Method for continuous catalytic amination of tetramethylpiperidone

Abstract

The present invention provides a method for continuous catalytic amination of tetramethylpiperidone, which comprises the following steps: continuously introducing a liquid raw material containing triacetoneamine, an amine compound and a catalyst into a microchannel reactor, and introducing hydrogen into the reactor to carry out a continuous catalytic amination reaction to obtain a tetramethylpiperidineamine compound; wherein the catalyst is an acidic activated carbon loaded with a transition metal element. The present invention effectively solves the problems in the prior art, such as short catalyst life, high cost and a large amount of wastewater, when preparing tetramethylpiperidineamine compounds by using catalysts such as Raney nickel and palladium on carbon.

Description

Technical Field

[0001] The present invention relates to the technical field of organic synthesis, and in particular, to a method for continuous catalytic amination of tetramethylpiperidone. Background Art

[0002] 2,2,6,6-tetramethylpiperidineamine compounds (hereinafter referred to as tetramethylpiperidineamine compounds) are important intermediates for hindered amine light stabilizers. They are mainly used in various hindered amine light stabilizer products such as light stabilizer 944, 119, and 660. The production efficiency and quality of tetramethylpiperidineamine compounds directly affect the production efficiency and quality of downstream products. Therefore, the development and improvement of the production process of tetramethylpiperidineamine compounds have attracted much attention from researchers.

[0003] Current industrial methods: 1) Batch method. Industrially, Raney nickel is mostly used as a catalyst to obtain tetramethylpiperidineamine compounds through batch hydrogenation. As is well known, Raney nickel is stored in an aqueous phase during transportation and storage. The presence of water causes more tetramethylpiperidinol impurities to be produced during the catalytic amination of tetramethylpiperidone. Therefore, a large amount of organic solvent is required to displace the water in Raney nickel before use, which undoubtedly increases the workload significantly and generates non-negligible wastewater. At the same time, using Raney nickel as a catalyst, the reaction time is relatively long, the reaction temperature is relatively high, and the catalyst will be worn during stirring, resulting in catalyst loss, thus changing the catalytic activity. Therefore, it is necessary to continuously add the catalyst. 2) Continuous method. Patent CN101522813A reports a method for synthesizing tetramethylpiperidineamine by using a noble metal-catalyzed high-pressure hydrogenation reduction amination method. Patent CN 109836370A reports a synthesis method for hydrogenation-amination reduction to synthesize piperidineamine within the pH range of 12 to 13. Patent CN110317162A reports a method for continuously synthesizing tetramethylpiperidineamine using a microchannel reactor. However, most of the above methods use catalysts such as Raney nickel or palladium-carbon for catalytic hydrogenation. However, using Raney nickel as a catalyst also faces various problems mentioned above. When using other inexpensive metal catalysts, the catalytic activity is relatively low, often requiring relatively harsh reaction conditions, and at the same time, the reaction selectivity is relatively poor. Therefore, improving the catalytic activity of inexpensive metals and reducing the requirements for reaction conditions are the current research focuses. 3) Electrochemical method. The article (Fioshin MY, Avrutskaya IA, Surov II, et al. Preparation of 2,2,6,6-tetramethyl-4-aminopiperidine and its substituted compounds by electroreduction of azomethines of 2,2,6,6-tetramethyl-4-oxopiperidine (triacetonamine) [J]. Collection of Czechoslovak chemical communications, 1987, 52(1): 182-191.) reports a synthesis method for electrochemically synthesizing tetramethylpiperidineamine. However, the equipment investment is high, the cost is large, large-scale production is restricted, and industrial production is not yet mature.

[0004] In view of this, the present invention is specifically proposed. Summary of the Invention

[0005] The main object of the present invention is to provide a method for continuous catalytic amination of tetramethylpiperidone, so as to solve the problems of short catalyst life, high cost, and a large amount of wastewater in the preparation of tetramethylpiperidineamine compounds using catalysts such as Raney nickel and palladium on carbon in the prior art.

[0006] To achieve the above object, according to one aspect of the present invention, there is provided a method for continuous catalytic amination of tetramethylpiperidone, which comprises the following steps: continuously introducing a liquid raw material containing triacetoneamine, an amine compound, and a catalyst into a microchannel reactor, and introducing hydrogen gas therein to carry out a continuous catalytic amination reaction to obtain a tetramethylpiperidineamine compound; wherein the catalyst is acidic activated carbon loaded with a transition metal element.

[0007] Further, in the catalyst, the transition metal element is one or more of nickel element, palladium element, tin element, copper element, and cobalt element. Preferably, the transition metal element is at least two of nickel element, palladium element, tin element, copper element, and cobalt element.

[0008] Further, the catalyst is prepared by the following method: mixing a soluble salt of a transition metal element, acidic activated carbon, and water, and drying to obtain a supported precursor; calcining the supported precursor in an inert atmosphere to obtain the catalyst; preferably, the soluble salt is a nitrate; preferably, the pH value of the acidic activated carbon is 2-6, more preferably 2-4.

[0009] Further, the weight ratio of the soluble salt to the acidic activated carbon is 0.1-1.7:10, more preferably 0.6-1.7:10; preferably, the particle size of the acidic activated carbon is 50-80 μm, more preferably 63-75 μm; preferably, the temperature for calcining the supported precursor is 300-450 °C, and the calcination time is 2-5 h.

[0010] Further, the amine compound is selected from liquid organic amine or inorganic amine compounds. Preferably, the amine compound is n-butylamine, hexamethylenediamine, or ammonia, and ammonia is added in the form of ammonia water.

[0011] Further, the molar ratio of triacetoneamine to the amine compound is 1:0.45-1.3.

[0012] Further, the dosage of the catalyst is 5-10% of the weight of triacetoneamine.

[0013] Further, during the continuous catalytic amination reaction, the flow rate of the liquid raw material is 50-100 mL / min, the hydrogen pressure is 0.2-1 MPa, and the reaction temperature is 70-80 °C.

[0014] Further, the residence time of the liquid raw material in the microchannel reactor is 30-60 s.

[0015] Further, before continuously introducing the liquid raw material into the microchannel reactor, the method further includes: preheating the liquid raw material to 50-60°C.

[0016] The present invention provides a method for continuous catalytic amination of tetramethylpiperidone, which includes the following steps: continuously introducing a liquid raw material containing triacetoneamine, an amine compound, and a catalyst into a microchannel reactor for continuous catalytic amination reaction to obtain a tetramethylpiperidineamine compound; wherein, the catalyst is acidic activated carbon loaded with a transition metal element.

[0017] The present invention uses a microchannel reactor to realize the continuous synthesis of tetramethylpiperidineamine compounds, and uses acidic activated carbon loaded with a transition metal element as a catalyst to participate in the catalytic amination reaction of the liquid raw material containing triacetoneamine and an amine compound in the microchannel reactor. On the one hand, the above catalyst can exhibit far better catalytic activity in the microchannel reactor than in the batch reaction process. Combined with the good mass transfer effect in the microchannel reactor, the reaction conditions are milder, the reaction efficiency is higher, and the catalyst life is also improved. And the above catalyst catalyzes the amination reaction of the liquid raw material containing triacetoneamine and an amine compound, and the effect is better. On the other hand, the present invention uses acidic activated carbon loaded with a transition metal element as a catalyst, which has low cost, does not require hydrogenation activation, and does not require a large amount of solvent to replace the water in the catalyst, greatly saving the production cost and generating no wastewater. Detailed implementation mode

[0018] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the embodiments.

[0019] As described in the background art section, when preparing tetramethylpiperidineamine compounds using catalysts such as Raney nickel and palladium-carbon in the prior art, there are problems such as short catalyst life, high cost, and a large amount of wastewater. To solve the above problems, the present invention provides a method for continuous catalytic amination of tetramethylpiperidone, which includes the following steps: continuously introducing a liquid raw material containing triacetoneamine, an amine compound, and a catalyst into a microchannel reactor for continuous catalytic amination reaction to obtain a tetramethylpiperidineamine compound; wherein, the catalyst is acidic activated carbon loaded with a transition metal element.

[0020] The present invention uses a microchannel reactor to achieve the continuous synthesis of tetramethylpiperidineamine compounds. An acidic activated carbon loaded with transition metal elements is used as a catalyst to participate in the catalytic amination reaction of liquid raw materials containing triacetoneamine and amine compounds in the microchannel reactor. On the one hand, the above catalyst can exhibit far better catalytic activity in the microchannel reactor than in the batch reaction process. Combined with the good mass transfer effect in the microchannel reactor, the reaction conditions are milder, the reaction efficiency is higher, and the catalyst life is also improved. Moreover, the above catalyst catalyzes the amination reaction of liquid raw materials containing triacetoneamine and amine compounds, and the effect is better. On the other hand, the present invention uses an acidic activated carbon loaded with transition metal elements as a catalyst, which is low in cost, does not require hydrogenation activation, and does not require a large amount of solvent to replace the water in the catalyst, greatly saving the production cost and generating no wastewater. In addition, the microchannel reaction can achieve continuous synthesis, with higher efficiency, shorter reaction time, lower temperature, and also avoids the generation of tetramethylpiperidinol impurities caused by long-term contact with the catalyst, thus making the product purity higher.

[0021] The above catalyst can form good dispersion in the liquid raw materials containing triacetoneamine and amine compounds, which is one of the reasons for its good catalytic activity. The transition metal elements in the catalyst can be used as active components, and common types in the art can be adopted. Preferably, the above transition metal elements are one or more of nickel element, palladium element, tin element, copper element and cobalt element. In order to further improve the catalytic activity and thus improve the product yield and purity, more preferably, the transition metal elements are at least two of nickel element, palladium element, tin element, copper element and cobalt element, such as nickel-cobalt element, nickel-copper element or copper-cobalt element.

[0022] In a preferred embodiment, the above catalyst is prepared by the following method: A soluble salt of a transition metal element, acidic activated carbon, and water are mixed and dried to obtain a supported precursor; the supported precursor is calcined in an inert atmosphere to obtain the catalyst. Through the above impregnation and calcination, the transition metal element can be more stably supported on the surface of the acidic activated carbon, thus having a better improvement effect on the stability of the catalyst. In addition, the catalyst prepared by the above method also has the advantages of light weight and very small bulk density, and can be directly used for the catalytic amination of piperidone without reduction after calcination. The metal ions are evenly dispersed on the surface of the catalyst, and the catalytic activity is higher. The metal ions interact with the surface of the catalyst, which can prevent the aggregation of active centers caused by long-term use of the catalyst; the selected carrier is acidic activated carbon, and the acidic sites of the carrier can interact with piperidone and amine, and co-catalyze with the metal ions. The smaller bulk density of the catalyst can further reduce its dispersion in the reaction solution, which is more conducive to the reaction in the microchannel reactor. To further exert the above advantages, preferably, the soluble salt is a nitrate. The nitrate undergoes an oxidation-reduction reaction and will produce nitrogen oxides that volatilize in the form of gas without residue. Preferably, the pH value of the acidic activated carbon is 2 to 6, more preferably 2 to 4. In the actual preparation process, the soluble salt can be dissolved in water, and then fully stirred with the acidic activated carbon, followed by standing, filtering, and drying to obtain the above supported precursor. The specific drying temperature is preferably 105 to 115 °C. The above inert gas includes but is not limited to nitrogen.

[0023] To make the transition metal element more fully loaded, thereby further improving the catalytic activity of the catalyst, in a preferred embodiment, the weight ratio of the above soluble salt to the acidic activated carbon is 0.1 to 1.7:10, more preferably 0.6 to 1.7:10. Considering further improving the dispersibility and catalytic activity of the catalyst and enabling it to act stably in the microchannel reactor, preferably, the particle size of the acidic activated carbon is 50 to 80 μm, more preferably 63 to 75 μm.

[0024] In a preferred embodiment, the temperature for calcining the supported precursor is 300 to 450 °C, and the calcination time is 2 to 5 h. Under the above calcination conditions, the loading of the active components in the catalyst is more stable, which has a better promoting effect on the improvement of the activity and stability of the catalyst.

[0025] The above-mentioned amine compounds can be adjusted according to the target compound, for example, adjusted according to the tetramethylpiperidine amine compounds to be generated. Of course, considering the reaction efficiency, in a preferred embodiment, the above-mentioned amine compounds are selected from liquid organic amine or inorganic amine compounds. Preferably, the amine compound is n-butylamine, hexamethylenediamine or ammonia, and ammonia is added in the form of ammonia water. To further improve the efficiency of the catalytic amination reaction, preferably, the molar ratio of triacetoneamine to the amine compound is 1:0.45 to 1.3. The dosage of the catalyst is 5 to 10% of the weight of triacetoneamine.

[0026] The microchannel reactor used in the present invention can be a common type in the synthesis field. To further improve the reaction efficiency, in a preferred embodiment, the radial width of the microchannels in the above-mentioned microchannel reactor is 800 to 1000 mm. With such a setting, a better mass transfer and heat transfer effect can be achieved.

[0027] To make the catalytic amination reaction more efficient and at the same time make the product purity higher, in a preferred embodiment, during the above-mentioned continuous catalytic amination reaction process, the flow rate of the liquid raw material is 50 to 100 mL / min, the hydrogen pressure is 0.2 to 1 MPa, and the reaction temperature is 70 to 80 °C. More preferably, the residence time of the liquid raw material in the microchannel reactor is 30 to 60 s.

[0028] In actual operation, to enable the liquid raw material to quickly perform mass transfer and heat transfer after entering the microchannel reactor, so as to further improve the reaction efficiency and product purity, in a preferred embodiment, before continuously introducing the liquid raw material into the microchannel reactor, the above method further includes: preheating the liquid raw material to 50 to 60 °C.

[0029] The following further describes the present application in detail with specific examples, and these examples should not be construed as limiting the scope claimed by the present application.

[0030] Example 1

[0031] Catalyst preparation: Add 1.7 g of nickel nitrate and 50 mL of water to a flask, heat up to 50 °C, add 10.0 g of activated carbon with a pH of 2 (particle size 63 - 75 μm), stir well and let stand, filter, dry at 110 °C, and calcine in a nitrogen atmosphere at 300 °C for 4 h to obtain a carbon-supported nickel catalyst.

[0032] Weigh 100.0 g (0.644 mol) of tetramethylpiperidone, 33.7 g (0.290 mol) of 1,6-hexanediamine and 10 g of the catalyst, place them in a preheated flask at 60 °C and mix evenly, then pump them into the microchannel reactor at a flow rate of 50 mL / min. The reactor temperature is 75 °C, the hydrogenation pressure is 1 MPa, the residence time is 60 s, and the reaction liquid accumulates in the storage tank.

[0033] The reaction solution was subjected to vacuum distillation to obtain tetramethylpiperidine hexamethylenediamine. The purity detected by GC was 99.5%, and the yield was 88.6%.

[0034] Example 2

[0035] Catalyst preparation: 0.8 g of nickel nitrate, 0.9 g of copper nitrate and 50 mL of water were added to a flask, heated to 50 °C, 10.0 g of activated carbon with a pH of 2 (particle size 63 - 75 μm) was added, stirred well and allowed to stand, filtered, dried at 110 °C, and calcined at 300 °C for 4 h in a nitrogen atmosphere to obtain a carbon-supported nickel-copper catalyst.

[0036] 100.0 g (0.644 mol) of tetramethylpiperidone, 33.7 g (0.290 mol) of 1,6-hexanediamine and 5 g of the catalyst were weighed and placed in a preheated flask at 60 °C and mixed evenly. Then it was pumped into a microchannel reactor at a flow rate of 50 mL / min. The reactor temperature was 75 °C, the hydrogenation pressure was 1 MPa, the residence time was 60 s, and the reaction solution was collected in a storage tank.

[0037] The reaction solution was subjected to vacuum distillation to obtain tetramethylpiperidine hexamethylenediamine. The purity detected by GC was 99.6%, and the yield was 95.7%.

[0038] Example 3

[0039] Catalyst preparation: 1.6 g of nickel nitrate, 0.1 g of cobalt nitrate and 50 mL of water were added to a flask, heated to 50 °C, 10.0 g of activated carbon with a pH of 2 (particle size 63 - 75 μm) was added, stirred well and allowed to stand, filtered, dried at 110 °C, and calcined at 300 °C for 4 h in a nitrogen atmosphere to obtain a carbon-supported nickel-cobalt catalyst.

[0040] 100.0 g (0.644 mol) of tetramethylpiperidone, 33.7 g (0.290 mol) of 1,6-hexanediamine and 10 g of the catalyst were weighed and placed in a preheated flask at 60 °C and mixed evenly. Then it was pumped into a microchannel reactor at a flow rate of 50 mL / min. The reactor temperature was 75 °C, the hydrogenation pressure was 1 MPa, the residence time was 60 s, and the reaction solution was collected in a storage tank.

[0041] The reaction solution was subjected to vacuum distillation to obtain tetramethylpiperidine hexamethylenediamine. The purity detected by GC was 99.5%, and the yield was 90.3%.

[0042] Example 4

[0043] Catalyst preparation: 0.8 g of nickel nitrate, 0.9 g of copper nitrate and 50 mL of water were added to a flask, heated to 50 °C, 10.0 g of activated carbon with a pH of 4 (particle size 63 - 75 μm) was added, stirred well and then allowed to stand, filtered, dried at 110 °C, and calcined in a nitrogen atmosphere at 400 °C for 4 h to obtain a carbon-supported nickel-copper catalyst.

[0044] 100.0 g (0.644 mol) of tetramethylpiperidone, 33.7 g (0.290 mol) of 1,6-hexanediamine and 5 g of the catalyst were weighed and placed in a preheated flask at 60 °C and mixed evenly, then pumped into a microchannel reactor at a flow rate of 50 mL / min. The reactor temperature was 75 °C, the hydrogenation pressure was 1 MPa, the retention time was 60 s, and the reaction solution was collected in a storage tank.

[0045] The reaction solution was distilled under reduced pressure to obtain tetramethylpiperidine hexanediamine. The purity detected by GC was 99.8%, and the yield was 95.4%.

[0046] Example 5

[0047] Catalyst preparation: 0.7 g of cobalt nitrate, 1.0 g of copper nitrate and 50 mL of water were added to a flask, heated to 50 °C, 10.0 g of activated carbon with a pH of 6 (particle size 63 - 75 μm) was added, stirred well and then allowed to stand, filtered, dried at 110 °C, and calcined in a nitrogen atmosphere at 400 °C for 4 h to obtain a carbon-supported cobalt-copper catalyst.

[0048] 100.0 g (0.644 mol) of tetramethylpiperidone, 33.7 g (0.290 mol) of 1,6-hexanediamine and 8 g of the catalyst were weighed and placed in a preheated flask at 60 °C and mixed evenly, then pumped into a microchannel reactor at a flow rate of 50 mL / min. The reactor temperature was 75 °C, the hydrogenation pressure was 1 MPa, the retention time was 60 s, and the reaction solution was collected in a storage tank.

[0049] The reaction solution was distilled under reduced pressure to obtain tetramethylpiperidine hexanediamine. The purity detected by GC was 99.2%, and the yield was 87.5%.

[0050] Example 6

[0051] Catalyst preparation: 1.7 g of cobalt nitrate and 50 mL of water were added to a flask, heated to 50 °C, 10.0 g of activated carbon with a pH of 4 (particle size 63 - 75 μm) was added, stirred well and then allowed to stand, filtered, dried at 110 °C, and calcined in a nitrogen atmosphere at 450 °C for 4 h to obtain a carbon-supported cobalt catalyst.

[0052] Weigh 100.0 g (0.644 mol) of tetramethylpiperidone, 61.2 g (0.837 mol) of n-butylamine and 5 g of catalyst, place them in a preheated flask at 60 °C and mix evenly. Then pump them into a microchannel reactor at a flow rate of 100 mL / min. The reactor temperature is 80 °C, the hydrogenation pressure is 0.2 MPa, the residence time is 30 s, and the reaction solution accumulates in the storage tank.

[0053] Distill the reaction solution under reduced pressure to obtain tetrabutylammonium piperidine. The purity detected by GC is 99.0%, and the yield is 90.3%.

[0054] Example 7

[0055] Catalyst preparation: Add 0.7 g of copper nitrate, 1.0 g of nickel nitrate and 50 mL of water to a flask, heat it to 50 °C, add 10.0 g of activated carbon with a pH of 2 (particle size 63 - 75 μm), stir well, let it stand, filter, dry at 110 °C, and then calcine in a nitrogen atmosphere at 450 °C for 4 h to obtain a carbon-supported nickel-copper catalyst.

[0056] Weigh 100.0 g (0.644 mol) of tetramethylpiperidone, 61.2 g (0.837 mol) of n-butylamine and 5 g of catalyst, place them in a preheated flask at 60 °C and mix evenly. Then pump them into a microchannel reactor at a flow rate of 75 mL / min. The reactor temperature is 80 °C, the hydrogenation pressure is 0.2 MPa, the residence time is 40 s, and the reaction solution accumulates in the storage tank.

[0057] Distill the reaction solution under reduced pressure to obtain tetrabutylammonium piperidine. The purity detected by GC is 99.5%, and the yield is 96.2%.

[0058] Example 8

[0059] Catalyst preparation: Add 1.0 g of copper nitrate, 0.7 g of cobalt nitrate and 50 mL of water to a flask, heat it to 50 °C, add 10.0 g of activated carbon with a pH of 4 (particle size 63 - 75 μm), stir well, let it stand, filter, dry at 110 °C, and then calcine in a nitrogen atmosphere at 450 °C for 4 h to obtain a carbon-supported copper-cobalt catalyst.

[0060] Weigh 100.0 g (0.644 mol) of tetramethylpiperidone, 61.2 g (0.837 mol) of n-butylamine and 8 g of catalyst, place them in a preheated flask at 60 °C and mix evenly. Then pump them into a microchannel reactor at a flow rate of 75 mL / min. The reactor temperature is 80 °C, the hydrogenation pressure is 0.5 MPa, the residence time is 40 s, and the reaction solution accumulates in the storage tank.

[0061] Distill the reaction solution under reduced pressure to obtain tetrabutylammonium piperidine. The purity detected by GC is 99.8%, and the yield is 97.0%.

[0062] Example 9

[0063] Catalyst preparation: Add 1.7 g of copper nitrate and 50 mL of water into a flask, heat up to 50 °C, add 10.0 g of activated carbon with a pH of 2 (particle size 63 - 75 μm), stir well and let it stand, filter, dry at 110 °C, and then calcine in a nitrogen atmosphere at 425 °C for 4 h to obtain a carbon-supported copper catalyst.

[0064] Weigh 100.0 g (0.644 mol) of tetramethylpiperidone, 51.8 g (0.708 mol) of n-butylamine and 10 g of the catalyst, place them in a preheated flask at 60 °C and mix evenly, then pump them into a microchannel reactor at a flow rate of 75 mL / min. The reactor temperature is 70 °C, the hydrogenation pressure is 0.5 MPa, the residence time is 40 s, and the reaction liquid accumulates in the storage tank.

[0065] Distill the reaction liquid under reduced pressure to obtain tetramethylpiperidine butylamine. The purity detected by GC is 98.9%, and the yield is 88.5%.

[0066] Example 10

[0067] Catalyst preparation: Add 1.2 g of nickel nitrate, 0.5 g of cobalt nitrate and 50 mL of water into a flask, heat up to 50 °C, add 10.0 g of activated carbon with a pH of 2 (particle size 63 - 75 μm), stir well and let it stand, filter, dry at 110 °C, and then calcine in a nitrogen atmosphere at 425 °C for 4 h to obtain a carbon-supported nickel-cobalt catalyst.

[0068] Weigh 100.0 g (0.644 mol) of tetramethylpiperidone, 51.8 g (0.708 mol) of n-butylamine and 7 g of the catalyst, place them in a preheated flask at 60 °C and mix evenly, then pump them into a microchannel reactor at a flow rate of 75 mL / min. The reactor temperature is 70 °C, the hydrogenation pressure is 0.7 MPa, the residence time is 40 s, and the reaction liquid accumulates in the storage tank.

[0069] Distill the reaction liquid under reduced pressure to obtain tetramethylpiperidine butylamine. The purity detected by GC is 99.4%, and the yield is 94.5%.

[0070] Example 11

[0071] Catalyst preparation: Add 0.6 g of copper nitrate, 1.1 g of cobalt nitrate and 50 mL of water into a flask, heat up to 50 °C, add 10.0 g of activated carbon with a pH of 2 (particle size 63 - 75 μm), stir well and let it stand, filter, dry at 110 °C, and then calcine in a nitrogen atmosphere at 425 °C for 4 h to obtain a carbon-supported copper-cobalt catalyst.

[0072] Weigh 100.0 g (0.644 mol) of tetramethylpiperidone, 12.1 g (0.712 mol) of ammonia water, and 6 g of catalyst, place them in a preheated flask at 60 °C, mix them evenly, then pump them into a microchannel reactor at a flow rate of 75 mL / min. The reactor temperature is 70 °C, the hydrogenation pressure is 0.5 MPa, the residence time is 40 s, and the reaction solution accumulates in the storage tank.

[0073] Distill the reaction solution under reduced pressure to obtain tetramethylpiperidine butylamine. The purity detected by GC is 99.8%, and the yield is 96.4%.

[0074] Example 12

[0075] The catalyst recovered by filtering the reaction solution of Example 10 is directly used in the following reaction.

[0076] Weigh 92.9 g (0.598 mol) of tetramethylpiperidone, 48.1 g (0.658 mol) of n-butylamine, and 6.5 g of catalyst, place them in a preheated flask at 60 °C, mix them evenly, then pump them into a microchannel reactor at a flow rate of 75 mL / min. The reactor temperature is 70 °C, the hydrogenation pressure is 0.7 MPa, the residence time is 40 s, and the reaction solution accumulates in the storage tank.

[0077] Distill the reaction solution under reduced pressure to obtain tetramethylpiperidine butylamine. The purity detected by GC is 99.2%, and the yield is 93.1%.

[0078] Comparative Example 1

[0079] Catalyst preparation: Add 0.8 g of nickel nitrate, 0.9 g of copper nitrate, and 50 mL of water to a flask, heat it to 50 °C, add 10.0 g of activated carbon with a pH of 8 (particle size 63 - 75 μm), stir well and let it stand, filter, dry at 110 °C, and calcine in a nitrogen atmosphere at 300 °C for 4 h to obtain a carbon-supported nickel-copper catalyst.

[0080] Weigh 100.0 g (0.644 mol) of tetramethylpiperidone, 33.7 g (0.290 mol) of 1,6-hexanediamine, and 5 g of catalyst, place them in a preheated flask at 60 °C, mix them evenly, then pump them into a microchannel reactor at a flow rate of 50 mL / min. The reactor temperature is 75 °C, the hydrogenation pressure is 1 MPa, the residence time is 60 s, and the reaction solution accumulates in the storage tank.

[0081] Distill the reaction solution under reduced pressure to obtain tetramethylpiperidine hexanediamine. The purity detected by GC is 98.8%, and the yield is 83.1%.

[0082] Comparative Example 2

[0083] Weigh 100.0 g (0.644 mol) of tetramethylpiperidone, 51.8 g (0.708 mol) of n-butylamine and 2 g of Raney nickel catalyst and place them in an autoclave. Heat to 100 °C and pressurize with hydrogen to 5 MPa. Stop the reaction after the pressure does not decrease.

[0084] Distill the reaction solution under reduced pressure to obtain tetramethylpiperidine butylamine. The purity detected by GC is 92.2% and the yield is 90.7%.

[0085] Recover the catalyst, activate it by hydrogenation and then put it into the following reaction:

[0086] Weigh 92.9 g (0.598 mol) of tetramethylpiperidone, 48.1 g (0.658 mol) of n-butylamine and 1.8 g of catalyst and place them in an autoclave. Heat to 100 °C and pressurize with hydrogen to 5 MPa. Stop the reaction after the pressure does not decrease. Distill the reaction solution under reduced pressure to obtain tetramethylpiperidine butylamine. The purity detected by GC is 89.9% and the yield is 65.5%.

[0087] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for continuous catalytic amination of tetramethylpiperidone, characterized in that, it comprises the following steps: Continuously introduce a liquid raw material containing triacetoneamine, an amine compound and a catalyst into a microchannel reactor, and introduce hydrogen into it to carry out a continuous catalytic amination reaction to obtain a tetramethylpiperidineamine compound; The amine compound is n-butylamine, hexamethylenediamine or ammonia, and ammonia is added in the form of ammonia water; During the continuous catalytic amination reaction, the flow rate of the liquid raw material is 50-100 mL / min, the hydrogen pressure is 0.2-1 MPa, and the reaction temperature is 70-80 °C; Among them, the catalyst is acidic activated carbon loaded with a transition metal element; the catalyst is prepared by the following method: Mix a soluble salt of the transition metal element, acidic activated carbon and water, and dry to obtain a supported precursor; Calcine the supported precursor in an inert atmosphere to obtain the catalyst; In the catalyst, the transition metal element is one or more of nickel element, palladium element, copper element and cobalt element; The soluble salt is a nitrate; The temperature for calcining the supported precursor is 300-450 °C, and the calcination time is 2-5 h.

2. The method according to claim 1, characterized in that, the transition metal element is at least two of nickel element, palladium element, copper element and cobalt element.

3. The method according to claim 1, characterized in that, the pH value of the acidic activated carbon is 2-6.

4. The method according to claim 1, characterized in that, the pH value of the acidic activated carbon is 2-4.

5. The method according to claim 1, characterized in that, the weight ratio of the soluble salt to the acidic activated carbon is 0.1-1.7:

10.

6. The method according to claim 5, characterized in that, the weight ratio of the soluble salt to the acidic activated carbon is 0.6-1.7:

10.

7. The method according to claim 1, characterized in that, the particle size of the acidic activated carbon is 50-80 μm.

8. The method according to claim 7, characterized in that, the particle size of the acidic activated carbon is 63-75 μm.

9. The method according to any one of claims 1 to 8, characterized in that, the molar ratio of the triacetoneamine to the amine compound is 1:0.45-1.

3.

10. The method according to any one of claims 1 to 8, characterized in that, the dosage of the catalyst is 5-10% of the weight of the triacetoneamine.

11. The method according to claim 1, characterized in that, the residence time of the liquid raw material in the microchannel reactor is 30-60 s.

12. The method according to claim 1, characterized in that, before continuously introducing the liquid raw material into the microchannel reactor, the method further comprises: preheating the liquid raw material to 50-60 °C.