A catalyst suitable for hydrogenation reduction of triacetoneamine to form tetramethylpiperidinol, its preparation method and application

Abstract

The application belongs to the technical field of catalytic reduction, and particularly relates to a catalyst suitable for hydrogenation reduction of triacetone amine to generate tetramethylpiperidinol, a preparation method and application thereof. The Cu-Pt / Al2O3-CeO2 catalyst is synthesized by a calcination-impregnation method. The Cu-Pt / Al2O3-CeO2 catalyst is used as a catalyst, a fixed bed reaction device is used, triacetone amine is used as a raw material, and hydrogenation reduction is performed to generate 2,2,6,6-tetramethyl-4-piperidinol (referred to as tetramethylpiperidinol). The application has the advantages of easy operation of the reaction device, high reliability, stable product quality, good catalyst effect and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of catalytic reduction, and particularly relates to a high-efficiency catalyst suitable for hydrogenation reduction of triacetone amine to generate tetramethylpiperidinol, a preparation method and application thereof. BACKGROUND

[0002] Tetramethylpiperidinol is an important intermediate for synthesizing hindered amine light stabilizers, is a white crystalline powder at room temperature, can be dissolved in organic solvents such as acetone, ethanol and chloroform, is slightly soluble in water, and has hygroscopicity. It also has a light stabilizing effect and has important uses in the pharmaceutical field. Hindered amine light stabilizers are one of the most effective light stabilizers for high molecular materials at present, are a class of organic amine compounds with steric hindrance effect, most of which have 2,2,6,6-tetramethyl-4-piperidinyl as the mother body, were developed by a Japanese company in the mid-1970s, are a new type of high-efficiency stabilizer, are used for anti-aging of high molecular materials such as plastics and rubbers, have a light stabilizing effect 2-4 times that of traditional absorption type light stabilizers, and have good compatibility with many resins, and are the fastest developing class of stabilizers at present.

[0003] At present, the synthesis of piperidinol mainly uses triacetone amine as the raw material, and is prepared by methods such as autoclave hydrogenation, chemical reduction, electrochemical reduction and catalytic hydrogenation. The industrial production mainly adopts the pressurized hydrogenation method in the catalytic hydrogenation method. However, the current catalysts reported for the preparation of piperidinol from triacetone amine by fixed bed hydrogenation have poor catalytic activity. For example, in “A continuous process for the production of 2,2,6,6-tetramethylpiperidin-4-ol catalyzed by Cu-Cr / γ-Al2O3, L X Yan”, a process for continuously producing 2,2,6,6-tetramethylpiperidin-4-ol in a fixed bed reactor using Cu-Cr / γ-Al2O3 is established, but the yield can only reach about 90%. CN202211208409.3 Cu-Ru double metal doped titanium silicon metal composite oxide catalyst and its application in the preparation of tetramethylpiperidinol from triacetone amine by fixed bed continuous hydrogenation, the Cu-Ru / TiSiOx catalyst prepared is used for the hydrogenation reduction of triacetone amine to synthesize tetramethylpiperidinol, the titanium silicon metal composite oxide (TiSiO x ) is used as the carrier, has a larger specific surface area and pore volume, has more active centers, and has stronger adsorption and mass transfer capacity, but the preparation process of the titanium silicon metal composite oxide carrier is complex and is not conducive to industrial production. Therefore, developing a continuous process for preparing tetramethylpiperidinol and screening a suitable catalyst are the keys to solving the industrial application. SUMMARY

[0004] In order to solve the problems in the background art, the present application uses copper nitrate trihydrate as a copper source, platinum nitrate as a platinum source, and cerium nitrate hexahydrate as a cerium source, and adopts a calcination-impregnation method to prepare a catalyst Cu-Pt / Al2O3-CeO2 and use it in a fixed bed reactor for continuous high-yield synthesis of tetramethylpiperidinol.

[0005] The preparation method of the Cu-Pt / Al2O3-CeO2 catalyst is as follows:

[0006] (1) A high-purity pseudo-boehmite, cerium nitrate hexahydrate, and ammonium tartrate are mixed and ground, dried at a certain temperature, and burned at a high temperature to a light yellow fluffy flocculent powder. After calcination, a composite carrier Al2O3-CeO2 is prepared.

[0007] (2) At room temperature, copper nitrate trihydrate, platinum nitrate, and deionized water are mixed uniformly to obtain solution A.

[0008] (3) The composite carrier Al2O3-CeO2 is pressed into a tablet, sieved into particles of a certain mesh size, and then solution A prepared above is added dropwise. After uniform mixing, it is left to stand overnight at room temperature. Then it is dried in an oven and finally calcined in a muffle furnace with programmed temperature rise to obtain the target catalyst Cu-Pt / Al2O3-CeO2.

[0009] The molar ratio of each component in the prepared Cu-Pt / Al2O3-CeO2 catalyst precursor

[0010] Cu(NO3)2·3H2O:Pt(NO3)2:Ce(NO3)3·6H2O:Al2O3·nH2O:C4H 12 N2O6=50:0.8~1.5:17.69:357.69:20.89.

[0011] As an improvement of the present application, the drying temperature in the catalyst preparation is 90-120℃, and the drying time is 8-12h. Preferably, the drying temperature in the preparation method is 100-120℃, and the drying time is 8-10h.

[0012] As an improvement of the present application, the calcination temperature in the catalyst preparation is 450-550℃, and the calcination time is 4-8h. Preferably, the calcination temperature in the preparation method is 500-550℃, and the calcination time is 4-6h.

[0013] As an improvement of the present application, the mass fraction of copper and platinum in the catalyst is 1-10wt.% and 0.3-1.0wt.%, respectively. Preferably, the mass fraction of copper and platinum in the catalyst is 5-10wt.% and 0.4-0.6wt.%, respectively.

[0014] As an improvement of the present application, the catalyst needs to be pressed into tablets, sieved and finally collected 20-40 mesh particles.

[0015] The present application also provides the application of the Cu-Pt / Al2O3-CeO2 catalyst prepared by the above preparation method in the preparation of tetramethylpiperidinol from triacetone amine.

[0016] The obtained catalyst is used in the reaction of catalyzing the preparation of tetramethylpiperidinol from triacetone amine, and the application method is as follows: a certain amount of catalyst is weighed and loaded in a fixed bed reactor, hydrogen is introduced, the temperature is programmed to 350℃ and kept for four hours for reduction, the temperature is lowered to the reaction temperature, triacetone amine solution is introduced, and after the reaction system is stable, it is analyzed by gas chromatography. Among them, the catalyst dosage is 5-15g; the flow rate of triacetone amine is 0.6mL / min, the reaction temperature is 70-90℃; and the total pressure is 1.5MPa.

[0017] Beneficial effects:

[0018] (1) The technical scheme realizes continuous flow reaction, and the components of the reactants realize full mixing and full contact with the catalyst in the catalyst layer in the fixed bed reactor;

[0019] (2) It can make triacetone amine in the reaction raw material almost completely converted, the selectivity of the target product is greater than 99%, and the yield of the product is high;

[0020] (3) The catalyst prepared by the present application has the advantages of large specific surface area, high activity and long service life, and the active components are uniformly distributed on the carrier;

[0021] (4) The addition of CeO2 can stabilize the crystal structure of γ-Al2O3, keep the active coating stable at high temperature, inhibit the loss of activity, and make the noble metal particles in the active coating keep dispersed, avoid the reduction of catalytic sites due to sintering, and cause activity loss. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 It is a scanning electron microscope graph of the catalyst obtained in Example 1. DETAILED DESCRIPTION

[0023] The present application will be further described below in combination with examples, but is not limited thereto.

[0024] Example 1

[0025] (1) 10.00g of commercially available pseudo-boehmite, 2.00g of cerium nitrate hexahydrate and 1.00g of ammonium tartrate are mixed and ground, dried at 120℃ for 10 hours, and burned to white fluffy powder at 500℃, to prepare a composite carrier Al2O3-Ce2O3 after calcination.

[0026] (2) Take 3.04 g of copper nitrate trihydrate, 0.08 g of platinum nitrate and 4.52 g of deionized water, mix them uniformly at room temperature to obtain solution A.

[0027] (3) Take 10.00 g of carrier Al2O3-CeO2, crush it into particles of 20-40 mesh, then add the above prepared solution A drop by drop, mix them uniformly, and then stand still at room temperature for 12 hours. Then put it into a 120°C oven to dry for 10 hours, and finally gradually heat it in a 500°C muffle furnace to calcine for 6 hours to obtain the target catalyst. The molar ratio of Cu(NO3)2·3H2O:Pt(NO3)2:Ce(NO3)3·6H2O:Al2O3·nH2O:C4H 12 N2O6=50:0.8:17.69:357.69:20.89.

[0028] (4) Take 10 g of the above catalyst and load it into a fixed bed reactor, pass hydrogen, program the temperature to rise to 350°C, reduce for 4 hours, and then reduce the temperature to 80°C for reaction. The flow rate of hydrogen is 50 mL / min, the flow rate of tripropylamine is 0.6 mL / min, and the reaction pressure is 1.5 MPa. After the reaction is stable, collect the reaction products and analyze them by gas chromatography. The average yield of the product is 99.7% after continuous operation for 240 hours.

[0029] Example 2

[0030] The molar ratio of Cu(NO3)2·3H2O:Pt(NO3)2:Ce(NO3)3·6H2O:Al2O3·nH2O:C4H 12 N2O6=50:0.8:17.69:357.69:20.89 in the Cu-Pt / Al2O3-CeO2 catalyst precursor prepared in step (3) is changed to Cu(NO3)2·3H2O:Pt(NO3)2:Ce(NO3)3·6H2O:Al2O3·nH2O:C4H 12 N2O6=50:1.5:17.69:357.69:20.89, and the other operations are the same as in Example 1. After the reaction is stable, collect the reaction products and analyze them by gas chromatography. The average yield of the product is 99.4% after continuous operation for 240 hours.

[0031] Example 3

[0032] The calcination temperature in step (1) is changed to 550°C, and the other operations are the same as in Example 1. After the reaction is stable, collect the reaction products and analyze them by gas chromatography. The average yield of the product is 99.0% after continuous operation for 240 hours.

[0033] Example 4

[0034] The calcination time in step (1) was changed to 4h, and other operations were the same as in Example 1. After the reaction was stable, the reaction product was collected and analyzed by gas chromatography. The average product yield was 99.1% after 240h of continuous operation.

[0035] Example 5

[0036] The drying temperature in step (1) was changed to 110°C, and other operations were the same as in Example 1. After the reaction was stable, the reaction product was collected and analyzed by gas chromatography. The average product yield was 99.3% after 240h of continuous operation.

[0037] Example 6

[0038] The drying time in step (1) was changed to 9h, and other operations were the same as in Example 1. After the reaction was stable, the reaction product was collected and analyzed by gas chromatography. The average product yield was 98.7% after 240h of continuous operation.

[0039] Example 7

[0040] The amount of catalyst in step (4) was changed to 5g, and other operations were the same as in Example 1. After the reaction was stable, the reaction product was collected and analyzed by gas chromatography. The average product yield was 98.9% after 240h of continuous operation.

[0041] Example 8

[0042] The hydrogen flow rate in step (4) was changed to 40mL / min, and other operations were the same as in Example 1. After the reaction was stable, the reaction product was collected and analyzed by gas chromatography. The average product yield was 98.2% after 240h of continuous operation.

[0043] Comparative Example 1

[0044] (1) 10.00g of commercially available high-purity pseudoboehmite was dried at 120°C for 10 hours, and a carrier γ-Al2O3was obtained by calcination at 500°C.

[0045] (2) 3.04g of copper nitrate trihydrate, 0.08g of platinum nitrate, and 5.40g of deionized water were mixed uniformly at room temperature to obtain solution A.

[0046] (3) 10.00g of the carrier γ-Al2O3was pressed into a tablet, sieved into particles of 20-40 mesh, and then solution A prepared above was added dropwise. After uniform mixing, it was left to stand at room temperature for 12 hours. Then it was dried in an oven at 120°C for 10 hours, and finally calcined at 550°C for 6 hours in a muffle furnace to obtain the target catalyst.

[0047] (4) Take 10 g of the above catalyst and load into a fixed bed reactor, pass hydrogen, program to heat to 350°C reduction for 4 hours, then cool to 70°C for reaction, hydrogen flow rate is 50 mL / min, tripropylamine flow rate is 0.6 mL / min, reaction pressure is 1.5 MPa. After the reaction is stable, collect the reaction product for analysis by gas chromatography, continuous operation for 240 h, the average yield of the product is 87.4%.

[0048] Comparative Example 2

[0049] Change the calcination temperature in step (3) to 550°C, and other operations are the same as Comparative Example 1. After the reaction is stable, collect the reaction product for analysis by gas chromatography, continuous operation for 240 h, the average yield of the product is 86.9%.

[0050] Comparative Example 3

[0051] (1) Take 4.6290 g of NaOH in a 50 mL beaker, then add 15 g of deionized water and stir until uniform, and name it solution A. Take 2.7004 g of KOH in a 50 mL beaker, then add 10 g of deionized water and stir until uniform, and name it solution B. Take 10 g of concentrated hydrochloric acid in a 50 mL beaker, then add 10 g of deionized water and stir until uniform, and name it solution C. Take 20.2640 g of water glass in a 150 mL beaker, then add the above solution A drop by drop and stir for 10 min, then add the prepared solution B drop by drop and stir, after the above system is stirred for 10 min, adjust the pH of the system to about 10.80 with solution C, when the pH is stable, add 13.1550 g of titanium trichloride solution in small amounts and dropwise, after stirring for 60 min after the dropwise addition is completed, load into a 50 mL polytetrafluoroethylene-lined reaction kettle, and crystallize statically at 230°C for 48 h. After crystallization is completed, wash and filter, the obtained solid is dried in a 120°C oven overnight, and calcined at 475°C for 5 h to obtain the carrier ETS-10. The molar ratio of the reaction gel system is TiO2:SiO2:Na2O:K2O:H2O = 1:6:5.7:1.41:171.2.

[0052] (2) At room temperature, mix 3.04 g of copper nitrate trihydrate, 0.08 g of platinum nitrate and 6.73 g of deionized water uniformly to obtain solution A.

[0053] (3) Take 10.00 g of the carrier ETS-10, press it into a tablet, sieve it into 20-40 mesh particles, then add the above prepared solution A drop by drop, after uniform mixing, stand at room temperature for 12 hours. Then put it into a 120°C oven and dry for 10 hours, finally program the temperature to 475°C in a muffle furnace and calcine for 6 hours to obtain the target catalyst Cu-Pt / ETS-10.

[0054] (4) 10 g of the above catalyst was charged into a fixed bed reactor, hydrogen was introduced, and programmed temperature reduction was carried out at 350°C for 4 hours, and then the temperature was lowered to 80°C for reaction. The flow rate of hydrogen was 50 mL / min, the flow rate of tripropylamine was 0.6 mL / min, and the reaction pressure was 1.5 MPa. After the reaction was stabilized, the reaction product was collected and analyzed by gas chromatography. The average yield of the product was 63.2% after continuous operation for 240 hours.

[0055] Comparative Example 4

[0056] (1) 10.00 g of commercially available pseudoboehmite, 2.00 g of cerium nitrate hexahydrate, and 1.00 g of ammonium tartrate were mixed and ground, dried at 120°C for 10 hours, and calcined at 500°C to a white fluffy powder. The composite support Al2O3-Ce2O3was prepared after calcination.

[0057] (2) 3.04 g of copper nitrate trihydrate, 0.25 g of cobalt nitrate hexahydrate, and 4.52 g of deionized water were mixed uniformly at room temperature to obtain solution A.

[0058] (3) 10.00 g of the support Al2O3-CeO2was pressed into a tablet and sieved into particles of 20-40 mesh. Then solution A prepared above was added dropwise, and after uniform mixing, it was left to stand at room temperature for 12 hours. Subsequently, it was dried in an oven at 120°C for 10 hours, and finally calcined at 500°C in a muffle furnace for 6 hours to obtain the target catalyst. The prepared Cu(NO3)2·3H2O:Co(NO3)2·6H2O:Ce(NO3)3·6H2O:Al2O3·nH2O:C4H 12 N2O6= 50:2.47:17.69:357.69:20.89.

[0059] (4) 10 g of the above catalyst was charged into a fixed bed reactor, hydrogen was introduced, and programmed temperature reduction was carried out at 350°C for 4 hours, and then the temperature was lowered to 80°C for reaction. The flow rate of hydrogen was 50 mL / min, the flow rate of tripropylamine was 0.6 mL / min, and the reaction pressure was 1.5 MPa. After the reaction was stabilized, the reaction product was collected and analyzed by gas chromatography. The average yield of the product was 90.4% after continuous operation for 240 hours.

[0060] Table 1: Comparison of texture property parameters of catalysts of examples and comparative examples

[0061]

[0062] The Cu-Pt / Al2O3-CeO2 catalyst prepared by the application has high specific surface area and bulk density, good thermal stability, more active centers, significantly improved conversion rate of triacetone amine and selectivity of tetramethylpiperidinol, and the addition of CeO2 can stabilize the crystal structure of γ-Al2O3, keep the activated coating stable at high temperature, inhibit the loss of activity, keep the noble metal particles in the active coating dispersed, avoid the reduction of catalytic sites due to sintering, and make the activity impaired.

[0063] The embodiments are preferred embodiments of the application, but the application is not limited to the above embodiments, and any obvious improvements, replacements or modifications made by those skilled in the art without departing from the essential content of the application shall fall within the protection scope of the application.

Claims

1. The application of a Cu-Pt / Al2O3-CeO2 catalyst, characterized in that, Cu-Pt / Al2O3-CeO2 catalyst was used to catalyze the continuous reduction of triacetone amine to tetramethylpiperidinol; The preparation method of the Cu-Pt / Al2O3-CeO2 catalyst is as follows: (1) Weigh high-purity boehmite, cerium nitrate hexahydrate and ammonium tartrate, mix and grind them, dry them and calcine them at high temperature to obtain composite carrier Al2O3-CeO2; (2) Weigh out copper nitrate trihydrate, platinum nitrate and deionized water and mix them evenly to obtain solution A; (3) After pressing the composite support Al2O3-CeO2 into tablets, it is sieved into particles and added to the prepared solution A. After it is mixed evenly, the catalyst precursor is obtained. It is left to stand overnight at room temperature, then placed in an oven to dry, and finally calcined in a muffle furnace with programmed temperature rise to obtain Cu-Pt / Al2O3-CeO2 catalyst.

2. The application as described in claim 1, characterized in that, The molar ratio of each component in the catalyst precursor is Cu(NO3)2·3H2O:Pt(NO3)2:Ce(NO3)3·6H2O:Al2O3·nH2O:C4H 12 N2O6=50:0.8~1.5:17.69:357.69:20.

89.

3. The application as described in claim 1, characterized in that, The drying temperature in steps (1) and (3) of catalyst preparation is 90~120 ºC, and the drying time is 8~12 h.

4. The application as described in claim 1, characterized in that, In the catalyst preparation, the calcination temperature in steps (1) and (3) is 450~550 ºC and the calcination time is 4~8 h.

5. The application as described in claim 1, characterized in that, The mass fractions of copper and platinum in the Cu-Pt / Al2O3-CeO2 catalyst are 1–10 wt.% and 0.3–1.0 wt.%, respectively.

6. The application as described in claim 1, characterized in that, The application method is as follows: the catalyst is weighed and loaded into a fixed-bed reactor, hydrogen is introduced, the temperature is programmed to rise to 350°C for reduction, the temperature is lowered to the reaction temperature, a triacetone amine solution is introduced, and after the reaction system is stable, the tetramethylpiperidinol is obtained by gas chromatography analysis.

7. The application as described in claim 1, characterized in that, The catalyst dosage was 5-15 g, the flow rate of triacetone amine was 0.6 mL / min, the reaction temperature was 70-90 ºC, and the total pressure was 1.5 MPa.

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