A continuous reaction device and preparation method for preparing secondary fatty acid amide

Abstract

The present invention belongs to the technical field of organic synthesis, and in particular to a continuous reaction device and preparation method for preparing fatty acid secondary amide. The continuous reaction device provided by the present invention includes a first reactor 3, an evaporator 4 connected to the first reactor outlet 3-3, a flash tower 5 connected to the evaporator 4, a second reactor 8 connected to the flash tower liquid outlet 5-1, and a collecting container 9 connected to the second reactor outlet 8-3; the second reactor 8 sidewall is provided with a catalyst inlet 8-2. After most of the fatty acids and primary amines react to form ammonium salts in the first reactor 3, dehydration reaction is carried out in the evaporator 4 and the flash tower 5 to obtain amides; finally, a catalyst is used in the second reactor 8 to promote the reaction of the remaining fatty acids and primary amines, thereby reducing the free acid value and amine value in the product. The continuous reaction device can achieve continuous production of fatty acid secondary amides, and ensure the stability and consistency of product quality.

Description

Technical Field

[0001] The invention belongs to the technical field of organic synthesis, and particularly relates to a continuous reaction device and a preparation method for preparing fatty acid secondary amides. Background Art

[0002] Secondary fatty acid amides are synthesized by reacting higher long-chain fatty acids (such as oleic acid, erucic acid, behenic acid, stearic acid, 12-hydroxystearic acid, etc.) with primary amines (such as octadecyl primary amine or oleyl primary amine, etc.). Secondary fatty acid amides mainly include stearyl erucamide, octadecyl stearamide, oleyl palmitamide, octadecyl behenamide, oleyl stearamide, oleyl behenamide, etc. They are a class of engineering plastic additives with excellent performance and are also additives for polymer composites. They have good heat resistance and stability, and have smoothness, lubrication, demolding, and scratch resistance. With the continuous expansion of the application field of engineering plastics and the high-quality development of polymer composites, higher requirements are placed on the quality stability of secondary fatty acid amides.

[0003] Currently, fatty acid secondary amides produced using a one-pot batch-by-batch stirred kettle reaction are difficult to ensure consistent and stable product quality across batches. This inconsistent quality hinders their widespread application in fields such as engineering plastics and polymer composites. Summary of the Invention

[0004] In view of this, the present invention provides a continuous reaction device and a preparation method. The continuous reaction device provided by the present invention can realize the continuous preparation of fatty acid secondary amides, thereby ensuring the stability and consistency of the quality of fatty acid secondary amides.

[0005] In order to solve the above technical problems, the present invention provides a continuous reaction device, comprising a first reactor 3, an evaporator 4 connected to the outlet 3-3 of the first reactor, a flash tower 5 connected to the evaporator 4, a second reactor 8 whose material inlet 8-1 is connected to the liquid outlet 5-1 of the flash tower, and a collecting container 9 connected to the outlet 8-3 of the second reactor;

[0006] The side wall of the second reactor 8 is provided with a catalyst inlet 8-2.

[0007] Preferably, the first reactor 3 is a vertical stirred tubular reactor, and a first raw material inlet 3-1 and a second raw material inlet 3-2 are provided at the lower end of the side wall of the first reactor 3; the first raw material inlet 3-1 is connected to a first feed pump 1; the second raw material inlet 3-2 is connected to a second feed pump 2.

[0008] Preferably, the second reactor 8 is a horizontal stirred tubular reactor;

[0009] The liquid outlet 5 - 1 and the material inlet 8 - 1 of the flash tower are connected by a transfer pump 6 .

[0010] Preferably, the catalyst inlet 8 - 2 is connected to a liquid inlet pump 7 .

[0011] Preferably, the evaporator 4 is a shell-and-tube falling film evaporator.

[0012] The present invention also provides a method for preparing fatty acid secondary amides using the continuous reaction device described in the above technical solution, comprising the following steps:

[0013] The fatty acid and the primary amine are continuously fed into the first reactor 3, and after a first amidation reaction is carried out in the first reactor 3, the mixture is sequentially fed into the evaporator 4 and the flash tower 5 through the outlet 3-3 of the first reactor for dehydration to obtain a mixture comprising fatty acid secondary amide, fatty acid and primary amine;

[0014] The mixture is continuously conveyed to the second reactor 8 and mixed with the liquid catalyst entering the second reactor 8 from the catalyst inlet 8-2 to carry out a second amidation reaction. The second amidation reaction product is conveyed to a collection container 9 to obtain fatty acid secondary amide.

[0015] Preferably, the temperature of the first amidation reaction is 166-178° C.; the pressure of the first amidation reaction is 0.1-0.25 MPa; and the time of the first amidation reaction is 8-16 min.

[0016] The temperature of the second amidation reaction is 172 to 182° C.; the pressure of the second amidation reaction is -0.1 to 0.05 MPa; and the time of the second amidation reaction is 15 to 30 minutes.

[0017] Preferably, the dehydration includes evaporative dehydration in the evaporator 4 and flash dehydration in the flash tower 5; the temperature of the evaporative dehydration is 170-180° C.; and the vacuum degree of the flash dehydration is less than or equal to 3500 Pa.

[0018] Preferably, the fatty acid comprises one or more of erucic acid, stearic acid, oleic acid, palmitic acid, behenic acid, 12-hydroxystearic acid and isostearic acid;

[0019] The primary amine is octadecyl primary amine or oleyl primary amine;

[0020] The molar ratio of the fatty acid to the primary amine is 1:0.91-0.99.

[0021] Preferably, the liquid catalyst comprises the following components in percentage by weight:

[0022] Butyl titanate 35-60%;

[0023] Isopropyl zirconate 10-30%;

[0024] Methyl silicone oil 20-40%;

[0025] The mass ratio of the liquid catalyst to the fatty acid is 0.2-0.8:100.

[0026] The present invention provides a continuous reaction device, comprising a first reactor 3, an evaporator 4 connected to the first reactor outlet 3-3, a flash tower 5 connected to the evaporator 4, a second reactor 8 having a material inlet 8-1 connected to the flash tower liquid outlet 5-1, and a collecting container 9 connected to the second reactor outlet 8-3; the second reactor 8 is provided with a catalyst inlet 8-2 on its sidewall. The present invention first performs an amidation reaction in the first reactor 3, causing most fatty acids to react with primary amines to form ammonium salts, and then performs a dehydration reaction in the evaporator 4 and the flash tower 5 to convert the ammonium salts formed in the first reactor 3 into amides. Finally, a catalyst is used in the second reactor 8 to promote the reaction of the remaining fatty acids with the primary amines, further reducing the free acid value and amine value in the product, thereby eliminating the product refining process. The continuous reaction device provided by the present invention can achieve continuous production of fatty acid secondary amides and ensure the stability and consistency of product quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the continuous reaction apparatus used in the embodiment, wherein 1 is the first feed pump, 2 is the second feed pump, 3 is the first reactor, 3-1 is the first raw material inlet, 3-2 is the second raw material inlet, 3-3 is the first reactor outlet, 4 is the evaporator, 5 is the flash tower, 5-1 is the flash tower liquid outlet, 6 is the transfer pump, 7 is the liquid feed pump, 8 is the second reactor, 8-1 is the material inlet, 8-2 is the catalyst inlet, 8-3 is the second reactor outlet, and 9 is the collection container. DETAILED DESCRIPTION

[0028] The present invention provides a continuous reaction device, comprising a first reactor 3. In the present invention, the first reactor 3 is preferably a vertical stirred tubular reactor, and the lower end of the side wall of the first reactor 3 is preferably provided with a first raw material inlet 3-1 and a second raw material inlet 3-2; the first raw material inlet 3-1 is preferably connected to a first feed pump 1; the second raw material inlet 3-2 is preferably connected to a second feed pump 2. In the present invention, a first reactor outlet 3-3 is provided at the upper end of the vertical stirred tubular reactor. In the present invention, the vertical stirred tubular reactor preferably includes an internal and external double heat exchange structure. In the present invention, a stirring paddle is preferably provided inside the vertical stirred tubular reactor, and the stirring paddle is preferably a plate-type spiral stirring paddle; the rotation speed of the stirring paddle is preferably 120 to 230 r / min, more preferably 150 to 200 r / min. In the present invention, the flow rate of the first reactor 3 is preferably 200-500 L / min, more preferably 300-400 L / min; the liquid holdup of the first reactor 3 is preferably 40-80 L, more preferably 50-70 L; the operating temperature of the first reactor 3 is preferably 0-220°C; and the operating pressure of the first reactor 3 is preferably -0.1-1.0 MPa.

[0029] The chemical reaction carried out in the first reactor 3 of the present invention can ensure that the reaction raw materials are mixed evenly, promote mass transfer and heat transfer, and ensure that the reaction proceeds quickly and stably.

[0030] The continuous reaction apparatus provided by the present invention includes an evaporator 4 connected to the outlet 3-3 of the first reactor. In the present invention, the evaporator 4 is preferably a shell-and-tube falling film evaporator, preferably equipped with a distributor and a film forming device on its upper portion. In the present invention, the evaporator 4 is capable of removing most of the water contained in the product in the first reactor 3.

[0031] The continuous reaction device provided by the present invention comprises a flash tower 5 connected to the evaporator 4. In the present invention, the flash tower 5 can further remove moisture from the product after being processed by the evaporator 4.

[0032] The continuous reaction device provided by the present invention includes a second reactor 8 in which a material inlet 8-1 is connected to a liquid outlet 5-1 of a flash tower. In the present invention, the second reactor 8 is a horizontal stirred tubular reactor, and a catalyst inlet 8-2 is provided on the side wall of the second reactor 8, and the catalyst inlet 8-2 is preferably connected to a liquid feed pump 7. The present invention utilizes a liquid feed pump 7 to transport the liquid catalyst to the second reactor 8. In the present invention, the horizontal stirred tubular reactor preferably includes an internal and external double heat exchange structure. In the present invention, a stirring paddle is preferably provided inside the vertical stirred tubular reactor, and the stirring paddle is preferably a plate-type spiral stirring paddle; the rotation speed of the stirring paddle is preferably 50 to 220 r / min, more preferably 80 to 150 r / min. In the present invention, the flow rate of the second reactor 8 is preferably 200-500 L / min, more preferably 300-400 L / min; the liquid holdup of the second reactor 8 is preferably 60-100 L, more preferably 70-90 L; the operating temperature of the second reactor 8 is preferably 0-230°C; and the operating pressure of the second reactor 8 is preferably -0.1-0.05 MPa.

[0033] The chemical reaction carried out in the second reactor 8 of the present invention can ensure that the reaction raw materials are mixed evenly, promote mass transfer and heat transfer, and ensure that the reaction proceeds quickly and stably.

[0034] In the present invention, the liquid outlet 5-1 of the flash column and the material inlet 8-1 are preferably connected by a transfer pump 6. In the present invention, the transfer pump 6 can transfer the liquid in the flash column to the second reactor 8.

[0035] The continuous reaction apparatus provided by the present invention further includes a collection container 9 connected to the outlet 8-3 of the second reactor. In the present invention, the collection container 9 is preferably a vacuum container; the vacuum container is preferably connected to a vacuum condensing device, and the water vapor generated in the collection container 9 enters the vacuum condensing device for condensation, thereby further removing moisture from the product in the collection container 9.

[0036] In the present invention, the continuous reaction apparatus preferably further comprises a control system. In the present invention, the control system is preferably a DCS control system. The present invention preferably utilizes the control system to control the temperature and pressure of the first reactor 1, the evaporator 4, the flash tower 5, the second reactor 8, and the collection container 9. The present invention preferably utilizes the control system to control the flow rates of the first feed pump 1, the second feed pump 2, the transfer pump 6, and the liquid feed pump 7, thereby enabling precise control of the temperature, pressure, flow rate, and other conditions required for the reaction.

[0037] The present invention also provides a method for preparing fatty acid secondary amides using the continuous reaction device described in the above technical solution, comprising the following steps:

[0038] The fatty acid and the primary amine are continuously fed into the first reactor 3, and after a first amidation reaction is carried out in the first reactor 3, the mixture is sequentially fed into the evaporator 4 and the flash tower 5 through the outlet 3-3 of the first reactor for dehydration to obtain a mixture comprising fatty acid secondary amide, fatty acid and primary amine;

[0039] The mixture is continuously conveyed to the second reactor 8 and mixed with the liquid catalyst entering the second reactor 8 from the catalyst inlet 8-2 to carry out a second amidation reaction. The second amidation reaction product is conveyed to a collection container 9 to obtain fatty acid secondary amide.

[0040] In the present invention, a fatty acid and a primary amine are continuously introduced into a first reactor 3. After a first amidation reaction in the first reactor 3, the mixture is sequentially introduced into an evaporator 4 and a flash tower 5 from the outlet 3-3 of the first reactor for dehydration, yielding a mixture comprising a fatty acid secondary amide, a fatty acid, and a primary amine. In the present invention, the fatty acid and the primary amine are preferably heated before the first amidation reaction. In the present invention, the temperature of the fatty acid after heating is preferably 140-165°C, more preferably 148-157°C; the temperature of the primary amine after heating is preferably 135-160°C, more preferably 140-158°C. In the present invention, the fatty acid and the primary amine are melted into a liquid by heating to facilitate delivery of the fatty acid and the primary amine using a feed pump. The ratio of the fatty acid and the primary amine is preferably controlled by adjusting the flow rate of the feed pump. In the present invention, the flow rate of the fatty acid is preferably 179-214 kg / h, more preferably 186-192 kg / h; the flow rate of the primary amine is preferably 141-196 kg / h, more preferably 158-194 kg / h.

[0041] In the present invention, the fatty acid preferably includes one or more of erucic acid, stearic acid, oleic acid, palmitic acid, behenic acid, 12-hydroxystearic acid, and isostearic acid, and more preferably erucic acid, stearic acid, palmitic acid, or behenic acid. In the present invention, when the fatty acid is two or more of the above-mentioned specific substances, the present invention has no particular limitation on the ratio of the above-mentioned specific substances, and can be determined according to the desired structure of the fatty acid secondary amide.

[0042] In the present invention, the primary amine is preferably octadecyl primary amine or oleyl primary amine, more preferably octadecyl primary amine.

[0043] In the present invention, the molar ratio of the fatty acid to the primary amine is preferably 1:0.91-0.99, more preferably 1:0.96-0.98.

[0044] In the present invention, the temperature of the first amidation reaction is preferably 166-178°C, more preferably 168-172°C; the pressure of the first amidation reaction is preferably 0.1-0.25 MPa, more preferably 0.15-0.2 MPa; the time of the first amidation reaction is preferably 8-16 min, more preferably 11-14 min, and further preferably 12-13 min.

[0045] The present invention causes the fatty acid and the primary amine to undergo a rapid amidation reaction in the first reactor 3, and subsequently causes the remaining fatty acid and the primary amine to undergo a further amidation reaction in the second reactor 8 under the action of a catalyst, thereby ensuring that the fatty acid and the primary amine react completely.

[0046] In the present invention, the dehydration preferably includes evaporative dehydration in the evaporator 4 and flash dehydration in the flash tower 5; the temperature of the evaporative dehydration is preferably 170-180°C; the flash dehydration is carried out in the flash tower 5, and the vacuum degree of the flash dehydration is preferably less than or equal to 3500Pa, more preferably less than 3000Pa, and further preferably 2000-2800Pa.

[0047] In the present invention, the water content of the product after evaporation and dehydration is preferably ≤2.0%, more preferably ≤1.2%. In the present invention, the water content of the product after flash evaporation and dehydration is preferably ≤0.6%, more preferably ≤0.4%.

[0048] The present invention can remove most of the water in the first amidation reaction product through evaporative dehydration, and can further remove the remaining water in the first amidation reaction product through flash dehydration. Partial amidation reaction also occurs during the dehydration process.

[0049] After obtaining the mixture, the present invention continuously conveys the mixture to the second reactor 8 and mixes it with the liquid catalyst entering the second reactor 8 through the catalyst inlet 8-2 to perform a second amidation reaction. The second amidation reaction product is conveyed to a collection container 9 to obtain a fatty acid secondary amide. In the present invention, the liquid catalyst preferably includes the following components in percentage by weight:

[0050] Butyl titanate 40-60%;

[0051] Isopropyl zirconate 10-30%;

[0052] Methyl silicone oil 20-40%.

[0053] In the present invention, the liquid catalyst preferably comprises 35-60% butyl titanate, more preferably 45-55%. In the present invention, the liquid catalyst preferably comprises 10-30% isopropyl zirconate, more preferably 20-25%. In the present invention, the liquid catalyst preferably comprises 20-40% methyl silicone oil, more preferably 30-35%. In the present invention, the liquid catalyst is beneficial to increasing the reaction rate of fatty acids and primary amines. In the present invention, the mass ratio of the liquid catalyst to the fatty acid is preferably 0.2-0.8:100, more preferably 0.5-0.6:100. In the present invention, the amount of the liquid catalyst is preferably controlled by adjusting the flow rate of the liquid inlet pump 7, and the flow rate of the liquid inlet pump is preferably 0.5-3.2 kg / h, more preferably 0.65-2.2 kg / h.

[0054] In the present invention, the ratio of the mixture and the catalyst is preferably controlled by adjusting the flow rate of the transfer pump 6. The flow rate of the transfer pump 6 is preferably 290 to 420 kg / h, more preferably 320 to 380 kg / h.

[0055] In the present invention, the temperature of the second amidation reaction is preferably 172-182° C., more preferably 176-180° C.; the pressure of the second amidation reaction is preferably 0.05-0.1 MPa, more preferably 0.06-0.08 MPa; the time of the second amidation reaction is preferably 15-30 min, more preferably 18-23 min, and further preferably 19-21 min.

[0056] In the present invention, after the second amidation reaction, the product of the second amidation reaction is preferably transferred to a collection container 9. The temperature in the collection container 9 is preferably 170-190°C, more preferably 175-179°C. The vacuum level in the collection container 9 is preferably less than or equal to 200 Pa, more preferably 50-150 Pa. The present invention limits the temperature and vacuum level of the collection container to the above ranges to facilitate the removal of moisture from the second amidation reaction product, thereby improving the purity of the fatty acid secondary amide. In the present invention, the water content of the fatty acid secondary amide is preferably ≤0.6%, more preferably ≤0.3%.

[0057] Secondary fatty acid amides are produced by an amidation-dehydration reaction between the corresponding fatty acid and a primary amine. The reaction rate is relatively fast in the early stages, but slows in the later stages. The present invention utilizes a vertical stirred tubular reactor for the early amidation reaction, with a falling-film evaporator and flash tower used to continuously and rapidly remove the generated water. For the later stages, a horizontal stirred tubular reactor is used, with an appropriately increased residence time. The reaction rate is increased by a liquid catalyst, resulting in a homogeneous catalytic reaction, while high-vacuum dehydration is simultaneously performed in a collection tank.

[0058] In order to further illustrate the present invention, the technical solutions provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0059] Example 1

[0060] use Figure 1 The apparatus shown prepares fatty acid secondary amides;

[0061] The octadecyl primary amine was heated and melted to obtain an octadecyl primary amine liquid having a temperature of 145±2° C., and the stearic acid was heated and melted to obtain a stearic acid liquid having a temperature of 150±2° C.; the octadecyl primary amine liquid was delivered to the first reactor 3 at a flow rate of 196 kg / h using a first feed pump 1; the stearic acid liquid was delivered to the first reactor 3 at a flow rate of 214 kg / h using a second feed pump 2; and the octadecyl primary amine liquid and the stearic acid liquid were subjected to a first amidation reaction in the first reactor 3 at a plate screw stirring blade speed of 200 r / min, a temperature of 170±2° C., and a pressure of 0.15 MPa for 11 minutes;

[0062] The product of the first amidation reaction is transferred to a falling film evaporator 4 and evaporated and dehydrated at 170° C. (water content ≤ 2.0%), and then enters a flash tower 5 for flash dehydration under a vacuum degree of 2600 Pa; the flash dehydrated mixture (water content ≤ 0.6%) is transferred to a horizontal stirred tubular second reactor 8 using a transfer pump 6 at a flow rate of 410 kg / h, and a liquid catalyst is added to the horizontal stirred tubular second reactor 8 using a liquid feed pump 7 at a flow rate of 0.65 kg / h; the liquid catalyst is composed of 55% butyl titanate, 10% isopropyl zirconate and 35% methyl silicone oil in terms of mass percentage;

[0063] The rotation speed of the plate-type spiral stirring paddle in the horizontal stirred tubular second reactor 8 is controlled to 150 r / min, the temperature to 178±2° C., and the pressure to 0.05 MPa, and a second amidation reaction is carried out for 18 minutes. The second amidation reaction product is transferred to a vacuum container 9, and the temperature in the vacuum container 9 is controlled to 180±2° C. and the vacuum degree to 100 Pa to obtain octadecyl stearamide with a water content of 0.3% or less. The process indicators such as temperature, flow rate and pressure at each point in the entire synthesis process are automatically controlled by the DCS process control system.

[0064] During the continuous production process, samples were taken from the vacuum container 9 every 15 minutes to analyze the quality of the product. The results are listed in Table 1.

[0065] Table 1 Test results of continuous synthesis of octadecyl stearamide

[0066]

[0067]

[0068] Example 2

[0069] use Figure 1 The apparatus shown prepares fatty acid secondary amides;

[0070] Heat and melt oleyl primary amine to obtain oleyl primary amine liquid at a temperature of 143±2° C., and heat and melt palmitic acid to obtain palmitic acid liquid at a temperature of 155±2° C.; use a first feed pump 1 to deliver the oleyl primary amine liquid to a first reactor 3 at a flow rate of 194 kg / h; use a second feed pump 2 to deliver the palmitic acid liquid to the first reactor 3 at a flow rate of 186 kg / h; and allow the oleyl primary amine liquid and the palmitic acid liquid to undergo a first amidation reaction in the first reactor 3 for 12 minutes under the conditions of a plate screw stirring blade speed of 200 r / min, a temperature of 173±2° C., and a pressure of 0.2 MPa;

[0071] The product of the first amidation reaction was transferred to a falling film evaporator 4 and evaporated and dehydrated at 174±2° C. (water content was 2.0%), and then entered a flash tower 5 for flash dehydration under a vacuum degree of 2000 Pa; the flash dehydrated product (water content was 0.6%) was transferred to a second horizontal stirred tubular reactor 8 using a transfer pump 6 at a flow rate of 380 kg / h, and a liquid catalyst was added to the horizontal stirred tubular reactor 8 using a liquid feed pump 7 at a flow rate of 2.2 kg / h; the liquid catalyst was composed of 45% butyl titanate, 25% isopropyl zirconate and 30% methyl silicone oil in terms of mass percentage;

[0072] The rotation speed of the plate screw stirring paddle in the horizontal stirred tubular second reactor 8 is controlled to 150 r / min, the temperature to 175±2° C., and the pressure to 0.05 MPa, and a second amidation reaction is carried out for 19 minutes; the second amidation reaction product is transferred to a vacuum container 9, and the temperature in the vacuum container 9 is controlled to 178±2° C. and the vacuum degree to 150 Pa to obtain oleyl palmitamide with a water content of 0.2%; the process indicators such as temperature, flow rate and pressure at each point in the entire synthesis process are automatically controlled by the DCS process control system.

[0073] During the continuous production process, samples were taken from the vacuum container 9 every 15 minutes to analyze the quality of the product. The results are listed in Table 2.

[0074] Table 2 Test results of continuous synthesis of oleyl palmitamide

[0075]

[0076] Example 3

[0077] use Figure 1 The apparatus shown prepares fatty acid secondary amides;

[0078] heating and melting octadecyl primary amine to obtain an octadecyl primary amine liquid at a temperature of 150±2° C., and heating and melting erucic acid to obtain an erucic acid liquid at a temperature of 160±2° C.; delivering the octadecyl primary amine liquid to the first reactor 3 at a flow rate of 158 kg / h using a first feed pump 1; delivering the erucic acid liquid to the first reactor 3 at a flow rate of 206 kg / h using a second feed pump 2; and subjecting the octadecyl primary amine liquid and the erucic acid liquid to a first amidation reaction in the first reactor 3 for 13 minutes under the conditions of a plate screw stirring blade speed of 160 r / min, a temperature of 169±2° C., and a pressure of 0.25 MPa;

[0079] The product of the first amidation reaction is transferred to a falling film evaporator 4 and evaporated and dehydrated at 173±2° C. (water content is 1.7%), and then enters a flash tower 5 for flash dehydration under a vacuum degree of 3000 Pa; the flash dehydrated product (water content is 0.5%) is transferred to a horizontal stirred tubular second reactor 8 using a transfer pump 6 at a flow rate of 300 kg / h, and a liquid catalyst is added to the horizontal stirred tubular second reactor 8 using a liquid feed pump 7 at a flow rate of 1.0 kg / h; the liquid catalyst is composed of 50% butyl titanate, 20% isopropyl zirconate and 30% methyl silicone oil in terms of mass percentage;

[0080] The rotation speed of the plate-type spiral stirring paddle in the horizontal stirred tubular second reactor 8 is controlled to 150 r / min, the temperature to 173±2° C., and the pressure to 0.08 MPa, and a second amidation reaction is carried out for 21 minutes. The second amidation reaction product is transferred to a vacuum container 9, and the temperature in the vacuum container 9 is controlled to 181±2° C. and the vacuum degree to 120 Pa to obtain octadecyl erucamide with a water content of 0.4%. Process indicators such as temperature, flow rate, and pressure at various points throughout the entire synthesis process are automatically controlled by the DCS process control system.

[0081] During the continuous production process, samples were taken from the vacuum container 9 every 15 minutes to analyze the quality of the product. The results are listed in Table 3.

[0082] Table 3 Test results of continuous synthesis of stearyl erucamide

[0083]

[0084]

[0085] Example 4

[0086] use Figure 1 The apparatus shown prepares fatty acid secondary amides;

[0087] Heat and melt oleyl primary amine to obtain an oleylamine liquid at a temperature of 140±2° C., and heat and melt behenic acid to obtain a behenic acid liquid at a temperature of 161±2° C.; use a first feed pump 1 to deliver the oleyl primary amine liquid to a first reactor 3 at a flow rate of 141 kg / h; use a second feed pump 2 to deliver the behenic acid liquid to the first reactor 3 at a flow rate of 191 kg / h; and conduct a first amidation reaction of the oleyl primary amine liquid and the behenic acid liquid in the first reactor 3 for 14 minutes under the conditions of a plate screw agitator with a speed of 200 r / min, a temperature of 174±2° C., and a pressure of 0.12 MPa;

[0088] The product of the first amidation reaction was transferred to a falling film evaporator 4 and evaporated and dehydrated at 178±2° C. (water content was 1.5%), and then entered a flash tower 5 for flash dehydration under a vacuum degree of 3000 Pa; the flash dehydrated product (water content was 0.6%) was transferred to a horizontal stirred tubular second reactor 8 using a transfer pump 6 at a flow rate of 320 kg / h, and a liquid catalyst was added to the horizontal stirred tubular second reactor 8 using a liquid feed pump 7 at a flow rate of 1.9 kg / h; the liquid catalyst was composed of 35% butyl titanate, 30% isopropyl zirconate and 35% methyl silicone oil in terms of mass percentage;

[0089] The plate-type spiral stirring paddle in the second horizontal stirred tubular reactor 8 was controlled to rotate at 120 r / min, the temperature at 178±2° C., and the pressure at 0.1 MPa, and the reaction was carried out for 23 minutes. The second amidation reaction product was transferred to a vacuum vessel 9, and the temperature in the vacuum vessel 9 was controlled to be 182±2° C. and the vacuum degree at 80 Pa to obtain oleyl behenamide with a water content of 0.45%. Process indicators such as temperature, flow rate, and pressure at various points throughout the synthesis process were automatically controlled by the DCS process control system.

[0090] During the continuous production process, samples were taken from the vacuum container 9 every 15 minutes to analyze the quality of the product. The results are listed in Table 4.

[0091] Table 4 Test results of continuous synthesis of oleyl behenamide

[0092]

[0093] Comparative Example 1

[0094] 214 kg of stearic acid and 196 kg of octadecyl primary amine were added to a 700 L batch reactor, the temperature was raised to 150 ± 2 ° C, stirring was started (speed was 110 r / min), and vacuum was evacuated (vacuum degree was 3200 Pa) for degassing and dehydration for 30 min, then the temperature was continued to rise to 170 ± 2 ° C, the exhaust valve was opened to start exhausting, and the pressure in the reactor was adjusted to 0.15 MPa. After continuing the reaction for 2 h, vacuum was started in the reactor, and 2.6 kg of butyl titanate catalyst was added. The temperature was continued to rise to 178 ± 2, and the reaction was continued for 3 h to obtain octadecyl stearamide. The quality of the synthesized product was sampled and analyzed; the results are listed in Table 5;

[0095] The preparation method of Comparative Example 1 was repeated to synthesize 5 batches of products. The test results of each batch are listed in Table 5.

[0096] Table 5 Test results of octadecyl stearamide synthesized in a batch reactor

[0097] batch Melting point Color Gardner Acid value mgKOH / g Amine value mgKOH / g 1 84.6 3.0 9.53 2.36 2 83.9 3.5 10.48 1.59 3 85.2 3.0 8.91 2.42 4 86.1 3.5 8.72 2.15 5 84.1 3.5 7.55 1.91

[0098] Comparative Example 2

[0099] 194 kg of oleyl primary amine and 186 kg of palmitic acid were added to a 700 L batch reactor, the temperature was raised to 155 ± 2 ° C, stirring was started (speed was 80 r / min), and vacuum was applied (vacuum degree was 2800 Pa) for degassing and dehydration for 30 minutes. Then the temperature was continued to be raised to 173 ± 2 ° C, the exhaust valve was opened to start exhausting, and the pressure in the reactor was adjusted to be ≤ 0.2 MPa. After reacting for 2 hours, vacuum was applied to the reactor, and 2.2 kg of phosphoric acid catalyst was added. The temperature was continued to be raised to 175 ± 2 ° C, and the reaction was continued for 3.5 hours to obtain oleyl palmitic acid amide. The quality of the product was analyzed by sampling. The results are listed in Table 6.

[0100] The preparation method of Comparative Example 2 was repeated to synthesize 5 batches of products. The test results of each batch are listed in Table 6.

[0101] Table 6 Test results of oleyl palmitamide synthesized in batch reactor

[0102]

[0103]

[0104] According to the test results of the products prepared in Examples 1 to 4 and Comparative Examples 1 to 2, the fatty acid secondary amide prepared by the continuous reaction apparatus provided by the present invention has stable quality and low acid value and amine value.

[0105] Although the above embodiment provides a detailed description of the present invention, it is only a part of the embodiments of the present invention, not all of the embodiments. People can also obtain other embodiments based on this embodiment without creativity, and these embodiments all fall within the scope of protection of the present invention.

Claims

1. A continuous reaction device for preparing fatty acid secondary amides, comprising a first reactor (3), an evaporator (4) connected to an outlet (3-3) of the first reactor, a flash tower (5) connected to the evaporator (4), a second reactor (8) having a material inlet (8-1) connected to a liquid outlet (5-1) of the flash tower, and a collecting container (9) connected to the outlet (8-3) of the second reactor; The side wall of the second reactor (8) is provided with a catalyst inlet (8-2); The first reactor (3) is a vertical stirred tubular reactor, the second reactor (8) is a horizontal stirred tubular reactor, and the evaporator (4) is a shell-and-tube falling film evaporator.

2. The continuous reaction device for preparing fatty acid secondary amide according to claim 1, wherein A first raw material inlet (3-1) and a second raw material inlet (3-2) are provided at the lower end of the side wall of the first reactor (3); the first raw material inlet (3-1) is connected to a first feed pump (1); and the second raw material inlet (3-2) is connected to a second feed pump (2).

3. The continuous reaction device for preparing fatty acid secondary amide according to claim 1, wherein The liquid outlet (5-1) and the material inlet (8-1) of the flash tower are connected by a transfer pump (6).

4. The continuous reaction device for preparing fatty acid secondary amide according to claim 1 or 3, wherein The catalyst inlet (8-2) is connected to a liquid inlet pump (7).

5. A method for preparing fatty acid secondary amides using the continuous reaction apparatus according to any one of claims 1 to 4, comprising the following steps: The fatty acid and the primary amine are continuously fed into the first reactor (3), undergo a first amidation reaction in the first reactor (3), and then enter the evaporator (4) and the flash tower (5) from the outlet (3-3) of the first reactor in sequence for dehydration to obtain a mixture comprising the fatty acid secondary amide, the fatty acid, and the primary amine; The mixture is continuously conveyed to the second reactor (8) and mixed with the liquid catalyst entering the second reactor (8) from the catalyst inlet (8-2) to carry out a second amidation reaction, and the second amidation reaction product is conveyed to a collection container (9) to obtain a fatty acid secondary amide.

6. The method according to claim 5, characterized in that The temperature of the first amidation reaction is 166-178° C.; the pressure of the first amidation reaction is 0.1-0.25 MPa; and the time of the first amidation reaction is 8-16 minutes. The temperature of the second amidation reaction is 172-182° C.; the pressure of the second amidation reaction is -0.1-0.05 MPa; and the time of the second amidation reaction is 15-30 min.

7. The method according to claim 5, characterized in that The dehydration includes evaporation dehydration in an evaporator (4) and flash dehydration in a flash tower (5); the temperature of the evaporation dehydration is 170-180° C.; and the vacuum degree of the flash dehydration is less than or equal to 3500 Pa.

8. The method according to claim 5, characterized in that The fatty acid comprises one or more of erucic acid, stearic acid, oleic acid, palmitic acid, behenic acid, 12-hydroxystearic acid and isostearic acid; The primary amine is octadecyl primary amine or oleyl primary amine; The molar ratio of the fatty acid to the primary amine is 1:0.91-0.

99.

9. The method according to claim 5 or 8, characterized in that The liquid catalyst comprises the following components in percentage by mass: Butyl titanate 35~60%; Isopropyl zirconate 10-30%; Methyl silicone oil 20~40%; The mass ratio of the liquid catalyst to the fatty acid is 0.2-0.8:100.

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