A high-efficiency and stable catalyst for synthesizing tetramethylpiperidinol by hydrogenation of triacetoneamine and a preparation method thereof
By preparing Ni, Al, Mg, and Mo composite catalysts via co-precipitation, the problems of low production efficiency and poor stability in the hydrogenation of triacetone amine to tetramethylpiperidinol were solved, enabling efficient and stable continuous production that meets the requirements of fixed-bed reactors.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- 宿迁联盛科技股份有限公司
- Filing Date
- 2024-04-17
- Publication Date
- 2026-07-07
AI Technical Summary
In existing technologies, the hydrogenation of triacetone amine to tetramethylpiperidinol has low production efficiency and high cost. Traditional catalysts have poor stability and pose safety hazards. Furthermore, fixed-bed reactors are prone to clogging, making it difficult to achieve efficient and stable continuous production.
A composite catalyst of four metals, Ni, Al, Mg and Mo, was synthesized by co-precipitation. After extrusion molding and reduction, the catalyst was packed into a fixed-bed reactor. Ni and Mo served as active centers, Mg and Al improved structural stability, guar gum and citric acid monohydrate improved pore structure, and water glass increased strength.
It achieves high efficiency, stability and high activity of catalyst, reduces production costs, meets the requirements of fixed-bed reaction, improves conversion rate and yield, and has good prospects for industrial application.
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Figure CN118341434B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of catalyst technology, specifically relating to a method for preparing a highly efficient and stable catalyst for the hydrogenation of triacetone amine to tetramethylpiperidinol. Background Technology
[0002] Tetramethylpiperidinol (TMP) is a crucial intermediate material in the fine chemical industry, particularly widely used in hindered amine light stabilizers (HALS) such as light stabilizers 622, 770, and 292. It also has extensive applications in pharmaceuticals, free radical scavengers, and antioxidants. With the rapid development and expansion of my country's fine chemical industry, the demand for TMP is growing exponentially. Developing low-cost, high-efficiency, and highly stable catalysts for continuous production processes has significant industrial application value.
[0003] Currently, industrial TMP production mostly employs a pressurized autoclave liquid-phase hydrogenation reduction process. This process is intermittent, resulting in low production efficiency, high labor costs, and inconsistent product quality. The catalyst used is Raney nickel, which requires a large quantity and has low stability. While catalyst and material addition and discharge processes require a nitrogen-protected environment, the risk of hydrogen and Raney nickel leakage remains, posing significant safety hazards. A fixed-bed continuous hydrogenation process could significantly improve production efficiency, reduce labor costs, enhance product quality and yield, improve production safety, and increase the automation level of the processing. Fixed-bed continuous hydrogenation can achieve efficient and stable continuous production of TMP, but it requires a highly efficient and stable catalyst. Traditional Raney nickel catalysts have small particle sizes; large particles of Raney nickel catalyst have disadvantages such as low activity and easy pulverization during use, posing a safety hazard of clogging fixed-bed pipelines. CN116037104A discloses a method for preparing a size-controllable ruthenium-carbon catalyst and its application in the preparation of tetramethylpiperidinol, using activated carbon as a carrier and impregnating ruthenium element via an impregnation method. The catalyst uses activated carbon as a support, but the support particles are small and have low strength. The surface support easily detaches into powdery solids, causing blockages in the fixed bed and pipelines, which is detrimental to the industrial application of the catalyst. The catalyst preparation process uses large amounts of concentrated hydrochloric acid and sodium hydroxide, requiring sophisticated equipment. The active component is the precious metal ruthenium, resulting in high catalyst preparation costs. CN115382569A discloses a novel, high-efficiency catalyst and its preparation method for the hydrogenation of triacetone amine catalyst to tetramethylpiperidinol, using a hydrothermal synthesis-deposition precipitation method to synthesize a composite catalyst containing Ni, Cu, and Al metal components with ZSM-5 zeolite molecular sieve as the core. The catalyst first prepares ZSM-5 zeolite molecular sieve, then loads Ni, Cu, and Al metals via deposition precipitation. This method is complex, has a long process flow, requires sophisticated equipment, consumes high energy, and has high production costs, making it unsuitable for industrial applications.
[0004] This invention synthesizes a composite catalyst containing four metals—Ni, Al, Mg, and Mo—using a simple co-precipitation method. The catalyst is then extruded, reduced, and packed into a fixed-bed reactor for the hydrogenation of triacetone amine to tetramethylpiperidinol. This catalyst features a simple preparation method, high activity, high selectivity, and high stability. Summary of the Invention
[0005] To address the aforementioned problems, this invention discloses a highly efficient and stable catalyst for the hydrogenation of triacetone amine to tetramethylpiperidinol and its preparation method. This catalyst can efficiently catalyze the hydrogenation of triacetone amine to tetramethylpiperidinol and can be used stably and continuously in a fixed-bed reaction process.
[0006] To achieve the above objectives, the technical solution of the present invention is as follows:
[0007] This invention provides a method for preparing a highly efficient and stable catalyst for the hydrogenation of triacetone amine to tetramethylpiperidinol, comprising the following steps:
[0008] (1) Prepare a mixed solution of nickel nitrate hexahydrate, aluminum nitrate nonahydrate, magnesium nitrate hexahydrate and ammonium molybdate tetrahydrate. The molar ratio of the metal salts is 30-70:10-50:10:1.4, and is denoted as solution A.
[0009] (2) Anhydrous sodium carbonate is mixed evenly with pure water. The concentration of anhydrous sodium carbonate is 1.0 to 2.0 mol / L, and it is denoted as solution B.
[0010] (3) Slowly add solution A to solution B until the pH is 8-10. After stirring for 30 minutes, filter, wash, dry and calcin to obtain powder C.
[0011] (4) After the powder C and the excipients are mixed evenly, they are extruded into strips using an extruder. After the shaped catalyst is placed at room temperature, it is dried, calcined, sieved, cut into strips, and reduced to obtain a catalyst with a length of 3-5 mm, denoted as Ni. w Al x Mg y Mo z .
[0012] Furthermore, in step (1), the mass ratio of nickel nitrate hexahydrate to water is 4 to 16:125.
[0013] Furthermore, in step (3), the catalyst is calcined at a temperature of 400–600°C for 3–7 hours.
[0014] Further, in step (4), the excipients are water, guar gum powder, water glass and citric acid monohydrate; the mass ratio of powder C, water, guar gum powder, water glass and citric acid monohydrate is 1:0.5~0.8:0.05~0.1:0.1~0.5:0.01~0.04.
[0015] Further, in step (4), the calcination temperature is 450-650℃ and the calcination time is 2-4h; the catalyst reduction temperature is 400-600℃ and the reduction time is 3-6h.
[0016] The present invention also provides a highly efficient and stable catalyst for the hydrogenation synthesis of tetramethylpiperidinol from triacetone amine prepared by the method described above.
[0017] The present invention also provides the application of the highly efficient and stable catalyst prepared by the method described above in the hydrogenation of triacetone amine to tetramethylpiperidinol.
[0018] The application method is as follows: 25-75 ml of catalyst is loaded into a fixed-bed reactor with an inner diameter of 3 cm and a length of 80 cm, and the reactor is installed. A feed solution composed of triacetone amine and isopropanol is prepared. The feed solution and hydrogen are continuously introduced into the fixed-bed reactor, and the reaction is continued at a reaction temperature of 110-130℃ and a reaction pressure of 1.3-1.7 MPa. After the reaction stabilizes, the reaction product is taken, and the content of tetramethylpiperidinol in the reaction product is detected by gas chromatography (GC).
[0019] Furthermore, the mass ratio of triacetoneamine to isopropanol is 1:1 to 4.
[0020] Furthermore, the feed liquid is prepared over 2–6 hours. -1 The gas is introduced into the fixed-bed reactor at a space velocity of 1:30 to 120, with the volume ratio of feed liquid to hydrogen being 1:30 to 120.
[0021] The reaction synthesis route used in this invention is as follows:
[0022]
[0023] The beneficial effects of this invention are as follows:
[0024] (1) A NiAlMgMo multi-component catalyst was synthesized by co-precipitation. This synthesis method is simple, the synthesis process is easy to control, and the catalyst preparation cost is low. The catalyst prepared by co-precipitation exhibits strong interactions between the metal elements, thus the active centers of the catalyst are not easily lost and the pore structure is not easily collapsed, resulting in high catalytic stability.
[0025] (2) The presence of Ni and Mo as active centers in the catalyst gives it high catalytic activity; the presence of Mg and Al enhances the structural stability of the catalyst, giving it high catalytic stability.
[0026] (3) The catalyst is extruded to better adapt to the requirements of the fixed bed, and the catalyst is less likely to be lost due to the scouring of the raw materials, resulting in a higher conversion rate and yield of the catalytic reaction. Guaranteed sesame powder and citric acid monohydrate are added to the extrusion feedstock to make the extrusion process smoother. After a short period of time, these two substances develop a porous structure in the original parts, further increasing the specific surface area of the catalyst. Water glass forms silica after calcination, further improving the strength of the catalyst.
[0027] (4) The synergistic effect of the four metals lowers the reduction temperature of the catalyst (e.g., Figure 1 As shown in the figure, this further reduces the energy consumption of catalyst reduction and saves production costs.
[0028] (5) The catalyst has high reactivity and mild reaction conditions. It can exhibit high reactivity, selectivity and stability under a wide range of reaction conditions. Using this catalyst and a fixed-bed reactor can achieve efficient, stable and continuous production of tetramethylpiperidinol, which has good industrial application prospects. Attached Figure Description
[0029] Figure 1 The above are H2-TPR analysis chromatograms of the catalysts prepared in Example 1 and Comparative Examples 1-4.
[0030] Figure 2 This study compares the catalytic activity and stability of the catalysts prepared in Example 1 and Comparative Examples 1-4 for the continuous hydrogenation of triacetone amine to tetramethylpiperidinol.
[0031] Figure 3 This is a schematic diagram illustrating the catalytic stability of the catalyst prepared in Example 1 in the reaction of continuous hydrogenation of triacetone amine to tetramethylpiperidinol;
[0032] Figure 4 This is a SEM image of the catalyst prepared in Example 1. Detailed Implementation
[0033] The present invention will be further illustrated below with reference to the accompanying drawings and specific embodiments. It should be understood that the following specific embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.
[0034] The manufacturers and models of the compounds used in the following examples are shown below; other chemical reagents used, unless otherwise specified, were obtained through conventional commercial channels.
[0035]
[0036] Example 1
[0037] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0038] (1) Weigh 546g of nickel nitrate hexahydrate, 101g of aluminum nitrate nonahydrate, 69g of magnesium nitrate hexahydrate and 47g of ammonium molybdate tetrahydrate and dissolve them in 1L of pure water. Stir until all the solids are dissolved and record this as solution A. The molar ratio of the metal elements in the mixture is Ni:Al:Mg:Mo = 70:10:10:10.
[0039] (2) Weigh 212g of anhydrous sodium carbonate and dissolve it in 1L of pure water. Stir until the solid is completely dissolved and record it as solution B.
[0040] (3) Slowly add solution A to solution B until the solution pH = 9, then stop adding. Stir for 30 min, filter, wash, dry at 100℃ for 12 h, and calcine at 450℃ for 5 h to obtain powder C.
[0041] (4) Powder C was mixed evenly with 70 wt.% water, 5 wt.% guar gum powder, 40 wt.% water glass and 3 wt.% citric acid monohydrate as extruders and then extruded into strips (mold type: 1.5B). The formed catalyst was placed at room temperature for 8 hours and then dried at 120℃ for 12 hours. The formed catalyst was calcined at 450℃ for 5 hours. The calcined catalyst was sieved to obtain 20-30 mesh strips. The broken catalyst was reduced at 500℃ for 5 hours in a hydrogen atmosphere to obtain a catalyst with a length of 3-5 mm, denoted as Ni. 70 Al 10 Mg 10 Mo 10 .
[0042] The fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine: 50 ml of the above catalyst was measured and packed into a fixed-bed reactor, and the reactor was installed. A feed solution with a mass ratio of triacetone amine to isopropanol of 1:4 was prepared; the feed solution was subjected to hydrogenation at a rate of 4 h / min. -1 The gas space velocity was continuously introduced into the fixed-bed reactor. The volume ratio of feed liquid to hydrogen was 1:60. The reaction temperature was 120℃ and the reaction pressure was 1.5MPa. After the reaction stabilized, 2ml of the reaction product was taken, and the content of tetramethylpiperidinol in the reaction product was detected by gas chromatography (GC). The average yield of tetramethylpiperidinol within 300h was 99.51% as determined by GC.
[0043] The mass percentages involved in step (4) refer to the mass percentage of each auxiliary material relative to powder C.
[0044] Example 2
[0045] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0046] Other conditions were the same as in Example 1, except that the amount of metal salt added in step (1) was changed: 390g nickel nitrate hexahydrate, 302g aluminum nitrate nonahydrate, 69g magnesium nitrate hexahydrate, and 47g ammonium molybdate tetrahydrate, with a molar ratio of Ni:Al:Mg:Mo = 50:30:10:10. GC analysis showed that the average yield of tetramethylpiperidinol within 300 hours was 99.12%.
[0047] Example 3
[0048] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0049] Other conditions were the same as in Example 1, except that the amount of metal salt added in step (1) was changed: 234g nickel nitrate hexahydrate, 503g aluminum nitrate nonahydrate, 69g magnesium nitrate hexahydrate, and 47g ammonium molybdate tetrahydrate, with a molar ratio of Ni:Al:Mg:Mo = 30:50:10:10. GC analysis showed that the average yield of tetramethylpiperidinol within 300 hours was 99.01%.
[0050] Example 4
[0051] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0052] Other conditions were the same as in Example 1, except that the amount of anhydrous sodium carbonate added in step (2) was changed to 106 g. GC analysis showed that the average yield of tetramethylpiperidinol within 300 h was 96.27%.
[0053] Example 5
[0054] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0055] Other conditions were the same as in Example 1, except that the pH of the solution at the endpoint of the addition in step (3) was changed to stop when the solution concentration was 8. GC analysis showed that the average yield of tetramethylpiperidinol within 300 hours was 98.76%.
[0056] Example 6
[0057] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0058] Other conditions were the same as in Example 1, except that the calcination temperature in step (3) was changed to 500°C. GC analysis showed that the average yield of tetramethylpiperidinol within 300 hours was 97.62%.
[0059] Example 7
[0060] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0061] Other conditions were the same as in Example 1, except that the calcination time in step (3) was changed to 3 hours. GC analysis showed that the average yield of tetramethylpiperidinol within 300 hours was 97.25%.
[0062] Example 8
[0063] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0064] Other conditions were the same as in Example 1, except that the reduction temperature in step (4) under a hydrogen atmosphere was changed to 400°C. GC analysis showed that the average yield of tetramethylpiperidinol within 300 hours was 96.58%.
[0065] Example 9
[0066] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0067] Other conditions were the same as in Example 1, except that the reduction time in step (4) under hydrogen atmosphere was changed to 3 hours. GC analysis showed that the average yield of tetramethylpiperidinol within 300 hours was 96.37%.
[0068] Example 10
[0069] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0070] Same as Example 1, except for the catalyst loading: 75 ml of catalyst was loaded, otherwise the same as in Example 1. GC analysis showed that the average yield of tetramethylpiperidinol within 300 h was 99.89%.
[0071] Example 11
[0072] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0073] Same as Example 1, except for the catalyst loading: 25 ml of catalyst was loaded, otherwise the same as in Example 1. GC analysis showed that the average yield of tetramethylpiperidinol within 300 h was 98.59%.
[0074] Example 12
[0075] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0076] Same as Example 1, except for the concentration of the feed solution: the triacetone amine content was 40 wt.%, and everything else remained the same as in Example 1. GC analysis showed that the average yield of tetramethylpiperidinol within 300 h was 99.15%.
[0077] Example 13
[0078] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0079] Same as Example 1, except for the concentration of the feed solution: the triacetone amine content was 10 wt.%, and everything else remained the same as in Example 1. GC analysis showed that the average yield of tetramethylpiperidinol within 300 h was 99.87%.
[0080] Example 14
[0081] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0082] Same as Example 1, except the space velocity of the feed liquid was changed: the feed liquid space velocity was 6 h⁻¹. -1 The rest is the same as in Example 1. GC analysis showed that the average yield of tetramethylpiperidinol within 300 hours was 98.54%.
[0083] Example 15
[0084] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0085] Same as Example 1, except the feed liquid hourly space velocity was changed: the feed liquid hourly space velocity was 2 h⁻¹. -1 The rest is the same as in Example 1. GC analysis showed that the average yield of tetramethylpiperidinol within 300 hours was 99.86%.
[0086] Example 16
[0087] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0088] Same as Example 1, except that the volume ratio of the feed liquid to hydrogen was changed to 1:30, otherwise the same as Example 1. GC analysis showed that the average yield of tetramethylpiperidinol within 300 hours was 98.65%.
[0089] Example 17
[0090] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0091] Same as Example 1, except that the volume ratio of the feed liquid to hydrogen was changed to 1:120, otherwise the same as Example 1. GC analysis showed that the average yield of tetramethylpiperidinol within 300 hours was 99.76%.
[0092] Example 18
[0093] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0094] Same as Example 1, except for the reaction temperature: the reaction temperature in the fixed-bed reactor was 110°C, and everything else was the same as in Example 1. GC analysis showed that the average yield of tetramethylpiperidinol within 300 hours was 98.68%.
[0095] Example 19
[0096] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0097] Same as Example 1, except for the reaction temperature: the reaction temperature in the fixed-bed reactor was 130°C, and everything else was the same as in Example 1. GC analysis showed that the average yield of tetramethylpiperidinol within 300 hours was 98.53%.
[0098] Example 20
[0099] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0100] Same as Example 1, except for the reaction pressure: the reaction pressure in the fixed-bed reactor was 1.3 MPa, and everything else was the same as in Example 1. GC analysis showed that the average yield of tetramethylpiperidinol within 300 h was 99.03%.
[0101] Example 21
[0102] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0103] Same as Example 1, except for the reaction pressure: the reaction pressure in the fixed-bed reactor was 1.7 MPa, and everything else was the same as in Example 1. GC analysis showed that the average yield of tetramethylpiperidinol within 300 h was 99.18%.
[0104] Comparative Example 1
[0105] The catalyst preparation steps for the fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine are as follows:
[0106] (1) Weigh 546g of nickel nitrate hexahydrate, 101g of aluminum nitrate nonahydrate and 47g of ammonium molybdate tetrahydrate and dissolve them in 1L of pure water. Stir until all the solids are dissolved and record this as solution A. The molar ratio of the metal elements in the mixture is Ni:Al:Mo = 70:10:10.
[0107] (2) Weigh 212g of anhydrous sodium carbonate and dissolve it in 1L of pure water. Stir until the solid is completely dissolved and record it as solution B.
[0108] (3) Slowly add solution A to solution B until the solution pH = 9 and then stop adding. After stirring for 30 min, filter, wash, dry at 100℃ for 12 h, and calcine at 450℃ for 5 h to obtain powder C.
[0109] (4) Powder C was mixed evenly with 70 wt.% water, 5 wt.% guar gum powder, 40 wt.% water glass and 3 wt.% citric acid monohydrate as extruders, and then extruded into strips (mold type: 1.5B). The formed catalyst was placed at room temperature for 8 hours and then dried at 120℃ for 12 hours. The formed catalyst was calcined at 450℃ for 5 hours. The calcined catalyst was sieved to obtain 20-30 mesh strips. The broken strips of catalyst were reduced at 500℃ for 5 hours in a hydrogen atmosphere to obtain catalyst denoted as Ni. 70 Al 10 Mo 10 .
[0110] The fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine: 50 ml of the above catalyst was measured and packed into a fixed-bed reactor, and the reactor was installed. A feed solution with a mass ratio of triacetone amine to isopropanol of 1:4 was prepared. The feed solution was then subjected to a 4-hour hydrogenation process. -1 The gas space velocity was continuously introduced into the fixed-bed reactor. The volume ratio of feed liquid to hydrogen was 1:60. The reaction temperature was 120℃ and the reaction pressure was 1.5MPa. After the reaction stabilized, 2ml of the reaction product was taken, and the content of tetramethylpiperidinol in the reaction product was detected by gas chromatography (GC). The yield of tetramethylpiperidinol after 120h was 90.76% as determined by GC.
[0111] The mass percentages involved in step (4) refer to the mass percentage of each auxiliary material relative to powder C.
[0112] Comparative Example 2
[0113] The amount of metal salt added in step (1) was changed to: 546g nickel nitrate hexahydrate, 101g aluminum nitrate nonahydrate, and 69g magnesium nitrate hexahydrate. Other operations were the same as in Comparative Example 1. The resulting catalyst was denoted as Ni. 70 Al 10 Mg 10 After the reaction stabilized, 2 ml of the reaction product was taken, and the content of tetramethylpiperidinol in the reaction product was detected by gas chromatography (GC). The yield of tetramethylpiperidinol after 120 h was 87.63% as determined by GC.
[0114] Comparative Example 3
[0115] Ni 70 Mg 10 Mo 10 Preparation of / MCM-41 catalyst: Ni was synthesized by equal volume impregnation method. 70 Mg 10 Mo 10For the / MCM-41 catalyst, firstly, 39g of nickel nitrate hexahydrate, 4.9g of magnesium nitrate hexahydrate, and 3.4g of ammonium molybdate tetrahydrate were dissolved in 35g of pure water to obtain a metal salt impregnation solution. Then, 70g of 20-30 mesh strips of MCM-41 were weighed and impregnated in equal volume. After impregnation, the catalyst was allowed to stand at room temperature for 8 hours, then dried at 120℃ for 12 hours, and finally calcined in a muffle furnace at 450℃ for 5 hours. The resulting catalyst is denoted as Ni. 70 Mg 10 Mo 10 / MCM-41.
[0116] The fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine: 50 ml of the above catalyst was measured and packed into a fixed-bed reactor, and the reactor was installed. A feed solution with a mass ratio of triacetone amine to isopropanol of 1:4 was prepared. The feed solution was then subjected to a 4-hour hydrogenation process. -1 The gas space velocity was continuously introduced into the fixed-bed reactor. The volume ratio of feed liquid to hydrogen was 1:60. The reaction temperature was 120℃ and the reaction pressure was 1.5MPa. After the reaction stabilized, 2ml of the reaction product was taken, and the content of tetramethylpiperidinol in the reaction product was detected by gas chromatography (GC). The yield of tetramethylpiperidinol after 120h was 96.21% as determined by GC.
[0117] Comparative Example 4
[0118] Ni 70 Mg 10 Mo 10 Preparation of γ-Al2O3 catalyst: Ni was synthesized by equal-volume impregnation method. 70 Mg 10 Mo 10 For the γ-Al₂O₃ catalyst, firstly, 39g of nickel nitrate hexahydrate, 4.9g of magnesium nitrate hexahydrate, and 3.4g of ammonium molybdate tetrahydrate were dissolved in 23g of pure water to obtain a metal salt impregnation solution. Then, 70g of 20-30 mesh strips of γ-Al₂O₃ were weighed and impregnated in equal volume. After impregnation, the catalyst was allowed to stand at room temperature for 8 hours, then dried at 120℃ for 12 hours, and finally calcined in a muffle furnace at 450℃ for 5 hours to obtain the corresponding Ni catalyst. 70 Mg 10 Mo 10 / γ-Al2O3.
[0119] The fixed-bed hydrogenation synthesis of tetramethylpiperidinol from triacetone amine: 50 ml of the above catalyst was measured and packed into a fixed-bed reactor, and the reactor was installed. A feed solution with a mass ratio of triacetone amine to isopropanol of 1:4 was prepared. The feed solution was then subjected to a 4-hour hydrogenation process. -1The gas space velocity was continuously introduced into the fixed-bed reactor. The volume ratio of feed liquid to hydrogen was 1:60. The reaction temperature was 120℃ and the reaction pressure was 1.5MPa. After the reaction stabilized, 2ml of the reaction product was taken, and the content of tetramethylpiperidinol in the reaction product was detected by gas chromatography (GC). The yield of tetramethylpiperidinol after 120h was 97.25% as determined by GC.
[0120] H2-TPR analysis chromatograms of the catalysts prepared in Example 1 and Comparative Examples 1-4 are shown below. Figure 1 As shown, the catalyst obtained in Example 1 has the lowest hydrogen reduction temperature and two relatively strong peaks, which is attributed to the presence of both Ni and Mo reduction centers in the catalyst. Since the catalyst obtained in the example has a large H2-TPR peak area, its reduction requires a large amount of hydrogen. Comparative Examples 1, 3, and 4 all have both Ni and Mo reduction centers, and their H2-TPR analysis graphs all show two reduction peaks; however, due to the different catalyst structures, the intensity of the Mo reduction peak varies.
[0121] Gas chromatography was used to compare the catalytic activity and stability of the catalysts prepared in Example 1 and Comparative Examples 1-4 in the continuous hydrogenation of triacetone amine to tetramethylpiperidinol. Figure 2 As shown. The catalyst prepared in Example 1 exhibits high catalytic activity and stability. After 120 hours of catalytic reaction, the average yield of tetramethylpiperidinol was 99.51%, and the yield remained relatively stable around this value for each sample. The catalysts prepared in Comparative Examples 1, 3, and 4 initially showed high reactivity and high yields of tetramethylpiperidinol. However, with increasing reaction time, the yields of tetramethylpiperidinol decreased to 72.15%, 90.16%, and 94.59%, respectively. This is because: the catalyst in Comparative Example 1 lacked the stabilizing agent Mg, resulting in a faster decrease in catalyst stability; the catalyst in Comparative Example 3 was prepared using an impregnation method with MCM-41 as the support, resulting in lower catalyst strength, and both its activity and stability decreased with increasing reaction time; the catalyst in Comparative Example 4 was also prepared using an impregnation method, and as the reaction proceeded, the active material was lost, leading to a decrease in both catalyst activity and stability. The catalyst prepared in Comparative Example 2 had a low initial reaction rate of only 92.82%. As the reaction time increased, the yield of tetramethylpiperidinol decreased to 81.71%, which was due to the lack of a second active center, Mo, in the catalyst.
[0122] A schematic diagram illustrating the catalytic stability of the catalyst prepared in Example 1 in the continuous hydrogenation of triacetone amine to tetramethylpiperidinol is shown below. Figure 3As shown in the figure. Samples were taken every 4 hours, with 2 ml of the reaction solution collected. Gas chromatography was used to determine the yield of tetramethylpiperidinol and the residual triacetone amine. After 16 weeks (nearly 2700 hours) of continuous use, the average yield of tetramethylpiperidinol was 99.5%, and the average residual triacetone amine was 0.1%. The catalyst exhibits high catalytic activity and stability, and has significant industrial application value.
[0123] The SEM image of the catalyst prepared in Example 1 is shown below. Figure 4 As shown, the catalyst is composed of fine particles, which allows the active centers of the catalyst to fully contact the raw materials, resulting in a high triacetone amine conversion rate in the catalytic reaction; the spherical structure is relatively stable, which also gives the catalyst high catalytic stability.
[0124] It should be noted that the above content merely illustrates the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. For those skilled in the art, various improvements and modifications can be made without departing from the principle of the present invention, and all such improvements and modifications fall within the scope of protection of the claims of the present invention.
Claims
1. A method for preparing a highly efficient and stable catalyst for the hydrogenation of triacetone amine to tetramethylpiperidinol, characterized in that, Includes the following steps: (1) Dissolve nickel nitrate hexahydrate, aluminum nitrate nonahydrate, magnesium nitrate hexahydrate and ammonium molybdate tetrahydrate in pure water to obtain solution A; (2) Anhydrous sodium carbonate is dissolved in pure water to obtain solution B; (3) Slowly add solution A to solution B until pH = 8~10, then stop adding. Stir for 30 minutes, then filter, wash, dry and calcin to obtain powder C; (4) After the powder C and the excipients are mixed evenly, they are extruded into strips by an extruder. After being placed at room temperature, they are dried, calcined, sieved, cut into strips and reduced to obtain a catalyst with a length of 3~5mm, denoted as Ni. w Al x Mg y Mo z ; In step (1), the molar ratio of nickel nitrate hexahydrate, aluminum nitrate nonahydrate, magnesium nitrate hexahydrate and ammonium molybdate tetrahydrate is 30~70:10~50:10:1.4; the mass ratio of nickel nitrate hexahydrate to water is 4~16:
125.
2. The method for preparing a highly efficient and stable catalyst for the hydrogenation of triacetone amine to tetramethylpiperidinol according to claim 1, characterized in that, In step (2), the concentration of anhydrous sodium carbonate in solution B is 1.0~2.0 mol / L.
3. The method for preparing a highly efficient and stable catalyst for the hydrogenation of triacetone amine to tetramethylpiperidinol according to claim 1, characterized in that, In step (3), the calcination temperature is 400~600℃ and the calcination time is 3~7h.
4. The method for preparing a highly efficient and stable catalyst for the hydrogenation of triacetone amine to tetramethylpiperidinol according to claim 1, characterized in that, In step (4), the excipients are water, guar gum powder, water glass and citric acid monohydrate; the mass ratio of powder C, water, guar gum powder, water glass and citric acid monohydrate is 1:0.1~0.4:0.05~0.1:0.1~0.5:0.01~0.
04.
5. The method for preparing a highly efficient and stable catalyst for the hydrogenation of triacetone amine to tetramethylpiperidinol according to claim 1, characterized in that, In step (4), the calcination temperature is 450~650℃ and the calcination time is 2~4h; the reduction temperature is 400~600℃ and the reduction time is 3~6h.
6. A highly efficient and stable catalyst for the hydrogenation synthesis of tetramethylpiperidinol from triacetone amine, prepared by the method according to any one of claims 1-5.
7. The application of a highly efficient and stable catalyst prepared by the method according to any one of claims 1-5 in the hydrogenation of triacetone amine to tetramethylpiperidinol.
8. The application of the highly efficient and stable catalyst according to claim 7 in the hydrogenation of triacetone amine to tetramethylpiperidinol, characterized in that, The application The process includes the following steps: a catalyst is packed into a fixed-bed reactor and installed inside the reactor; a triacetone amine isopropanol feedstock solution is prepared; the feedstock solution and hydrogen are continuously introduced into the fixed-bed reactor; the reaction is carried out continuously at a certain temperature and pressure; after the reaction stabilizes, the reaction product is taken; and the content of tetramethylpiperidinol in the reaction product is detected by gas chromatography.
9. The application of the highly efficient and stable catalyst according to claim 8 in the hydrogenation of triacetone amine to tetramethylpiperidinol, characterized in that, In a fixed-bed reactor with an inner diameter of 3 cm and a length of 80 cm, 25-75 ml of catalyst is packed; the feed solution is a mixture of triacetone amine and isopropanol in a mass ratio of 1:1-4; the feed space velocity of the feed solution is 2-6 h⁻¹. -1 The volume ratio of the raw material liquid to hydrogen is 1:30~120; the reaction temperature is 110~130℃; and the reaction pressure is 1.3~1.7MPa.