CN116836068B - Method for continuously producing 3-methylamino-1, 2-propanediol - Google Patents
Method for continuously producing 3-methylamino-1, 2-propanediol Download PDFInfo
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- CN116836068B CN116836068B CN202311098959.9A CN202311098959A CN116836068B CN 116836068 B CN116836068 B CN 116836068B CN 202311098959 A CN202311098959 A CN 202311098959A CN 116836068 B CN116836068 B CN 116836068B
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- methylamino
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- monomethylamine
- aqueous solution
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- WOMTYMDHLQTCHY-UHFFFAOYSA-N 3-methylamino-1,2-propanediol Chemical compound CNCC(O)CO WOMTYMDHLQTCHY-UHFFFAOYSA-N 0.000 title claims abstract description 95
- 238000000034 method Methods 0.000 title claims abstract description 59
- BAVYZALUXZFZLV-UHFFFAOYSA-N Methylamine Chemical compound NC BAVYZALUXZFZLV-UHFFFAOYSA-N 0.000 claims abstract description 214
- 238000006243 chemical reaction Methods 0.000 claims abstract description 87
- 238000001704 evaporation Methods 0.000 claims abstract description 74
- 239000007864 aqueous solution Substances 0.000 claims abstract description 63
- 238000006386 neutralization reaction Methods 0.000 claims abstract description 56
- 238000002425 crystallisation Methods 0.000 claims abstract description 53
- 230000008025 crystallization Effects 0.000 claims abstract description 53
- 238000002156 mixing Methods 0.000 claims abstract description 23
- 238000000926 separation method Methods 0.000 claims abstract description 8
- 238000007670 refining Methods 0.000 claims abstract description 7
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 116
- 239000012452 mother liquor Substances 0.000 claims description 59
- 238000010521 absorption reaction Methods 0.000 claims description 47
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 claims description 44
- 238000004821 distillation Methods 0.000 claims description 37
- 230000008020 evaporation Effects 0.000 claims description 37
- URWVQQSVEPXYET-UHFFFAOYSA-N 1-chloropropane-1,2,3-triol Chemical compound OCC(O)C(O)Cl URWVQQSVEPXYET-UHFFFAOYSA-N 0.000 claims description 32
- 238000005576 amination reaction Methods 0.000 claims description 29
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Chemical compound O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 25
- 238000010438 heat treatment Methods 0.000 claims description 21
- 238000005406 washing Methods 0.000 claims description 19
- 239000007788 liquid Substances 0.000 claims description 18
- 239000007789 gas Substances 0.000 claims description 17
- 239000012295 chemical reaction liquid Substances 0.000 claims description 14
- 239000000243 solution Substances 0.000 claims description 13
- 238000010924 continuous production Methods 0.000 claims description 10
- 239000012071 phase Substances 0.000 claims description 10
- 238000011084 recovery Methods 0.000 claims description 6
- 239000000203 mixture Substances 0.000 claims description 5
- 239000007792 gaseous phase Substances 0.000 claims 1
- 239000002994 raw material Substances 0.000 abstract description 11
- 238000004519 manufacturing process Methods 0.000 abstract description 9
- 230000000630 rising effect Effects 0.000 abstract description 2
- 230000009286 beneficial effect Effects 0.000 abstract 1
- 238000004064 recycling Methods 0.000 abstract 1
- 239000000047 product Substances 0.000 description 45
- 230000001276 controlling effect Effects 0.000 description 28
- 239000011780 sodium chloride Substances 0.000 description 18
- 150000003839 salts Chemical class 0.000 description 12
- PEDCQBHIVMGVHV-UHFFFAOYSA-N Glycerine Chemical compound OCC(O)CO PEDCQBHIVMGVHV-UHFFFAOYSA-N 0.000 description 11
- QXJIABOUHLYVHP-UHFFFAOYSA-N n-chloromethanamine Chemical compound CNCl QXJIABOUHLYVHP-UHFFFAOYSA-N 0.000 description 10
- 150000001414 amino alcohols Chemical class 0.000 description 8
- 239000012043 crude product Substances 0.000 description 8
- 239000003054 catalyst Substances 0.000 description 7
- 238000004880 explosion Methods 0.000 description 7
- 239000000463 material Substances 0.000 description 7
- NQMRYBIKMRVZLB-UHFFFAOYSA-N methylamine hydrochloride Chemical compound [Cl-].[NH3+]C NQMRYBIKMRVZLB-UHFFFAOYSA-N 0.000 description 7
- 230000003068 static effect Effects 0.000 description 7
- 239000003513 alkali Substances 0.000 description 6
- 239000000126 substance Substances 0.000 description 6
- 231100000331 toxic Toxicity 0.000 description 6
- 230000002588 toxic effect Effects 0.000 description 6
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 5
- 230000000903 blocking effect Effects 0.000 description 5
- 238000000746 purification Methods 0.000 description 5
- 235000011187 glycerol Nutrition 0.000 description 4
- 239000007791 liquid phase Substances 0.000 description 4
- 230000001105 regulatory effect Effects 0.000 description 4
- 238000010025 steaming Methods 0.000 description 4
- 239000002872 contrast media Substances 0.000 description 3
- 239000000706 filtrate Substances 0.000 description 3
- 239000011259 mixed solution Substances 0.000 description 3
- YMFOWIJFFPALOW-UHFFFAOYSA-N 2-(methylamino)propane-1,3-diol Chemical class CNC(CO)CO YMFOWIJFFPALOW-UHFFFAOYSA-N 0.000 description 2
- UIIMBOGNXHQVGW-UHFFFAOYSA-M Sodium bicarbonate Chemical compound [Na+].OC([O-])=O UIIMBOGNXHQVGW-UHFFFAOYSA-M 0.000 description 2
- 125000001309 chloro group Chemical group Cl* 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 238000007599 discharging Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000005485 electric heating Methods 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000011343 solid material Substances 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- OWLPKHRSZQWPON-UHFFFAOYSA-N 3-(methylamino)propane-1,2-diol;hydrochloride Chemical compound Cl.CNCC(O)CO OWLPKHRSZQWPON-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 239000002585 base Substances 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 239000000498 cooling water Substances 0.000 description 1
- 230000006837 decompression Effects 0.000 description 1
- 238000011033 desalting Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000005611 electricity Effects 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910000041 hydrogen chloride Inorganic materials 0.000 description 1
- IXCSERBJSXMMFS-UHFFFAOYSA-N hydrogen chloride Substances Cl.Cl IXCSERBJSXMMFS-UHFFFAOYSA-N 0.000 description 1
- 238000003384 imaging method Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000010253 intravenous injection Methods 0.000 description 1
- DGAIEPBNLOQYER-UHFFFAOYSA-N iopromide Chemical compound COCC(=O)NC1=C(I)C(C(=O)NCC(O)CO)=C(I)C(C(=O)N(C)CC(O)CO)=C1I DGAIEPBNLOQYER-UHFFFAOYSA-N 0.000 description 1
- 229960002603 iopromide Drugs 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 238000011085 pressure filtration Methods 0.000 description 1
- 230000001568 sexual effect Effects 0.000 description 1
- 238000007086 side reaction Methods 0.000 description 1
- -1 small molecule amine Chemical class 0.000 description 1
- 235000017557 sodium bicarbonate Nutrition 0.000 description 1
- 229910000030 sodium bicarbonate Inorganic materials 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000001308 synthesis method Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 231100000419 toxicity Toxicity 0.000 description 1
- 230000001988 toxicity Effects 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C213/00—Preparation of compounds containing amino and hydroxy, amino and etherified hydroxy or amino and esterified hydroxy groups bound to the same carbon skeleton
- C07C213/02—Preparation of compounds containing amino and hydroxy, amino and etherified hydroxy or amino and esterified hydroxy groups bound to the same carbon skeleton by reactions involving the formation of amino groups from compounds containing hydroxy groups or etherified or esterified hydroxy groups
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C213/00—Preparation of compounds containing amino and hydroxy, amino and etherified hydroxy or amino and esterified hydroxy groups bound to the same carbon skeleton
- C07C213/08—Preparation of compounds containing amino and hydroxy, amino and etherified hydroxy or amino and esterified hydroxy groups bound to the same carbon skeleton by reactions not involving the formation of amino groups, hydroxy groups or etherified or esterified hydroxy groups
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C213/00—Preparation of compounds containing amino and hydroxy, amino and etherified hydroxy or amino and esterified hydroxy groups bound to the same carbon skeleton
- C07C213/10—Separation; Purification; Stabilisation; Use of additives
Abstract
The invention discloses a method for continuously producing high-purity 3-methylamino-1, 2-propanediol, which sequentially comprises the following steps: (1) mixing reaction; (2) evaporating and recycling; (3) neutralization crystallization; (4) centrifugal separation; and (5) refining. The beneficial effects are that: the invention provides a method for continuously producing high-purity 3-methylamino-1, 2-propanediol, which adopts a continuous flow production process, has low labor intensity, high safety, higher productivity than intermittent kettle type operation process, ensures the product yield, improves the product yield, has simple temperature rising and controlling processes, has low requirements on manual operation, reduces the dosage of monomethylamine aqueous solution, and further reduces the raw material cost.
Description
Technical Field
The invention relates to the technical field of 3-methylamino-1, 2-propanediol production, in particular to a method for continuously producing 3-methylamino-1, 2-propanediol.
Background
3-methylamino-1, 2-propanediol is an organic small molecule amine intermediate for the nonionic contrast agent iopromide; it has good security and imaging effect; 3-methylamino-1, 2-propanediol is used as a water-soluble contrast agent, has the advantages of large water solubility, low viscosity, good tolerance and low intravenous injection toxicity, and is an ideal CT enhanced scanning contrast agent. The patent No. CN200910256073.6 discloses a synthesis method of 3-methylamino-1, 2-propanediol, which is an intermittent kettle operation process, namely, chlorglycerol, monomethylamine aqueous solution, amination catalyst NaOH solution and NaHCO 3 Adding the materials into a reaction kettle, stirring to fully mix the materials, and carrying out amination reaction in two temperature sections; then removing the aminated liquid monomethylamine and water, and then distilling and purifying the filtered filtrate; however, the above process has the following problems: 1. the labor intensity of personnel is high, the frequency of contacting toxic and harmful substances is high, and the productivity of a single kettle is low; 2. due to the strong alkali of the chlorglycerolThe method is extremely unstable under the sexual condition, chlorine atoms can be removed to generate glycerol, so that in the amination reaction process, sodium bicarbonate and sodium hydroxide are used as catalysts, the chlorine atoms of the chlorglycerol are extremely easy to be removed to generate glycerol, the glycerol cannot be subjected to amination reaction with monomethylamine, the yield of a product is greatly influenced, and the yield (the ratio of the actual yield value to the theoretical yield value) of the product is lower; 3. the process carries out amination reaction in two temperature sections, the heating and temperature control processes are complicated, and the requirement of the industrial production process on manual operation is high; 4. the temperature of the second temperature section of the amination reaction of the process is 55-65 ℃, so that the monomethylamine aqueous solution is easily gasified, the dosage of the monomethylamine aqueous solution is increased to ensure the yield of products, and the raw material cost is further increased.
Patent No. CN 201510234763.7 discloses a method for synthesizing 3-methylamino-1, 2-propanediol by a pipeline reactor, mixing chloroglycerol and monomethylamine gas, introducing the mixture into the pipeline reactor for amination reaction to obtain 3-methylamino-1, 2-propanediol solution and monomethylamine hydrochloride, absorbing excessive unreacted monomethylamine, press-filtering monomethylamine hydrochloride, recovering and selling, and finally evaporating and purifying to obtain 3-methylamino-1, 2-propanediol solution. But has the following problems: 1. mixing the chlorglycerol and the monomethylamine gas under the high pressure of 2.2-2.3 Mpa, and then entering a pipeline reactor for amination reaction, wherein the whole system needs special high-pressure resistant equipment, has high production cost, and the monomethylamine gas is inflammable, is easy to rub and generate static electricity when being conveyed under high pressure, and can easily cause the safety problem of explosion when encountering air; 2. the critical pressure of monomethylamine is 4.07Mpa, the pressure of amination reaction is 2.2-2.95Mpa, so monomethylamine is still in a gaseous state, and a static mixer is adopted for mixing gas and liquid, so that the monomethylamine gas and the chloroglycerol liquid cannot be fully and uniformly mixed, the amination reaction effect of monomethylamine gas and the chloroglycerol liquid cannot be good, the reaction cannot be fully carried out, and the product yield and the purity are affected, so that the yield is only 86.93%, and the purity is only 99.81%; 3. the 3-methylamino-1, 2-propanediol produced by the reaction of monomethylamine and chloroglycerol can be preferentially and directly hydrochloride with hydrogen chloride produced by the reaction, instead of directly hydrochloride of monomethylamine, strong base (generally sodium hydroxide) is added to free hydrochloride after the reaction is finished, the pH of the solution is regulated to 11-12, and 3-methylamino-1, 2-propanediol and sodium chloride are formed, so that the 3-methylamino-1, 2-propanediol can be obtained in high yield. In the patent, no strong alkali is introduced, and the reaction liquid is directly subjected to pressure filtration and desalting and then is distilled to obtain a product containing a large amount of 3-methylamino-1, 2-propanediol hydrochloride impurities, so that the product quality is reduced; 4. in the patent, the monoamine hydrochloride generated in the reaction process is easy to separate out from the reaction liquid, agglomerate on the inner wall of the pipeline reactor, influence the heat exchange of the pipeline reactor, gradually block the pipeline reactor, the synthetic process is 2.2-2.95MPa, and once the block is formed, the safety risk of explosion accidents is extremely high; meanwhile, the scaling and the blockage of the pipeline can also cause the increase of abnormal shutdown times of equipment, and the method is not suitable for industrial continuous production; 5. the above patent discloses that the post-treatment mode is kettle distillation, and known side reactions produce isomers of 2-methylamino-1, 3-propanediol, and conventional kettle distillation cannot realize effective separation of 2-methylamino-1, 3-propanediol from its isomers; thus reducing the purity of the product and further reducing the quality of the product.
Disclosure of Invention
The invention aims to provide a method for continuously producing 3-methylamino-1, 2-propanediol, which ensures production safety and improves product yield.
The purpose of the invention is implemented by the following technical scheme: a method for continuously producing 3-methylamino-1, 2-propanediol, which sequentially comprises the following steps:
(1) Mixing reaction: the method comprises the steps of mixing 30% -40% of monomethylamine aqueous solution and chloroglycerol according to the mass ratio of 10-20:1, mixing, continuously feeding the mixture into a reaction tower, uniformly mixing and carrying out amination reaction, wherein the reaction temperature is 20-40 ℃, and the reaction pressure is 0.2-0.3Mpa, so as to obtain a reaction liquid and a gas phase;
the reaction equation for a particular amination reaction is as follows:
(2) And (3) evaporation recovery: continuously heating and evaporating the reaction liquid obtained in the step (1) at a temperature of 100-120 ℃ for 3-6 hours to obtain an evaporation mother liquid and monomethylamine steam;
(3) And (3) neutralization crystallization: mixing the evaporation mother liquor obtained in the step (2) with sodium hydroxide for neutralization reaction, wherein the mass ratio of the sodium hydroxide to the chloroglycerol is 0.9-1.5:1, a step of; then carrying out continuous evaporation crystallization to obtain concentrated mother liquor and water vapor;
the reaction equation for a particular neutralization reaction is as follows:
(4) And (3) centrifugal separation: centrifugally separating the concentrated mother liquor obtained in the step (3), and separating out crude sodium chloride salt to obtain 3-methylamino-1, 2-propanediol mother liquor;
(5) Refining: and (3) performing crude distillation and rectification on the 3-methylamino-1, 2-propanediol mother liquor obtained in the step (4) to obtain the 3-methylamino-1, 2-propanediol product.
Further, the gas phase in the step (1), the monomethylamine vapor in the step (2) and the water vapor in the step (3) are condensed and then sent to an absorption tower to be recovered to form monomethylamine aqueous solution, and when the concentration of the monomethylamine aqueous solution is lower than 30%, the monomethylamine aqueous solution with the concentration of 40% is sent into the absorption tower.
Further, the concentration of the aqueous monomethylamine solution in step (1) is preferably 35% to 40%.
Further, the mass ratio of the monomethylamine aqueous solution and the chloroglycerol in step (1) is preferably 15:1.
further, the reaction temperature in step (1) is preferably 25 to 32 ℃.
Further, in the step (3), the temperature of the evaporative crystallization is 105-110 ℃, and the time of the evaporative crystallization is 3-3.5 h.
Further, the crude sodium chloride salt in the step (4) is washed, and the washing solution is subjected to continuous evaporation crystallization in the step (3).
The invention has the advantages that:
1. the invention provides a method for continuously producing 3-methylamino-1, 2-propanediol, which specifically adopts a continuous flow production process, has low labor intensity, and can seal operators without contacting toxic and harmful substances basically; meanwhile, the reaction pressure is only 0.2-0.3Mpa, special equipment is not needed, and the monomethylamine aqueous solution and the chloroglycerol are adopted to enter the reaction tower for mixed reaction, so that the explosion is not easy to occur, the safety is high, and the equipment purchasing cost is low.
2. The invention provides a method for continuously producing 3-methylamino-1, 2-propanediol, naOH and NaHCO are not introduced in the mixing reaction process 3 The catalyst, the aqueous solution of the monomethylamine reacts with the chlorglycerol to generate the methylamino hydrochloride, the redundant monomethylamine is evaporated and recovered, then sodium hydroxide is added in the neutralization crystallization process, the methylamino hydrochloride is effectively neutralized into 3-methylamino-1, 2-propanediol, the product yield is further ensured, the product yield and the product purity are improved, the product yield is more than 90%, and the product purity is more than 99.95%.
3. The invention provides a method for continuously producing 3-methylamino-1, 2-propanediol, wherein after being mixed, monomethylamine aqueous solution and chloroglycerol are continuously sent into a reaction tower to be uniformly mixed and subjected to amination reaction, the reaction temperature is only 20-40 ℃, the heating and temperature control processes are simple, and the requirement on manual operation is not high; meanwhile, the monomethylamine aqueous solution is not easy to gasify, so that the consumption of the monomethylamine aqueous solution is reduced, and the cost of raw materials is further reduced.
4. The invention provides a method for continuously producing 3-methylamino-1, 2-propanediol, which is suitable for industrial continuous production, and simultaneously reduces the safety risk, and the problem of blocking a system pipeline is avoided because monomethylamine hydrochloride is not generated in the mixed reaction.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 is a diagram of a process system according to the present invention.
Static mixer 1, first-stage reaction tower 2, second-stage reaction tower 3, first-stage absorption tower 4, first-stage evaporator 5, second-stage evaporator 6, third-stage evaporator 7, second-stage absorption tower 8, neutralization crystallization kettle 9, crude distillation kettle 10, rectifying still 11.
Detailed Description
The present invention will be described in further detail by way of examples.
Example 1: as shown in fig. 1, a method for continuously producing 3-methylamino-1, 2-propanediol comprises the following steps in order:
(1) Mixing reaction: feeding 38% monomethylamine aqueous solution into a static mixer 1 at a flow rate of 720L/h and a flow rate of 62kg/h for mixing, feeding the mixed solution into a first-stage reaction tower 2, feeding a liquid phase into a second-stage reaction tower 3 from the bottom, controlling the reaction temperature to be 20-40 ℃, controlling the reaction pressure to be 0.2-0.3Mpa, and feeding liquid flowing out from a discharge port at the lower part of the second-stage reaction tower 3 after amination reaction into a reaction liquid, wherein all the chloroglycerol is converted into 3-methylamino-1, 2-propanediol and amino alcohol; the temperature raising and controlling process is simple, and the requirement on manual operation is not high; meanwhile, the monomethylamine aqueous solution is not easy to gasify, so that the consumption of the monomethylamine aqueous solution is reduced, and the cost of raw materials is further reduced; no monomethylamine hydrochloride is generated in the mixed reaction, so that the problem of blocking a system pipeline is avoided, and the method is suitable for industrial continuous production.
The gas phase discharged from the tops of the first-stage reaction tower 2 and the second-stage reaction tower 3 enters an air cooler and a water cooler to be condensed, and then enters a first-stage absorption tower 4 to be absorbed to form a monomethylamine aqueous solution with the concentration of 38 percent as a raw material for the amination reaction.
(2) And (3) evaporation recovery: and (3) continuously heating and evaporating the reaction liquid obtained in the step (1), namely sequentially entering a first-stage evaporator 5 (steam heating, controlling the evaporation temperature to be 100-105 ℃ and the pressure to be 0.2-0.3 MPa), a second-stage evaporator 6 (steam heating, controlling the evaporation temperature to be 110-115 ℃ and normal pressure) and a third-stage evaporator 7 (negative pressure to be-0.06-0.08 MPa and the temperature to be 90-110 ℃) for evaporating, dehydrating and removing monomethylamine to obtain an evaporation mother liquor and monomethylamine steam.
The monomethylamine vapor discharged from the first-stage evaporator 5 is condensed by a condenser and then enters the first-stage absorption tower 4 for absorption, and the monomethylamine vapor discharged from the second-stage evaporator 6 is condensed and then enters the second-stage absorption tower 8 for absorption.
The monomethylamine aqueous solution recovered by the primary absorption tower 4 is recycled for the amination reaction in the step (1), when the monomethylamine aqueous solution content in the primary absorption tower 4 is lower than 30%, the monomethylamine aqueous solution with the concentration of 40% is replenished into the secondary absorption tower 8, and the monomethylamine aqueous solution in the secondary absorption tower 8 is used for replenishing the consumption of the monomethylamine aqueous solution in the primary absorption tower 4.
(3) And (3) neutralization crystallization: and (3) automatically flowing the evaporation mother liquor obtained in the step (2) into a neutralization crystallization kettle 9, adding 48kg/h of sodium hydroxide into the neutralization crystallization kettle 9 through a sodium hydroxide feed pump and a sodium hydroxide flow regulating valve, and completing the neutralization reaction of the evaporation mother liquor and the alkali liquor in the neutralization crystallization kettle 9, and evaporating part of water. Stopping feeding when a certain liquid level is reached in the neutralization crystallization kettle 9, controlling the pressure to be minus 0.06 to minus 0.08MPa, the evaporating crystallization temperature to be 90-110 ℃, evaporating and crystallizing for 3.5 hours to obtain concentrated mother liquor, and closing an evaporating mother liquor feeding valve and a sodium hydroxide feeding program of the neutralization crystallization kettle 9. The evaporation mother liquor feed valve of the other neutralization crystallization kettle 9 is opened, and simultaneously, the sodium hydroxide feed procedure is opened, and the above-mentioned feed neutralization reaction operation is repeated. The concentrated mother liquor after neutralization is discharged from the bottom of the neutralization crystallization kettle 9.
(4) And (3) centrifugal separation: centrifugally separating the concentrated mother liquor obtained in the step (3), and separating out crude sodium chloride salt to obtain 3-methylamino-1, 2-propanediol mother liquor; and (3) conveying the sodium chloride crude salt to a salt washing kettle, washing with washing water, dissolving 3-methylamino-1, 2-propanediol in the sodium chloride crude salt in water, evaporating, centrifuging to obtain sodium chloride, storing the sodium chloride in a warehouse, and continuously evaporating and crystallizing the centrifuged washing liquid in the step (3).
(5) Refining: and (3) performing crude distillation and rectification on the 3-methylamino-1, 2-propanediol mother liquor obtained in the step (4) to obtain the 3-methylamino-1, 2-propanediol product.
a. And (3) rough steaming: transferring the 3-methylamino-1, 2-propanediol mother liquor into a crude distillation kettle 10 through a transfer pump, stopping feeding when the feeding amount in the crude distillation kettle 10 reaches 3000kg, performing reduced pressure distillation, controlling the kettle temperature to be 145-155 ℃ and the pressure to be 100-200pa, and performing primary purification on the 3-methylamino-1, 2-propanediol mother liquor. 2813kg of crude 3-methylamino-1, 2-propanediol was obtained. The main component of the residue in the distillation still is amino alcohol, about 128kg.
b. And (3) rectifying: 3000Kg of 3-methylamino-1, 2-propanediol crude product is transferred into a rectifying still 11 by a pump, the steam of a jacket of the still and an evaporator is started to heat, the temperature of the still is kept at 155-160 ℃, the pressure of the still is 50-150pa, reduced pressure rectification is carried out, a primary fraction is collected, 53Kg of primary fraction is obtained, and the primary fraction is collected and rectified again with the crude product of the next batch. After the primary distillation is finished, the finished product is received, 2937kg of 3-methylamino-1, 2-propanediol finished product is obtained, and compared with the theoretical value of the 3-methylamino-1, 2-propanediol finished product, the actual yield is 91.80%, and the purity of the finished product is 99.96%.
The invention provides a method for continuously producing 3-methylamino-1, 2-propanediol, which specifically adopts a continuous flow production process, has low labor intensity, and can seal operators without contacting toxic and harmful substances basically; meanwhile, the reaction pressure is only 0.2-0.3Mpa, no special equipment is needed, and the monomethylamine aqueous solution and the chlorglycerol are adopted to enter a reaction tower for mixed reaction, so that the explosion is not easy to occur, the safety is high, the equipment purchasing cost is low, and NaOH and NaHCO are not introduced in the mixed reaction process 3 The catalyst, the aqueous solution of the monomethylamine reacts with the chlorglycerol to generate the methylamino hydrochloride, the redundant monomethylamine is evaporated and recovered, then sodium hydroxide is added in the neutralization crystallization process, and the methylamino hydrochloride is effectively neutralized into 3-methylamino-1, 2-propanediol, thereby ensuring the yield of products and improving the yield and purity of the products.
Example 2: a method for continuously producing 3-methylamino-1, 2-propanediol, which sequentially comprises the following steps:
(1) Mixing reaction: mixing 30% monomethylamine aqueous solution with a flow rate of 620L/h and a flow rate of 62kg/h in a static mixer 1, then feeding the mixture into a first-stage reaction tower 2, feeding a liquid phase into a second-stage reaction tower 3 from the bottom, controlling the reaction temperature to be 20-40 ℃, controlling the reaction pressure to be 0.2-0.3Mpa, and enabling liquid flowing out from a discharge port at the lower part of the second-stage reaction tower 3 after amination reaction to be reaction liquid, wherein all the chloroglycerol is converted into 3-methylamino-1, 2-propanediol and amino alcohol; the temperature raising and controlling process is simple, and the requirement on manual operation is not high; meanwhile, the monomethylamine aqueous solution is not easy to gasify, so that the consumption of the monomethylamine aqueous solution is reduced, and the cost of raw materials is further reduced; in the mixed reaction, monomethylamine hydrochloride is not generated, so that the problem of blocking a system pipeline is avoided, the method is suitable for industrial continuous production, and meanwhile, the safety risk is reduced.
The gas phase discharged from the tops of the first-stage reaction tower 2 and the second-stage reaction tower 3 enters an air cooler and a water cooler to be condensed, and then enters a first-stage absorption tower 4 to be absorbed to form 30% monomethylamine aqueous solution which is used as a raw material for the amination reaction.
(2) And (3) evaporation recovery: and (3) continuously heating and evaporating the reaction liquid obtained in the step (1), namely sequentially entering a first-stage evaporator 5 (steam heating, controlling the evaporation temperature to be 100-105 ℃ and the pressure to be 0.2-0.3 MPa), a second-stage evaporator 6 (steam heating, controlling the evaporation temperature to be 110-115 ℃ and normal pressure) and a third-stage evaporator 7 (negative pressure to be-0.06-0.08 MPa and the temperature to be 90-110 ℃) for evaporating, dehydrating and removing monomethylamine to obtain an evaporation mother liquor and monomethylamine steam.
The monomethylamine vapor discharged from the first-stage evaporator 5 is condensed by a condenser and then enters the first-stage absorption tower 4 for absorption, and the monomethylamine vapor discharged from the second-stage evaporator 6 is condensed and then enters the second-stage absorption tower 8 for absorption.
The monomethylamine aqueous solution recovered by the primary absorption tower 4 is recycled for the amination reaction in the step (1), when the monomethylamine aqueous solution content in the primary absorption tower 4 is lower than 30%, the monomethylamine aqueous solution with the concentration of 40% is replenished into the secondary absorption tower 8, and the monomethylamine aqueous solution in the secondary absorption tower 8 is used for replenishing the consumption of the monomethylamine aqueous solution in the primary absorption tower 4.
(3) And (3) neutralization crystallization: and (3) automatically flowing the evaporation mother liquor obtained in the step (2) into a neutralization crystallization kettle 9, adding sodium hydroxide into the neutralization crystallization kettle 9 by adjusting the flow rate of the sodium hydroxide to 62kg/h through a sodium hydroxide feed pump and a sodium hydroxide flow rate adjusting valve, and completing the neutralization reaction of the evaporation mother liquor and the alkali liquor in the neutralization crystallization kettle 9 and evaporating part of water. Stopping feeding when a certain liquid level is reached in the neutralization crystallization kettle 9, controlling the pressure to be minus 0.06 to minus 0.08MPa, the evaporating crystallization temperature to be 90-110 ℃, evaporating and crystallizing for 3.5 hours to obtain concentrated mother liquor, and closing an evaporating mother liquor feeding valve and a sodium hydroxide feeding program of the neutralization crystallization kettle 9. The evaporation mother liquor feed valve of the other neutralization crystallization kettle 9 is opened, and simultaneously, the sodium hydroxide feed procedure is opened, and the above-mentioned feed neutralization reaction operation is repeated. The concentrated mother liquor after neutralization is discharged from the bottom of the neutralization crystallization kettle 9.
(4) And (3) centrifugal separation: centrifugally separating the concentrated mother liquor obtained in the step (3), and separating out crude sodium chloride salt to obtain 3-methylamino-1, 2-propanediol mother liquor; and (3) conveying the sodium chloride crude salt to a salt washing kettle, washing with washing water, dissolving 3-methylamino-1, 2-propanediol in the sodium chloride crude salt in water, evaporating, centrifuging to obtain sodium chloride, storing the sodium chloride in a warehouse, and continuously evaporating and crystallizing the centrifuged washing liquid in the step (3).
(5) Refining: and (3) performing crude distillation and rectification on the 3-methylamino-1, 2-propanediol mother liquor obtained in the step (4) to obtain the 3-methylamino-1, 2-propanediol product.
a. And (3) rough steaming: transferring the 3-methylamino-1, 2-propanediol mother liquor into a crude distillation kettle 10 through a transfer pump, stopping feeding when the feeding amount in the crude distillation kettle 10 reaches 3000kg, performing reduced pressure distillation, controlling the kettle temperature to be 145-155 ℃ and the pressure to be 100-200pa, and performing primary purification on the 3-methylamino-1, 2-propanediol mother liquor. 2765kg of crude 3-methylamino-1, 2-propanediol was obtained. The main component of the residue in the distillation still is amino alcohol, about 172kg.
b. And (3) rectifying: 3000Kg of 3-methylamino-1, 2-propanediol crude product is transferred into a rectifying still 11 by a pump, the steam of a jacket of the still and an evaporator is started to heat, the temperature of the still is kept at 155-160 ℃, the pressure of the still is 50-150pa, reduced pressure rectification is carried out, a primary fraction is collected, 72Kg of primary fraction is obtained, and the primary fraction is collected and rectified again with the crude product of the next batch. After the primary distillation is finished, the finished product is received, 2932kg of 3-methylamino-1, 2-propanediol finished product is obtained, and compared with the theoretical value of the 3-methylamino-1, 2-propanediol finished product, the actual yield is 90.08 percent, and the purity of the finished product is 99.95 percent.
The invention provides a method for continuously producing 3-methylamino-1, 2-propanediol, which specifically adopts a continuous flow production process, has low labor intensity, and can seal operators without contacting toxic and harmful substances basically; meanwhile, the reaction pressure is only 0.2-0.3Mpa, no special equipment is needed, and the monomethylamine aqueous solution and the chlorglycerol are adopted to enter a reaction tower for mixed reaction, so that the explosion is not easy to occur, the safety is high, the equipment purchasing cost is low, and NaOH and NaHCO are not introduced in the mixed reaction process 3 The catalyst, the aqueous solution of the monomethylamine reacts with the chlorglycerol to generate the methylamino hydrochloride, the redundant monomethylamine is evaporated and recovered, then sodium hydroxide is added in the neutralization crystallization process, and the methylamino hydrochloride is effectively neutralized into 3-methylamino-1, 2-propanediol, thereby ensuring the yield of products and improving the yield and purity of the products.
Example 3: a method for continuously producing 3-methylamino-1, 2-propanediol, which sequentially comprises the following steps:
(1) Mixing reaction: introducing 35% monomethylamine aqueous solution into a static mixer 1 at 1040L/h and 62kg/h to mix, introducing the mixed solution into a first-stage reaction tower 2, introducing a liquid phase into a second-stage reaction tower 3 from the bottom, controlling the reaction temperature to be 20-40 ℃, controlling the reaction pressure to be 0.2-0.3Mpa, and allowing the liquid flowing out from a discharge port at the lower part of the second-stage reaction tower 3 after amination reaction to be reaction liquid, wherein all the chloroglycerol is converted into 3-methylamino-1, 2-propanediol and amino alcohol; the temperature raising and controlling process is simple, and the requirement on manual operation is not high; meanwhile, the monomethylamine aqueous solution is not easy to gasify, so that the consumption of the monomethylamine aqueous solution is reduced, and the cost of raw materials is further reduced; no monomethylamine hydrochloride is generated in the mixed reaction, so that the problem of blocking a system pipeline is avoided, and the method is suitable for industrial continuous production.
The gas phase discharged from the tops of the first-stage reaction tower 2 and the second-stage reaction tower 3 enters an air cooler and a water cooler to be condensed, and then enters a first-stage absorption tower 4 to be absorbed to form a monomethylamine aqueous solution with the concentration of 35 percent as a raw material for the amination reaction.
(2) And (3) evaporation recovery: and (3) continuously heating and evaporating the reaction liquid obtained in the step (1), namely sequentially entering a first-stage evaporator 5 (steam heating, controlling the evaporation temperature to be 100-105 ℃ and the pressure to be 0.2-0.3 MPa), a second-stage evaporator 6 (steam heating, controlling the evaporation temperature to be 110-115 ℃ and normal pressure) and a third-stage evaporator 7 (negative pressure to be-0.06-0.08 MPa and the temperature to be 90-110 ℃) for evaporating, dehydrating and removing monomethylamine to obtain an evaporation mother liquor and monomethylamine steam.
The monomethylamine vapor discharged from the first-stage evaporator 5 is condensed by a condenser and then enters the first-stage absorption tower 4 for absorption, and the monomethylamine vapor discharged from the second-stage evaporator 6 is condensed and then enters the second-stage absorption tower 8 for absorption.
The monomethylamine aqueous solution recovered by the primary absorption tower 4 is recycled for the amination reaction in the step (1), when the monomethylamine aqueous solution content in the primary absorption tower 4 is lower than 30%, the monomethylamine aqueous solution with the concentration of 40% is replenished into the secondary absorption tower 8, and the monomethylamine aqueous solution in the secondary absorption tower 8 is used for replenishing the consumption of the monomethylamine aqueous solution in the primary absorption tower 4.
(3) And (3) neutralization crystallization: and (3) automatically flowing the evaporation mother liquor obtained in the step (2) into a neutralization crystallization kettle 9, adding 84kg/h of sodium hydroxide into the neutralization crystallization kettle 9 through a sodium hydroxide feed pump and a sodium hydroxide flow regulating valve, and completing the neutralization reaction of the evaporation mother liquor and the alkali liquor in the neutralization crystallization kettle 9, and evaporating part of water. Stopping feeding when a certain liquid level is reached in the neutralization crystallization kettle 9, controlling the pressure to be minus 0.06 to minus 0.08MPa, the evaporating crystallization temperature to be 90-110 ℃, evaporating and crystallizing for 3.5 hours to obtain concentrated mother liquor, and closing an evaporating mother liquor feeding valve and a sodium hydroxide feeding program of the neutralization crystallization kettle 9. The evaporation mother liquor feed valve of the other neutralization crystallization kettle 9 is opened, and simultaneously, the sodium hydroxide feed procedure is opened, and the above-mentioned feed neutralization reaction operation is repeated. The concentrated mother liquor after neutralization is discharged from the bottom of the neutralization crystallization kettle 9.
(4) And (3) centrifugal separation: centrifugally separating the concentrated mother liquor obtained in the step (3), and separating out crude sodium chloride salt to obtain 3-methylamino-1, 2-propanediol mother liquor; and (3) conveying the sodium chloride crude salt to a salt washing kettle, washing with washing water, dissolving 3-methylamino-1, 2-propanediol in the sodium chloride crude salt in water, evaporating, centrifuging to obtain sodium chloride, storing the sodium chloride in a warehouse, and continuously evaporating and crystallizing the centrifuged washing liquid in the step (3).
(5) Refining: and (3) performing crude distillation and rectification on the 3-methylamino-1, 2-propanediol mother liquor obtained in the step (4) to obtain the 3-methylamino-1, 2-propanediol product.
a. And (3) rough steaming: transferring the 3-methylamino-1, 2-propanediol mother liquor into a crude distillation kettle 10 through a transfer pump, stopping feeding when the feeding amount in the crude distillation kettle 10 reaches 3000kg, performing reduced pressure distillation, controlling the kettle temperature to be 145-155 ℃ and the pressure to be 100-200pa, and performing primary purification on the 3-methylamino-1, 2-propanediol mother liquor. 2807kg of crude 3-methylamino-1, 2-propanediol are obtained. The main component of the residue in the distillation still is amino alcohol, about 137kg.
b. And (3) rectifying: 3000Kg of 3-methylamino-1, 2-propanediol crude product is transferred into a rectifying still 11 by a pump, the steam of a jacket of the still and an evaporator is started to heat, the temperature of the still is kept at 155-160 ℃, the pressure of the still is 50-150pa, decompression rectification is carried out, a primary fraction is collected, 57.2Kg of primary fraction is obtained, and the primary fraction is rectified again with the crude product of the next batch after being collected. After the primary distillation is finished, the finished product is received, 2920kg of 3-methylamino-1, 2-propanediol finished product is obtained, and compared with the theoretical value of the 3-methylamino-1, 2-propanediol finished product, the actual yield is 91.07 percent, and the purity of the finished product is 99.98 percent.
The invention provides a method for continuously producing 3-methylamino-1, 2-propanediol, which specifically adopts a continuous flow production process, has low labor intensity, and can seal operators without contacting toxic and harmful substances basically; meanwhile, the reaction pressure is only 0.2-0.3Mpa, special equipment is not needed, and the monomethylamine aqueous solution and the chlorglycerol are adopted to enter a reaction tower for mixed reaction, so that the explosion is not easy to occur, the safety is high, and equipment is purchased simultaneouslyThe cost is low, naOH and NaHCO are not introduced in the mixing reaction process 3 The catalyst, the aqueous solution of the monomethylamine reacts with the chlorglycerol to generate the methylamino hydrochloride, the redundant monomethylamine is evaporated and recovered, then sodium hydroxide is added in the neutralization crystallization process, and the methylamino hydrochloride is effectively neutralized into 3-methylamino-1, 2-propanediol, thereby ensuring the yield of products and improving the yield and purity of the products.
Example 4: a method for continuously producing 3-methylamino-1, 2-propanediol, which sequentially comprises the following steps:
(1) Mixing reaction: feeding 38% monomethylamine aqueous solution into a static mixer 1 at a flow rate of 720L/h and a flow rate of 62kg/h for mixing, feeding the mixed solution into a first-stage reaction tower 2, feeding a liquid phase into a second-stage reaction tower 3 from the bottom, controlling the reaction temperature to be 20-40 ℃, controlling the reaction pressure to be 0.2-0.3Mpa, and feeding liquid flowing out from a discharge port at the lower part of the second-stage reaction tower 3 after amination reaction into a reaction liquid, wherein all the chloroglycerol is converted into 3-methylamino-1, 2-propanediol and amino alcohol; the temperature raising and controlling process is simple, and the requirement on manual operation is not high; meanwhile, the monomethylamine aqueous solution is not easy to gasify, so that the consumption of the monomethylamine aqueous solution is reduced, and the cost of raw materials is further reduced; no monomethylamine hydrochloride is generated in the mixed reaction, so that the problem of blocking a system pipeline is avoided, and the method is suitable for industrial continuous production.
The gas phase discharged from the tops of the first-stage reaction tower 2 and the second-stage reaction tower 3 enters an air cooler and a water cooler to be condensed, and then enters a first-stage absorption tower 4 to be absorbed to form a monomethylamine aqueous solution with the concentration of 38 percent as a raw material for the amination reaction.
(2) And (3) evaporation recovery: and (3) continuously heating and evaporating the reaction liquid obtained in the step (1), namely sequentially entering a first-stage evaporator 5 (steam heating, controlling the evaporation temperature to be 100-105 ℃ and the pressure to be 0.2-0.3 MPa), a second-stage evaporator 6 (steam heating, controlling the evaporation temperature to be 110-115 ℃ and normal pressure) and a third-stage evaporator 7 (negative pressure to be-0.06-0.08 MPa and the temperature to be 90-110 ℃) for evaporating, dehydrating and removing monomethylamine to obtain an evaporation mother liquor and monomethylamine steam.
The monomethylamine vapor discharged from the first-stage evaporator 5 is condensed by a condenser and then enters the first-stage absorption tower 4 for absorption, and the monomethylamine vapor discharged from the second-stage evaporator 6 is condensed and then enters the second-stage absorption tower 8 for absorption.
The monomethylamine aqueous solution recovered by the primary absorption tower 4 is recycled for the amination reaction in the step (1), when the monomethylamine aqueous solution content in the primary absorption tower 4 is lower than 30%, the monomethylamine aqueous solution with the concentration of 40% is replenished into the secondary absorption tower 8, and the monomethylamine aqueous solution in the secondary absorption tower 8 is used for replenishing the consumption of the monomethylamine aqueous solution in the primary absorption tower 4.
(3) And (3) neutralization crystallization: and (3) automatically flowing the evaporation mother liquor obtained in the step (2) into a neutralization crystallization kettle 9, adding 50kg/h of sodium hydroxide into the neutralization crystallization kettle 9 through a sodium hydroxide feed pump and a sodium hydroxide flow regulating valve, and completing the neutralization reaction of the evaporation mother liquor and the alkali liquor in the neutralization crystallization kettle 9, and evaporating part of water. Stopping feeding when a certain liquid level is reached in the neutralization crystallization kettle 9, controlling the pressure to be minus 0.06 to minus 0.08MPa, the evaporating crystallization temperature to be 90-110 ℃, evaporating and crystallizing for 3.5 hours to obtain concentrated mother liquor, and closing an evaporating mother liquor feeding valve and a sodium hydroxide feeding program of the neutralization crystallization kettle 9. The evaporation mother liquor feed valve of the other neutralization crystallization kettle 9 is opened, and simultaneously, the sodium hydroxide feed procedure is opened, and the above-mentioned feed neutralization reaction operation is repeated. The concentrated mother liquor after neutralization is discharged from the bottom of the neutralization crystallization kettle 9.
(4) And (3) centrifugal separation: centrifugally separating the concentrated mother liquor obtained in the step (3), and separating out crude sodium chloride salt to obtain 3-methylamino-1, 2-propanediol mother liquor; and (3) conveying the sodium chloride crude salt to a salt washing kettle, washing with washing water, dissolving 3-methylamino-1, 2-propanediol in the sodium chloride crude salt in water, evaporating, centrifuging to obtain sodium chloride, storing the sodium chloride in a warehouse, and continuously evaporating and crystallizing the centrifuged washing liquid in the step (3).
(5) Refining: and (3) performing crude distillation and rectification on the 3-methylamino-1, 2-propanediol mother liquor obtained in the step (4) to obtain the 3-methylamino-1, 2-propanediol product.
a. And (3) rough steaming: transferring the 3-methylamino-1, 2-propanediol mother liquor into a crude distillation kettle 10 through a transfer pump, stopping feeding when the feeding amount in the crude distillation kettle 10 reaches 3000kg, performing reduced pressure distillation, controlling the kettle temperature to be 145-155 ℃ and the pressure to be 100-200pa, and performing primary purification on the 3-methylamino-1, 2-propanediol mother liquor. 2599kg of crude 3-methylamino-1, 2-propanediol was obtained. The main component of the residue in the distillation still is amino alcohol, about 389kg.
b. And (3) rectifying: 3000Kg of 3-methylamino-1, 2-propanediol crude product is transferred into a rectifying still 11 by a pump, the steam of a jacket of the still and an evaporator is started to heat, the temperature of the still is kept at 155-160 ℃, the pressure of the still is 50-150pa, reduced pressure rectification is carried out, a primary fraction of 132Kg is obtained after collecting, and the primary fraction is rectified again with the crude product of the next batch after collecting. After the primary distillation is finished, the finished product is received, 2803kg of 3-methylamino-1, 2-propanediol finished product is obtained, and the actual yield of the 3-methylamino-1, 2-propanediol finished product is 80.94% compared with the theoretical value.
The invention provides a method for continuously producing 3-methylamino-1, 2-propanediol, which specifically adopts a continuous flow production process, has low labor intensity, and can seal operators without contacting toxic and harmful substances basically; meanwhile, the reaction pressure is only 0.2-0.3Mpa, no special equipment is needed, and the monomethylamine aqueous solution and the chlorglycerol are adopted to enter a reaction tower for mixed reaction, so that the explosion is not easy to occur, the safety is high, the equipment purchasing cost is low, and NaOH and NaHCO are not introduced in the mixed reaction process 3 The catalyst, the aqueous solution of the monomethylamine reacts with the chlorglycerol to generate the methylamino hydrochloride, the redundant monomethylamine is evaporated and recovered, then sodium hydroxide is added in the neutralization crystallization process, and the methylamino hydrochloride is effectively neutralized into 3-methylamino-1, 2-propanediol, thereby ensuring the yield of products and improving the yield and purity of the products.
Comparative example 1:
1. amination reaction: sequentially adding 100g of NaHCO into a high-pressure reaction kettle at normal temperature 3 510g of 40% monomethylamine aqueous solution and 250g of chlorglycerol, wherein when the chlorglycerol is added, the strong exothermic phenomenon is accompanied, the kettle temperature is increased to 70 ℃, in order to ensure the experiment safety, the jacket is adopted to be introduced with cooling water for cooling, the dropwise adding temperature is controlled to be 20-30 ℃ in a manner of dropwise adding the chlorglycerol, and the time is 3.5 hours, and the chlorglycerol is dropwise addedAfter the glycerin is finished, 90g of 40% NaOH is slowly added into the flask, stirring is carried out for 1 hour, an electric heating sleeve is started for heating, the reaction is carried out for 80 minutes at 42 ℃, then the temperature is increased to 60 ℃ within 10 minutes, the reaction is carried out for 120 minutes at 60 ℃, and the reaction pressure is 0.07MPa.
2. Treating an amination solution: opening the emptying valve of the reaction kettle, and slowly discharging the monomethylamine gas in the reaction kettle into the monomethylamine absorption tank. When the pressure in the reaction kettle is not available, transferring the amination solution into a 1000ml glass flask for distillation to recover monomethylamine and water, adding 50ml of water for washing because a large amount of sodium chloride solids remain in the kettle, heating materials in the distillation flask by using an electric heating sleeve, starting a water ring pump for vacuumizing when the gas phase temperature reaches 101 ℃, continuing heating, stopping heating when the materials reach 115 ℃, and continuing vacuumizing. After the monomethylamine is recovered, the temperature of the material is reduced to 60 ℃, the material in the distillation kettle is pressed into a filter pressing tank by compressed air, the solid material is removed by filtration, the filtered solid material is intensively treated, and the filtrate is used for rough distillation.
3. And (3) distillation and purification: heating filtrate in the distillation still, preparing 40wt% NaOH solution by using condensate recovered before gas phase temperature is 60 ℃, recovering condensate between 60 ℃ and 100 ℃ as a front cut, and adding the front cut into the next distilled material for full utilization. When the gas phase temperature exceeds 100 ℃ and the rising trend is continued, the distillation still is cooled to 80 ℃, a vacuum unit is started, the vacuum degree in the scraper film evaporator is kept above 0.099MPa, the temperature is 140 ℃, a discharging valve at the lower part of the distillation still is opened, the scraper film evaporator is fed, and the feeding speed is 0.1m 3 And (3) distilling to obtain qualified 3-methylamino-1, 2-propanediol.
The dehydrated mother liquor is treated by adopting the process, almost no front fraction is extracted, 125.44g of 3-methylamino-1, 2-propanediol product is obtained by evaporating by adopting a wiped film evaporator, and kettle residue: 114.05g, the actual yield of the 3-methylamino-1, 2-propanediol product was 52% compared to the theoretical value. It is evident that the actual yields of the 3-methylamino-1, 2-propanediol finished products produced in examples 1-4 of the present invention are significantly higher than in comparative example 1.
The foregoing is a preferred embodiment of the present invention, and it will be apparent to those skilled in the art that modifications and variations can be made without departing from the principles of the present invention, and such modifications and variations are to be regarded as being within the scope of the invention.
Claims (7)
1. A method for continuously producing 3-methylamino-1, 2-propanediol, which is characterized by comprising the following steps in sequence:
(1) Mixing reaction: the method comprises the steps of mixing 30% -40% of monomethylamine aqueous solution and chloroglycerol according to the mass ratio of 10-20:1, mixing, continuously feeding the mixture into a reaction tower, uniformly mixing and carrying out amination reaction, wherein the reaction temperature is 20-40 ℃, and the reaction pressure is 0.2-0.3Mpa, so as to obtain a reaction liquid and a gas phase;
(2) And (3) evaporation recovery: continuously heating and evaporating the reaction liquid obtained in the step (1) at a temperature of 100-120 ℃ for 3-6 hours to obtain an evaporation mother liquid and monomethylamine steam;
(3) And (3) neutralization crystallization: mixing the evaporation mother liquor obtained in the step (2) with sodium hydroxide for neutralization reaction, wherein the mass ratio of the sodium hydroxide to the chloroglycerol is 0.9-1.5:1, a step of; then carrying out continuous evaporation crystallization to obtain concentrated mother liquor and water vapor;
(4) And (3) centrifugal separation: centrifugally separating the concentrated mother liquor obtained in the step (3), and separating out crude sodium chloride salt to obtain 3-methylamino-1, 2-propanediol mother liquor;
(5) Refining: and (3) performing crude distillation and rectification on the 3-methylamino-1, 2-propanediol mother liquor obtained in the step (4) to obtain the 3-methylamino-1, 2-propanediol product.
2. The method for continuously producing 3-methylamino-1, 2-propanediol according to claim 1, wherein the gaseous phase in step (1), the monomethylamine vapor in step (2) and the water vapor in step (3) are condensed and then fed to an absorption column to recover monomethylamine aqueous solution, and when the concentration of monomethylamine aqueous solution is lower than 30%, monomethylamine aqueous solution having a concentration of 40% is fed to the absorption column.
3. A process for the continuous production of 3-methylamino-1, 2-propanediol according to claim 1, characterized in that the aqueous monomethylamine solution concentration in step (1) is 35% -40%.
4. A method for continuously producing 3-methylamino-1, 2-propanediol according to claim 1, wherein the mass ratio of the aqueous monomethylamine solution to the chloroglycerol in step (1) is 15:1.
5. a process for the continuous production of 3-methylamino-1, 2-propanediol according to claim 1, wherein the reaction temperature in step (1) is 25-32 ℃.
6. The continuous process for producing 3-methylamino-1, 2-propanediol according to claim 1, wherein in step (3), the temperature of the evaporative crystallization is 105 to 110 ℃, and the time of the evaporative crystallization is 3 to 3.5 hours.
7. A process for the continuous production of 3-methylamino-1, 2-propanediol according to claim 1, wherein the crude sodium chloride salt in step (4) is washed and the washing solution is subjected to continuous evaporative crystallization in step (3).
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