a dimethylamine aqueous solution and a cyanolyase aqueous solution are simultaneously and continuously introduced into a tubular reactor, the temperature of the materials in the tubular reactor is controlled to be 20°C, the reaction liquid of the tubular reactor is introduced into a condenser for cooling, the material temperature at the discharge port of the condenser is 5°C, the materials coming out of the condenser are continuously introduced into a storage tank, and then continuously introduced into a six-stage countercurrent extraction centrifuge at a flow rate of 11564.5kg / h for continuous extraction from the storage tank, the flow rate of the extractant dichloromethane is 4000kg / h, the water phase coming out of the six-stage countercurrent extraction centrifuge is simply evaporated to remove a small amount of the extractant in the water phase, and the remaining water phase enters a biochemical wastewater treatment system, and the oil phase mixture obtained by extraction enters a storage tank and then is discharged at a flow rate of 8155kg / h. The crude dimethylglycine nitrile produced from the tower bottom is continuously introduced into the distillation tower at a flow rate of 4165 kg / h, and the vacuum degree of the distillation tower is controlled to be 14.5 KPa, the tower top temperature is 84-85 ° C, and the tower bottom temperature is 102 ° C. The dimethylglycine nitrile product continuously produced from the tower top is produced into the finished product tank at a rate of 4000 kg / h after cooling. The content of the produced product is 99.3%, and the pure yield is 85.54%. The high-boiling substances produced from the tower bottom material are produced at a rate of 165 kg / h, placed in a special storage tank, and regularly handed over to relevant departments for treatment.

[0066] Comparative Example 4

[0067] This comparative example provides a continuous production process of dimethylglycine nitrile, which is different from Example 2 only in that the material temperature in the tubular reactor is changed, and specifically comprises the following steps:

[0068] A 41.9% formaldehyde aqueous solution, a 99.6% hydrocyanic acid solution, and a 42.5% dimethylamine aqueous solution were added at a molar ratio of 1.005:1.0:1.01 and automatically controlled by a regulating valve and a mass flow meter. The flow rate of hydrocyanic acid was set to 600 kg / h, the flow rate of formaldehyde aqueous solution was set to 1592.5 kg / h, the flow rate of dimethylamine aqueous solution was set to 2368.5 kg / h, and the concentration of hydroxynitrile lyase aqueous solution was set to 2×10 9 U / L, and the flow rate of the cyanolyase aqueous solution was 40 kg / h.

[0069] A formaldehyde aqueous solution, hydrocyanic acid, a dimethylamine aqueous solution and a cyanolyase aqueous solution are simultaneously and continuously introduced into a tubular reactor, the temperature of the materials in the tubular reactor is controlled to be 0°C, the reaction liquid of the tubular reactor is introduced into a condenser for cooling, the material temperature at the discharge port of the condenser is 0°C, the material coming out of the condenser is continuously introduced into a storage tank, and then continuously introduced into a six-stage countercurrent extraction centrifuge at a flow rate of 4601kg / h from the storage tank for continuous extraction, the flow rate of the extractant ethylene dichloride is 5000kg / h, the water phase coming out of the six-stage countercurrent extraction centrifuge is simply evaporated to remove a small amount of the extractant in the water phase, and the remaining water phase enters the biochemical wastewater treatment system, the oil phase mixture obtained by extraction enters the storage tank, and then enters the The solvent is put into the desolventizing tower for desolventizing, the bottom temperature of the desolventizing tower is controlled to be 114°C, the top temperature is 83.5-84°C, the extraction amount of the condensed solvent at the top of the tower is 4990kg / h, and it directly enters the solvent tank for recycling. The crude dimethylglycine nitrile extracted from the bottom of the tower is continuously introduced into the distillation tower at a flow rate of 1650kg / h, the vacuum degree of the distillation tower is controlled to be 10.0KPa, the top temperature is 77-78°C, and the bottom temperature is 100°C. The dimethylglycine nitrile product continuously extracted from the top of the tower is extracted into the finished product tank at a rate of 1580kg / h after cooling. The content of the extracted product is 99.60%, and the pure yield is 84.64%. The high-boiling substances in the bottom of the tower are extracted at a rate of 70kg / h, placed in a special storage tank, and regularly handed over to relevant departments for processing.

[0070] Comparative Example 5

[0071] This comparative example provides a continuous production process of dimethylglycine nitrile, which is different from Example 2 only in that the hydroxynitrile lyase in Example 2 is replaced by a sarcosine-sodium sarcosinate aqueous solution, and specifically comprises the following steps:

[0072] A 41.9% formaldehyde aqueous solution, a 99.6% hydrocyanic acid solution and a 42.5% dimethylamine aqueous solution were added at a molar ratio of 1.005:1.0:1.01, and the flow rate was automatically controlled by a regulating valve and a mass flow meter. The flow rate of hydrocyanic acid was set to 600 kg / h, the flow rate of formaldehyde aqueous solution was set to 1592.5 kg / h, the flow rate of dimethylamine aqueous solution was set to 2368.5 kg / h, and the sarcosine-sodium sarcosinate aqueous solution was used as a catalyst, and the flow rate was controlled to 200 kg / h (wherein, the sarcosine-sodium sarcosinate aqueous solution was an aqueous solution prepared from 88.3 kg of sarcosine, 40.5 kg of 30% sodium sarcosinate solution and 71.2 kg of water).

[0073] A formaldehyde aqueous solution, hydrocyanic acid, a dimethylamine aqueous solution and a cyanolyase aqueous solution are simultaneously and continuously introduced into a tubular reactor, the temperature of the materials in the tubular reactor is controlled to be 30° C. The reaction liquid of the tubular reactor is introduced into a condenser for cooling, the material temperature at the discharge port of the condenser is 5° C. The material coming out of the condenser is continuously introduced into a storage tank, and then continuously introduced from the storage tank into a six-stage countercurrent extraction centrifuge at a flow rate of 4761 kg / h for continuous extraction, the flow rate of the extractant dichloroethane is 5000 kg / h, and the water phase coming out of the six-stage countercurrent extraction centrifuge is simply evaporated to remove a small amount of the extractant in the water phase, and the remaining water phase enters a biochemical wastewater treatment system (the wastewater contains sodium salt, which increases the difficulty and cost of wastewater treatment). The extracted oil phase mixture enters the storage tank and then enters the desolventizing tower at a flow rate of 6730kg / h for desolventizing. The bottom temperature of the desolventizing tower is controlled to be 114°C, the top temperature is 83.5-84°C, the extraction amount of the condensed solvent at the top of the tower is 4990kg / h, and it directly enters the solvent tank for recycling. The crude dimethylglycine nitrile extracted from the bottom of the tower is continuously passed into the distillation tower at a flow rate of 1740kg / h. The vacuum degree of the distillation tower is controlled to be 10.0KPa, the top temperature is 77-78°C, and the bottom temperature is 100°C. The dimethylglycine nitrile product continuously extracted from the top of the tower is extracted into the finished product tank at a rate of 1720kg / h after cooling. The content of the extracted product is 99.0%, and the pure yield is 91.58%. The high-boiling substances in the bottom of the tower are extracted at a rate of 20kg / h, placed in a special storage tank, and regularly handed over to relevant departments for processing. The product yield, content and wastewater treatment in this comparative example did not achieve the expected treatment effect.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modification, equivalent substitution or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A continuous production process of dimethylglycine nitrile, characterized in that: The steps include: Step a, continuously introducing formaldehyde aqueous solution, hydrocyanic acid, dimethylamine aqueous solution and cyanocyanate lyase aqueous solution into a reactor for reaction at 10° C. to 40° C., and cooling to obtain a dimethylglycine nitrile reaction solution; Step b, continuously passing the dimethylglycine nitrile into a multi-stage countercurrent extraction device to obtain an oil phase mixture and an aqueous phase; Step c, continuously passing the oil phase mixture into a desolventizing tower for desolventizing to obtain a crude dimethylglycine nitrile product; Step d, distilling the crude dimethylglycine nitrile to obtain a dimethylglycine nitrile product; The aqueous solution of hydroxynitrile lyase is an aqueous solution of aliphatic (R)-hydroxynitrile lyas; the molar ratio of formaldehyde, hydrocyanic acid and dimethylamine is (1-1.01):1:(1-1.01).

2. The continuous production process of dimethylglycine nitrile as claimed in claim 1, characterized in that: The specific steps include: A formaldehyde aqueous solution, hydrocyanic acid, a dimethylamine aqueous solution and a hydroxynitrile lyase aqueous solution are continuously introduced into a tubular reactor at a temperature of 10°C to 40°C; the dimethylglycine nitrile reaction liquid coming out of the tubular reactor is cooled in a cooler and then continuously introduced into a multi-stage countercurrent extraction device for extraction; the oil phase mixture obtained by extraction is continuously introduced into a desolventizing tower to remove the solvent; the crude dimethylglycine nitrile obtained in the bottom of the tower is continuously introduced into a distillation tower, and the dimethylglycine nitrile product is collected from the top of the tower.

3. The continuous production process of dimethylglycine nitrile as claimed in claim 1 or 2, characterized in that: The mass concentration of the formaldehyde aqueous solution is 35% to 50%; and / or The mass concentration of the dimethylamine aqueous solution is 40% to 45%.

4. The continuous production process of dimethylglycine nitrile as claimed in claim 3, characterized in that: The flow rate of the hydrocyanic acid is 500kg / h to 1000kg / h.

5. The continuous production process of dimethylglycine nitrile according to claim 1 or 2, characterized in that: The concentration of the cyanolyase aqueous solution is 1×10 9 U / L~2×10 9 U / L.

6. The continuous production process of dimethylglycine nitrile as claimed in claim 5, characterized in that: The added amount of the cyanohydrin lyase aqueous solution is 0.5% to 2% of the total mass of the formaldehyde aqueous solution, hydrocyanic acid and dimethylamine aqueous solution.

7. The continuous production process of dimethylglycine nitrile as claimed in claim 1, characterized in that: The extractant of the multi-stage countercurrent extraction device is at least one of dichloromethane, dichloroethane or chloroform.

8. The continuous production process of dimethylglycine nitrile according to claim 1 or 7, characterized in that: The multi-stage countercurrent extraction device is a six-stage countercurrent extraction device.

9. The continuous production process of dimethylglycine nitrile according to claim 1 or 7, characterized in that: The mass ratio of the extractant to the dimethylglycine nitrile reaction solution in each stage of the extraction device is 0.8:1 to 2:

1.

10. The continuous production process of dimethylglycine nitrile according to claim 1, characterized in that: The top temperature of the distillation tower is 77°C to 86°C, the bottom temperature is 100°C to 105°C, and the vacuum degree is 10KPa to 15KPa.