Method and device for preparing tetramethylpiperidinol through continuous catalytic hydrogenation
Through the continuous catalytic hydrogenation method and the use of composite catalysts, the problems of uneven quality and high production costs of tetramethylpiperidol products in the prior art have been solved, and efficient and stable industrial production has been achieved.
Patent Information
- Application Number
- CN202510233921.0
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-28
- Publication Date
- 2025-05-27
AI Technical Summary
In the existing process of preparing tetramethylpiperidol by liquid phase catalytic hydrogenation, the reaction conversion rate and selectivity are inconsistent, resulting in uneven product quality, and high solvent and catalyst consumption, and high production costs.
The continuous catalytic hydrogenation method is adopted to achieve continuous production of the process through the ingredients, hydrogenation, gas-liquid separation and purification steps, and a composite catalyst and a tubular fixed bed reactor.
The quality stability of tetramethylpiperidol product is achieved, with a yield of up to 99.1%, and a purity of more than 99.9%, which reduces the occurrence of side reactions and energy consumption of distillation, extends the service life of the catalyst, and reduces production costs.
Smart Images
Figure CN120040338A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of tetramethylpiperidinol, and more particularly to a method and apparatus for continuously catalytic hydrogenation to prepare tetramethylpiperidinol. Background Art
[0002] Light stabilizers can effectively prevent the aging of polymer materials and extend their service life, so they are widely used in synthetic materials such as plastics, rubbers, and fibers. With the continuous expansion of the application fields of polymer materials, especially the increase in outdoor products, the importance of light stabilizers has become increasingly obvious, and they have become the additives with the fastest growing consumption.
[0003] Hindered amine light stabilizers are a new type of highly efficient stabilizers developed by Sankyo Co., Ltd. in Japan in the mid-1970s. They are currently the light stabilizers with the best performance. They can effectively improve the anti-ultraviolet performance of polymers and the performance of anti-γ radiation. Their light stabilization effect is 2-4 times that of traditional absorption-type light stabilizers. They have good compatibility with many resins and will not change with the thickness of the products. Hindered amine light stabilizers are non-toxic, colorless, easy to obtain raw materials, simple to synthesize, and have good compatibility with many resins. They are particularly suitable for products such as fibers, films, and tapes. At present, their applications have covered fields such as agricultural films, engineering plastics, and polymer coatings.
[0004] Different from the action mode of ultraviolet stabilizers, the functional groups of hindered amine light stabilizers belong to the alicyclic amine structure. They do not absorb any light with a wavelength greater than 260m by themselves and cannot quench excited state molecules. However, under oxidative conditions such as heat and light, the amino groups in the hindered amine molecules can be converted into corresponding nitrogen oxide free radicals. They can capture polymer free radicals and alkoxy free radicals, making them lose their activity; quench high-energy excited states including singlet oxygen; decompose peroxides existing and accumulating in the polymer, converting them into relatively stable alcohol and ketone compounds, thereby inhibiting the photooxidative degradation reaction. The esters and peroxide esters generated in the free radical reaction can react with the free radicals and alkoxy free radicals in the polymer and return to the original state. Such self-regeneration ability enables a hindered amine molecule to capture multiple polymer free radicals in the polymer, thus having high anti-photoaging performance.
[0005] Tetramethylpiperidone is the only parent body of existing hindered amine light stabilizers. However, due to its poor stability, it generally changes from the original milky white to light yellow or even brownish red after being placed in an environment with air for 3-4 days. Therefore, existing hindered amine light stabilizers are usually derived from the intermediate 2,2,6,6-tetramethyl-4-piperidinol (i.e., tetramethylpiperidinol) obtained by hydrogenation reduction using tetramethylpiperidone as a raw material.
[0006] Therefore, tetramethylpiperidinol is an important intermediate for synthesizing hindered amine light stabilizers; at the same time, tetramethylpiperidinol is also an important intermediate for products such as bleaching agents, polymerization inhibitors, and epoxy resin crosslinking agents.
[0007] Currently, there are mainly the following methods for preparing tetramethylpiperidinol by reducing tetramethylpiperidone: 1. Catalytic hydrogenation method, including pressurized hydrogenation method and atmospheric pressure hydrogenation method; the catalytic hydrogenation method is the main method for industrial production at present; 2. Chemical reduction method, using aluminum isopropoxide, sodium borohydride, etc. as reducing agents to reduce tetramethylpiperidone to tetramethylpiperidinol. However, the reducing agents used in this method are relatively expensive, and the post-treatment of the reaction is more complicated, so it is rarely used industrially; 3. Electrochemical reduction method, tetramethylpiperidone is reduced to tetramethylpiperidinol at the cathode in the electrolytic cell. However, due to the high production energy consumption and the complex structure of the electrolytic cell of this method, it is generally not used industrially.
[0008] In the catalytic hydrogenation method mainly used industrially, German researchers used Raney-Ni as a catalyst and a liquid-phase hydrogenation pressure of 0.49 - 9.8 MPa for the preparation method, and the yield of tetramethylpiperidinol can reach about 95%. Czech researchers reported the preparation method using Ni / Cr 2 O 3 、NiO / Al 2 O 3 as catalysts, and the yield of tetramethylpiperidinol is about 86 - 93%, but the reaction conditions are harsh. Ciba reported a preparation method using Ru / C as a catalyst and water as a solvent, and the yield of tetramethylpiperidinol is 91 - 97%.
[0009] The inventor has found through research that in the current process of preparing tetramethylpiperidinol by liquid-phase catalytic hydrogenation, batch production is carried out in a kettle reactor or a tower reactor. During the production process, the process conditions of different production batches are not unified, resulting in different reaction conversion rates, selectivities, etc. for different production batches, with a large difference, and ultimately leading to the problem of non-uniform quality of tetramethylpiperidinol products. At the same time, this process method also has the problems of large consumption of solvents and catalysts participating in the reaction and high production costs. Summary of the Invention
[0010] In order to solve the technical problems existing in the prior art, the present invention provides a method and device for continuously catalytic hydrogenation to prepare tetramethylpiperidinol to achieve the following invention purposes: (1)In the process of preparing tetramethylpiperidinol by the existing liquid-phase catalytic hydrogenation method, during the batch production process using a kettle reactor or a tower reactor, the reaction conversion rate, selectivity, etc. of different production batches are not the same, and the problem of non-uniform quality of tetramethylpiperidinol products exists. (2)In the process of preparing tetramethylpiperidinol by the existing liquid-phase catalytic hydrogenation method, the consumption of the solvent and catalyst participating in the reaction is relatively large, and the production cost is high.
[0011] To solve the above technical problems, the technical solutions adopted in the present invention are as follows: A method for continuously catalytic hydrogenation to prepare tetramethylpiperidinol, which consists of the following steps: batching, hydrogenation, gas-liquid separation, and refining; The method of batching is that tetramethylpiperidone and ethanol are continuously fed into a batching kettle and mixed evenly to obtain a mixed material; The method of hydrogenation is that after the mixed material is preheated, it is continuously fed into a tubular fixed-bed reactor filled with a composite catalyst, and the hydrogen pressure is controlled to be 1-5 MPa, and the hydrogenation temperature is 90-200 °C to carry out the hydrogenation reaction, and the hydrogenation product is continuously obtained; The method of gas-liquid separation is to carry out gas-liquid separation on the hydrogenation product to obtain a liquid-phase crude product and uncondensed gas; after the uncondensed gas is condensed, a condensed liquid-phase crude product and non-condensable gas are obtained; the non-condensable gas is recycled to the tubular fixed-bed reactor for hydrogenation reaction; The liquid-phase crude product and the condensed liquid-phase crude product are refined to obtain tetramethylpiperidinol.
[0012] Preferably, in the batching, the temperature of the batching kettle is controlled to be 59-61 °C, and the residence time of tetramethylpiperidone and ethanol in the batching kettle is 10-30 min; The weight ratio of tetramethylpiperidone to ethanol is 1-5:1.
[0013] Preferably, in the hydrogenation, the preheating temperature of the mixed material is 90-100 °C, and the feeding speed of the mixed material continuously fed into the tubular fixed-bed reactor filled with the composite catalyst is 0.8-1.2 mL / min.
[0014] Preferably, the method of refining is that the liquid-phase crude product and the condensed liquid-phase crude product are mixed and heated to 70-80 °C, kept warm until no gas distills out, and then vacuum rectified to obtain tetramethylpiperidinol.
[0015] Furthermore, the composite catalyst is prepared by the following steps: carrier modification, loading; The method for modifying the carrier is as follows: magnesium basic carbonate, glyceryl trilaurate, and betaine citrate are put into deionized water. After mixing evenly, the temperature is raised to 45 - 55 °C, and then ground evenly to obtain a grinding slurry. Then, the grinding slurry is mixed with pseudo-boehmite and dilute nitric acid and ground evenly to obtain a mixture. After preheating, the mixture is calcined at 450 - 550 °C to obtain a modified alumina carrier. The method for loading is as follows: the modified alumina carrier is put into a loading solution, stirred, and then the solid is separated. The solid is dried and calcined at 250 - 350 °C and then at 400 - 450 °C to obtain a composite catalyst. The loading solution is deionized water in which copper nitrate, nickel nitrate, and chromium nitrate are dispersed.
[0016] Preferably, in the modification of the carrier, the heating rate for calcination at 450 - 550 °C is 3 - 6 °C / min; the calcination time at 450 - 550 °C is 4 - 6 h. The weight ratio of magnesium basic carbonate, glyceryl trilaurate, betaine citrate, pseudo-boehmite, dilute nitric acid, and deionized water is 50 - 55:4 - 5:2 - 4:700 - 800:15 - 18:1000 - 1200. The concentration of the dilute nitric acid is 4 - 8 wt%.
[0017] Preferably, in the loading process, the heating rate for calcination at 250 - 350 °C is 1 - 3 °C / min, and the calcination time at 250 - 350 °C is 1 - 2 h; the heating rate for calcination at 400 - 450 °C is 3 - 6 °C / min, and the calcination time at 400 - 450 °C is 1 - 2 h.
[0018] Preferably, in the loading process, the weight ratio of the modified alumina carrier to the loading solution is 1:4 - 5. The weight ratio of copper nitrate, nickel nitrate, chromium nitrate, and deionized water in the loading solution is 3 - 5:10 - 12:3 - 5:120 - 150.
[0019] A device for continuously catalytic hydrogenation to prepare tetramethylpiperidinol by implementing the foregoing method includes: a material preheating unit, a fixed-bed reaction unit, and a refining unit. The material preheating unit includes: a batching kettle and a preheater. The fixed-bed reaction unit includes: a tubular fixed-bed reactor, a gas-liquid separation tank, and a condenser. The refining unit includes: a crude product tank. At the top of the batching kettle, there are a raw material inlet and a solvent inlet. The discharge port at the bottom of the batching kettle is connected to the tube-side inlet of the preheater through a feeding pump, so that the batching kettle continuously receives tetramethylpiperidone and ethanol, and after obtaining a mixed material, continuously feeds it into the preheater. The tube discharge port of the preheater is connected to the top feed port of the tubular fixed-bed reactor. The bottom discharge port of the tubular fixed-bed reactor is connected to the material inlet of the gas-liquid separation tank. The material outlet of the gas-liquid separation tank is connected to the crude product tank, so that the mixed material is continuously fed into the tubular fixed-bed reactor for hydrogenation after preheating, and the liquid-phase crude product after gas-liquid separation of the hydrogenation product is introduced into the crude product tank.
[0020] Further, the uncondensed gas outlet of the gas-liquid separation tank is connected to the shell feed port of the preheater; The shell discharge port of the preheater is connected to the tube feed port of the condenser; The tube discharge port of the condenser is respectively connected to the feed port of the hydrogen compressor and the feed port of the crude product tank; so as to receive the uncondensed gas from the preheater, after being condensed by the condenser, the non-condensable gas is compressed and then returned to the tubular fixed-bed reactor for hydrogenation; the condensed liquid-phase crude product enters the crude product tank.
[0021] Specifically, in the material preheating unit, there are a tetramethylpiperidone metering tank, an ethanol metering tank, a batching kettle, and a preheater; The bottom discharge port of the tetramethylpiperidone metering tank is connected to the raw material inlet at the top of the batching kettle. After being metered, tetramethylpiperidone is continuously fed into the batching kettle; the bottom discharge port of the ethanol metering tank is connected to the solvent inlet at the top of the batching kettle. After being metered, ethanol is continuously fed into the batching kettle; The batching kettle is provided with a material heating module, a material cooling module, and a material stirring module; the mixed material discharge port at the bottom of the batching kettle is connected to the tube feed port of the preheater, and the mixed material in the batching kettle is continuously fed into the preheater; The preheater is provided with tubes and a shell; the tube discharge port of the preheater is connected to the top feed port of the tubular fixed-bed reactor in the fixed-bed reaction unit. After being preheated by the preheater, the mixed material is continuously fed into the tubular fixed-bed reactor for hydrogenation; the shell feed port of the preheater is connected to the uncondensed gas outlet of the gas-liquid separation tank in the fixed-bed reaction unit. The uncondensed gas in the gas-liquid separation tank enters the shell of the preheater and serves as a heat medium to preheat the mixed material; the shell discharge port of the preheater is connected to the tube feed port of the condenser in the fixed-bed reaction unit, and the uncondensed gas heat medium in the shell of the preheater enters the condenser for condensation.
[0022] In the fixed-bed reaction unit, there are a tubular fixed-bed reactor, a gas-liquid separation tank, a condenser, and a hydrogen compressor; The top of the tubular fixed-bed reactor is provided with a material feed inlet, the middle and lower parts are provided with a hydrogen inlet, and the bottom is provided with a hydrogenation material discharge outlet; the material feed inlet of the tubular fixed-bed reactor is connected to the tube discharge outlet of the preheater in the material preheating unit; the hydrogen inlet of the tubular fixed-bed reactor is connected to the hydrogen gas source and the tube discharge outlet of the condenser, so that the non-condensable gas (hydrogen) after condensation by the condenser is compressed and then returned to the tubular fixed-bed reactor for hydrogenation; the hydrogenation material discharge outlet of the tubular fixed-bed reactor is connected to the material inlet of the gas-liquid separation tank, and the hydrogenation material continuously enters the gas-liquid separation tank for gas-liquid separation; a composite catalyst is filled in the tubular fixed-bed reactor, and the mixed material reacts with hydrogen in the fixed-bed reactor; The gas-liquid separation tank is provided with a material inlet and outlet and a non-condensable gas outlet; the material inlet of the gas-liquid separation tank is connected to the hydrogenation material discharge outlet of the tubular fixed-bed reactor; the material outlet of the gas-liquid separation tank is connected to the crude product tank in the refining unit, and the liquid-phase crude product in the gas-liquid separation tank is temporarily stored in the crude product tank and then subjected to vacuum distillation to obtain tetramethylpiperidinol; the non-condensable gas outlet of the gas-liquid separation tank is connected to the shell inlet of the preheater in the material preheating unit; The condenser is provided with a tube inlet and a tube outlet; the tube inlet of the condenser is connected to the shell discharge outlet of the preheater in the material preheating unit; the tube outlet of the condenser is respectively connected to the inlet of the hydrogen compressor and the inlet of the crude product tank; the condenser is used to receive the non-condensable gas from the preheater, and after condensation by the condenser, the non-condensable gas (hydrogen) is compressed by the hydrogen compressor and then returned to the tubular fixed-bed reactor for hydrogenation; the condensate (condensed liquid-phase crude product) enters the crude product tank for temporary storage.
[0023] A crude product tank is arranged in the refining unit; The crude product tank is provided with a material inlet and outlet and a gas phase outlet; the material inlet of the crude product tank is respectively connected to the material outlet of the gas-liquid separation tank and the tube discharge outlet of the condenser to receive the liquid-phase crude product from the gas-liquid separation tank and the condensed liquid-phase crude product from the condenser; the material outlet of the crude product tank is connected to the vacuum distillation device; the gas in the crude product tank is discharged through the gas phase outlet at the top of the tank, and the material in the crude product tank is subjected to vacuum distillation to obtain tetramethylpiperidinol.
[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The method and device for continuously catalytic hydrogenation to prepare tetramethylpiperidinol of the present invention realizes continuous hydrogenation production from the original batch production, realizes continuous production of the process, effectively overcomes the problems of different reaction conversion rates and selectivities in different batches and uneven product quality caused by batch production in the prior art, and the quality of the prepared tetramethylpiperidinol product is stable, and the yield can reach 99.1%, which can meet the requirements of high-efficiency and large-scale industrial production.
[0025] (2) The method and device for continuously catalytic hydrogenation to prepare tetramethylpiperidinol of the present invention adopt a composite catalyst, effectively improving the conversion rate of tetramethylpiperidone and the yield of tetramethylpiperidinol. The purity of the obtained tetramethylpiperidinol product exceeds 99.9%, and the conversion rate of tetramethylpiperidone can reach 99.5%.
[0026] (3) The method and device for continuously catalytic hydrogenation to prepare tetramethylpiperidinol of the present invention effectively reduce the occurrence of side reactions, with low impurity content, easy for product rectification and purification. While obtaining high product purity, the energy consumption of rectification and purification is effectively reduced; compared with the prior art, the energy consumption is reduced by more than 10%.
[0027] (4) The method and device for continuously catalytic hydrogenation to prepare tetramethylpiperidinol of the present invention adopt a tubular fixed-bed production process. The hydrogen recycling operation is simple, and the hydrogen use efficiency is high. The amount of hydrogen consumed for producing one ton of tetramethylpiperidinol is 142 - 145 Nm³; (5) The method and device for continuously catalytic hydrogenation to prepare tetramethylpiperidinol of the present invention greatly reduce the solvent usage and consumption, and effectively eliminate the side reactions generated by the solvent.
[0028] (6) The method and device for continuously catalytic hydrogenation to prepare tetramethylpiperidinol of the present invention greatly extend the service life of the catalyst. The service life of the catalyst exceeds 1 year, the usage and consumption of the catalyst are greatly reduced, and the production cost is effectively reduced. Brief Description of the Drawings
[0029] Figure 1 It is a schematic diagram of the device for continuously catalytic hydrogenation to prepare tetramethylpiperidinol of the present invention; In the figure, 1 - tetramethylpiperidone metering tank, 2 - ethanol metering tank, 3 - batching kettle, 4 - preheater, 5 - tubular fixed-bed reactor, 6 - gas-liquid separation tank, 7 - condenser, 8 - hydrogen compressor, 9 - crude product tank. Detailed Embodiments
[0030] In order to have a clearer understanding of the technical features, objectives and effects of the present invention, the specific embodiments of the present invention are now described.
[0031] Example 1 This example provides a method for continuously catalytic hydrogenation to prepare tetramethylpiperidinol, which is as follows: 1. Batching After tetramethylpiperidone and ethanol are respectively metered, they are continuously fed into the batching kettle 3. Under the stirring condition of 30 rpm, the temperature of the batching kettle 3 is controlled at 59 °C, and the residence time of the material is 10 min. The obtained mixed material is continuously fed into the preheater 4 through a feeding pump.
[0032] Among them, the weight ratio of tetramethylpiperidone to ethanol is 2:1.
[0033] 2. Hydrogenation The mixed material prepared in the batching step is transferred from the batching kettle 3 to the preheater 4 by a feeding pump, preheated to 90 °C, and then fed into the tubular fixed-bed reactor 5 filled with a composite catalyst at a feeding rate of 0.8 mL / min by continuous top feeding; meanwhile, normal-temperature hydrogen enters the tubular fixed-bed reactor 5; the hydrogen pressure in the tubular fixed-bed reactor 5 is controlled to be 1.0 MPa and the temperature is 90 °C for hydrogenation reaction; the hydrogenated product after the hydrogenation reaction in the tubular fixed-bed reactor 5 continuously flows out from the bottom of the tubular fixed-bed reactor 5.
[0034] In the hydrogenation step, a pressure automatic control system is set to keep the pressure in the tubular fixed-bed reactor 5 stable during the reaction process.
[0035] The composite catalyst is prepared by the following method: 1) Carrier modification Put a predetermined amount of basic magnesium carbonate, glyceryl trilaurate, and citrulline betaine into deionized water, stir at 200 rpm for 20 min; then raise the temperature to 45 °C and grind at 500 rpm for 5 min to obtain a ground slurry; then mix the ground slurry with pseudo-boehmite and dilute nitric acid and grind at 400 rpm for 30 min to obtain a mixture; place the mixture in an environment of 100 °C, keep warm for 2 h, and then raise the temperature to 450 °C at a heating rate of 3 °C / min and keep warm for 4 h to obtain a modified alumina carrier.
[0036] Among them, the weight ratio of basic magnesium carbonate, glyceryl trilaurate, citrulline betaine, pseudo-boehmite, dilute nitric acid, and deionized water is 50:4:2:700:15:1000.
[0037] The concentration of the dilute nitric acid is 4 wt%.
[0038] In the modified alumina carrier, the magnesium oxide content is 4.5 wt%.
[0039] 2) Loading Put the modified alumina carrier into a loading solution with a weight 4 times that of the carrier, stir at 20 rpm for 2 h, and filter out the solid; place the solid in an environment of 105 °C and let it stand for 2 h; then raise the temperature to 250 °C at a heating rate of 1 °C / min and keep warm and calcine for 1 h; then raise the temperature to 400 °C at a heating rate of 3 °C / min and keep warm and calcine for 1 h, and naturally cool to room temperature to obtain the composite catalyst.
[0040] The load solution consists of the following components: copper nitrate, nickel nitrate, chromium nitrate, and deionized water. Among them, the weight ratio of copper nitrate, nickel nitrate, chromium nitrate, and deionized water is 3:10:3:120.
[0041] 3. Gas-liquid separation The hydrogenation product after the hydrogenation reaction flows from the tubular fixed-bed reactor 5 into the gas-liquid separation tank 6 for gas-liquid separation. The liquid-phase crude product flows into the crude product tank 9 in the refining unit; the uncondensed gas enters the condenser 7 and is condensed at a temperature of 10°C. The condensed liquid (i.e., the condensed liquid-phase crude product) flows into the crude product tank 9 in the refining unit, and the non-condensable gas (i.e., hydrogen) is compressed by the hydrogen compressor 8 and then re-enters the tubular fixed-bed reactor 5 for the hydrogenation step.
[0042] 4. Refining The crude product tank 9 in the refining unit is heated to 70°C and kept warm. During the heat preservation process, the gas in the crude product tank 9 is discharged through the tank top. After heat preservation until no gas distills out, the liquid in the crude product tank 9 is subjected to vacuum distillation to obtain tetramethylpiperidinol.
[0043] As Figure 1 shown, this embodiment also provides a device for continuously catalytic hydrogenation to prepare tetramethylpiperidinol for implementing the foregoing method, which is provided with: a material preheating unit, a fixed-bed reaction unit, and a refining unit.
[0044] The material preheating unit is provided with a tetramethylpiperidone metering tank 1, an ethanol metering tank 2, a batching kettle 3, and a preheater 4.
[0045] The bottom discharge port of the tetramethylpiperidone metering tank 1 is connected to the raw material inlet pipeline at the top of the batching kettle 3. After being metered, tetramethylpiperidone is continuously fed into the batching kettle 3. The bottom discharge port of the ethanol metering tank 2 is connected to the solvent inlet pipeline at the top of the batching kettle 3. After being metered, ethanol is continuously fed into the batching kettle 3.
[0046] The batching kettle 3 is also provided with a material heating module, a material cooling module, and a material stirring module. Under the predetermined temperature condition, tetramethylpiperidone and ethanol are mixed evenly in the batching kettle 3. The mixed material discharge port at the bottom of the batching kettle 3 is connected to the tube-side inlet of the preheater 4, and the mixed material in the batching kettle is continuously fed into the preheater 4.
[0047] The preheater 4 is provided with tube bundles and a shell. The outlet of the tube bundles of the preheater 4 is connected to the top inlet of the tubular fixed-bed reactor 5 in the fixed-bed reaction unit. After the mixed materials are preheated by the preheater, they are continuously fed into the tubular fixed-bed reactor 5 for hydrogenation. The inlet of the shell of the preheater 4 is connected to the uncondensed gas outlet of the gas-liquid separation tank 6 in the fixed-bed reaction unit. The uncondensed gas in the gas-liquid separation tank 6 enters the shell of the preheater 4 and serves as a heat medium to preheat the mixed materials. The outlet of the shell of the preheater 4 is connected to the inlet of the tube bundles of the condenser 7 in the fixed-bed reaction unit, and the uncondensed gas heat medium in the shell of the preheater 4 enters the condenser 7 for condensation.
[0048] In the fixed-bed reaction unit, a tubular fixed-bed reactor 5, a gas-liquid separation tank 6, a condenser 7, and a hydrogen compressor 8 are provided.
[0049] The top of the tubular fixed-bed reactor 5 is provided with a material inlet, the middle and lower parts are provided with hydrogen inlets, and the bottom is provided with a hydrogenation product outlet. The material inlet of the tubular fixed-bed reactor 5 is connected to the outlet of the tube bundles of the preheater 4 in the material preheating unit. The hydrogen inlet of the tubular fixed-bed reactor 5 is connected to the hydrogen gas source and the outlet of the tube bundles of the condenser 7, so that the uncondensed gas (hydrogen) after condensation in the condenser 7 is compressed and then returned to the tubular fixed-bed reactor 5 for hydrogenation. The hydrogenation product outlet of the tubular fixed-bed reactor 5 is connected to the material inlet of the gas-liquid separation tank 6, and the hydrogenation products continuously enter the gas-liquid separation tank for gas-liquid separation. The tubular fixed-bed reactor 5 is filled with a composite catalyst, and the mixed materials react with hydrogen in the tubular fixed-bed reactor 5.
[0050] The gas-liquid separation tank 6 is provided with a material inlet and outlet and an uncondensed gas outlet. The material inlet of the gas-liquid separation tank 6 is connected to the hydrogenation product outlet of the tubular fixed-bed reactor 5. The material outlet of the gas-liquid separation tank 6 is connected to the crude product tank 9 in the refining unit. After the liquid-phase crude product is temporarily stored in the crude product tank 9, vacuum distillation is carried out. The uncondensed gas outlet is connected to the inlet of the shell of the preheater 4 in the material preheating unit.
[0051] After the hydrogenation products of the tubular fixed-bed reactor 5 are subjected to gas-liquid separation in the gas-liquid separation tank 6, the liquid phase flows into the crude product tank 9 in the refining unit. The uncondensed gas is cooled by the preheater 4 and condensed by the condenser 7, and then enters the uncondensed gas (hydrogen). After being compressed by the hydrogen compressor 8, it is returned to the tubular fixed-bed reactor 5 for hydrogenation. The condensate (i.e., the condensed liquid-phase crude product) enters the crude product tank 9 for temporary storage.
[0052] Further, the condenser 7 is provided with a tube bundle feed port and a tube bundle discharge port; the tube bundle feed port of the condenser 7 is connected to the shell discharge port of the preheater 4 in the material preheating unit; the tube bundle discharge port of the condenser 7 is respectively connected to the feed port of the hydrogen compressor 8 and the feed port of the crude product tank 9; the condenser 7 is used to receive the uncondensed gas from the preheater 4. After being condensed by the condenser 7, the non-condensable gas (hydrogen) is compressed by the hydrogen compressor 8 and then returned to the tubular fixed-bed reactor 5 for hydrogenation; the condensate (i.e., the condensed liquid-phase crude product) enters the crude product tank 9 for temporary storage.
[0053] A crude product tank 9 is arranged in the refining unit. Among them, the crude product tank 9 is provided with a material inlet and outlet and a gas-phase outlet; the material inlet of the crude product tank 9 is respectively connected to the material outlet of the gas-liquid separation tank 6 and the tube bundle discharge port of the condenser 7, so as to receive the liquid-phase crude product from the gas-liquid separation tank 6 and the condensate (i.e., the condensed liquid-phase crude product) of the condenser 7; the material outlet of the crude product tank 9 is connected to the vacuum distillation device; the gas in the crude product tank is discharged through the gas-phase outlet on the tank top, and the material in the crude product tank 9 is subjected to vacuum distillation to obtain tetramethylpiperidinol.
[0054] Example 2 This example provides a method for continuously catalytic hydrogenation to prepare tetramethylpiperidinol, which is as follows: 1. Batching After being metered respectively, tetramethylpiperidone and ethanol are continuously fed into the batching kettle 3. Under the stirring condition of 45 rpm, the temperature of the batching kettle 3 is controlled at 60 °C, and the residence time of the material is 15 min. The obtained mixed material is continuously fed into the preheater 4 by a feeding pump.
[0055] Among them, the weight ratio of tetramethylpiperidone to ethanol is 3:1.
[0056] 2. Hydrogenation The mixed material prepared in the batching step is transferred from the batching kettle 3 to the preheater 4 by a feeding pump, preheated to 95 °C, and then fed into the tubular fixed-bed reactor 5 filled with a composite catalyst at a feeding speed of 1 mL / min by a continuous top-feeding method; at the same time, normal-temperature hydrogen enters the tubular fixed-bed reactor 5; the hydrogen pressure in the tubular fixed-bed reactor 5 is controlled at 2.0 MPa, and the temperature is 130 °C for hydrogenation reaction; the hydrogenation product after the hydrogenation reaction in the tubular fixed-bed reactor 5 continuously flows out from the bottom of the tubular fixed-bed reactor 5.
[0057] In the hydrogenation step, a pressure automatic control system is set to keep the pressure in the tubular fixed-bed reactor 5 stable during the reaction process.
[0058] The composite catalyst is prepared by the following method: 1) Carrier modification Put a predetermined amount of basic magnesium carbonate, glyceryl trilaurate, and betaine citrate into deionized water, and stir for 30 min at a rotation speed of 300 rpm; then raise the temperature to 50 °C and grind for 8 min under a grinding condition of 600 rpm to obtain a ground slurry; then mix the ground slurry with pseudo-boehmite and dilute nitric acid, and grind for 40 min under a grinding condition of 450 rpm to obtain a mixture; place the mixture in an environment of 102 °C, keep it warm for 3 h, and then raise the temperature to 500 °C at a heating rate of 5 °C / min and keep it warm for 5 h to obtain a modified alumina support.
[0059] Among them, the weight ratio of basic magnesium carbonate, glyceryl trilaurate, betaine citrate, pseudo-boehmite, dilute nitric acid, and deionized water is 53:4.5:3:750:16:1100.
[0060] The concentration of the dilute nitric acid is 6 wt%.
[0061] In the modified alumina support, the magnesium oxide content is 5 wt%.
[0062] 2) Loading Put the modified alumina support into a loading solution with a weight 4.5 times that of the support, stir at 40 rpm for 2.5 h, and filter out the solid; place the solid in an environment of 110 °C and let it stand for 2.5 h; then raise the temperature to 300 °C at a heating rate of 2 °C / min and keep it calcined for 1.5 h; then raise the temperature to 420 °C at a heating rate of 5 °C / min and keep it calcined for 1.5 h; after the calcination is completed, naturally cool it to room temperature to obtain a composite catalyst.
[0063] The loading solution consists of the following components: copper nitrate, nickel nitrate, chromium nitrate, and deionized water. Among them, the weight ratio of copper nitrate, nickel nitrate, chromium nitrate, and deionized water is 4:11:4:135.
[0064] 3. Gas-liquid separation The hydrogenation product after the hydrogenation reaction flows from the tubular fixed-bed reactor 5 into the gas-liquid separation tank 6 for gas-liquid separation. The liquid-phase crude product flows into the crude product tank 9 in the refining unit; the uncondensed gas enters the condenser 7 and is condensed at a temperature of 12 °C. The condensed liquid (i.e., the condensed liquid-phase crude product) flows into the crude product tank 9 in the refining unit, and the non-condensable gas (i.e., hydrogen) is compressed by the hydrogen compressor 8 and then re-enters the tubular fixed-bed reactor 5 for the hydrogenation step.
[0065] 4. Refining The crude product tank 9 in the refining unit is heated to 75 °C and kept warm. During the warming process, the gas in the crude product tank 9 is discharged through the tank top. After warming until no gas distills out, the liquid in the crude product tank 9 is subjected to vacuum distillation to obtain tetramethylpiperidinol.
[0066] The device for continuously catalytic hydrogenation to prepare tetramethylpiperidinol used in this example is the same as that in Example 1.
[0067] Example 3 A method for continuously catalytic hydrogenation to prepare tetramethylpiperidinol is as follows: 1. Batching After being metered respectively, tetramethylpiperidone and ethanol are continuously fed into the batching kettle 3. Under the stirring condition of 60 rpm, the temperature of the batching kettle 3 is controlled at 61 °C, and the residence time of the materials is 30 min to obtain a mixed material, which is continuously fed into the preheater 4 by a feeding pump.
[0068] Among them, the weight ratio of tetramethylpiperidone to ethanol is 5:1.
[0069] 2. Hydrogenation The mixed material prepared in the batching step is transferred from the batching kettle 3 into the preheater 4 by a feeding pump, preheated to 100 °C, and then fed into the tubular fixed-bed reactor 5 filled with a composite catalyst at a feeding rate of 1.2 mL / min by a continuous top-feeding method; meanwhile, normal-temperature hydrogen enters the tubular fixed-bed reactor 5; the hydrogen pressure in the tubular fixed-bed reactor 5 is controlled at 5.0 MPa, and the temperature is 200 °C for hydrogenation reaction; the hydrogenation product after the hydrogenation reaction in the tubular fixed-bed reactor 5 continuously flows out from the bottom of the tubular fixed-bed reactor 5.
[0070] In the hydrogenation step, a pressure automatic control system is set to keep the pressure in the tubular fixed-bed reactor 5 stable during the reaction process.
[0071] The composite catalyst is prepared by the following method: 1) Carrier modification Put a predetermined amount of basic magnesium carbonate, glyceryl trilaurate, and citric acid betaine into deionized water, stir at a speed of 400 rpm for 40 min; then heat up to 55 °C and grind for 10 min under the grinding condition of 800 rpm to obtain a ground slurry; then mix the ground slurry with pseudoboehmite and dilute nitric acid, and grind for 50 min under the grinding condition of 500 rpm to obtain a mixture; place the mixture in an environment of 105 °C, keep it warm for 4 h, and then heat it up to 550 °C at a heating rate of 6 °C / min and keep it warm for 6 h to obtain a modified alumina carrier.
[0072] Among them, the weight ratio of basic magnesium carbonate, glyceryl trilaurate, citric acid betaine, pseudoboehmite, dilute nitric acid, and deionized water is 55:5:4:800:18:1200.
[0073] The concentration of the dilute nitric acid is 8 wt%.
[0074] In the modified alumina support, the magnesium oxide content is 5.5 wt%.
[0075] 2) Loading Put the modified alumina support into a loading solution with a weight 5 times that of the support, stir at 50 rpm for 3 h, and filter out the solid; place the solid in an environment at 115 °C and let it stand for 3 h; then, at a heating rate of 3 °C / min, heat up to 350 °C and keep it calcined for 2 h; then, at a heating rate of 6 °C / min, heat up to 450 °C and keep it calcined for 2 h; after the calcination is completed, let it cool naturally to room temperature to obtain the composite catalyst.
[0076] The loading solution consists of the following components: copper nitrate, nickel nitrate, chromium nitrate, and deionized water. Among them, the weight ratio of copper nitrate, nickel nitrate, chromium nitrate, and deionized water is 5:12:5:150.
[0077] 3. Gas-liquid separation The hydrogenation product after the hydrogenation reaction flows from the tubular fixed-bed reactor 5 into the gas-liquid separation tank 6 for gas-liquid separation. The liquid-phase crude product flows into the crude product tank 9 in the refining unit; the uncondensed gas enters the condenser 7 and is condensed at a temperature of 20 °C. The condensed liquid (i.e., the condensed liquid-phase crude product) flows into the crude product tank 9 in the refining unit, and the non-condensable gas (i.e., hydrogen) is compressed by the hydrogen compressor 8 and then re-enters the tubular fixed-bed reactor 5 for the hydrogenation step.
[0078] 4. Refining The crude product tank 9 in the refining unit is heated to 80 °C and kept warm. During the warming process, the gas in the crude product tank 9 is discharged through the tank top. After warming until no gas distills out, the liquid in the crude product tank 9 is subjected to vacuum distillation to obtain tetramethylpiperidinol.
[0079] The device for continuously catalytic hydrogenation to prepare tetramethylpiperidinol used in this example is the same as that in Example 1.
[0080] Comparative Example 1 Use the method for continuously catalytic synthesis of tetramethylpiperidinol in Example 2 and the device for continuously catalytic synthesis of tetramethylpiperidinol in Example 1. The difference is that the support modification step in the preparation of the composite catalyst is omitted, and γ-alumina is used instead of the modified alumina support and put into the loading solution for loading treatment.
[0081] Use the methods and devices for continuously catalytic hydrogenation to prepare tetramethylpiperidinol described in Examples 1-3 and Comparative Example 1 to continuously produce tetramethylpiperidinol. Detect the purity of the tetramethylpiperidinol prepared in Examples 1-3 and Comparative Example 1, as well as the reaction yield, conversion rate of tetramethylpiperidone in each example, and calculate the hydrogen consumption per ton of tetramethylpiperidinol produced. The specific detection results are as follows:
[0082] Furthermore, the catalytic lifetimes of the composite catalysts prepared in Examples 1-3 and Comparative Example 1 were tested. The method for continuously catalytically synthesizing tetramethylpiperidinol described in Example 2 was used to continuously produce tetramethylpiperidinol; during the continuous catalytic production, the continuous and stable supply of each raw material was maintained, and the temperature and pressure of each reaction device were kept stable. The effective catalytic duration of the composite catalyst was recorded, and the test results are as follows:
[0083] Unless otherwise specified, the percentages used in the present invention are all mass percentages.
[0084] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, 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 preparing tetramethylpiperidinol by continuous catalytic hydrogenation, characterized in that: The method comprises the following steps: batching, hydrogenation, gas-liquid separation, and refining; The batching method comprises the following steps: continuously feeding tetramethyl piperidone and ethanol into a batching kettle (3) and mixing them evenly to obtain a mixed material; The hydrogenation method comprises the following steps: after the mixed material is preheated, it is continuously fed into a tubular fixed bed reactor (5) filled with a composite catalyst, and the hydrogen pressure is controlled to be 1-5 MPa and the hydrogenation temperature is controlled to be 90-200° C. to carry out a hydrogenation reaction and continuously obtain a hydrogenation product; The gas-liquid separation method comprises: performing gas-liquid separation on the hydrogenation product to obtain a crude liquid phase product and uncondensed gas; condensing the uncondensed gas to obtain a condensed liquid phase crude product and uncondensed gas; and recycling the uncondensed gas to the tubular fixed bed reactor (5) for hydrogenation reaction; The crude liquid phase product and the condensed liquid phase crude product are refined to obtain tetramethylpiperidinol.
2. The method for preparing tetramethyl piperidine alcohol by continuous catalytic hydrogenation according to claim 1, wherein In the batching, the temperature of the batching kettle (3) is controlled to be 59-61° C., and the residence time of tetramethyl piperidone and ethanol in the batching kettle (3) is 10-30 min; The weight ratio of tetramethyl piperidone to ethanol is 1-5:
1.
3. The method for preparing tetramethyl piperidine alcohol by continuous catalytic hydrogenation according to claim 1, characterized in that, During the hydrogenation, the preheating temperature of the mixed material is 90-100° C., and the mixed material is continuously fed into the tubular fixed bed reactor (5) at a feeding rate of 0.8-1.2 mL / min.
4. The method for preparing tetramethyl piperidine alcohol by continuous catalytic hydrogenation according to claim 1, characterized in that: The refining method comprises the following steps: mixing the crude liquid phase product and the crude condensed liquid phase product, heating the mixture to 70-80° C., maintaining the temperature until no gas is distilled out, and then performing vacuum distillation to obtain tetramethylpiperidinol.
5. The method for preparing tetramethyl piperidine alcohol by continuous catalytic hydrogenation according to claim 1, characterized in that, The composite catalyst is prepared by the following steps: carrier modification and loading; The carrier modification method comprises the following steps: adding basic magnesium carbonate, glyceryl trilaurate, and betaine citric acid into deionized water, and mixing them evenly; heating the mixture to 45-55° C., and grinding the mixture evenly to obtain a grinding slurry; mixing the grinding slurry with pseudo-boehmite and dilute nitric acid, and grinding the mixture evenly to obtain a mixture; preheating the mixture, and then calcining the mixture at 450-550° C. to obtain a modified alumina carrier; The loading method comprises: putting the modified alumina carrier into the loading liquid, stirring, and separating to obtain a solid; the solid is dried, calcined at 250-350° C., and calcined at 400-450° C. to obtain a composite catalyst; The loading liquid is deionized water dispersed with copper nitrate, nickel nitrate and chromium nitrate.
6. The method for preparing tetramethyl piperidine alcohol by continuous catalytic hydrogenation according to claim 5, characterized in that: In the carrier modification, the heating rate of calcination at 450-550°C is 3-6°C / min; the calcination time at 450-550°C is 4-6h; The weight ratio of basic magnesium carbonate, trilaurin, betaine citric acid, pseudoboehmite, dilute nitric acid and deionized water is 50-55:4-5:2-4:700-800:15-18:1000-1200; The concentration of dilute nitric acid is 4-8wt%.
7. The method for preparing tetramethyl piperidine alcohol by continuous catalytic hydrogenation according to claim 5, characterized in that: In the load, the heating rate of calcination at 250-350°C is 1-3°C / min, and the calcination time at 250-350°C is 1-2h; the heating rate of calcination at 400-450°C is 3-6°C / min, and the calcination time at 400-450°C is 1-2h.
8. The method for preparing tetramethyl piperidine alcohol by continuous catalytic hydrogenation according to claim 5, characterized in that: In the loading, the weight ratio of the modified alumina carrier to the loading liquid is 1:4-5; The weight ratio of copper nitrate, nickel nitrate, chromium nitrate and deionized water in the loading liquid is 3-5:10-12:3-5:120-150.
9. A device for preparing tetramethylpiperidinol by continuous catalytic hydrogenation according to any one of claims 1 to 8, characterized in that: It includes: material preheating unit, fixed bed reaction unit and refining unit; The material preheating unit comprises: a batching kettle (3) and a preheater (4); The fixed bed reaction unit comprises: a tubular fixed bed reactor (5), a gas-liquid separation tank (6), and a condenser (7); The refining unit comprises: a crude product tank (9); The top of the batching kettle (3) is provided with a raw material inlet and a solvent inlet, and the discharge port at the bottom of the batching kettle (3) is connected to the tube feed port of the preheater (4) via a feed pump, so that the batching kettle (3) continuously receives tetramethyl piperidone and ethanol, obtains a mixed material and continuously feeds it to the preheater (4); The tube discharge port of the preheater (4) is connected to the top feed port of the tubular fixed bed reactor (5), the bottom discharge port of the tubular fixed bed reactor (5) is connected to the material inlet of the gas-liquid separation tank (6), and the material outlet of the gas-liquid separation tank (6) is connected to the crude product tank (9), so that the mixed material is continuously fed into the tubular fixed bed reactor (5) for hydrogenation after preheating, and the liquid phase crude product of the hydrogenation product after gas-liquid separation is introduced into the crude product tank (9).
10. The device for preparing tetramethylpiperidinol by continuous catalytic hydrogenation according to claim 9, characterized in that: The uncondensed gas outlet of the gas-liquid separation tank (6) is connected to the shell feed port of the preheater (4); The shell outlet of the preheater (4) is connected to the tube inlet of the condenser (7); The tube discharge port of the condenser (7) is respectively connected to the feed port of the hydrogen compressor (8) and the feed port of the crude product tank (9); so as to receive the uncondensed gas from the preheater (4) and condense it, and then return the uncondensed gas to the tubular fixed bed reactor (5) for hydrogenation after compression; the condensed liquid phase crude product enters the crude product tank (9).