Ester tertiary amines and continuous process for their preparation

Abstract

The application discloses a tertiary amine ester and a continuous process for preparing the same, and the preparation method comprises the following steps: obtaining a mixed solution of dialkyl ethanol amine and an alkaline catalyst, and a mixed solution of fatty acid ester and a stabilizer; continuously metering the two mixed solutions into a mixer for mixing; preheating the obtained mixture to 150-200 DEG C and then inputting the mixture into a micro-tube reactor for ester exchange reaction at 170-220 DEG C; inputting the obtained reaction material into a falling-film evaporator, condensing and recovering gas-phase evaporated material at the upper portion, and inputting liquid-phase high-temperature material at the lower portion into a buffer tank; and then directly refining the material in the buffer tank or further adding the material into a circulation preparation. The application overcomes the problem of poor stability control of the intermittent reaction, and has very high raw material conversion rate and product preparation efficiency.

Description

Technical Field

[0001] This invention relates to the technical field of ester amine synthesis methods, and particularly to a method for synthesizing ester-based tertiary amines from fatty acid esters and dialkylethanolamines. Background Technology

[0002] Ester-based tertiary amines are a special class of fine chemicals that can be used as various industrial intermediates to further synthesize detergents, cosmetic surfactants, plastic antistatic agents, cationic bactericides and bacteriostatic agents, fiber softeners, brighteners, paper reinforcing antistatic agents, and metalworking lubricants, etc.

[0003] In existing industrial preparations, ester-based tertiary amines are mostly obtained by batch esterification reactions of fatty acids and dialkylethanolamine under the action of acidic catalysts. For example, the existing technical literature "Research on the Synthesis Process of Ester-based Gemini Quaternary Ammonium Salt Softeners" (Niu Hua et al., Fine Chemicals, 2010, 27(8): 823-828) discloses a method for synthesizing ester-based tertiary amines using dimethylethanolamine and stearic acid under the action of sulfuric acid catalyst and toluene azeotropic dehydrating agent at 100-110℃. In this method, dimethylaminoethanol is in 15% excess, the batch reaction time is 7 hours, and the conversion rate of stearic acid is 96.6%. The existing technical literature "Synthesis of Ester-based Asymmetric Biquaternary Ammonium Salt Surfactants" (Xu Qun et al., Fine Chemicals, 2004, 21(12): 903-905) discloses a method for synthesizing ester-based tertiary amines using lauric acid and dimethylethanolamine at 140℃ under the catalysis of p-toluenesulfonic acid. This method requires a 10-hour batch reaction, and the conversion rate of lauric acid is over 95%.

[0004] The above preparation methods require long-term intermittent reactions, resulting in insufficient stability in process control and product quality. The raw material conversion rate is still not ideal, and the acidic catalysts used in the preparation cause severe corrosion to the equipment and easily lead to raw material discoloration. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a continuous process for preparing ester-based tertiary amines and the resulting ester-based tertiary amines. This preparation method uses dialkylethanolamine and fatty acid esters as raw materials to continuously synthesize ester-based tertiary amines under the action of an alkaline catalyst, overcoming the problem of poor stability control in batch reactions. Simultaneously, it exhibits extremely high raw material conversion rate and product preparation efficiency.

[0006] The technical solution of the present invention is as follows:

[0007] A continuous process method for preparing ester-based tertiary amines, comprising:

[0008] (1) Under an inert atmosphere, a mixed solution of dialkylethanolamine and catalyst is obtained by heating to 80-120°C, namely, a mixed solution of dialkylethanolamine;

[0009] (2) Under an inert atmosphere, a mixed solution of fatty acid esters and stabilizers is obtained by heating to 80-120°C, namely, a mixed solution of fatty acid esters;

[0010] (3) The dialkylethanolamine mixture and the fatty acid ester mixture are continuously added to the mixer at a flow rate ratio using a metering pump to obtain a mixture.

[0011] (4) The mixture is fed into a preheater and heated to 150-200°C to obtain preheated material;

[0012] (5) The preheated material is fed into a microtube reactor and transesterification reaction is carried out at 170-220°C to obtain the reactant material;

[0013] (6) The reactants are fed into a falling film evaporator, and the upper gas phase evaporate is condensed and recovered; the lower liquid phase high temperature material is fed into a buffer tank, and then purified to obtain the ester-based tertiary amine.

[0014] The catalyst is selected from one or more of alkali metal hydroxides and alkali metal alkoxides; the stabilizer is selected from one or more of antioxidants, p-tert-butylphenol, vitamin C, and sodium hypophosphite; the flow rate ratio allows the molar ratio of the dialkylethanolamine to the fatty acid ester per unit time to be (3-5):1; the mass of the catalyst used is 0.2-5% of the mass of the fatty acid ester; the mass of the stabilizer used is 0.2-1.0‰ of the mass of the fatty acid ester.

[0015] According to some specific embodiments of the present invention, the continuous process preparation method further includes: adding high-temperature materials entering the buffer tank into the mixer at a circulation ratio via a circulation pump to participate in the preparation again, and refining the remaining high-temperature materials to obtain the ester-based tertiary amine; the circulation ratio is the mass flow ratio of the high-temperature materials added to the mixer to the fatty acid esters added to the mixer.

[0016] According to some specific embodiments of the present invention, the cycle ratio is (0-4):1.

[0017] According to some specific embodiments of the present invention, the alkyl group of the dialkylethanolamine is selected from C1 to C3 alkyl groups, and more preferably, the dialkylethanolamine is selected from one or more of dimethylethanolamine, diethylethanolamine, methylethylethanolamine, methylisopropylethanolamine, and diisopropylethanolamine.

[0018] According to some specific embodiments of the present invention, the fatty acid ester is a C8 to C22 fatty acid ester.

[0019] According to some specific embodiments of the present invention, the catalyst is selected from one or more of sodium hydroxide, potassium hydroxide, sodium methoxide, potassium methoxide, sodium ethoxide, and potassium ethoxide; more preferably, the catalyst is selected from one or more of sodium hydroxide, potassium hydroxide, sodium ethoxide, and potassium ethoxide.

[0020] According to some specific embodiments of the present invention, the microtube reactor has an inner diameter of 3 to 20 mm and a length of 10 to 100 m, and is filled with glass microspheres with a diameter of 1 to 2 mm.

[0021] According to some specific embodiments of the present invention, the apparent residence time of the preheated material in the microtube reactor is 10 to 300 min.

[0022] According to some specific embodiments of the present invention, the residence time of the mixture in the preheater is 1 / 3 of the apparent residence time of the preheated material in the microtube reactor.

[0023] According to some specific embodiments of the present invention, the pressure of the falling film evaporator is atmospheric pressure, the thickness of the formed liquid film is 1-3 mm, the temperature of the upper feed inlet is 160-200°C, the temperature of the lower liquid phase is 130-150°C, and the outlet temperature of the upper gas phase is 90-130°C.

[0024] The present invention has the following beneficial effects:

[0025] (1) In this invention, fatty acid esters and dialkylethanolamine are reacted to synthesize ester-based tertiary amines. An alkaline catalyst is used in the reaction, which can effectively avoid the problems of equipment corrosion and raw material discoloration caused by the use of acid catalysts in the direct esterification reaction of fatty acids.

[0026] (2) The continuous process preparation of the present invention uses a microtube reactor instead of a traditional batch reactor, which enhances the heat and mass transfer of materials, greatly improves the chemical reaction rate, reduces the residence time of materials at high temperature, shortens the reaction time, and enables the conversion rate of raw material fatty acid esters to be higher than 99%, simplifying the separation and purification process.

[0027] (3) The continuous process preparation of the present invention adopts falling film separation technology, which enhances the separation of reaction byproducts low carbon alcohols. It can improve the temperature stability of materials and reduce the concentration of low carbon alcohols in materials through high temperature material circulation, thereby promoting the forward progress of the transesterification reaction.

[0028] (4) The continuous process preparation method of the present invention improves the production efficiency, process controllability and reliability of ester-based tertiary amines. Compared with the traditional batch preparation in a reactor, the present invention has higher volumetric efficiency, better control stability, higher raw material conversion rate and higher process safety. Attached Figure Description

[0029] Figure 1 This is a flowchart illustrating the continuous process for preparing ester-based tertiary amines in this invention. Detailed Implementation

[0030] The present invention will now be described in detail with reference to embodiments and accompanying drawings. However, it should be understood that the embodiments and drawings are for illustrative purposes only and do not constitute any limitation on the scope of protection of the present invention. All reasonable modifications and combinations included within the inventive spirit of the present invention fall within the scope of protection of the present invention.

[0031] See attached document Figure 1 In some specific embodiments, the continuous process preparation method of the ester-based tertiary amine of the present invention includes:

[0032] (1) Add dialkylethanolamine and catalyst to the raw material preparation tank, and stir and mix thoroughly under nitrogen flow at a temperature of 80-120°C to obtain a dialkylethanolamine mixed solution.

[0033] (2) Add fatty acid esters and stabilizers to another raw material preparation tank, and stir and mix thoroughly under a nitrogen flow at a temperature of 80-120°C to obtain a fatty acid ester mixed solution.

[0034] (3) Dialkylethanolamine mixed solution and fatty acid ester mixed solution are continuously fed into the mixer by a dialkylethanolamine metering pump and a fatty acid ester metering pump to mix the two, or when there is circulating material from a high-temperature material buffer tank, the three are mixed to obtain a mixed material.

[0035] (4) The mixture is directly fed into the preheater and indirectly heated to 150-200°C by high-temperature steam and / or heat transfer oil to obtain preheated material;

[0036] (5) The preheated material is directly fed into the microtube reactor to carry out the transesterification reaction and obtain the reactant material;

[0037] (6) The reactants enter the falling film evaporator from the upper feed port and flow downward in the form of a thin film under the action of the rotating scraper. The low-boiling-point by-product alcohol is evaporated and carried out, and then condensed and recovered by the condenser. The high-temperature material at the bottom of the falling film evaporator enters the high-temperature material buffer tank through the overflow pipe. After that, it is directly refined or continues to be recycled.

[0038] The process of the cyclic reaction is as follows:

[0039] (7) The high-temperature material in the high-temperature material buffer tank is added to the mixer through a high-temperature circulating pump at a specific circulation ratio and mixed with the material in the mixer. The high-temperature material outside the circulation ratio is output through an external pump for refining. The circulation ratio is the ratio of the flow rate of the high-temperature material from the high-temperature circulating pump to the flow rate of the fatty acid ester.

[0040] In a more specific embodiment, the continuous process preparation method of the ester-based tertiary amine of the present invention includes: (1) mixing dialkylethanolamine and catalyst in a certain proportion in a raw material preparation tank, maintaining the temperature at 80-120°C in a nitrogen flow.

[0041] (2) Mix fatty acid esters and stabilizers in a certain proportion in a raw material preparation tank, and maintain the temperature at 80-120°C in a nitrogen flow.

[0042] (3) Dialkylethanolamine metering pump and fatty acid ester metering pump continuously deliver materials to the high-efficiency mixer at a certain ratio and flow rate, and the materials are efficiently mixed together in the mixer with the circulating materials from the high-temperature material buffer tank of the falling film evaporator.

[0043] (4) The material that has been uniformly mixed by the high-efficiency mixer is directly fed into the raw material preheating heat exchanger and heated to 150-200°C by high-temperature steam or heat transfer oil.

[0044] (5) The material exiting the preheating heat exchanger directly enters the microtube reactor for ester exchange reaction.

[0045] (6) The material coming out of the microtube reactor directly enters the upper part of the falling film evaporator. Under the rotating scraper, it flows downward as a thin film. The low-fraction by-product alcohol is evaporated and carried out, and then condensed and recovered by the condenser on the top of the falling film evaporator. The high-temperature material at the bottom of the falling film evaporator enters the high-temperature material buffer tank through the overflow pipe.

[0046] (7) The material in the high-temperature material buffer tank is circulated to the high-efficiency mixer before the raw material preheater by the high-temperature circulating pump according to the agreed circulation ratio, and is efficiently mixed with the fresh material; some of the material is pumped to the subsequent ester-based tertiary amine refining process.

[0047] Preferably, the catalyst is selected from one or more of alkali metal hydroxides and alkali metal alkoxides; more preferably, the catalyst is selected from one or more of sodium hydroxide, potassium hydroxide, sodium methoxide, potassium methoxide, sodium ethoxide, and potassium ethoxide; even more preferably, the catalyst is selected from one or more of sodium hydroxide, potassium hydroxide, sodium ethoxide, and potassium ethoxide.

[0048] Preferably, the amount of catalyst used is 0.2% to 5% of the mass of the fatty acid ester, more preferably 0.8% to 3.0%.

[0049] Preferably, the alkyl group in the dialkylethanolamine is one or more of C1 to C3 alkyl groups, such as dimethylethanolamine, diethylethanolamine, methylethylethanolamine, methylisopropylethanolamine, diisopropylethanolamine, and more preferably, dimethylethanolamine (DMEA) and / or diethylethanolamine (DEEA).

[0050] Preferably, the stabilizer is selected from one or more of antioxidants such as antioxidant 1076, antioxidant 1010, p-tert-butylphenol, vitamin C, and sodium hypophosphite; more preferably, it is selected from vitamin C and / or sodium hypophosphite.

[0051] Preferably, the amount of stabilizer used is 0.2‰ to 1.0‰ of the mass of the fatty acid ester, and more preferably, it is 0.5‰ to 0.8‰.

[0052] Preferably, the fatty acid ester is selected from one or more low-carbon alcohol esters of fatty acids, such as fatty acid methyl ester and / or fatty acid ethyl ester; it can be a fatty acid ester with a single carbon chain length or a combination of fatty acid esters with different carbon chain lengths; the carbon chain of the fatty acid ester is C8 to C22, more preferably C10 to C18.

[0053] Preferably, the mixer is a high-efficiency mixer, which can be a dynamic mixer or a static mixer.

[0054] Preferably, the flow ratio of dialkylethanolamine and fatty acid ester is controlled to be (3-5) / 1, more preferably (2-4) / 1, and even more preferably (3-4) / 1.

[0055] The cycle ratio can be selectively set according to the carbon chain length of the fatty acid ester. Preferably, the cycle ratio is (0-4) / 1 (mass ratio), more preferably (0-3) / 1, and even more preferably (0-1.5) / 1.

[0056] The preheater can be selected as a shell-and-tube heat exchanger, in which the mixed material flows inside the tubes and the heat exchange medium, such as steam and / or high-temperature heat transfer oil, flows between the tubes. The temperature of the material after preheating by the preheater is preferably controlled at 150-200°C, more preferably 160-190°C, and even more preferably 170-180°C.

[0057] The microtube reactor is preferably a microtube reactor with an inner diameter φ = 3-20 mm, a length L = 10-100 m, and uniformly filled with glass microspheres with a diameter d = 1-2 mm; it can be selected in the form of a single microtube or a combination of multiple microtubes according to the material processing capacity requirements.

[0058] Preferably, the microtube reactor maintains the temperature of the material inside the reactor using high-temperature heat transfer oil and / or steam.

[0059] Preferably, the apparent residence time of the material in the microtube reactor is 10 to 300 minutes, more preferably 20 to 120 minutes, and even more preferably 30 to 60 minutes.

[0060] Preferably, in the falling film evaporator, the liquid film thickness is adjusted to 1-3 mm, the pressure is atmospheric pressure, the upper feed inlet temperature is 160-200℃, more preferably 170-180℃, the lower liquid phase temperature is 130-150℃, and the upper gas phase outlet temperature is 90-130℃, more preferably 90-110℃.

[0061] Preferably, the high-temperature material buffer tank is equipped with a sampling port, a circulation pump, and an external pump. When the material reaches stability and is sampled and analyzed through the sampling port to meet the process requirements, that is, when the conversion rate of fatty acid esters reaches more than 95%, the circulation ratio can be reduced, and more crude tertiary amines generated by the transesterification reaction can be transported externally for purification and separation.

[0062] The technical solution of the present invention will be further demonstrated below with reference to the embodiments.

[0063] Example 1

[0064] Dimethylaminoethanol lauryl ester (C) was synthesized via the following steps. 12 Dimethyl diethanolamine carboxylate):

[0065] (1) Under nitrogen protection, add 3560 g (40 mol) of dimethylethanolamine to a 5L three-necked flask, add 17 g of potassium hydroxide catalyst (0.8‰ of the mass of methyl lauryl ester), heat to 85°C with thorough stirring, and mix evenly to obtain a dimethylethanolamine mixed solution.

[0066] (2) Under nitrogen protection, add 2140 g (10 mol) of methyl laurate and 10.7 g of sodium hypophosphite (0.5‰ of the mass of methyl laurate) to another 5L three-necked flask, heat to 100°C with stirring, and mix thoroughly to obtain a methyl laurate mixed solution.

[0067] (3) Two micro-metering pumps are used to deliver materials to the static mixer at a flow rate of 5.93 g / min for the dimethyl ethanolamine mixed solution and 3.57 g / min for the methyl laurate mixed solution, respectively, to maintain the molar ratio of dimethyl ethanolamine to methyl laurate at 4.0:1.0. The mixed raw materials exiting the static mixer are continuously fed into a single-coil preheater with a diameter of 3 mm and a length of 20 m, which is immersed in a sand bath at a temperature of 160 °C. The material stays in the preheater for t1 = 12 minutes and is preheated to 160 °C. The material in the preheater then enters a single-tube microtube reactor with a diameter of 3 mm and a length of 60 m, which is filled with glass microspheres with an average particle size of d = 1 mm and is completely immersed in high-temperature heat transfer oil at 180 °C. The apparent residence time of the material in the microtube reactor is t2 = 36 minutes, and a catalytic transesterification reaction is carried out.

[0068] (4) The material from the outlet of the microtube reactor was added to a 1L scraped-film evaporator preheated to 110℃. The methanol generated by the reaction evaporated and entered the methanol condenser as a gas phase for recovery. The liquid phase in the evaporator was added to a 10L glass reaction flask with a heat-insulating jacket. Sampling and analysis showed that the conversion rate of methyl laurate was 99.2%, which was relatively complete, and it was not recycled to the static mixer. The content of dimethylaminoethanol laurate in the material of the glass reaction flask was determined to be 50.34wt%, dimethylethanolamine 49.5wt%, methyl laurate 0.1wt%, and other substances 0.03wt%; it was directly sent to subsequent separation and purification.

[0069] Example 2

[0070] The same preparation process as in Example 1 was used, except that the flow rates of the methyl laurate mixed solution and the dimethylaminoethanol mixed solution were changed, and the residence time t1 of the material in the preheater and the apparent residence time t2 of the material in the microtube reactor were adjusted accordingly. The changes and the preparation results are shown in the table below:

[0071]

[0072]

[0073] It can be seen that, under the same microtube reactor and temperature control, different material ratios altered the residence time and consequently the conversion rate of methyl laurate. At lower dimethylethanolamine / methyl laurate molar ratios, despite prolonged residence time, the methyl laurate conversion rate remained relatively low, indicating that the molar ratio had a greater impact on the conversion rate of methyl laurate than residence time. However, increasing the molar ratio of the raw materials significantly increased the methyl laurate conversion rate, even though it shortened the residence time. When the molar ratio exceeded 3.0, the methyl laurate conversion rate was >95%, while the amount of impurities introduced by other side reactions was also lower.

[0074] Example 3

[0075] The same preparation process as in Example 1 was used, except that the flow rates of the methyl laurate mixed solution and the dimethylaminoethanol mixed solution were changed, and the process of adding the material from the glass reaction flask back into the static mixer according to the recycling ratio was added. The residence time t1 of the material in the preheater and the apparent residence time t2 of the material in the microtube reactor were adjusted accordingly. The changes and the preparation results are shown in the table below:

[0076]

[0077] It can be seen that increasing the molar ratio of dimethylethanolamine to methyl laurate and increasing the recycling ratio can promote the conversion of methyl laurate, but it also increases the residence time of dimethylaminoethanol in the system, which will increase side reactions and increase the content of other impurities in the product.

[0078] Example 4

[0079] Dimethylaminoethanol myristate (C) was synthesized via the following steps. 14 Dimethyl diethanolamine carboxylate):

[0080] (1) Under nitrogen protection, add 3560 g (40 mol) of dimethylethanolamine to a 5L three-necked flask, add 19.4 g of potassium hydroxide catalyst (0.8‰ of the mass of methyl myristate), heat to 85°C with thorough stirring, and mix evenly to obtain a dimethylethanolamine mixed solution.

[0081] (2) Under nitrogen protection, add 2420 g (10 mol) of methyl myristate and 12.1 g of sodium hypophosphite (0.5‰ of the mass of methyl myristate) to another 5L three-necked flask, heat to 100°C with stirring, and mix thoroughly to obtain a methyl myristate mixed solution.

[0082] (3) Two micro-metering pumps were used to deliver materials to the static mixer at a flow rate of 5.93 g / min for the dimethyl ethanolamine mixed solution and 4.03 g / min for the methyl myristate mixed solution, respectively, to maintain the molar ratio of dimethyl ethanolamine to methyl myristate at 4.0:1.0. The mixed raw materials exiting the static mixer were continuously fed into a single-coil preheater with a diameter of 3 mm and a length of 20 m, which was immersed in a sand bath at 160 °C. The material was preheated to 160 °C for a residence time of t1 = 12.2 minutes. The material in the preheater was then fed into a single-tube microtube reactor with a diameter of 3 mm and a length of 60 m, which was filled with glass microspheres with an average particle size of d = 1 mm and completely immersed in high-temperature heat transfer oil at 180 °C. The apparent residence time of the material in the microtube reactor was t2 = 36.6 minutes, and the catalytic transesterification reaction was carried out.

[0083] (4) The material from the outlet of the microtube reactor was added to a 1L scraped-film evaporator preheated to 110℃. The methanol generated by the reaction evaporated and entered the methanol condenser as a gas phase for recovery. The liquid phase in the evaporator was added to a 10L glass reaction flask with an insulation jacket. Sampling and analysis showed that the conversion rate of methyl myristate was 98.6%, which was relatively complete, and it was not recycled to the static mixer. The material in the glass reaction flask contained 52.6% dimethylaminoethanol myristate, 47.1% dimethylethanolamine, 0.2% methyl myristate, and 0.1% other substances; it was directly sent for separation and purification.

[0084] Example 5

[0085] Dimethylaminoethanol palmitate (C) was synthesized via the following steps. 16 Dimethyl diethanolamine carboxylate):

[0086] (1) Under nitrogen protection, add 3560 g (40 mol) of dimethylethanolamine to a 5L three-necked flask, add 21.64 g of potassium hydroxide catalyst (0.8‰ of the mass of methyl palmitate), heat to 85°C with thorough stirring, and mix evenly to obtain a dimethylethanolamine mixed solution.

[0087] (2) Under nitrogen protection, add 2705 g (10 mol) of methyl palmitate and 13.5 g of sodium hypophosphite (0.5‰ of the mass of methyl palmitate) to another 5L three-necked flask, heat to 100°C with stirring, and mix thoroughly to obtain a methyl palmitate mixed solution.

[0088] (3) Two micro-metering pumps were used to deliver materials to the static mixer at a flow rate of 5.93 g / min for the dimethyl ethanolamine mixed solution and 4.51 g / min for the methyl palmitate mixed solution, respectively, to maintain the molar ratio of dimethyl ethanolamine to methyl palmitate at 4.0:1.0. The mixed raw materials exiting the static mixer were continuously fed into a single-coil preheater with a diameter of 3 mm and a length of 20 m, which was immersed in a sand bath at a temperature of 160 °C. The material was preheated to 160 °C for a residence time of t1 = 11.5 minutes. The material in the preheater was then fed into a single-tube microtube reactor with a diameter of 3 mm and a length of 60 m, which was filled with glass microspheres with an average particle size of d = 1 mm and completely immersed in high-temperature heat transfer oil at 180 °C. The apparent residence time of the material in the microtube reactor was t2 = 34.5 minutes, and the catalytic transesterification reaction was carried out.

[0089] (4) The material from the outlet of the microtube reactor was added to a 1L scraped-film evaporator preheated to 110℃. The methanol generated by the reaction evaporated and entered the methanol condenser as a gas phase for recovery. The liquid phase in the evaporator was added to a 10L glass reaction flask with an insulation jacket. Sampling and analysis showed that the conversion rate of methyl palmitate was 98.2%, which was relatively complete, and it was not recycled to the static mixer. The material in the glass reaction flask contained 54.1% dimethylaminoethanol palmitate, 45.0% dimethylethanolamine, 0.8% methyl palmitate, and 0.1% other substances; it was directly sent to subsequent separation and purification.

[0090] Example 6

[0091] Dimethylaminoethanol stearate (C) was synthesized via the following steps. 18 Dimethyl diethanolamine carboxylate):

[0092] (1) Under nitrogen protection, add 3560 g (40 mol) of dimethylethanolamine to a 5L three-necked flask, add 23.88 g of potassium hydroxide catalyst (0.8‰ of the mass of methyl stearate), heat to 85°C with thorough stirring, and mix evenly to obtain a dimethylethanolamine mixed solution.

[0093] (2) Under nitrogen protection, add 2985 g (10 mol) of methyl stearate and 14.9 g of sodium hypophosphite (0.5‰ of the mass of methyl stearate) to another 5L three-necked flask, heat to 100°C with stirring, and mix thoroughly to obtain a methyl stearate mixed solution.

[0094] (3) Two micro-metering pumps are used to deliver materials to the static mixer at a flow rate of 5.93 g / min for the dimethyl ethanolamine mixed solution and 4.98 g / min for the methyl stearate mixed solution, respectively, to maintain the molar ratio of dimethyl ethanolamine to methyl stearate at 4.0:1.0. The mixed raw materials exiting the static mixer are continuously fed into a single-coil preheater with a diameter of 3 mm and a length of 20 m, which is immersed in a sand bath at a temperature of 160 °C. The material stays in the preheater for t1 = 11.0 minutes and is preheated to 160 °C. The material in the preheater then enters a single-tube microtube reactor with a diameter of 3 mm and a length of 60 m, which is filled with glass microspheres with an average particle size of d = 1 mm and is completely immersed in high-temperature heat transfer oil at 180 °C. The apparent residence time of the material in the microtube reactor is t2 = 33.0 minutes, and a catalytic transesterification reaction is carried out.

[0095] (4) The material from the outlet of the microtube reactor was added to a 1L scraped-film evaporator preheated to 110℃. The methanol generated by the reaction evaporated and entered the methanol condenser as a gas phase for recovery. The liquid phase in the evaporator was added to a 10L glass reaction flask with an insulation jacket. Sampling and analysis showed that the conversion rate of methyl stearate was 97.5%, which was relatively complete, and it was not recycled to the static mixer. The material in the glass reaction flask contained 55.8% dimethylaminoethanol stearate, 43.0% dimethylethanolamine, 1.1% methyl stearate, and 0.1% other substances; it was directly sent to subsequent separation and purification.

[0096] Example 7

[0097] The following steps are used to synthesize dimethylaminoethanol fish oil fatty acid ester (C 16 / C 18 / C 20 Dimethyl diethanolamine carboxylate):

[0098] (1) Under nitrogen protection, add 3560 g (40 mol) of dimethylethanolamine to a 5L three-necked flask, add 23.09 g of potassium hydroxide catalyst (0.8‰ of the mass of fish oil fatty acid methyl ester), heat to 85°C with thorough stirring, and mix evenly to obtain a dimethylethanolamine mixed solution.

[0099] (2) Under nitrogen protection, add 2886 g (10 mol) of fish oil fatty acid methyl ester and 14.8 g of sodium hypophosphite (0.5‰ of the mass of fish oil fatty acid methyl ester) to another 5L three-necked flask, heat to 100℃ with stirring, and mix thoroughly to obtain a fish oil fatty acid methyl ester mixed solution.

[0100] (3) Two micro-metering pumps were used to deliver materials to the static mixer at a flow rate of 5.93 g / min for the dimethyl ethanolamine mixed solution and 4.81 g / min for the fish oil fatty acid methyl ester mixed solution, respectively, to maintain the molar ratio of dimethyl ethanolamine and fish oil fatty acid methyl ester at 4.0:1.0. The mixed raw materials exiting the static mixer were continuously fed into a single-coil preheater with a diameter of 3 mm and a length of 20 m, which was immersed in a sand bath at 160 °C. The material was preheated to 160 °C for a residence time of t1 = 11.0 minutes. The material in the preheater was then fed into a single-tube microtube reactor with a diameter of 3 mm and a length of 60 m, which was filled with glass microspheres with an average particle size of d = 1 mm and completely immersed in high-temperature heat transfer oil at 180 °C. The apparent residence time of the material in the microtube reactor was t2 = 33.0 minutes, and the catalytic transesterification reaction was carried out.

[0101] (4) The material from the outlet of the microtube reactor was added to a 1L scraped-film evaporator preheated to 110℃. The methanol generated by the reaction evaporated and entered the methanol condenser as a gas phase for recovery. The liquid phase in the evaporator was added to a 10L glass reaction flask with a heat-insulating jacket. Sampling and analysis showed that the conversion rate of fish oil fatty acid methyl ester was 98.5%, which was relatively complete, and it was not recycled to the static mixer. The material in the glass reaction flask contained 55.6% fish oil fatty acid dimethylaminoethanol ester, 43.6% dimethylethanolamine, 0.7% fish oil fatty acid methyl ester, and 0.1% other substances; it was directly sent to subsequent separation and purification.

[0102] The above embodiments are merely preferred embodiments of the present invention, and the scope of protection of the present invention is not limited to the above embodiments. All technical solutions falling within the scope of the present invention's concept are within the scope of protection of the present invention. It should be noted that for those skilled in the art, improvements and modifications made without departing from the principles of the present invention should also be considered within the scope of protection of the present invention.

Claims

1. A continuous process method for preparing ester-based tertiary amines, characterized in that, It includes: (1) Under an inert atmosphere, a mixed solution of dialkylethanolamine and catalyst is obtained by heating to 80-120°C, namely, a mixed solution of dialkylethanolamine; (2) Under an inert atmosphere, a mixed solution of fatty acid esters and stabilizers is obtained by heating to 80-120°C, namely, a mixed solution of fatty acid esters; (3) The dialkylethanolamine mixture and the fatty acid ester mixture are continuously added to the mixer at a flow rate ratio using a metering pump to obtain a mixture. (4) The mixture is fed into a preheater and heated to 150-200°C to obtain preheated material; (5) The preheated material is fed into a microtube reactor and transesterification reaction is carried out at 170-220°C to obtain the reactant material; (6) The reactants are fed into a falling film evaporator, and the upper gas phase evaporate is condensed and recovered; the lower liquid phase high temperature material is fed into a buffer tank, and then purified to obtain the ester-based tertiary amine. The catalyst is selected from one or more of alkali metal hydroxides and alkali metal alkoxides; the stabilizer is selected from sodium hypophosphite; the flow rate ratio is such that the molar ratio of the dialkylethanolamine to the fatty acid ester per unit time is (3-5):1; the mass of the catalyst used is 0.2-5% of the mass of the fatty acid ester; and the mass of the stabilizer used is 0.2-1.0‰ of the mass of the fatty acid ester.

2. The continuous process preparation method according to claim 1, characterized in that, It also includes: adding the high-temperature material entering the buffer tank into the mixer at a circulation ratio via a circulation pump to participate in the preparation again, and refining the remaining high-temperature material to obtain the ester-based tertiary amine; the circulation ratio is the mass flow ratio of the high-temperature material added to the mixer to the fatty acid ester added to the mixer.

3. The continuous process preparation method according to claim 2, characterized in that, The cycle ratio is (0-4):

1.

4. The continuous process preparation method according to claim 1, characterized in that, in, The alkyl group of the dialkylethanolamine is selected from C1 to C3 alkyl groups; and / or, the fatty acid ester is a C8 to C22 fatty acid ester; and / or, the catalyst is selected from one or more of sodium hydroxide, potassium hydroxide, sodium methoxide, potassium methoxide, sodium ethoxide, and potassium ethoxide.

5. The continuous process preparation method according to claim 1, characterized in that, in, The dialkylethanolamine is selected from one or more of dimethylethanolamine, diethylethanolamine, methylethylethanolamine, methylisopropylethanolamine, and diisopropylethanolamine; and / or the catalyst is selected from one or more of sodium hydroxide, potassium hydroxide, sodium ethoxide, and potassium ethoxide.

6. The continuous process preparation method according to claim 1, characterized in that, The microtube reactor has an inner diameter of 3–20 mm and a length of 10–100 m, and is filled with glass microspheres with a diameter of 1–2 mm.

7. The continuous process preparation method according to claim 1, characterized in that, The apparent residence time of the preheated material in the microtube reactor is 10–300 min.

8. The continuous process preparation method according to claim 1, characterized in that, The residence time of the mixture in the preheater is 1 / 3 of the apparent residence time of the preheated material in the microtube reactor.

9. The continuous process preparation method according to claim 1, characterized in that, The falling film evaporator operates at atmospheric pressure, forms a liquid film thickness of 1–3 mm, has an upper inlet temperature of 160–200 °C, a lower liquid phase temperature of 130–150 °C, and an upper gas phase outlet temperature of 90–130 °C.

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