Catalyst for preparing epoxypropane by propylene epoxidation and method for preparing epoxypropane by propylene epoxidation

Abstract

The application discloses a catalyst for preparing propylene oxide by propylene epoxidation, which comprises a nitrogen-containing ligand and a TS-1 molecular sieve loaded with metal oxide; the content of metal in the metal oxide is 0.01%-2% based on 100% of the mass of the TS-1 molecular sieve; the silicon-titanium ratio in the TS-1 molecular sieve is 30-200; and the metal in the metal oxide loaded on the TS-1 molecular sieve is in-situ coordinated with the nitrogen-containing ligand to form a catalyst in the process of preparing propylene oxide by propylene epoxidation. By using the catalyst, the safety hidden danger caused by the excessively high concentration of hydrogen peroxide in the traditional liquid-phase propylene epoxidation preparation method is solved, the problem that the pore of a titanium-silicon molecular sieve catalyst is easily blocked and deactivated is solved, and the conversion rate of hydrogen peroxide with a concentration of 5%-40%, the yield and selectivity of propylene oxide are effectively improved.

Description

Technical Field

[0001] This invention belongs to the field of chemical technology, specifically relating to a catalyst for the propylene epoxidation process to produce propylene oxide and a method for preparing propylene oxide by propylene epoxidation. Background Technology

[0002] Propylene oxide (PO) is an important basic organic chemical raw material, ranking third in production volume among propylene derivatives after polypropylene and acrylonitrile. Currently, the main industrial production methods for propylene oxide are the chlorohydrin process and the co-oxidation process. The chlorohydrin process uses olefins and chlorine as raw materials, has a relatively short process flow, mature technology, high operating load flexibility, good product selectivity, high yield, and relatively safe production. It also has low requirements for the purity of the propylene raw material and requires less investment. However, the process suffers from severe equipment corrosion, high Cl2 consumption, and the generation of large amounts of wastewater and waste residue. While the co-oxidation process overcomes the pollution, corrosion, and chlorine resource requirements of the chlorohydrin process, it has a long process flow, high investment, large by-product volume, and limited market access. With increasing market demand, the two traditional main industrial methods, the chlorohydrin process and the co-oxidation process, are no longer sufficient to meet current atom economy and green chemistry requirements. The production of propylene oxide (HPPO) by oxidizing propylene with hydrogen peroxide as an oxygen source has gradually replaced the chlorohydrin process due to its greener process and simpler flow.

[0003] Currently, the HPPO production process uses TS-1 as a catalyst, with a hydrogen peroxide concentration of 50%-70% (mostly 50%). High concentrations of hydrogen peroxide pose significant safety risks during transportation, storage, and use. Furthermore, the pores of TS-1 are prone to clogging, leading to catalyst deactivation and decreased reactivity. All of these factors contribute to the high cost and energy consumption of the HPPO process. Despite considerable efforts by researchers both domestically and internationally in developing catalysts for the HPPO process and their applications, progress remains slow.

[0004] For example, Chinese patent document CN101045716 uses phosphotungsten heteropolyacid as a catalyst to achieve the catalytic epoxidation reaction of propylene. A high-concentration H2O2 aqueous solution is used as the oxidant, increasing the concentration of propylene oxide in the reaction system. In the presence of 40%-90% hydrogen peroxide, the conversion rate of hydrogen peroxide can reach over 90%, reducing separation energy consumption. Simultaneously, it reduces the water content in the system, decreasing the hydrolysis of the heteropolyacid catalyst and improving its stability. However, the catalyst cannot be recovered, leading to higher costs, and even lower concentrations of hydrogen peroxide cannot achieve efficient production of ethylene oxide.

[0005] Chinese patent document CN1103765C proposes using active oxides such as hydrogen peroxide or organic peroxides on heterogeneous catalysts such as titanium silica molecular sieves or silica-supported titanium dioxide to oxidize propylene to propylene oxide. However, this catalyst has a low efficiency in utilizing hydrogen peroxide and poor recyclability.

[0006] Chinese patent document CN113145116A discloses an integral TS-1 catalyst. A metal framework is placed in a chemical vapor deposition (CVD) furnace, and a mixture of raw material gases and other gases is introduced into the furnace. Heating is then performed to grow a Si-doped carbon layer on the metal framework. After growth, the catalyst is cooled to obtain the integral TS-1 catalyst support. However, this catalyst reacts at a relatively high temperature, resulting in the generation of a significant amount of byproducts such as propylene glycol ethers.

[0007] Chinese patent document CN111718313A discloses a method for preparing propylene oxide using TS-1. The catalyst used in this method is TS-1. The oxygen content in the exhaust gas varies under different conditions, requiring complex operations to ensure that the oxygen content in the exhaust gas meets the requirements for safe operation.

[0008] Chinese patent document CN112978757A discloses a method for preparing a sheet-like titanium-silicon molecular sieve TS-1. This sheet-like titanium-silicon molecular sieve TS-1 has an MFI topology, which improves the exothermic diffusion path in the straight pore direction of the molecular sieve, thereby increasing the conversion rate of hydrogen peroxide and the selectivity of propylene oxide. However, this catalyst also suffers from instability and poor recyclability.

[0009] Chinese patent document CN109876857A discloses a method for catalyzing the epoxidation of propylene in microchannels using a metalloporphyrin-supported titanium-silicon molecular sieve. This method produces a metalloporphyrin-supported titanium-silicon molecular sieve that significantly increases the yield of propylene oxide and is suitable for direct scale-up to industrial production. However, the yield of propylene oxide obtained by this catalyst and method is still relatively low, only around 80%, and the selectivity is also low.

[0010] Chinese patent document CN111085205A discloses a method for preparing a structurally modified TS-1 catalyst based on porous carbon metal. This catalyst can improve the selectivity of propylene oxide, solve the problem of catalyst separation from the reaction liquid, significantly improve production efficiency, and reduce production costs. However, the catalyst has low selectivity, which can lead to excessive ineffective decomposition of hydrogen peroxide and excessively high oxygen concentration at the end of the reaction.

[0011] Chinese patent document CN102558100A discloses a method for propylene epoxidation catalyzed by titanium-silicon molecular sieves. An inorganic salt alkaline buffer solution is added to the propylene epoxidation reaction zone. This inorganic salt alkaline buffer solution is a mixed solution composed of a weak base salt and its conjugate acid. The inorganic salt alkaline buffer solution is composed of a weak base such as an ammonium salt, borate, phosphate, or carbonate, and its conjugate acid. Adding a small amount of inorganic alkaline buffer solution to the reaction solution can effectively inhibit the ring-opening reaction between the product propylene oxide and the solvent. The buffer can be an alkaline buffer solvent such as an ammonium salt, borate, or phosphate. The selectivity for propylene oxide can reach 97.49%, the yield of propylene oxide is 96.56%, and the conversion rate of hydrogen peroxide is 99.12%. However, this method uses a buffer salt, which generates a large amount of saline wastewater, putting pressure on environmental protection.

[0012] Chinese patent document CN112791744A discloses a modified titanium-silicon molecular sieve, comprising: a titanium-silicon molecular sieve, a metal compound, and a non-metal oxide. In the presence of this catalyst and auxiliaries, cyclohexene is mixed with hydrogen peroxide and subjected to an oxidation reaction to obtain cyclohexane oxide. The auxiliaries are selected from pyridine, imidazole, methylimidazolium, etc. The modified titanium-silicon molecular sieve exhibits excellent stability, effectively improving the oxidation activity of cyclohexene, and demonstrating good selectivity and reaction stability in the catalytic synthesis of cyclohexane oxide. This method modifies the molecular sieve by adding metals and non-metals to improve the reaction activity. However, the catalytic system of this method is only suitable for the epoxidation of cyclohexene, and its effect is poor when applied to the oxidation of propylene to ethylene oxide. Summary of the Invention

[0013] To address the problems and areas for improvement in existing technologies, this invention provides a catalyst for the production of propylene oxide via propylene epoxidation. This catalyst solves the safety hazards caused by excessively high hydrogen peroxide concentrations in traditional propylene epoxidation methods, as well as the problem of easy pore blockage and deactivation of titanium-silicon molecular sieve catalysts.

[0014] To achieve the above objectives, the present invention provides the following technical solution:

[0015] A catalyst for the propylene epoxidation process to produce propylene oxide comprises a nitrogen-containing ligand and a TS-1 molecular sieve supported on a metal oxide.

[0016] Based on the mass of the TS-1 molecular sieve as 100%, the metal content in the metal oxide is 0.01%-2%; the silicon-to-titanium ratio in the TS-1 molecular sieve is 30-200.

[0017] The metal in the metal oxide supported on the TS-1 molecular sieve coordinates in situ with the nitrogen-containing ligand to form a catalyst during the propylene epoxidation process to produce propylene oxide.

[0018] Optionally, in the catalyst for the propylene epoxidation process to produce propylene oxide provided by the present invention, the metal is selected from any one of copper, iron, manganese, nickel, and cobalt.

[0019] Optionally, in the catalyst for the propylene epoxidation process to propylene oxide provided by the present invention, the nitrogen-containing compound...

[0020] Among them, R 1 R 2 R 3 R 4 R 5 R 6 R 7 R 8 R 9 R 10 R 11 R 12 R 13 R 14 R 15 R 16 R 17 R 18 R 19 R 20 Each is independently selected from hydrogen, unsubstituted or substituted aryl groups (C6-C10), straight-chain or branched alkyl groups (C1-C5), and cycloalkyl groups (C5-C6);

[0021] Preferred, R 1 R 5 R 6 Each is independently selected from hydrogen, methyl, ethyl, or phenyl;

[0022] R 2 R 3 R 4 R 15 R 16 R 17 R 18 R 19 R 20 Each of the following is independently selected from hydrogen, methyl, ethyl, phenyl, cyclohexane, or cyclopentane;

[0023] R 7 R 8 R 9 R 10 R 11 R 12 R 13 R 14 Each is independently selected from hydrogen, methyl, or ethyl.

[0024] This invention also provides a method for preparing propylene oxide by propylene epoxidation, using the catalyst described above for the propylene epoxidation method, and comprising the following steps:

[0025] A catalyst was formed by in-situ coordination of TS-1 molecular sieve containing nitrogen ligands and supported metal oxides in a system of propylene, 5%-40% hydrogen peroxide and solvent, and the catalyst was used to catalyze the epoxidation reaction of propylene to obtain propylene oxide.

[0026] The molar ratio of the nitrogen-containing ligand to the hydrogen peroxide is (0.01-1):100.

[0027] Optionally, in the method for preparing propylene oxide by propylene epoxidation provided by the present invention, the epoxidation reaction is carried out at a temperature of 25-80°C for a time of 0.5-6 hours.

[0028] Optionally, in the method for preparing propylene oxide by epoxidation of propylene provided by the present invention, the pressure of the epoxidation reaction is 0.1-1 MPa.

[0029] Optionally, in the method for preparing propylene oxide by propylene epoxidation provided by the present invention, the solvent is selected from any one of anhydrous methanol, water, anhydrous ethanol, acetonitrile, isopropanol, anhydrous acetone, industrial methanol, and industrial ethanol.

[0030] Optionally, in the method for preparing propylene oxide by epoxidation provided by the present invention, the epoxidation reaction is carried out in a reaction vessel and includes the following steps:

[0031] Nitrogen-containing ligands, TS-1 molecular sieves loaded with metal oxides, solvents, and 5%-40% hydrogen peroxide are added to a reactor. The gas in the reactor is then replaced with nitrogen and propylene gas, respectively. Propylene is introduced to carry out an epoxidation reaction. After the reaction is completed, the reactor is separated to obtain crude propylene oxide and a catalyst.

[0032] Optionally, in the method for preparing propylene oxide by epoxidation provided by the present invention, the epoxidation reaction is carried out in a fixed-bed reactor and includes the following steps:

[0033] TS-1 molecular sieves loaded with metal oxides are packed into a fixed bed. Then, a mixed solution of nitrogen-containing ligands, solvent, and 5%-40% hydrogen peroxide is added to the fixed bed, and propylene gas is introduced to carry out an epoxidation reaction to obtain propylene oxide. Preferably, the flow rate of the mixed solution of nitrogen-containing ligands, solvent, and 5%-40% hydrogen peroxide added to the fixed bed is 1-3 ml / min relative to the catalyst usage. -1 g -1 ;

[0034] In the epoxidation reaction, the molar ratio of propylene gas to hydrogen peroxide is (1-2):1.

[0035] The preparation method of the TS-1 molecular sieve supported on metal oxides mentioned in this invention is not specifically limited, and any conventional method in the industry can be used, such as the following method:

[0036] 1) After thoroughly mixing the solution of the metal precursor with the titanium-silicon molecular sieve TS-1, let it stand (e.g., sonicate for 0.5-2 hours and then let it stand for 8-15 hours);

[0037] 2) Add the alkaline liquid to the solution in step 1), keep it at room temperature for 10-15 hours under stirring, filter, wash with deionized water until neutral, dry at 80-120℃ for 10-15 hours, and calcine in a muffle furnace at 400-800℃ for 3-12 hours to obtain TS-1 molecular sieve loaded with metal oxide.

[0038] In step 1), the metal precursor is selected from soluble metal salts, such as any one of copper acetate, copper nitrate, ferric acetate, ferric nitrate, manganese acetate, manganese nitrate, nickel acetate, nickel nitrate, cobalt nitrate, and cobalt acetate.

[0039] The solvent used in the solution of the metal precursor is one or more of water, methanol, ethanol, acetone, and isopropanol.

[0040] In step 2), the alkaline solution can be selected from one or more of the following: sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, ammonia, and hydrazine hydrate. The concentration and amount of the alkaline solution are not specifically limited, as long as it can adjust the pH of the system to 8-14. The atmosphere during calcination can be any of air, nitrogen, or argon.

[0041] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0042] This invention addresses the problems existing in the use of the TS-1 catalyst for the epoxidation of propylene to prepare ethylene oxide. It improves upon the traditional titanium-silicon molecular sieve catalyst by first loading an inexpensive metal onto a titanium-silicon TS-1 molecular sieve, and then forming a nitrogen-metal / TS-1 molecular sieve catalyst in situ with a nitrogen-containing ligand during the propylene epoxidation reaction. By using the catalyst of this invention, not only are the safety hazards caused by excessively high hydrogen peroxide concentrations and the problem of easy pore blockage and deactivation of titanium-silicon molecular sieve catalysts in traditional liquid-phase propylene epoxidation methods solved, but the conversion rate of hydrogen peroxide at concentrations of 5%-40%, the yield of propylene oxide, and the selectivity are also effectively improved. This catalyst is suitable not only for reactors but also for fixed-bed reactors, achieving a hydrogen peroxide conversion rate of 98% and a propylene oxide selectivity of 99%. Furthermore, when using the catalyst provided by this invention to prepare ethylene oxide from propylene, the solvent in the reaction can be recycled, resulting in no waste, low cost, and high efficiency. Compared to adding nitrogen-containing ligands during the reaction process in this invention, if the nitrogen-containing ligands are doped with titanium-silicon molecular sieves and calcined, the resulting catalyst is added to the reaction system, resulting in a significant reduction in catalyst reaction efficiency. Detailed Implementation

[0043] The present invention will now be described in detail through embodiments. It should be noted that the following embodiments are only for further illustration of the present invention and should not be construed as limiting the scope of protection of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above description.

[0044] For any experimental steps or conditions not specified in the examples and comparative examples, the procedures and conditions described in the literature in this field can be followed. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0045] Example 1

[0046] 0.15 g of copper acetate was completely dissolved in 500 ml of ethanol. Then, 500 g of TS-1 (Si:Ti = 200:1) was added, and the mixture was sonicated for 1 hour. After standing for 12 hours, NaOH solution was added to adjust the pH to 10. The mixture was then refluxed at 80°C for 12 hours, followed by vacuum distillation to remove most of the solvent. The mixture was then dried in a drying oven at 100°C for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 400°C under air for 3 hours. The final yield was 0.01% (mass content) Cu / TS-1.

[0047] 8g of 0.01% Cu / TS-1, 90mg of 25% ammonia, 640ml of anhydrous methanol, and 192ml of 10% hydrogen peroxide were added to the PTFE lining of a metal reactor. The reactor was sealed, and the gas in the reactor was completely purged with nitrogen and propylene gas, respectively. The reactor was then placed in a metal bath and heated to 25°C. The propylene gas was then turned on, and the gas pressure was maintained at 0.6MPa. After reacting for 6 hours, the reactor was placed in an ice-water bath to cool down. The reactor was then opened, and the catalyst and reaction liquid were separated by centrifugation. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. 2ml of the liquid was taken and titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0048] Example 2

[0049] 8.3 g of ferric acetate was completely dissolved in 500 ml of methanol. Then, 500 g of TS-1 (Si:Ti = 200:1) was added, and the mixture was sonicated for 1 hour. After standing for 12 hours, KOH solution was added to adjust the pH to 12. The mixture was then refluxed at 80°C for 12 hours, followed by vacuum distillation to remove most of the solvent. The mixture was then dried in a drying oven at 100°C for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 450°C under air for 5 hours. The final product was 0.5% Fe / TS-1.

[0050] 8 g of 0.5% Fe / TS-1, 400 mg of 2,2'-bipyridine, 640 ml of anhydrous ethanol, and 128 ml of 15% hydrogen peroxide were added to the PTFE liner of a metal reactor. The reactor was sealed, and the gas in the reactor was completely purged with nitrogen and propylene gas, respectively. The reactor was then placed in a metal bath and heated to 40°C. The propylene gas was then turned on, and the gas pressure was maintained at 0.7 MPa. After reacting for 0.5 h, the reactor was placed in an ice-water bath to cool down. The reactor was then opened, and the catalyst and reaction liquid were separated by centrifugation. 2 ml of the liquid was taken and the yield of propylene oxide was determined by GC. 2 ml of the liquid was taken and titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0051] Example 3

[0052] 16.6 g of ferric acetate was completely dissolved in 800 ml of methanol. Then, 500 g of TS-1 (Si:Ti = 100:1) was added, and the mixture was sonicated for 1 hour. After standing for 12 hours, KOH solution was added to adjust the pH to 12. The mixture was then refluxed at 80°C for 12 hours, followed by vacuum distillation to remove most of the solvent. The mixture was then dried in a drying oven at 100°C for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 450°C under air for 5 hours. This yielded 1% Fe / TS-1.

[0053] 8g of 1% Fe / TS-1, 400mg of 2-2'-bipyridine, 640ml of anhydrous ethanol, and 128ml of 15% hydrogen peroxide were added to the PTFE lining of a metal reactor. The reactor was sealed, and the gas in the reactor was completely purged with nitrogen and propylene gas, respectively. The reactor was then placed in a metal bath and heated to 40°C. The propylene gas was then turned on, and the gas pressure was maintained at 0.5MPa. After reacting for 0.5h, the reactor was placed in an ice-water bath to cool down. The reactor was then opened, and the catalyst and reaction liquid were separated by centrifugation. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. 2ml of the liquid was taken and titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0054] Example 4

[0055] 2.5 g of cobalt acetate was completely dissolved in 500 ml of ethanol. Then, 500 g of TS-1 (Si:Ti = 200:1) was added, and the mixture was sonicated for 1 hour. After standing for 12 hours, Na₂CO₃ solution was added to adjust the pH to 10. The mixture was then refluxed at 80°C for 12 hours, followed by vacuum distillation to remove most of the solvent. The mixture was then dried in a drying oven at 100°C for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 600°C under N₂ atmosphere for 7 hours. The final product was 0.1% Co / TS-1.

[0056] 8g of 0.1% Co / TS-1, 200mg of pyridine, 640ml of anhydrous acetone, and 64ml of 30% hydrogen peroxide were added to the PTFE lining of a metal reactor. The reactor was sealed, and the gas in the reactor was completely purged with nitrogen and propylene gas, respectively. The reactor was then placed in a metal bath and heated to 50°C. The propylene gas was then turned on, and the gas pressure was maintained at 0.3MPa. After 2 hours, the reactor was placed in an ice-water bath to cool down. The reactor was then opened, and the catalyst and reaction liquid were separated by centrifugation. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. 2ml of the liquid was taken and titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0057] Example 5

[0058] 37.5 g of cobalt acetate was completely dissolved in 500 ml of ethanol. Then, 500 g of TS-1 (Si:Ti = 200:1) was added, and the mixture was sonicated for 1 hour. After standing for 12 hours, Na₂CO₃ solution was added to adjust the pH to 10. The mixture was then refluxed at 80°C for 12 hours, followed by vacuum distillation to remove most of the solvent. The mixture was then dried in a drying oven at 100°C for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 600°C under N₂ atmosphere for 7 hours. This yielded 1.5% Co / TS-1.

[0059] 8g of 1.5% Co / TS-1, 200mg of pyridine, 640ml of anhydrous acetone, and 64ml of 30% hydrogen peroxide were added to the PTFE lining of a metal reactor. The reactor was sealed, and the gas in the reactor was completely purged with nitrogen and propylene gas, respectively. The reactor was then placed in a metal bath and heated to 50°C. The propylene gas was then turned on, and the gas pressure was maintained at 0.3MPa. After 2 hours, the reactor was placed in an ice-water bath to cool down. The reactor was then opened, and the catalyst and reaction liquid were separated by centrifugation. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. 2ml of the liquid was taken and titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0060] Example 6

[0061] 5g of cobalt nitrate hexahydrate was completely dissolved in 500ml of deionized water. Then, 500g of TS-1 (Si:Ti = 200:1) was added, and the mixture was sonicated for 1 hour, allowed to stand for 12 hours, and then K₂CO₃ solution was added to adjust the pH to 10. After reflux at 80℃ for 12 hours, most of the solvent was removed by vacuum distillation. The mixture was then dried in a drying oven at 100℃ for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 450℃ under air for 9 hours. The final product was 0.2% Co / TS-1.

[0062] 8 g of 0.2% Co / TS-1, 998 mg of 2-2'-bipyridine, 640 ml of isopropanol, and 64 ml of 30% hydrogen peroxide were added to the PTFE liner of a metal reactor. The reactor was sealed, and the gas in the reactor was completely purged with nitrogen and propylene gas, respectively. The reactor was then placed in a metal bath and heated to 70°C. The propylene gas was then turned on, and the gas pressure was maintained at 0.1 MPa. After 2 hours, the reactor was placed in an ice-water bath to cool down. The reactor was then opened, and the catalyst and reaction liquid were separated by centrifugation. 2 ml of the liquid was taken and the yield of propylene oxide was determined by GC. 2 ml of the liquid was taken and titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0063] Example 7

[0064] 5g of cobalt nitrate hexahydrate was completely dissolved in 500ml of deionized water. Then, 500g of TS-1 (Si:Ti = 50:1) was added, and the mixture was sonicated for 1 hour, allowed to stand for 12 hours, and K₂CO₃ solution was added to adjust the pH to 10. After reflux at 80℃ for 12 hours, most of the solvent was removed by vacuum distillation. The mixture was then dried in a drying oven at 100℃ for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 450℃ under air for 9 hours. The final product was 0.2% Co / TS-1.

[0065] 8 g of 0.2% Co / TS-1, 998 mg of 2-2'-bipyridine, 640 ml of isopropanol, and 64 ml of 30% hydrogen peroxide were added to the PTFE liner of a metal reactor. The reactor was sealed, and the gas in the reactor was completely purged with nitrogen and propylene gas, respectively. The reactor was then placed in a metal bath and heated to 80°C. The propylene gas was then turned on, and the gas pressure was maintained at 0.3 MPa. After 2 hours, the reactor was placed in an ice-water bath to cool down. The reactor was then opened, and the catalyst and reaction liquid were separated by centrifugation. 2 ml of the liquid was taken and the yield of propylene oxide was determined by GC. 2 ml of the liquid was taken and titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0066] Example 8

[0067] 5g of cobalt nitrate hexahydrate was completely dissolved in 500ml of deionized water. Then, 500g of TS-1 (Si:Ti = 200:1) was added, and the mixture was sonicated for 1 hour, allowed to stand for 12 hours, and then K₂CO₃ solution was added to adjust the pH to 10. After reflux at 80℃ for 12 hours, most of the solvent was removed by vacuum distillation. The mixture was then dried in a drying oven at 100℃ for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 450℃ under air for 9 hours. The final product was 0.2% Co / TS-1.

[0068] 8 g of 0.2% Co / TS-1, 998 mg of 2-2'-bipyridine, 640 ml of isopropanol, and 64 ml of 30% hydrogen peroxide were added to the PTFE liner of a metal reactor. The reactor was sealed, and the gas in the reactor was completely purged with nitrogen and propylene gas, respectively. The reactor was then placed in a metal bath and heated to 80°C. The propylene gas was then turned on, and the gas pressure was maintained at 0.3 MPa. After 2 hours, the reactor was placed in an ice-water bath to cool down. The reactor was then opened, and the catalyst and reaction liquid were separated by centrifugation. 2 ml of the liquid was taken and the yield of propylene oxide was determined by GC. 2 ml of the liquid was taken and titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0069] Example 9

[0070] 45g of manganese nitrate tetrahydrate was completely dissolved in 500ml of acetone. Then, 500g of TS-1 (Si:Ti = 200:1) was added, and the mixture was sonicated for 1 hour, allowed to stand for 12 hours, and then NH3·H2O solution was added to adjust the pH to 14. After reflux at 80℃ for 12 hours, most of the solvent was removed by vacuum distillation. The mixture was then dried in a drying oven at 100℃ for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 700℃ under argon for 12 hours. The final product was 2% Mn / TS-1.

[0071] 8g of 2% Mn / TS-1, 100mg of 1,10-phenanthroline, 640ml of anhydrous methanol, and 64ml of 5% hydrogen peroxide were added to the PTFE lining of a metal reactor. The reactor was sealed, and the gas in the reactor was completely purged with nitrogen and propylene gas, respectively. The reactor was then placed in a metal bath and heated to 70°C. The propylene gas was then turned on, and the gas pressure was maintained at 1MPa. After 4 hours, the reactor was placed in an ice-water bath to cool down. The reactor was then opened, and the catalyst and reaction liquid were separated by centrifugation. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. 2ml of the liquid was taken and titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0072] Example 10

[0073] 1.1 g of manganese acetate tetrahydrate was completely dissolved in 500 ml of ethanol. Then, 500 g of TS-1 (Si:Ti = 30:1) was added. The solution was sonicated for 1 hour, then allowed to stand for 12 hours. NH3·H2O solution was added to adjust the pH to 10. After reflux at 80°C for 12 hours, most of the solvent was removed by vacuum distillation. The solution was then dried in a drying oven at 100°C for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 450°C under air for 5 hours. The final product was 0.5% Mn / TS-1.

[0074] 8g of 0.5% Mn / TS-1, 400mg of cyclopentanamine, 640ml of anhydrous acetonitrile, and 384ml of 5% hydrogen peroxide were added to the PTFE lining of a metal reactor. The reactor was sealed, and the gas in the reactor was completely purged with nitrogen and propylene gas, respectively. The reactor was then placed in a metal bath and heated to 40°C. The propylene gas was then turned on, and the gas pressure was maintained at 0.4MPa. After 6 hours, the reactor was placed in an ice-water bath to cool down. The reactor was then opened, and the catalyst and reaction liquid were separated by centrifugation. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. 2ml of the liquid was taken and titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0075] Example 11

[0076] 4.5 g of nickel nitrate was completely dissolved in 500 ml of isopropanol. Then, 500 g of TS-1 (Si:Ti = 200:1) was added. The solution was sonicated for 1 hour, then allowed to stand for 12 hours. NH3·H2O solution was added to adjust the pH to 10. After reflux at 80°C for 12 hours, most of the solvent was removed by vacuum distillation. The solution was then dried in a drying oven at 100°C for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 800°C under N2 atmosphere for 6 hours. This yielded 0.5% Ni / TS-1.

[0077] 8g of 0.5% Ni / TS-1, 600mg of terpyridine, 640ml of industrial methanol, and 48ml of 40% hydrogen peroxide were added to the PTFE lining of a metal reactor. The reactor was sealed, and the gas in the reactor was completely purged with nitrogen and propylene gas, respectively. The reactor was then placed in a metal bath and heated to 60°C. The propylene gas was then turned on, and the gas pressure was maintained at 0.8MPa. After 1.5h, the reactor was placed in an ice-water bath to cool down. The reactor was then opened, and the catalyst and reaction liquid were separated by centrifugation. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. 2ml of the liquid was taken and titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0078] Example 12

[0079] 33.2 g of ferric acetate was completely dissolved in 500 ml of methanol. Then, 500 g of TS-1 (Si:Ti = 200:1) was added, and the mixture was sonicated for 1 hour. After standing for 12 hours, KOH solution was added to adjust the pH to 12. The mixture was then refluxed at 80°C for 12 hours, followed by vacuum distillation to remove most of the solvent. The mixture was then dried in a drying oven at 100°C for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 450°C under argon for 5 hours. This yielded 2% Fe / TS-1.

[0080] First, the 2% Fe / TS-1 catalyst was tableted using a tablet press, then sieved, and 5g of the catalyst was packed into a fixed bed. A solution of 800ml methanol, 240ml 5% hydrogen peroxide, and 70mg cyclohexylamine was prepared and pumped into the fixed bed using a plunger pump at a flow rate of 5ml / min. Propylene gas was introduced at a flow rate of 112ml / min. The pressure in the fixed bed was maintained at 0.4MPa, and the temperature at 40℃. The reaction mixture was separated by a gas-liquid separator. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. Another 2ml of the liquid was titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0081] Example 13

[0082] 0.11 g of manganese acetate tetrahydrate was completely dissolved in 500 ml of anhydrous ethanol. Then, 500 g of TS-1 (Si:Ti = 200:1) was added. The solution was sonicated for 1 hour, then allowed to stand for 12 hours. NH3·H2O solution was added to adjust the pH to 10. After reflux at 80°C for 12 hours, most of the solvent was removed by vacuum distillation. The solution was then dried in a drying oven at 100°C for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 450°C under air for 5 hours. The final result was 0.05% Mn / TS-1.

[0083] First, the 0.05% Mn / TS-1 catalyst was tableted using a tablet press, then sieved, and 5g of the catalyst was packed into a fixed bed. A solution of 800ml methanol, 40ml 30% hydrogen peroxide, and 240mg 2-2'-bipyridine was prepared and pumped into the fixed bed using a plunger pump at a flow rate of 5ml / min. Propylene gas was introduced at a flow rate of 120ml / min. The pressure in the fixed bed was maintained at 0.6MPa, and the temperature at 40℃. The reaction mixture was separated by a gas-liquid separator. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. Another 2ml of the liquid was titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0084] Example 14

[0085] 0.75 g of copper acetate was completely dissolved in 500 ml of industrial ethanol. Then, 500 g of TS-1 (Si:Ti = 200:1) was added, and the mixture was sonicated for 1 hour. After standing for 12 hours, NaOH solution was added to adjust the pH to 10. The mixture was then refluxed at 80°C for 12 hours, followed by vacuum distillation to remove most of the solvent. The mixture was then dried in a drying oven at 100°C for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 400°C under air for 3 hours. The final product was 0.05% Cu / TS-1.

[0086] First, the 0.05% Cu / TS-1 catalyst was tableted using a tablet press, then sieved, and 5g of the catalyst was packed into a fixed bed. A solution of 800ml methanol, 30ml 40% hydrogen peroxide, and 240mg 2-2'-bipyridine was prepared and pumped into the fixed bed using a plunger pump at a flow rate of 5ml / min. Propylene gas was introduced at a flow rate of 130ml / min. The pressure in the fixed bed was maintained at 0.6MPa, and the temperature at 40℃. The reaction mixture was separated by a gas-liquid separator. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. Another 2ml of the liquid was titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0087] Example 15

[0088] 0.25 g of cobalt nitrate hexahydrate was completely dissolved in 500 ml of deionized water. Then, 500 g of TS-1 (Si:Ti = 200:1) was added, and the mixture was sonicated for 1 hour, allowed to stand for 12 hours, and K₂CO₃ solution was added to adjust the pH to 10. After reflux at 80 °C for 12 hours, most of the solvent was removed by vacuum distillation. The mixture was then dried in a drying oven at 100 °C for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 450 °C under oxygen for 9 hours. The final product was 0.01% Co / TS-1.

[0089] First, the 0.01% Co / TS-1 catalyst was tableted using a tablet press, then sieved, and 5g of the tablet was packed into a fixed bed. A solution of 800ml methanol, 30ml 40% hydrogen peroxide, and 140mg 25% NH3·H2O was prepared and pumped into the fixed bed using a plunger pump at a flow rate of 5ml / min. Propylene gas was introduced at a flow rate of 140ml / min. The pressure in the fixed bed was maintained at 0.6MPa, and the temperature at 40℃. The reaction mixture was separated by a gas-liquid separator. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. Another 2ml of the liquid was titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0090] Example 16

[0091] 22 mg of manganese acetate tetrahydrate was completely dissolved in 500 ml of ethanol. Then, 500 g of TS-1 (Si:Ti = 200:1) was added. The solution was sonicated for 1 hour, allowed to stand for 12 hours, and then NH3·H2O solution was added to adjust the pH to 10. After reflux at 80 °C for 12 hours, most of the solvent was removed by vacuum distillation. The solution was then dried in a drying oven at 100 °C for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 450 °C under air for 5 hours. The final result was 0.01% Mn / TS-1.

[0092] First, the 0.01% Mn / TS-1 catalyst was tableted using a tablet press, then sieved, and 5g of the catalyst was packed into a fixed bed. A solution of 800ml methanol, 60ml 20% hydrogen peroxide, and 4mg 25% NH3·H2O was prepared and pumped into the fixed bed using a plunger pump at a flow rate of 5ml / min. Propylene gas was introduced at a flow rate of 112ml / min. The pressure in the fixed bed was maintained at 0.6MPa, and the temperature at 40℃. The reaction mixture was separated by a gas-liquid separator. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. Another 2ml of the liquid was titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0093] Example 17

[0094] 4.5g of nickel nitrate was completely dissolved in 500ml of isopropanol. Then, 500g of TS-1 (Si:Ti = 200:1) was added, and the mixture was sonicated for 1 hour. After standing for 12 hours, NH3·H2O solution was added to adjust the pH of the solvent to 10. After reflux at 80℃ for 12 hours, most of the solvent was removed by vacuum distillation. The mixture was then dried in a drying oven at 100℃ for 12 hours. Finally, the dried TS-1 was placed in a muffle furnace and calcined at 800℃ under N2 gas for 6 hours to obtain 0.5% Ni / TS-1.

[0095] 8g of 0.5% Ni / TS-1, 300mg of 2,3-dimethyl-2,3-butanediamine, 640ml of anhydrous methanol, and 48ml of 40% hydrogen peroxide were added to the PTFE lining of a metal reactor. The reactor was sealed, and the gas in the reactor was completely purged with nitrogen and propylene gas, respectively. The reactor was then placed in a metal bath and heated to 60°C. The propylene gas was then turned on, and the gas pressure was maintained at 0.8MPa. After 1.5h, the reactor was placed in an ice-water bath to cool down. The reactor was then opened, and the catalyst and reaction liquid were separated by centrifugation. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. 2ml of the liquid was taken and titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0096] Example 18

[0097] 4.5 g of nickel nitrate was completely dissolved in 500 ml of isopropanol. Then, 500 g of TS-1 (Si:Ti = 200:1) was added, and the mixture was sonicated for 1 hour, allowed to stand for 12 hours, and then the pH was adjusted to 10 by adding NH3·H2O solution. After reflux at 80℃ for 12 hours, most of the solvent was removed by vacuum distillation. The mixture was then dried in a drying oven at 100℃ for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 800℃ under N2 atmosphere for 6 hours. The final product was 0.5% Ni / TS-1.

[0098] 8g of 0.5% Ni / TS-1, 300mg of terpyridine, 640ml of anhydrous methanol, and 48ml of 40% hydrogen peroxide were added to the PTFE lining of a metal reactor. The reactor was sealed, and the gas in the reactor was completely purged with nitrogen and propylene gas, respectively. The reactor was then placed in a metal bath and heated to 60°C. The propylene gas was then turned on, and the gas pressure was maintained at 0.8MPa. After 1.5h, the reactor was placed in an ice-water bath to cool down. The reactor was then opened, and the catalyst and reaction liquid were separated by centrifugation. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. 2ml of the liquid was taken and titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0099] Example 19

[0100] 4.5 g of nickel nitrate was dissolved completely in 500 ml of isopropanol. Then, 500 g of TS-1 (Si:Ti = 200:1) was added, and the mixture was sonicated for 1 hour. After standing for 12 hours, NH3·H2O solution was added to adjust the pH of the system to 10. After reflux at 80 °C for 12 hours, most of the solvent was removed by vacuum distillation. The mixture was then dried in a drying oven at 100 °C for 12 hours. Finally, the dried TS-1 was placed in a muffle furnace and calcined at 800 °C under N2 gas for 6 hours to obtain 0.5% Ni / TS-1.

[0101] 8 g of 0.5% Ni / TS-1, 280 mg of 2,2'-bipyridine, 640 ml of anhydrous acetonitrile, and 48 ml of 40% hydrogen peroxide were added to the PTFE lining of a metal reactor. The reactor was sealed, and the gas in the reactor was completely purged with nitrogen and propylene gas, respectively. The reactor was then placed in a metal bath and heated to 60 °C. The propylene gas was then turned on, and the gas pressure was maintained at 0.8 MPa. After 1.5 h, the reactor was placed in an ice-water bath to cool down. The reactor was then opened, and the catalyst and reaction liquid were separated by centrifugation. 2 ml of the liquid was taken and the yield of propylene oxide was determined by GC. 2 ml of the liquid was taken and titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0102] Example 20

[0103] 4.5 g of nickel nitrate was completely dissolved in 500 ml of isopropanol. Then, 500 g of TS-1 (Si:Ti = 200:1) was added. The solution was sonicated for 1 hour and allowed to stand for 12 hours. NH3·H2O solution was added to adjust the pH to 10. After reflux at 80°C for 12 hours, most of the solvent was removed by vacuum distillation. The solution was then dried in a drying oven at 100°C for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 800°C under N2 atmosphere for 6 hours. This yielded 0.5% Ni / TS-1.

[0104] 8g of 0.5% Ni / TS-1, 800mg of ligand L3, 640ml of industrial ethanol, and 48ml of 40% hydrogen peroxide were added to the PTFE lining of a metal reactor. The reactor was sealed, and the gas in the reactor was completely purged with nitrogen and propylene gas, respectively. The reactor was then placed in a metal bath and heated to 60°C. The propylene gas was then turned on, and the gas pressure was maintained at 0.8MPa. After 1.5h, the reactor was placed in an ice-water bath to cool down. The reactor was then opened, and the catalyst and reaction liquid were separated by centrifugation. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. 2ml of the liquid was taken and titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0105] Example 21

[0106] 0.25 g of copper acetate was completely dissolved in 500 ml of industrial ethanol. Then, 500 g of TS-1 (Si:Ti = 200:1) was added, and the mixture was sonicated for 1 hour. After standing for 12 hours, NaOH solution was added to adjust the pH to 10. The mixture was then refluxed at 80°C for 12 hours, followed by vacuum distillation to remove most of the solvent. The mixture was then dried in a drying oven at 100°C for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 400°C in air for 3 hours. The final result was 0.01% Cu / TS-1.

[0107] First, the 0.01% Cu / TS-1 catalyst was tableted using a tablet press, then sieved, and 5g of the tablet was packed into a fixed bed. 800ml of methanol, 240ml of 5% hydrogen peroxide, and 6mg of 25% hydrazine solution were prepared and pumped into the fixed bed using a plunger pump at a flow rate of 5ml / min. Propylene gas was introduced at a flow rate of 150ml / min. The pressure in the fixed bed was maintained at 0.6MPa, and the temperature at 40℃. The reaction mixture was separated by a gas-liquid separator. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. Another 2ml of the liquid was titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0108] Example 22

[0109] The catalyst was prepared as shown in Example 21.

[0110] First, the 0.01% Cu / TS-1 catalyst was tableted using a tablet press, then sieved, and 5g of the tablet was packed into a fixed bed. 800ml of methanol, 30ml of 40% hydrogen peroxide, and 0.04ml of 25% ammonia solution were prepared and pumped into the fixed bed using a plunger pump at a flow rate of 10ml / min. Propylene gas was introduced at a flow rate of 200ml / min. The pressure in the fixed bed was maintained at 0.6MPa, and the temperature at 60℃. The reaction mixture was separated by a gas-liquid separator. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. Another 2ml of the liquid was titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0111] Example 23

[0112] The catalyst was prepared as shown in Example 16.

[0113] First, the 0.01% Mn / TS-1 catalyst was tableted using a tablet press, then sieved, and 5g of the catalyst was packed into a fixed bed. A solution of 800ml methanol, 60ml 20% hydrogen peroxide, and 240mg 2-2'-bipyridine was prepared and pumped into the fixed bed using a plunger pump at a flow rate of 15ml / min. Propylene gas was introduced at a flow rate of 168ml / min. The pressure in the fixed bed was maintained at 0.7MPa, and the temperature at 80℃. The reaction mixture was separated by a gas-liquid separator. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. Another 2ml of the liquid was titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0114] Example 24

[0115] The catalyst was prepared as shown in Example 16.

[0116] First, the 0.01% Mn / TS-1 catalyst was tableted using a tablet press, then sieved, and 1g of catalyst was packed into a fixed bed. A solution of 800ml methanol, 60ml 20% hydrogen peroxide, and 350mg ligand L1 was prepared and pumped into the fixed bed using a plunger pump at a flow rate of 1ml / min. Propylene gas was introduced at a flow rate of 20ml / min. The pressure in the fixed bed was maintained at 0.6MPa, and the temperature at 50℃. The reaction mixture was separated by a gas-liquid separator. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. Another 2ml of the liquid was titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0117] Example 25

[0118] The catalyst was prepared as shown in Example 16.

[0119] First, the 0.01% Mn / TS-1 catalyst was tableted using a tablet press, then sieved, and 1g of catalyst was packed into a fixed bed. A solution of 800ml methanol, 60ml 20% hydrogen peroxide, and 50mg ligand L2 was prepared and pumped into the fixed bed using a plunger pump at a flow rate of 1ml / min. Propylene gas was introduced at a flow rate of 20ml / min. The pressure in the fixed bed was maintained at 0.4MPa, and the temperature at 40℃. The reaction mixture was separated by a gas-liquid separator. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. Another 2ml of the liquid was titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0120] Example 26

[0121] 2.5 g of cobalt acetate was completely dissolved in 500 ml of ethanol. Then, 500 g of TS-1 (Si:Ti = 200:1) was added, and the mixture was sonicated for 1 hour. After standing for 12 hours, Na₂CO₃ solution was added to adjust the pH to 10. The mixture was then refluxed at 80°C for 12 hours, followed by vacuum distillation to remove most of the solvent. The mixture was then dried in a drying oven at 100°C for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 600°C under N₂ atmosphere for 7 hours. The final product was 0.1% Co / TS-1.

[0122] First, the 0.1% Co / TS-1 catalyst was tableted using a tablet press, then sieved, and 5g of the tablet was packed into a fixed bed. 800ml of methanol, 40ml of 30% hydrogen peroxide, and 200mg of pyridine were prepared and pumped into the fixed bed using a plunger pump at a flow rate of 5ml / min. Propylene gas was introduced at a flow rate of 130ml / min. The pressure in the fixed bed was maintained at 0.4MPa, and the temperature at 40℃. The reaction mixture was separated using a gas-liquid separator. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. Another 2ml of the liquid was titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0123] The corresponding ligand structures in the above embodiments are shown below:

[0124]

[0125] Among them, ligand L1 was prepared according to the following reference [1], ligand L2 was prepared according to the following reference [2], and ligand L3 was prepared according to the following reference [3].

[0126] [1] Zamalyutin, VV; et al. Russian Journal ofOrganic Chemistry(2018), 54(3),419-425.

[0127] [2]Vermaak, Vincent; et al. Advanced Synthesis&Catalysis (2020), 362(24), 5788-5793.

[0128] [3]Stolzenberg, Alan M.; Glazer, Paul A.; Foxman, Bruce M. InorganicChemistry(1986), 25(7),983-91.

[0129] Comparative Example 1

[0130] 0.15 g of copper acetate was completely dissolved in 500 ml of ethanol. Then, 500 g of TS-1 (Si:Ti = 200:1) was added, and the mixture was sonicated for 1 hour. After standing for 12 hours, NaOH solution was added to adjust the pH to 10. The mixture was refluxed at 80°C for 12 hours, and most of the solvent was removed by vacuum distillation. The mixture was then dried in a drying oven at 100°C for 12 hours. The dried TS-1 was then impregnated with 500 g of 25% ammonia for 12 hours, dried again in a drying oven at 100°C for 12 hours, and finally calcined in air at 400°C for 3 hours. The final product was 0.01% Cu-N / TS-1.

[0131] 8g of 0.01% Cu-N / TS-1, 640ml of anhydrous methanol, and 192ml of 10% hydrogen peroxide were added to the PTFE lining of a metal reactor. The reactor was sealed, and the gas in the reactor was completely purged with nitrogen and propylene gas, respectively. The reactor was then placed in a metal bath and heated to 25°C. The propylene gas was then turned on, and the gas pressure was maintained at 0.6MPa. After reacting for 6 hours, the reactor was placed in an ice-water bath to cool. The reactor was then opened, and the catalyst and reaction liquid were separated by centrifugation. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. 2ml of the liquid was taken and titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0132] Comparative Example 2

[0133] 8g of TS-1 (Si:Ti = 200:1), 640ml of industrial methanol, and 192ml of 10% hydrogen peroxide were added to the PTFE lining of a metal reactor. The reactor was sealed, and the gas in the reactor was completely purged with nitrogen and propylene gas, respectively. The reactor was then placed in a metal bath and heated to 25°C. The propylene gas was then turned on, and the gas pressure was maintained at 0.6MPa. After reacting for 6 hours, the reactor was placed in an ice-water bath to cool down. The reactor was then opened, and the catalyst and reaction liquid were separated by centrifugation. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. 2ml of the liquid was taken and titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0134] Comparative Example 3

[0135] 45g of nickel nitrate was completely dissolved in 500ml of isopropanol. Then, 500g of TS-1 (Si:Ti = 200:1) was added. The solution was sonicated for 1 hour and allowed to stand for 12 hours. NH3·H2O solution was added to adjust the pH to 10. After reflux at 80℃ for 12 hours, most of the solvent was removed by vacuum distillation. The solution was then dried in a drying oven at 100℃ for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 800℃ under N2 atmosphere for 6 hours. This yielded 5% Ni / TS-1.

[0136] 8g of 5% Ni / TS-1, 800mg of ligand L3, 640ml of industrial ethanol, and 48ml of 40% hydrogen peroxide were added to the PTFE lining of a metal reactor. The reactor was sealed, and the gas in the reactor was completely purged with nitrogen and propylene gas, respectively. The reactor was then placed in a metal bath and heated to 60°C. The propylene gas was then turned on, and the gas pressure was maintained at 0.8MPa. After 1.5h, the reactor was placed in an ice-water bath to cool down. The reactor was then opened, and the catalyst and reaction liquid were separated by centrifugation. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. 2ml of the liquid was taken and titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0137] Comparative Example 4

[0138] 22 mg of manganese acetate tetrahydrate was completely dissolved in 500 ml of ethanol. Then, 500 g of TS-1 (Si:Ti = 200:1) was added. The solution was sonicated for 1 hour, allowed to stand for 12 hours, and then NH3·H2O solution was added to adjust the pH to 10. After reflux at 80 °C for 12 hours, most of the solvent was removed by vacuum distillation. The solution was then dried in a drying oven at 100 °C for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 450 °C under air for 5 hours. The final result was 0.01% Mn / TS-1.

[0139] First, the 0.01% Mn / TS-1 catalyst was tableted using a tablet press, then sieved, and 5g of the tablet was packed into a fixed bed. 800ml of methanol, 60ml of 20% hydrogen peroxide, and 4g of 25% NH3·H2O solution were prepared and pumped into the fixed bed using a plunger pump at a flow rate of 5ml / min. Propylene gas was introduced at a flow rate of 220ml / min. The pressure in the fixed bed was maintained at 0.6MPa, and the temperature at 40℃. The reaction mixture was separated using a gas-liquid separator. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. Another 2ml of the liquid was titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0140] Comparative Example 5

[0141] 2.5g of cobalt acetate and 2.5g of ammonium molybdate were completely dissolved in 500ml of ethanol. Then, 500g of TS-1 (Si:Ti = 50:1) was added, and the mixture was sonicated for 1 hour. After standing for 12 hours, Na2CO3 solution was added to adjust the pH to 10. The mixture was then refluxed at 80℃ for 12 hours, followed by vacuum distillation to remove most of the solvent. The mixture was then dried in a drying oven at 120℃ for 12 hours. Finally, the dried TS-1 was calcined in a muffle furnace at 600℃ under N2 atmosphere for 7 hours. The final product was 0.1% Co-0.5% Mo / TS-1.

[0142] First, the 0.1% Co-0.5% Mo TS-1 catalyst was tableted using a tablet press, then sieved, and 5g of the tablet was packed into a fixed bed. 800ml of methanol, 60ml of 20% hydrogen peroxide, and 200mg of pyridine were prepared and pumped into the fixed bed using a plunger pump at a flow rate of 5ml / min. Propylene gas was introduced at a flow rate of 120ml / min. The pressure in the fixed bed was maintained at 0.4MPa, and the temperature at 40℃. The reaction mixture was separated by a gas-liquid separator. 2ml of the liquid was taken and the yield of propylene oxide was determined by GC. Another 2ml of the liquid was titrated with KMnO4 solution until the solution turned red and the color remained unchanged for 30 seconds. The conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide in this reaction were calculated. The specific results are shown in Table 1.

[0143] Calculation formula:

[0144] Hydrogen peroxide conversion rate = (n1-n2) / n1*100%

[0145] Propylene oxide yield = n3 / n1 * 100%

[0146] Hydrogen peroxide effective utilization rate = n3 / (n1-n2)*100%

[0147] Where n1 is the number of moles of hydrogen peroxide before the reaction, n2 is the number of moles of hydrogen peroxide after the reaction, and n3 is the number of moles of propylene oxide produced.

[0148] Table 1

[0149]

[0150]

[0151] As shown in the table above, this invention significantly improves the selectivity of propylene oxide by modifying the TS-1 supported metal and adjusting the nitrogen-containing ligands added to the reaction system, increasing it from 29% to 99%. Furthermore, this catalyst is suitable for a wide range of hydrogen peroxide concentrations, achieving good yields and selectivity in concentrations ranging from 5% to 40%. In addition, the catalyst is recyclable, greatly reducing costs.

[0152] Specifically, as can be seen from the comparison between Example 1 and Comparative Example 1, after adjusting the order of adding nitrogen-containing ligands, although the final conversion rate of hydrogen peroxide is high, the yield of propylene oxide is low and the effective utilization rate of hydrogen peroxide is low, indicating that it cannot suppress the generation of by-products.

[0153] As can be seen from the comparison between Example 1 and Comparative Example 2, when no metal was used to support the TS-1 catalyst and no nitrogen-containing ligand was added, the conversion rate of hydrogen peroxide, the yield of propylene oxide, and the effective utilization rate of hydrogen peroxide were all significantly reduced, indicating that the propylene epoxidation reaction was less effective when TS-1 was used alone as a catalyst.

[0154] As can be seen from the comparison between Example 20 and Comparative Example 3, increasing the metal loading can improve the conversion rate of hydrogen peroxide, but it also leads to an increase in by-products.

[0155] As can be seen from the comparison between Example 16 and Comparative Example 4, excessive use of nitrogen-containing ligands will lead to a significant decrease in the conversion rate of hydrogen peroxide and the yield of propylene oxide, and will also increase the amount of by-products.

[0156] As can be seen from the comparison between Example 26 and Comparative Example 5, when TS-1 is modified with metal and non-metal oxides and pyridine is used as a catalyst for propylene epoxidation, the hydrogen peroxide conversion rate, propylene oxide yield and effective utilization rate of hydrogen peroxide are significantly reduced.

[0157] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A method for producing propylene oxide via propylene epoxidation, characterized in that, The epoxidation reaction is carried out in a fixed-bed reactor and includes the following steps: TS-1 molecular sieves loaded with metal oxides are filled into a fixed bed, then a mixed solution of nitrogen-containing ligands, solvent and 5%-40% hydrogen peroxide is added to the fixed bed, and propylene gas is introduced to carry out the epoxidation reaction to obtain propylene oxide; during the epoxidation reaction, the molar ratio of propylene gas to hydrogen peroxide is (1-2):

1. Based on the mass of the TS-1 molecular sieve as 100%, the mass content of the metal in the metal oxide is 0.01%-2%, and the silicon-to-titanium ratio in the TS-1 molecular sieve is 30-200; The metal in the metal oxide supported on the TS-1 molecular sieve coordinates with the nitrogen-containing ligand in situ to form a catalyst during the propylene epoxidation process to produce propylene oxide. The metal is selected from any one of copper, iron, manganese, nickel, and cobalt; The molar ratio of the nitrogen-containing ligand to the hydrogen peroxide is (0.01-1):100; The nitrogen-containing ligand is selected from any one of them; Among them, R 1 R 2 R 3 R 4 R 5 R 6 R 7 R 8 R 9 R 10 R 11 R 12 R 13 R 14 R 15 R 16 R 17 R 18 R 19 R 20 Each of the following is independently selected from hydrogen, unsubstituted or substituted aryl groups from C6 to C10, straight-chain or branched alkyl groups from C1 to C5, and cycloalkyl groups from C5 to C6.

2. The method as described in claim 1, characterized in that, R 1 R 5 R 6 Each is independently selected from hydrogen, methyl, ethyl, or phenyl; R 2 R 3 R 4 R 15 R 16 R 17 R 18 R 19 R 20 Each of the following is independently selected from hydrogen, methyl, ethyl, phenyl, cyclohexane, or cyclopentane; R 7 R 8 R 9 R 10 R 11 R 12 R 13 R 14 Each is independently selected from hydrogen, methyl, or ethyl.

3. The method as described in claim 1, characterized in that, The epoxidation reaction is carried out at a temperature of 25-80℃ for a time of 0.5-6 hours.

4. The method as described in claim 1, characterized in that, The pressure of the epoxidation reaction is 0.1-1 MPa.

5. The method as described in claim 1, characterized in that, The solvent is selected from any one of anhydrous methanol, water, anhydrous ethanol, acetonitrile, isopropanol, anhydrous acetone, industrial methanol, and industrial ethanol.

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