A production process for 2,2,6,6-tetramethylpiperidine hexamethylenediamine

Abstract

This invention discloses a production process for 2,2,6,6-tetramethylpiperidine hexamethylenediamine. Triacetone amine and 1,6-hexamethylenediamine are added to a premixing reactor, followed by a catalyst. Stirring is initiated, and the reactor temperature is controlled at 70-80°C. The mixture is then uniformly introduced into multiple microchannel reactors, with hydrogen continuously supplied for the reaction. The reaction solution is then vented. The catalyst and reaction solution are separated using a precision filter, and the catalyst is reused. The reaction solution is then transferred to a distillation vessel for purification. This invention offers the following advantages over traditional batch reactor production processes: higher reaction content, increased product yield, and increased production revenue; continuous production capability, reduced production time, and improved production efficiency; convenient equipment disassembly and maintenance during industrial production, reducing maintenance costs; and the microchannel reactors in this application are equipped with an inlet mixing zone and an outlet mixing zone to ensure uniform distribution of the solid catalyst in the reaction solution, preventing localized reactions and avoiding deposition and blockage.

Description

Technical Field

[0001] This invention belongs to the field of chemical synthesis technology, specifically relating to a production process for 2,2,6,6-tetramethylpiperidine hexamethylenediamine. Background Technology

[0002] Hindered amine light stabilizers are anti-aging additives used in polymer materials such as plastics and rubber. Their light stabilizing effect is 2 to 4 times that of traditional absorption-type light stabilizers, and they have good compatibility with many resins. 2,2,6,6-Tetramethylpiperidine hexamethylenediamine is a key intermediate for the best-performing polymeric high molecular weight hindered amine light stabilizer currently in use.

[0003] Currently, the traditional reaction process for 2,2,6,6-tetramethylpiperidine hexamethylenediamine is mainly based on batch reaction and is carried out in two steps. First, a condensation reaction is carried out to produce the 2,2,6,6-tetramethylpiperidine hexamethylenediamine intermediate, and then a batch hydrogenation reaction is carried out. The traditional process has a long reaction time, is accompanied by the generation of impurities, has a low conversion rate, poor reaction continuity, and low yield.

[0004] To overcome the shortcomings of traditional batch reactors, the 2,2,6,6-tetramethylpiperidine hexamethylenediamine production process provided by this invention utilizes a microchannel reactor and a continuous production process, significantly shortening the reaction time, improving reaction efficiency, and enhancing both conversion rate and selectivity. The microchannel reactor provided by this invention has a large specific surface area, high transfer rate, short contact time, and fewer byproducts. Using the microchannel continuous flow reactor provided by this invention results in stable quality of the 2,2,6,6-tetramethylpiperidine hexamethylenediamine synthesis process, with reduced types and stable content of impurities. Summary of the Invention

[0005] To address the aforementioned problems, this invention discloses a production process for 2,2,6,6-tetramethylpiperidine hexamethylenediamine.

[0006] To achieve the above object, the technical solution of the present invention is as follows:

[0007] A process for producing 2,2,6,6-tetramethylpiperidine hexamethylenediamine includes the following steps:

[0008] Step 1: Add triacetoneamine and 1,6-hexanediamine to the premixing vessel, then add the catalyst, start stirring, stir evenly for 0.5 to 1 hour, then slowly turn on the heating, control the temperature inside the vessel at 70 to 80℃ to react and obtain the premix;

[0009] Step 2: Using a transfer pump, control the feed flow rate and feed the premix obtained in Step 1 into multiple microchannel reactors at a uniform speed. Slowly turn on the heating and control the temperature of the microchannel reactors. Continuously feed hydrogen into the microchannel reactors to carry out the reaction. Let the premix stay in the microchannels for 1 to 5 hours to react.

[0010] Step 3: The reaction liquid after the reaction in Step 2 continues to flow into the reaction liquid transfer tank for evacuation. The evacuated reaction liquid is then passed through a precision filter to separate the catalyst and the reaction liquid. The catalyst is transferred to a catalyst receiving tank and returned to the premixing vessel for reuse. The filtered reaction liquid is transferred to a distillation vessel for purification to obtain 2,2,6,6-tetramethylpiperidinehexanediamine.

[0011] The process route is as follows:

[0012] .

[0013] Further, in step 1, the molar ratio of triacetone amine to 1,6-hexanediamine is 2~2.6:1; the amount of catalyst used is 1%~10% of the total mass of triacetone amine and 1,6-hexanediamine.

[0014] Furthermore, in step 1, the catalyst is one or more of Raney nickel, Raney copper, and palladium on carbon catalyst.

[0015] Furthermore, in step 1, the catalyst has a mesh size of 100-500 mesh.

[0016] Furthermore, in step 1, the temperature inside the reactor is controlled at 70~80℃, and the reaction is carried out for 1~3 hours.

[0017] Further, in step 2, the flow rate is controlled at 1~100 kg / h, and the premix obtained in step 1 is uniformly fed into multiple microchannel reactors. Hydrogen gas is continuously introduced into the microchannel reactors, and the hydrogen gas pressure is controlled at 1~3 MPa to carry out the reaction.

[0018] Furthermore, the temperature inside the microchannel reactor is controlled at 90-120℃.

[0019] Furthermore, the microchannel reactor includes one or more microchannel reaction units, which can be connected in parallel or series. Each microchannel reaction unit includes an upper plate, a reaction plate, and a lower plate. The upper plate has one or more inlets and outlets, and the lower plate has an etched inlet area and an outlet area. The surface of the reaction plate is etched with a material inlet, an inlet mixing area, a reaction channel, an outlet mixing area, and a material outlet. The material inlet and outlet are located at opposite ends of the reaction plate, with the material inlet connected to the inlet mixing area and the material outlet connected to the outlet mixing area. A dehydrator is also provided between the microchannel reaction units, containing dehydrating resin; the reaction solution undergoes hydrogenation after dehydration.

[0020] Furthermore, both the inlet mixing zone and the outlet mixing zone include multiple flow-disrupting holes, and the inlet mixing zone also includes multiple flow-equalizing platforms, which are perpendicular to the material flow direction; the inlet mixing zone and the outlet mixing zone are connected through multiple reaction channels. Two or more reaction channels can be connected in parallel or in series; multiple flow-dividing platforms are provided in the reaction channels.

[0021] Furthermore, the flow equalization platform near the turbulence hole is tangentially arranged to the turbulence hole, the turbulence hole penetrates the reaction plate, and the turbulence hole corresponds to the inlet area and outlet area of ​​the lower plate in a stacked manner; the inlet area and outlet area are respectively connected to an inert gas tank, and inert gas is introduced into the turbulence hole.

[0022] In another embodiment of the present invention, the inlet zone can be connected to the material, which enters the inlet mixing zone through the turbulence hole. The material is then mixed more evenly by the obstruction of the flow equalization table before entering the reaction channel. The outlet zone is connected to the inert gas tank, which introduces inert gas into the turbulence hole of the outlet mixing zone. The gas agitates the reaction liquid, making the solid catalyst mix more evenly in the reaction liquid and avoiding the deposition of solid catalyst that could cause blockage.

[0023] Furthermore, the cross-sectional shape of the flow equalization platform is one of triangle, rectangle, square, and trapezoid. Preferably, the cross-sectional shape of the flow equalization platform is one of triangle, rectangle, square, and trapezoid with rounded corners at the top. The height of the flow equalization platform is lower than the depth of the inlet mixing zone. The flow equalization platform increases the mixing time of the reactants in the inlet mixing zone, increases the time for the gas in the turbulence hole to agitate the reaction liquid, makes the solid catalyst mix more evenly in the reaction liquid, and avoids the deposition of solid catalyst and blockage.

[0024] The beneficial effects of the present invention are:

[0025] (1) High reaction content can improve product yield and increase production revenue.

[0026] (2) It can realize continuous production, reduce production time and improve production efficiency.

[0027] (3) During industrial production, the equipment is easy to disassemble and repair, reducing maintenance costs.

[0028] (4) The microchannel reactor of this application is provided with an inlet mixing zone and an outlet mixing zone. The inlet mixing zone is provided with a turbulence hole and a flow equalization platform. An inert gas is introduced into the turbulence hole. The gas agitates the incoming material. With the guidance of the flow equalization platform, the reactants are mixed evenly, ensuring that the solid catalyst is evenly distributed in the reaction liquid and that there is no local reaction. The outlet mixing zone is also provided with a turbulence hole to ensure that the solid catalyst is evenly distributed in the reaction liquid and to avoid deposition and blockage. Attached Figure Description

[0029] Figure 1 This is a flow chart of the production process of 2,2,6,6-tetramethylpiperidine hexamethylenediamine according to the present invention;

[0030] Figure 2 This is a schematic diagram of the microchannel reaction unit of the present invention;

[0031] Figure 3 For the present invention Figure 2 Enlarged view of the reaction plate;

[0032] Figure 4 This is the gas phase spectrum of the 2,2,6,6-tetramethylpiperidine hexamethylenediamine content in Example 1 of the present invention;

[0033] Figure 5 This is the gas phase spectrum of the 2,2,6,6-tetramethylpiperidine hexamethylenediamine content in Example 2 of the present invention;

[0034] Figure 6 This is the gas phase spectrum of the 2,2,6,6-tetramethylpiperidine hexamethylenediamine content in Comparative Example 1 of the present invention;

[0035] Explanation of reference numerals in the attached figures:

[0036] 1. Premixing vessel; 2. Microchannel reactor; 3. Reaction liquid transfer tank; 4. Precision filter; 5. Catalyst receiving tank; 6. Distillation vessel; 7. Dehydrator; 201. Upper plate; 202. Reaction plate; 203. Lower plate; 204. Feed inlet; 205. Discharge outlet; 206. Inlet zone; 207. Outlet zone; 208. Material inlet; 209. Inlet mixing zone; 210. Turbulence hole; 211. Flow equalization platform; 212. Reaction channel; 213. Flow splitter; 214. Material outlet; 215. Outlet mixing zone. Implementation

[0037] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the present invention. Example 1

[0038] After adding 3232 kg of triacetone amine to the premixing vessel, add 1100 kg of 1,6-hexanediamine, and finally add 88 kg of [unspecified material - likely a specific type of amine].

[0039] After the 300-mesh Raney nickel catalyst was added, stirring was started, and steam heating was initiated. The premixing vessel was slowly heated to 75°C, and the microchannel reactor was heated to 110°C. After stirring in the premixing vessel for 1.5 hours, the feed flow rate was controlled at 4 kg / h using a transfer pump, and the material in the premixing vessel was uniformly fed into the microchannel reactor. After passing through a dehydrator, hydrogen gas was continuously introduced into the microchannel reactor at a pressure controlled at 2.5 MPa for reaction. The residence time of the material in the premixing vessel in the microchannel reactor was 1.1 hours. The reaction liquid after reaction continuously flowed into a reaction liquid transfer tank for evacuation. The evacuated reaction liquid was then passed through a precision filter to separate the Raney nickel catalyst and the reaction liquid. The Raney nickel catalyst was transferred to a catalyst receiving tank and returned to the premixing vessel for reuse. The filtered reaction liquid was transferred to a distillation vessel for distillation purification to obtain 3502 kg of 2,2,6,6-tetramethylpiperidine hexamethylenediamine, with a yield of 94.5%.

[0040] The process route of this invention is as follows:

[0041] . Example 2

[0042] After adding 3080 kg of triacetone amine to the premixing vessel, add 1000 kg of 1,6-hexanediamine, and finally add 200 kg of [mesh size missing].

[0043] After the 360-mesh Raney copper catalyst was added, stirring was started, and steam heating was initiated. The premixing vessel was slowly heated to 80°C, and the microchannel reactor was heated to 110°C. After stirring in the premixing vessel for 2 hours, the feed flow rate was controlled at 3 kg / h using a transfer pump, and the material in the premixing vessel was uniformly fed into the microchannel reactor. After passing through a dehydrator, hydrogen gas was continuously introduced into the microchannel reactor at a pressure controlled at 2.5 MPa for reaction. The residence time of the material in the premixing vessel in the microchannel reactor was 1.43 hours. The reaction liquid after reaction continuously flowed into a reaction liquid transfer tank for evacuation. The evacuated reaction liquid was then passed through a precision filter to separate the Raney nickel catalyst and the reaction liquid. The Raney nickel catalyst was transferred to a catalyst receiving tank and returned to the premixing vessel for reuse. The filtered reaction liquid was transferred to a distillation vessel for distillation purification to obtain 3510 kg of 2,2,6,6-tetramethylpiperidine hexamethylenediamine, with a yield of 94.71%. Example 3

[0044] After adding 3193 kg of triacetone amine to the premixing vessel, add 1000 kg of 1,6-hexanediamine, and finally add 100 kg of [mesh size missing] [unclear text - likely a specific type of amine].

[0045] 400-mesh Raney nickel catalyst and 225 kg of 200-mesh palladium-on-carbon catalyst were added. After the addition was complete, stirring was started, and the premixing vessel was slowly heated to 80°C. The microchannel reactor was heated to 105°C. After stirring in the premixing vessel for 2.5 hours, the feed flow rate was controlled at 2 kg / h using a transfer pump, and the material in the premixing vessel was uniformly fed into the microchannel reactor. After passing through a dehydrator, hydrogen gas was continuously introduced into the microchannel reactor at a pressure controlled at 2.3 MPa for reaction. The residence time of the material in the premixing vessel in the microchannel reactor was 2.3 hours. The reaction liquid was continuously flowed into a reaction liquid transfer tank for evacuation. The evacuated reaction liquid was then passed through a precision filter to separate the Raney nickel catalyst and the reaction liquid. The Raney nickel catalyst was transferred to a catalyst receiving tank and returned to the premixing vessel for reuse. The filtered reaction liquid was transferred to a distillation vessel for distillation purification to obtain 3459 kg of 2,2,6,6-tetramethylpiperidine hexamethylenediamine, with a yield of 93.34%. Example 4

[0046] After adding 3193 kg of triacetone amine to the premixing vessel, add 1000 kg of 1,6-hexanediamine, and finally add 100 kg of [mesh size missing] [unclear text - likely a specific type of amine].

[0047] 400-mesh Raney nickel catalyst and 225 kg of 200-mesh palladium-on-carbon catalyst were added. After the addition was complete, stirring was started, and the premixing vessel was slowly heated to 80°C. The microchannel reactor was heated to 120°C. After stirring in the premixing vessel for 3 hours, the feed flow rate was controlled at 1 kg / h using a transfer pump, and the material in the premixing vessel was uniformly fed into the microchannel reactor. After passing through a dehydrator, hydrogen gas was continuously introduced into the microchannel reactor at a pressure controlled at 2.3 MPa for reaction. The residence time of the material in the premixing vessel in the microchannel reactor was 4.5 hours. The reaction liquid after the reaction continuously flowed into a reaction liquid transfer tank for evacuation. The evacuated reaction liquid was then passed through a precision filter to separate the Raney nickel catalyst and the reaction liquid. The Raney nickel catalyst was transferred to a catalyst receiving tank and returned to the premixing vessel for reuse. The filtered reaction liquid was transferred to a distillation vessel for distillation purification to obtain 3580 kg of 2,2,6,6-tetramethylpiperidine hexamethylenediamine, with a yield of 96.60%. Example 5

[0048] After adding 2950 kg of triacetone amine to the premixing vessel, add 1000 kg of 1,6-hexanediamine, and finally add 50 kg of [mesh size missing].

[0049] After the 300-mesh palladium-on-carbon catalyst was added, stirring was started, and the premixing vessel was slowly heated to 70°C, while the microchannel reactor was heated to 90°C. After stirring in the premixing vessel for 1 hour, the feed flow rate was controlled at 3.8 kg / h using a transfer pump, and the material in the premixing vessel was uniformly fed into the microchannel reactor. After passing through a dehydrator, hydrogen gas was continuously introduced into the microchannel reactor at a pressure controlled at 1 MPa for reaction. The residence time of the material in the premixing vessel in the microchannel reactor was 1.05 hours. The reaction liquid after reaction continuously flowed into a reaction liquid transfer tank for evacuation. The evacuated reaction liquid was then passed through a precision filter to separate the Raney nickel catalyst and the reaction liquid. The Raney nickel catalyst was transferred to a catalyst receiving tank and returned to the premixing vessel for reuse. The filtered reaction liquid was transferred to a distillation vessel for distillation purification to obtain 3260 kg of 2,2,6,6-tetramethylpiperidine hexamethylenediamine, with a yield of 87.97%. Example 6

[0050] After adding 3230 kg of triacetone amine to the premixing vessel, add 1000 kg of 1,6-hexanediamine, and finally add 50 kg of [mesh size missing].

[0051] A 400-mesh Raney nickel catalyst, 25 kg of a 200-mesh Raney copper catalyst, and 30 kg of a 200-mesh palladium-on-carbon catalyst were added. After the addition was complete, stirring was started, and the premixing vessel was slowly heated to 80°C. The microchannel reactor was heated to 110°C. After stirring in the premixing vessel for 2 hours, the feed flow rate was controlled at 1.8 kg / h using a transfer pump, and the material in the premixing vessel was uniformly fed into the microchannel reactor. After passing through a dehydrator, hydrogen gas was continuously introduced into the microchannel reactor, and the hydrogen pressure was controlled at 3 MPa for reaction. The residence time of the material in the premixing vessel in the microchannel reactor was 2.4 hours. The reaction liquid after the reaction continues to flow into the reaction liquid transfer tank for evacuation. After evacuation, the reaction liquid passes through a precision filter to separate the Raney nickel catalyst from the reaction liquid. The Raney nickel catalyst is transferred to a catalyst receiving tank and reused in the premixing tank. The filtered reaction liquid is transferred to a distillation tank for distillation purification to obtain 3389 kg of 2,2,6,6-tetramethylpiperidine hexamethylenediamine, with a yield of 91.47%. Example 7

[0052] Process flow as follows Figure 1 As shown, the system includes a premixing tank 1, a microchannel reactor 2, a reaction liquid transfer tank 3, a precision filter 4, a catalyst receiving tank 5, a distillation tank 6, and a dehydrator 7. After the raw materials are added to the premixing tank 1 for reaction, the flow rate is controlled to enter the microchannel reactor 2. After the hydrogen reaction is completed, the reaction liquid enters the reaction liquid transfer tank 3 for venting. The vented reaction liquid passes through the precision filter 4 to separate the catalyst and the reaction liquid. The catalyst is transferred to the catalyst receiving tank 5 and returned to the premixing tank for reuse. The filtered reaction liquid is transferred to the distillation tank 6 for purification.

[0053] The microchannel reactor of this invention includes one or more microchannel reaction units, which can be connected in parallel or series. A dehydrator 7 is also provided between the microchannel reaction units, and the dehydrator 7 contains dehydrating resin. The reaction solution undergoes hydrogenation reaction after dehydration. The structure of the microchannel reaction unit is as follows: Figure 2-Figure 3 As shown, the microchannel reaction unit includes an upper plate 201, a reaction plate 202, and a lower plate 203. The upper plate 201 is provided with one or more inlets 204 and outlets 205. The lower plate 203 is etched with an inlet region 206 and an outlet region 207. The surface of the reaction plate 202 is etched with a material inlet 208, an inlet mixing region 209, a reaction channel 212, an outlet mixing region, and a material outlet 214. The material inlet 208 and the material outlet 214 are respectively located at both ends of the reaction plate 202. The material inlet 208 is connected to the inlet mixing region 209, and the material outlet 214 is connected to the outlet mixing region. The upper plate of the microchannel reaction unit requiring hydrogenation is provided with two or more inlets 204, one of which can be used for hydrogenation.

[0054] Both the inlet mixing zone 209 and the outlet mixing zone include multiple flow-disrupting holes 210. The inlet mixing zone 209 also includes multiple flow-equalizing platforms 211, which are perpendicular to the material flow direction. The inlet mixing zone 209 and the outlet mixing zone are connected through multiple reaction channels 212. Two or more reaction channels 212 can be connected in parallel or in series. Multiple flow-dividing platforms 213 are provided in the reaction channels 212.

[0055] The flow equalization platform 211, which is close to the turbulence hole 210, is tangentially arranged to the turbulence hole 210. The turbulence hole 210 penetrates the reaction plate 202 and is stacked with the inlet area 206 and outlet area 207 of the lower plate 203. The inlet area 206 and outlet area 207 are respectively connected to inert gas tanks, and inert gas is introduced into the turbulence hole 210.

[0056] In another embodiment of the present invention, the inlet zone 206 can be connected to the material, which enters the inlet mixing zone 209 through the turbulence hole 210. The material is then mixed more evenly by the obstruction of the flow equalization table 211 before entering the reaction channel 212. The outlet zone 207 is connected to the inert gas tank, which introduces inert gas into the turbulence hole 210 of the outlet mixing zone. The gas agitates the reaction liquid, making the solid catalyst mix more evenly in the reaction liquid and avoiding the deposition of solid catalyst that could cause blockage.

[0057] The cross-sectional shape of the flow equalization platform 211 is one of the following: triangle, rectangle, square, trapezoid. Preferably, the cross-sectional shape of the flow equalization platform 211 is one of the following: triangle, rectangle, square, trapezoid with rounded corners at the top. The height of the flow equalization platform 211 is lower than the depth of the inlet mixing zone 209. The flow equalization platform 211 increases the mixing time of the reactants in the inlet mixing zone 209, increases the time for the gas in the turbulence hole 210 to agitate the reaction liquid, makes the solid catalyst more uniformly mixed in the reaction liquid, and avoids the deposition of solid catalyst and blockage.

[0058] The microchannel reactor described in Examples 1-6 above all utilizes the microchannel reactor described in this example. Comparative Example 1

[0059] Example 1 was compared with a traditional batch reactor. The condensation reactor was purged with nitrogen. 3232 kg of triacetone amine and 1100 kg of 1,6-hexanediamine were injected into the reactor, and stirring was started. The heating valve on the condensation reactor was opened, and the temperature was slowly raised to 75°C using steam. After stirring and reacting for 10 hours, the vacuum pump was turned on, and the steam regulating valve was used to maintain the temperature inside the reactor at 75°C. The water produced in the reaction was condensed under vacuum through the dehydration condenser of the condensation reactor and collected in a wastewater receiving tank. The reaction conversion rate in this step was 92%.

[0060] All the materials from the condensation reaction were transferred to the hydrogenation reactor, and 88 kg of 300-mesh Raney nickel catalyst was pumped into the reactor. The steam inlet valve of the hydrogenation reactor was opened, and the temperature was slowly increased until the reactor temperature reached 70°C. The steam heating valve was then closed, and the residual heat of the steam was used for further heating. At this time, the hydrogen valve was opened to pressurize and maintain the pressure inside the hydrogenation reactor at 2.5 MPa. The temperature inside the reactor was controlled by the steam regulating valve and the circulating water system, maintaining it at 110°C. Samples were taken for testing after 10 hours of hydrogenation reaction; the reaction conversion rate for this step was 93%.

[0061] The reaction liquid after the reaction continues to flow into the hydrogenation reaction liquid transfer tank for venting. The vented reaction liquid is then passed through a precision filter to separate the Raney nickel catalyst and the hydrogenation reaction liquid. The Raney nickel catalyst is transferred to a catalyst receiving tank for reuse in the hydrogenation reactor. The filtered hydrogenation reaction liquid is then transferred to a distillation reactor for distillation purification to obtain 3096 kg of 2,2,6,6-tetramethylpiperidine hexamethylenediamine, with a yield of 83.56%. Comparative Example 2

[0062] Example 2 was compared with a traditional batch reactor. The condensation reactor was purged with nitrogen, and 3080 kg of triacetone amine and 1000 kg of 1,6-hexanediamine were injected into the reactor, respectively. Stirring was started. The heating valve on the condensation reactor was opened, and the temperature was slowly raised to 80°C by steam. After stirring for 8 hours, the vacuum pump was turned on, and the steam regulating valve was controlled to maintain the temperature inside the reactor at 80°C. The water produced in the reaction was condensed under vacuum through the dehydration condenser of the condensation reactor and collected in a wastewater receiving tank. The reaction conversion rate of this step was 90%.

[0063] All the materials from the condensation reaction were transferred to the hydrogenation reactor, and 200 kg of 300-mesh Raney nickel catalyst was pumped into the reactor. The steam inlet valve of the hydrogenation reactor was opened, and the temperature was slowly increased until the reactor temperature reached 75°C. The steam heating valve was then closed, and the residual heat of the steam was used for further heating. At this time, the hydrogen valve was opened to pressurize and maintain the pressure inside the hydrogenation reactor at 2.5 MPa. The temperature inside the reactor was controlled by the steam regulating valve and the circulating water system, maintaining it at 110°C. Samples were taken for testing after 9 hours of hydrogenation reaction; the reaction conversion rate for this step was 92%.

[0064] The reaction liquid after the reaction continues to flow into the hydrogenation reaction liquid transfer tank for venting. The vented reaction liquid is then passed through a precision filter to separate the Raney nickel catalyst and the hydrogenation reaction liquid. The Raney nickel catalyst is transferred to a catalyst receiving tank for reuse in the hydrogenation reactor. The filtered hydrogenation reaction liquid is then transferred to a distillation reactor for distillation purification to obtain 2810 kg of 2,2,6,6-tetramethylpiperidine hexamethylenediamine, with a yield of 75.81%. Comparative Example 3

[0065] The structure of the microchannel reactor is shown in Example 7, except that this comparative example does not include flow disturbance holes and flow equalization platforms. This apparatus was used to prepare 2,2,6,6-tetramethylpiperidine hexamethylenediamine, using the same method as in Example 6, yielding 3103 kg of 2,2,6,6-tetramethylpiperidine hexamethylenediamine, with a yield of 83.73%.

[0066] It should be noted that the above content merely illustrates the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, various improvements and modifications can be made without departing from the principle of the present invention, and all such improvements and modifications fall within the scope of protection of the claims of the present invention.

Claims

1. A process for producing 2,2,6,6-tetramethylpiperidine hexamethylenediamine, characterized in that, The following steps are involved: Step 1: Add triacetone amine and 1,6-hexanediamine to the premixing vessel (1), then add the catalyst, turn on the stirring, stir evenly, heat slowly, and control the temperature inside the vessel at 70~80℃ to obtain the premix; Step 2: Control the flow rate and feed the premix obtained in Step 1 into multiple microchannel reactors (2) at a uniform rate. Continuously feed hydrogen into the microchannel reactors (2) to carry out the reaction. Step 3: The reaction liquid after the reaction in step 2 continues to flow into the reaction liquid transfer tank (3) for venting. The vented reaction liquid passes through a precision filter (4) to separate the catalyst and the reaction liquid. The catalyst is transferred to the catalyst receiving tank (5) and then returned to the premixing tank (1) for reuse. The filtered reaction liquid is transferred to the distillation tank (6) for purification to obtain 2,2,6,6-tetramethylpiperidinehexanediamine. The process route is as follows: ； The microchannel reactor (2) includes one or more microchannel reaction units, and a water separator (7) is also provided between the microchannel reaction units. The microchannel reaction unit includes an upper plate (201), a reaction plate (202) and a lower plate (203). The upper plate (201) is provided with one or more inlets (204) and outlets (205). The lower plate (203) is etched with an inlet area (206) and an outlet area (207). The surface of the reaction plate (202) is etched with a material inlet (208), an inlet mixing area (209), a reaction channel (212), an outlet mixing area (215) and a material outlet (214). The material inlet (208) and the material outlet (214) are respectively located at both ends of the reaction plate (202). The material inlet (208) is connected to the inlet mixing area (209), and the material outlet (214) is connected to the outlet mixing area (215). Both the inlet mixing zone (209) and the outlet mixing zone (215) include multiple flow-disrupting holes (210). The inlet mixing zone (209) also includes multiple flow-equalizing platforms (211), which are perpendicular to the material flow direction. The inlet mixing zone (209) and the outlet mixing zone (215) are connected through multiple reaction channels (212). The flow equalization platform (211) is tangentially arranged with the turbulence hole (210), the turbulence hole (210) penetrates the reaction plate (202), and the turbulence hole (210) is stacked and corresponds to the inlet area (206) and outlet area (207) of the lower plate (203); The cross-sectional shape of the flow equalization platform (211) is one of triangle, rectangle, square, or trapezoid, and the height of the flow equalization platform (211) is lower than the depth of the inlet mixing zone (209).

2. The production process of 2,2,6,6-tetramethylpiperidine hexamethylenediamine according to claim 1, characterized in that, In step 1, the molar ratio of triacetone amine to 1,6-hexanediamine is 2~2.6:1; the amount of catalyst used is 1%~10% of the total mass of triacetone amine and 1,6-hexanediamine.

3. The production process of 2,2,6,6-tetramethylpiperidine hexamethylenediamine according to claim 2, characterized in that, In step 1, the catalyst is one or more of Raney nickel, Raney copper, and palladium on carbon, and the catalyst mesh size is 100~500 mesh.

4. The production process of 2,2,6,6-tetramethylpiperidine hexamethylenediamine according to claim 1, characterized in that, In step 1, the temperature inside the reactor is controlled at 70~80℃, and the reaction is carried out for 1~3 hours.

5. The production process of 2,2,6,6-tetramethylpiperidine hexamethylenediamine according to claim 1, characterized in that, In step 2, the flow rate is controlled at 1~100kg / h, and the premix obtained in step 1 is fed into multiple microchannel reactors (2) at a uniform speed. Hydrogen is continuously fed into the microchannel reactors (2) and the hydrogen pressure is controlled at 1~3Mpa to carry out the reaction.

6. The production process of 2,2,6,6-tetramethylpiperidine hexamethylenediamine according to claim 5, characterized in that, The residence time in multiple microchannel reactors (2) is 1 to 5 hours, and the temperature inside the microchannel reactors (2) is controlled at 90 to 120°C.

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