Method for preparing 1, 2-propylene glycol based on built-in membrane filter

Abstract

The invention relates to a method for preparing 1, 2-propylene glycol based on a built-in membrane filter, which is characterized by comprising the following steps: respectively and continuously feeding propylene and hydrogen peroxide into a reactor, reacting the propylene with the hydrogen peroxide in the presence of a catalyst to obtain a reaction product, discharging a trace amount of non-condensable gas from the top of the reactor, a reaction product is sent to a catalyst separator for oil-water phase separation to obtain an upper-layer oil phase and a lower-layer water phase; an upper-layer oil phase is circulated back to the reactor, a lower-layer water phase is filtered into a turbid solution and a clear solution through a built-in membrane filter in the catalyst separator, the turbid solution is pressurized through a catalyst circulating pump, then is fed into a reaction cooler to be cooled and is circulated back to the reactor, and the clear solution is fed into a reaction product separation system to separate 1, 2-propylene glycol from reaction byproducts. According to the method, the separation of unreacted propylene and the titanium silicalite molecular sieve / reaction product is realized by utilizing the hydrophilicity of the titanium silicalite molecular sieve and the water solubility of 1, 2-propylene glycol, the separation of the titanium silicalite molecular sieve and the reaction product is realized by utilizing a membrane filter arranged in a catalyst separator, and the efficient operation of reaction and catalyst separation is realized.

Description

Technical Field

[0001] This invention relates to a method for producing organic chemical raw materials, and more specifically, to a method for preparing 1,2-propanediol. Background Technology

[0002] 1,2-Propanediol is a colorless, odorless, viscous, hygroscopic liquid that is an important raw material for the production of unsaturated polyesters, polyurethane resins, epoxy resins, surfactants, and plasticizers.

[0003] Currently, the main industrial production processes for 1,2-propanediol include transesterification, glycerol hydrogenolysis, and propylene oxide hydration.

[0004] Transesterification is the most important process for producing 1,2-propanediol. Although transesterification is a mature technology with high atom utilization, it suffers from poor product quality, a long process flow, and high energy consumption.

[0005] CN101848884A discloses a method for preparing 1,2-propanediol by hydrogenation of glycerol. This method employs at least three fixed-bed reactors connected in series. In the presence of a heterogeneous copper catalyst, at a temperature of 173-185°C and a pressure of 200 bar, glycerol undergoes hydrogenation to yield 1,2-propanediol, with a glycerol conversion of 99.61% and a 1,2-propanediol selectivity of 97.37%. Due to the harsh reaction conditions and high equipment requirements, this method limits its industrial application.

[0006] CN108779053A discloses a technology for preparing 1,2-propanediol from propylene via hydrogen peroxide reaction, which features a short process and low energy consumption. This technology uses propylene and hydrogen peroxide as raw materials, and heteropolytungstic acid + phase transfer catalyst + inorganic acid as catalysts. It can achieve a two-step reaction in one reactor: propylene and hydrogen peroxide react to produce propylene oxide, and propylene oxide reacts with water to produce 1,2-propanediol. However, due to the use of a homogeneous catalyst system, catalyst separation is relatively difficult. Summary of the Invention

[0007] In a solvent-free heterogeneous system, the hydrophilicity of titanium silicate molecular sieves and the water solubility of 1,2-propanediol enable oil-water phase separation. The titanium silicate molecular sieves are uniformly dispersed in the aqueous phase, allowing for the separation of unreacted propylene from the titanium silicate molecular sieves / reaction products. Furthermore, a built-in membrane filter in a catalyst separator further separates the titanium silicate molecular sieves from the reaction products, forming a continuous and complete method for producing 1,2-propanediol, encompassing both synthesis and catalyst separation. Based on this, the present invention is formulated.

[0008] Therefore, the object of the present invention is to provide a method for preparing 1,2-propanediol suitable for solvent-free heterogeneous systems.

[0009] To achieve the above objectives, this invention provides a method for preparing 1,2-propanediol based on a built-in membrane filter. The method involves continuously feeding propylene and hydrogen peroxide into a reactor. In the presence of a catalyst, propylene and hydrogen peroxide react to obtain reaction products. A small amount of non-condensable gas is discharged from the top of the reactor. The reaction products are sent to a catalyst separator for oil-water separation to obtain an upper oil phase and a lower aqueous phase. The upper oil phase is recycled back to the reactor, while the lower aqueous phase is filtered into turbid liquid and clear liquid by the built-in membrane filter in the catalyst separator. The turbid liquid is pressurized by a catalyst circulation pump and sent to a reaction heat exchanger for cooling before being recycled back to the reactor. The clear liquid is sent to a reaction product separation system for the separation of 1,2-propanediol and reaction byproducts. The built-in membrane filter comprises one or more parallel membrane modules. Each membrane module consists of multiple membrane tubes and a corresponding clear liquid collection pipe. One end of the membrane tube is closed, and the other end is open and connected through the collection pipe. The clear liquid permeates from the outside of the membrane tube to the inside, is collected by the collection pipe, and is discharged through the clear liquid discharge line.

[0010] The method provided by this invention involves the reaction of propylene and hydrogen peroxide in a heterogeneous system to synthesize 1,2-propanediol and the subsequent separation of the catalyst. This method utilizes the hydrophilicity of the titanium silicate molecular sieve and the water solubility of 1,2-propanediol to separate unreacted propylene from the titanium silicate molecular sieve / reaction products. A membrane filter integrated into the catalyst separator further separates the titanium silicate molecular sieve from the reaction products. This achieves highly efficient operation of the reaction and catalyst separation processes.

[0011] The preparation method provided by the present invention also has the following advantages: (1) no solvent is used, thus avoiding solvent separation and reducing energy consumption; (2) propylene and reaction products are separated by oil-water phase separation, thus reducing energy consumption; (3) the problem of catalyst sedimentation is solved. Attached Figure Description

[0012] Figure 1 Schematic diagram of single-reactor reaction and catalyst separation process.

[0013] Figure 2 Schematic diagram of a three-reactor series reaction and catalyst separation process.

[0014] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the following detailed description to explain the invention, but do not constitute a limitation thereof.

[0015] In the attached diagram:

[0016] 1. Propylene; 2. Hydrogen peroxide; 3. Co-catalyst; 4. Reactor; 4-1. Reactor; 4-2. Reactor; 4-3. Reactor; 5. Reaction products; 6. Catalyst separator; 7. Upper oil phase; 8. Propylene circulation pump; 9. Lower aqueous phase; 10. Catalyst circulation pump; 11. Membrane filter; 12. Clear liquid; 13. Turbid liquid; 14. Reaction heat exchanger; 15. Non-condensable gas; 16. Propylene total feed. Detailed Implementation

[0017] A method for preparing 1,2-propanediol based on a built-in membrane filter is characterized in that propylene and hydrogen peroxide are continuously fed into a reactor. In the presence of a catalyst, propylene and hydrogen peroxide react to obtain reaction products. A small amount of non-condensable gas is discharged from the top of the reactor, and the reaction products are sent to a catalyst separator for oil-water separation to obtain an upper oil phase and a lower aqueous phase. The upper oil phase is recycled back to the reactor, and the lower aqueous phase is filtered into turbid liquid and clear liquid by the built-in membrane filter in the catalyst separator. The turbid liquid is pressurized by a catalyst circulation pump and sent to a reaction heat exchanger for cooling and then recycled back to the reactor. The clear liquid is sent to a reaction product separation system for the separation of 1,2-propanediol and reaction byproducts. The built-in membrane filter includes one or more parallel membrane modules. Each membrane module consists of multiple membrane tubes and a corresponding clear liquid collection pipe. One end of the membrane tube is closed, and the other end is open and connected through the collection pipe. The clear liquid permeates from the outside of the membrane tube to the inside of the membrane tube, is collected by the collection pipe, and is discharged through the clear liquid discharge line.

[0018] In the method provided by this invention, the reactor includes multiple reactors connected in series, with a total number of 2 to 6 reactors, preferably 2 to 3. When there are multiple reactors, they can be connected in series, and overflow operation is achieved between the multiple reactors through elevation differences. The multiple reactors are arranged from high to low according to the elevation difference to achieve material flow. When multiple reactors are connected in series, hydrogen peroxide is fed in a multi-stage feeding method with multiple reactors feeding simultaneously.

[0019] In the method provided by this invention, a hydrogen peroxide feed distributor is provided in each reactor. The distributor can be a loop type, a branch type, or a nozzle type, with a loop type being the preferred type.

[0020] In the method provided by this invention, the reactor is equipped with a stirrer, with 1 to 3 layers of stirring paddles, and the stirring paddles can be paddle-type, propeller-type, turbine-type, or a combination of two or more of these types. The reactor is also equipped with baffles, with 2 to 6 baffles in total. An overflow weir is provided in the reactor to better facilitate material discharge. A flow guide tube is provided in the reactor to enhance mixing and optimize the fluid flow pattern.

[0021] In the method provided by this invention, a stirring paddle is provided at the bottom of the catalyst separator to stir the aqueous phase material in the lower layer, preventing the titanium-silicon molecular sieve from settling due to excessive residence time. The stirring paddle is a propeller type, turbine type, anchor type, frame type, or a combination thereof, and the number of stirring paddle layers is 1 to 3. An overflow weir is provided inside the catalyst separator.

[0022] In the method provided by this invention, a backwashing line is provided on the membrane filter's clarified liquid outlet line for backwashing the membrane tube. The backwashing medium is either the reaction clarified liquid or deionized water. Since the reaction clarified liquid has a composition similar to that of the reaction system materials and has little impact on the reaction, the reaction clarified liquid is preferred as the backwashing medium. The membrane tube is made of ceramic, metal, or high-density polyethylene, preferably metal or high-density polyethylene. The membrane tube has a filtration accuracy of 0.01–50 μm.

[0023] In the method provided by this invention, the catalyst includes a titanium-silicon molecular sieve and a co-catalyst.

[0024] The titanium-silicon molecular sieve catalyst is a titanium-silicon molecular sieve or a titanium-silicon molecular sieve containing tin and / or zirconium. The titanium species in the framework of the titanium-silicon molecular sieve have excellent performance in activating oxidants to catalyze the oxidation of organic molecules. The titanium-silicon molecular sieve is a common type, such as MFI type titanium-silicon molecular sieve (e.g., TS-1 molecular sieve), MEL type titanium-silicon molecular sieve (e.g., TS-2 molecular sieve), BEA type titanium-silicon molecular sieve (e.g., Ti-β molecular sieve), MWW type titanium-silicon molecular sieve (e.g., Ti-MCM-22 molecular sieve), MOR type titanium-silicon molecular sieve (e.g., Ti-MOR molecular sieve), TUN type titanium-silicon molecular sieve (e.g., Ti-TUN molecular sieve), hexagonal titanium-silicon molecular sieve (e.g., Ti-MCM-41 molecular sieve, Ti-SBA-15 molecular sieve), and other structural titanium-silicon molecular sieves (e.g., Ti-ZSM-48 molecular sieve). Preferably, the titanium-silicon molecular sieve is at least one selected from MFI-type titanium-silicon molecular sieve, MEL-type titanium-silicon molecular sieve, and BEA-type titanium-silicon molecular sieve. More preferably, the titanium-silicon molecular sieve is an MFI-type titanium-silicon molecular sieve. The MFI-type titanium-silicon molecular sieve can be a TS-1 molecular sieve prepared by conventional methods such as hydrothermal synthesis or post-processing synthesis; it can be a titanium-silicon molecular sieve with a hierarchical porous structure (i.e., a pore distribution within the molecular sieve crystal in the range of 2-50 nm is obtained by fitting the molecular sieve pore distribution curve to the N2 adsorption-desorption curve using BJH fitting); it can be a hollow titanium-silicon molecular sieve (HTS) with an internal hollow structure (i.e., TEM characterization shows that there is one or more internal cavities within the molecular sieve crystal); or it can be a titanium-silicon molecular sieve with a plate-like, spherical, hexagonal prism shape, or an open surface. This invention does not impose specific limitations on these types. For better technical effects, the MFI-type titanium-silicon molecular sieve of this invention is more preferably a titanium-silicon molecular sieve with a hierarchical porous structure as described above and / or a hollow titanium-silicon molecular sieve (HTS) with a hollow structure.

[0025] The cocatalyst is one or more selected from phosphoric acid solution, hydrochloric acid solution, and sulfuric acid solution. Alternatively, the cocatalyst is one or more selected from cation exchange resin, tin-silicon molecular sieve, and zirconium-silicon molecular sieve. The cocatalyst may also be a combination of one or more selected from phosphoric acid solution, hydrochloric acid solution, and sulfuric acid solution with one or more selected from cation exchange resin, tin-silicon molecular sieve, and zirconium-silicon molecular sieve (e.g., synthesized according to the method described in patent CN113509958A).

[0026] When one or more of phosphoric acid solution, hydrochloric acid solution and sulfuric acid solution are used as co-catalysts, the co-catalysts are continuously added to the reactor, or the co-catalysts may be added to the reactor after being mixed with hydrogen peroxide.

[0027] When one or more of cation exchange resin, tin-silicon molecular sieve and zirconium-silicon molecular sieve are used as co-catalysts, the weight ratio of co-catalyst to titanium-silicon molecular sieve is preferably (0.2-5):1.

[0028] The co-catalyst is selected from one or more of phosphoric acid solution, hydrochloric acid solution and sulfuric acid solution, and a combination thereof selected from one or more of cation exchange resin, tin-silicon molecular sieve and zirconium-silicon molecular sieve.

[0029] In the method provided by this invention, when one or more of phosphoric acid solution, hydrochloric acid solution, and sulfuric acid solution are used as co-catalysts, the amount of co-catalyst added is adjusted to reduce the H+ content in the lower aqueous phase material of the catalyst separator. + The concentration was maintained at 10. -6 -10 mol / L, preferably maintained at a concentration of 10 mol / L. -3 -1mol / L.

[0030] The turbid liquid contains titanium-silicon molecular sieves, while the clear liquid does not contain titanium-silicon molecular sieves.

[0031] The method provided by this invention utilizes the hydrophilicity of titanium-silicon molecular sieve catalysts to effectively integrate the reaction steps and the product separation process of the built-in membrane in a solvent-free heterogeneous reaction system, thus successfully achieving oil-water phase separation. By setting a stirrer in the lower aqueous phase region of the catalyst separator, the catalyst is uniformly dispersed using a stirring paddle under the premise of oil-water phase separation, ensuring that the titanium-silicon molecular sieve catalyst is uniformly dispersed in the aqueous phase without settling.

[0032] In the method provided by this invention, the reaction temperature of propylene and hydrogen peroxide is 20-100℃, preferably 30-80℃; the propylene reacts under liquid phase conditions at a reaction pressure of 1.0-5.0 MPa, preferably 1.2-3.8 MPa. The molar ratio of propylene in the total propylene feed to hydrogen peroxide in the hydrogen peroxide feed is 1-30:1, preferably 2-10:1. The mass ratio of the circulating catalyst, titanium-silicon molecular sieve catalyst, to hydrogen peroxide is 0.2-20:1, preferably 1-5:1.

[0033] The present invention will be further described below with reference to the accompanying drawings and embodiments, but this should not be construed as limiting the present invention.

[0034] The technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. Furthermore, the following are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0035] Example 1

[0036] Propylene and hydrogen peroxide reacted in a stirred reactor with an effective volume of 5.2 L at a temperature of 45 °C and a pressure of 2.0 MPa. The reactor contained 150 g of titanium silicate molecular sieve catalyst (TiO2 mass content 2.93%, MFI structure, prepared according to the method described in Example 1 of CN1301599A). The feed rates were: 12 g / h of fresh propylene and 35 g / h of hydrogen peroxide (30 w%). A 2 mol / h H3PO4 solution was added to the reactor using the hydrogen peroxide feed line to maintain the pH of the aqueous phase in the catalyst separator at 1.75. The circulating propylene rate was 24 g / h, and the circulating catalyst rate was 100 g / h.

[0037] Both the reactor and the catalyst separator are equipped with baffles and overflow weirs. The reactor is stirred by a propeller-type agitator with a rotation speed of 500 rpm, while the catalyst separator is stirred by an anchor-type agitator with a rotation speed of 80 rpm. The catalyst separator contains a 10 mm diameter, 200 mm long sintered metal membrane tube with a filtration accuracy of 0.2 μm. The backwash medium is the filtered clear liquid.

[0038] After the device had been running stably for 6 hours, samples of the clarified liquid from the membrane filter were taken for analysis. The analysis of unreacted hydrogen peroxide in the reaction products was performed by titration, and the composition of the reaction products was determined by gas chromatography. The data are shown in Table 1. The "Other" item in Table 1 represents the sum of small amounts of byproducts such as acetaldehyde, propylene oxide, and acetic acid.

[0039] Example 2

[0040] Example 1 was repeated, with propylene reacting with hydrogen peroxide at 60°C and 2.8 MPa, while keeping other parameters unchanged. After the apparatus had been running stably for 6 hours, samples of the clarified liquid from the membrane filter were taken for analysis. The data are shown in Table 1.

[0041] Example 3

[0042] Example 1 was repeated, with propylene reacting with hydrogen peroxide at 30°C and 1.6 MPa, while keeping other parameters unchanged. After the apparatus had been running stably for 6 hours, samples of the clarified liquid from the membrane filter were taken for analysis. The data are shown in Table 1.

[0043] Example 4

[0044] Repeat Example 1, reacting propylene with hydrogen peroxide at 45°C and 2.0 MPa. The feed rates were: 35 g / h fresh propylene and 100 g / h hydrogen peroxide (30 wt%). A 2 mol / h H3PO4 solution was added to the reactor via the hydrogen peroxide feed line to maintain the pH of the aqueous phase in the catalyst separator at 1.75. The circulating propylene rate was 70 g / h, and the circulating catalyst rate was 300 g / h. After 3 hours of stable operation, samples of the clarified liquid from the membrane filter were taken for analysis. The data are shown in Table 1.

[0045] Example 5

[0046] Repeat Example 1, adding a 2 mol / h H3PO4 solution to the reactor, maintaining the pH of the aqueous phase in the catalyst separator at 5, and keeping other conditions unchanged. After the device has been running stably for 6 hours, samples of the clarified liquid from the membrane filter were taken for analysis. The data are shown in Table 1.

[0047] Example 6

[0048] Repeat Example 1, adding a 2 mol / h H2SO4 solution to the reactor, maintaining the pH of the aqueous phase in the catalyst separator at 1.75, and keeping other conditions unchanged. After the device has been running stably for 6 hours, samples of the clarified liquid from the membrane filter were taken for analysis. The data are shown in Table 1.

[0049] Example 7

[0050] Preparation of zirconium-silicon molecular sieve (MFI structure): A silicon source (tetraethyl orthosilicate, silica, calculated as silicon dioxide), zirconium propoxide, tetrapropylammonium hydroxide (25 wt%, hydroxide purity greater than 99.5%) solution, and water were mixed in a molar ratio of 1 (tetraethyl orthosilicate: silica = 1:2):0.02:0.2:30 and aged at 80°C for 5 h to obtain a sol; then the sol was crystallized at 170°C for 72 h; finally, the solid product was obtained by filtration from the slurry, and further dried at 120°C for 6 h and calcined at 550°C for 6 h to obtain a zirconium-silicon molecular sieve (ZrO2 mass content 2.17%, MFI structure).

[0051] Example 1 was repeated, with the reactor containing 150g of titanium-silicon molecular sieve catalyst and 150g of zirconium-silicon molecular sieve (MFI structure); no other acid solutions were added, the pH value was not controlled, and other conditions remained unchanged. After the device had been running stably for 6 hours, samples of the clarified liquid from the membrane filter were taken for analysis. The data are shown in Table 1.

[0052] Table 1

[0053]

Claims

1. A method for preparing 1,2-propanediol based on an embedded membrane filter, characterized in that... The method involves continuously feeding propylene and hydrogen peroxide into a reactor. In the presence of a catalyst, propylene and hydrogen peroxide react to obtain reaction products. A small amount of non-condensable gas is discharged from the top of the reactor, while the reaction products are sent to a catalyst separator for oil-water separation to obtain an upper oil phase and a lower aqueous phase. The upper oil phase is recycled back to the reactor, while the lower aqueous phase is filtered into turbid and clear liquids by a membrane filter built into the catalyst separator. The turbid liquid is pressurized by a catalyst circulation pump and sent to a reaction heat exchanger for cooling before being recycled back to the reactor. The clear liquid is sent to a reaction product separation system for the separation of 1,2-propanediol and reaction byproducts. The built-in membrane filter includes one or more parallel membrane modules. Each membrane module consists of multiple membrane tubes and a corresponding clear liquid collection pipe. One end of the membrane tube is closed, and the other end is open and connected through the collection pipe. The clear liquid permeates from the outside of the membrane tube to the inside of the membrane tube, is collected by the collection pipe, and is discharged through the clear liquid discharge line.

2. The method according to claim 1, characterized in that, The reactor comprises multiple reactors connected in series, with a total number of 2 to 6 reactors, preferably 2 to 3. Overflow operation is achieved between the multiple reactors through the height difference.

3. The method according to claim 2, characterized in that, When multiple reactors are connected in series, hydrogen peroxide is fed into the reactors in a multi-stage feeding method where multiple reactors feed simultaneously.

4. The method according to claim 1, characterized in that, The reactor is equipped with a hydrogen peroxide feed distributor, which can be a loop type, a branch type, or a nozzle type, with the loop type being the preferred type.

5. The method according to claim 1, characterized in that, The reactor is equipped with a stirrer, with 1 to 3 layers of stirring paddles, and the stirring paddles can be paddle type, propeller type, turbine type, or a combination of two or more of these stirring paddle types.

6. The method according to claim 1, characterized in that, The reactor is equipped with baffles, and the number of baffles is 2-6.

7. The method according to claim 1, characterized in that, The reactor is equipped with an overflow weir.

8. The method according to claim 1, characterized in that, The reactor is equipped with a flow guide tube.

9. The method according to claim 1, characterized in that, The catalyst separator is equipped with a stirring paddle at the bottom.

10. The method according to claim 9, characterized in that, The agitator can be a propeller, turbine, anchor, frame, or a combination thereof, and the number of agitator layers can be 1 to 3.

11. The method according to claim 1, characterized in that, The catalyst separator is equipped with an overflow weir.

12. The method according to claim 1, characterized in that, The membrane filter discharge line is equipped with a backwashing line for backwashing the membrane tubes.

13. The method according to claim 12, characterized in that, The medium for backwashing is either reaction solution or deionized water, preferably reaction solution.

14. The method according to claim 1, characterized in that, The membrane tube is made of ceramic, metal or high-density polyethylene, preferably metal or high-density polyethylene.

15. The method according to claim 1 or 14, characterized in that, The membrane tube has a filtration accuracy of 0.01~50μm.

16. The method according to claim 1, characterized in that, The catalyst includes titanium-silicon molecular sieves and a co-catalyst.

17. The method according to claim 16, characterized in that, The titanium-silicon molecular sieve is a titanium-silicon molecular sieve containing tin and / or zirconium.

18. The method according to claim 16, characterized in that, The co-catalyst is a phosphoric acid solution, a hydrochloric acid solution, or a sulfuric acid solution.

19. The method according to claim 18, characterized in that, The co-catalyst is continuously added to the reactor.

20. The method according to claim 16, characterized in that, The co-catalyst is one or more of cation exchange resin, tin-silicon molecular sieve, and zirconium-silicon molecular sieve.

21. The method according to claim 20, characterized in that, The weight ratio of the co-catalyst to the titanium-silicon molecular sieve is (0.2-5):

1.

22. The method according to claim 16, characterized in that, The co-catalyst is selected from one or more of phosphoric acid solution, hydrochloric acid solution and sulfuric acid solution, and a combination thereof selected from one or more of cation exchange resin, tin-silicon molecular sieve and zirconium-silicon molecular sieve.

23. The method according to claim 16, characterized in that, By adjusting the amount of co-catalyst added, the H in the lower aqueous phase material in the catalyst separator can be reduced. + The concentration is 10 -6 ~10 mol / L, with a preferred concentration of 10 mol / L. -3 ~1mol / L.

24. The method according to claim 1, characterized in that, The turbid liquid contains titanium-silicon molecular sieves, while the clear liquid does not contain titanium-silicon molecular sieves.

25. The method according to claim 1, wherein the reaction temperature of propylene and hydrogen peroxide is 20–100°C, preferably 30–80°C; the propylene reacts under liquid phase conditions, and the reaction pressure is 1.0–5.0 MPa, preferably 1.2–3.8 MPa.

26. The method according to claim 1, characterized in that, The molar ratio of propylene to hydrogen peroxide is 1 to 30:1, preferably 2 to 10:

1.

27. The method according to claim 1, characterized in that, The mass ratio of titanium silicate molecular sieve to hydrogen peroxide in the reactor is 0.2 to 20:1, preferably 1 to 5:1.

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