A preparation method of TCPP flame retardant

Abstract

The present invention provides a method for preparing a TCPP flame retardant. Specifically, a silver-modified molecular sieve is first prepared, and then a supported Lewis acid catalyst is prepared using the modified molecular sieve as a carrier. The supported Lewis acid catalyst can efficiently catalyze the reaction of phosphorus oxychloride and propylene oxide to produce the TCPP flame retardant. After the reaction, the catalyst and the reaction liquid can be separated by simple filtration, eliminating the need for alkaline washing of the reaction liquid, significantly reducing wastewater production. Furthermore, the catalyst can be recycled without special treatment, with up to 20 or more batches of recycling required, significantly increasing the catalyst's service life.

Description

Technical Field

[0001] The invention belongs to the technical field of flame retardants, and particularly relates to a preparation method of a TCPP flame retardant. Background Art

[0002] TCPP is an organic phosphate flame retardant with the chemical name tris(2-chloropropyl) phosphate. It is used as an additive flame retardant and is widely used in various polymer materials such as polyurethane soft foam, rigid foam plastics, epoxy resin, phenolic resin, etc. It has significant flame retardant effect and certain plasticizing effect.

[0003] The industrial preparation method of TCPP is well known to those skilled in the art. It uses phosphorus oxychloride and propylene oxide as raw materials and reacts them under the catalysis of Lewis acids. Among them, the commonly used Lewis acid catalysts are aluminum trichloride and titanium tetrachloride.

[0004] Currently, the common industrial process for TCPP production is as follows: first, a Lewis acid catalyst is dissolved in phosphorus oxychloride, propylene oxide is added dropwise at a certain temperature, the reaction temperature is controlled within a certain range during the addition, and after the addition is completed, the reaction is continued at this temperature until the intermediate is completely converted, thereby obtaining a crude TCPP product. The crude product undergoes post-processing and refinement to obtain the finished product, which includes steps such as alkali washing, water washing, and vacuum distillation dehydration. The purpose of alkali washing is mainly to remove the catalyst from the reaction solution. In traditional production processes, the catalyst cannot be reused, and the catalyst treatment process produces a large amount of process wastewater, increasing production costs.

[0005] Patent CN111153934 reports the use of a supported solid catalyst, replacing the traditional Lewis acid catalyst, in the preparation of the flame retardant TCPP from phosphorus oxychloride and propylene oxide. While this method allows for separation of the catalyst from the reaction solution by simple filtration after the reaction, the reaction solution still requires alkali and water washing, and the catalyst must be regenerated before recycling.

[0006] Therefore, in order to solve the problems existing in the prior art, it is very necessary to develop a method that can easily separate the catalyst, reduce the amount of wastewater used, and significantly increase the service life of the catalyst. Summary of the Invention

[0007] The present invention provides a method for preparing a TCPP flame retardant. This method effectively separates the reaction solution from the catalyst by simple filtration, avoiding process wastewater generated by catalyst treatment. Furthermore, the catalyst exhibits high activity and stability, and can be reused for more than 20 batches.

[0008] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0009] A method for preparing a TCPP flame retardant, comprising the following steps:

[0010] S1: adding a soluble silver salt to a solvent and stirring until completely dissolved, adding MCM-48 molecular sieves, allowing to stand, drying, and calcining to prepare a silver-modified molecular sieve carrier;

[0011] S2: dissolving the Lewis acid in a solvent, adding the modified molecular sieve support of S1, allowing to stand, drying, and calcining to prepare a modified molecular sieve-supported Lewis acid catalyst;

[0012] S3: The supported catalyst of S2 is dispersed in phosphorus oxychloride, and propylene oxide is introduced into the reaction to obtain the flame retardant TCPP.

[0013] The catalyst of the present invention adopts soluble silver salt to be impregnated on the surface of molecular sieve. Molecular sieve, especially M41S series molecular sieve, belongs to nano-mesoporous material, has special pore structure, and good long-range periodicity, stable skeleton and good transmission performance, is suitable for the transmission of macromolecules, further forms a new silver-doped structure in the roasting process, and this structure can form a strong interaction force with transition metal chloride, effectively adjusts the electron distribution state of Lewis acid active site, Lewis acid load is relatively firm, does not have dissolution problem, after the reaction is completed, can effectively separate the reaction solution from the catalyst by simple filtration, greatly reduces the large amount of process wastewater generated by treating the catalyst, effectively reduces production cost. At the same time, the obtained catalyst has high activity and good stability, and can be recycled without special treatment during use.

[0014] In the present invention, the solvent described in S1 is a saturated aliphatic alcohol of C1 to C4, preferably one or more of methanol, ethanol, and isopropanol, more preferably isopropanol; preferably, the volume of the solvent is 5 to 20 ml / g, preferably 10 to 15 ml / g, based on the mass of the molecular sieve; preferably, the mass of the silver element contained in the soluble silver salt is 0.5% to 20.0% of the mass of the molecular sieve, preferably 1.0% to 15.0%.

[0015] In the present invention, the standing time in S1 is 1 to 3 days.

[0016] In the present invention, the drying in S1 is performed in a rotary kiln at 100-150° C. for 8-12 hours.

[0017] In the present invention, the calcination in S1 is performed at 450-650° C. for 5-10 hours.

[0018] In the present invention, the Lewis acid described in S2 is a chloride of a transition metal, preferably one or more of anhydrous magnesium chloride, anhydrous zinc chloride, anhydrous aluminum chloride, and anhydrous ferric chloride, more preferably anhydrous magnesium chloride and / or anhydrous zinc chloride.

[0019] In the present invention, the solvent described in S2 is a saturated aliphatic alcohol of C1 to C4, preferably one or more of methanol, ethanol, and isopropanol, more preferably ethanol; preferably, the mass fraction of the solvent is 80 to 90%, calculated as an ethanol solution containing Lewis acid; preferably, the mass ratio of the Lewis acid described in S2 to the modified molecular sieve is (0.1 to 0.8):1, preferably (0.3 to 0.6):1.

[0020] In the present invention, the standing time in S2 is 5 to 10 hours.

[0021] In the present invention, the drying in S2 is drying in a rotary kiln at 80-120°C.

[0022] In the present invention, the calcination in S2 is performed at 200-300° C. for 3-5 hours.

[0023] Another object of the present invention is to provide a TCPP flame retardant product.

[0024] A TCPP flame retardant is prepared by the above-mentioned preparation method. The flame retardant is obtained by reacting phosphorus oxychloride with propylene oxide, and comprises a silver-modified molecular sieve and a supported Lewis acid catalyst thereof.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The catalyst will not dissolve. After the reaction is completed, the reaction liquid and the catalyst can be effectively separated by simple filtration, which greatly reduces the large amount of process wastewater generated by the treatment of the catalyst and effectively reduces production costs.

[0027] (2) The catalyst has high activity and good stability. It can be recycled without special treatment during use. The catalyst can be recycled more than 20 times, effectively reducing production costs. DETAILED DESCRIPTION

[0028] The present invention will be further described below through specific examples. The examples of the present invention are only for illustration of the present invention and do not limit the scope of the present invention.

[0029] (1) Description of analysis and experimental methods:

[0030] TCPP content analysis: gas chromatography area normalization method (GC)

[0031] (2) Sources of raw materials and reagents in various embodiments of the present invention:

[0032] Anhydrous magnesium chloride: 99.9%, Aladdin

[0033] Anhydrous zinc chloride: 99.95%, Aladdin

[0034] Anhydrous aluminum chloride: AR, 99%, Aladdin

[0035] Anhydrous ferric chloride: 98%, Aladdin

[0036] Phosphorus oxychloride: 99.5%, Yanfeng Technology

[0037] Propylene oxide: >99.5%, Wanhua Chemical

[0038] MCM-41 molecular sieve: Klamar

[0039] MCM-48 molecular sieve: Klamar

[0040] MCM-50 molecular sieve: Klamar

[0041] SBA-15 molecular sieve: Aladdin

[0042] Silver Nitrate: AR, 99%, Aladdin

[0043] Silver acetate: 99.95%, Aladdin

[0044] Silver perchlorate: ≥98%, Aladdin

[0045] Gold trichloride: 99%, J&K

[0046] Palladium chloride: 98%, Aladdin

[0047] Unless otherwise specified, other raw materials and reagents were purchased from commercial sources.

[0048] (3) Equipment information used in various embodiments of the present invention:

[0049] High-temperature rotary tube furnace: Zhengzhou Nuotai Technology Co., Ltd. PT-T1700-L80-X

[0050] Büchner funnel with ground sand core: Hinwell 350ml G2

[0051] Constant temperature low temperature bath: Ningbo Tianheng Instrument Factory THD-0515

[0052] Mechanical stirring: IKA RW20

[0053] Vacuum diaphragm pump: KNF SC920

[0054] Example 1

[0055] Synthesis of supported catalysts:

[0056] Weigh 1.27g of silver nitrate and add it to 120ml of isopropanol, stir until completely dissolved, weigh 10g of MCM-48 molecular sieve and immerse it in the above solution, stir evenly, let it stand at room temperature for 2 days, and then dry it at 130℃ for 10h. Then place the sample in a quartz boat and place it in a tube furnace. Under a nitrogen atmosphere, first increase the temperature to 550℃ at a rate of 10℃ / min, keep the temperature constant for 8h, and finally cool it to room temperature under a nitrogen atmosphere to obtain a silver-modified molecular sieve.

[0057] 4.06 g of anhydrous magnesium chloride was weighed and added to 23.02 g of anhydrous ethanol. After mixing, 10.14 g of modified molecular sieve was weighed and added to the above solution. After thorough stirring, the mixture was allowed to stand for 8 h. The mixture was dried in a rotary kiln at 100 ° C until the mass was constant. The mixture was calcined at 270 ° C for 4 h to obtain 11.4 g of modified molecular sieve-supported Lewis acid catalyst A with an anhydrous magnesium chloride loading of 19.99 wt%;

[0058] TCPP flame retardant synthesis:

[0059] 154.1 g of phosphorus oxychloride (purity 99.5%) and 2.3 g of catalyst A were added to a four-necked flask, and the temperature was slowly raised to 50° C. 176.9 g of propylene oxide was added dropwise to the flask, and the reaction temperature was controlled at 50° C. After the addition of propylene oxide was completed, the reaction was continued for 3 h to obtain 333.2 g of crude TCPP. The crude TCPP was filtered through a sand core funnel to separate the catalyst, the filtrate was sampled and analyzed, and the catalyst was recycled. The experimental results are listed in Table 2.

[0060] Example 2

[0061] Synthesis of supported catalysts:

[0062] Weigh 0.15g of silver acetate and add it to 100ml of isopropanol, stir until completely dissolved, weigh 10g of MCM-41 molecular sieve and immerse it in the above solution, stir evenly, let it stand at room temperature for 2 days, and then dry it at 130℃ for 10h. Then place the sample in a quartz boat and place it in a tube furnace. Under a nitrogen atmosphere, first increase the temperature to 550℃ at a rate of 10℃ / min, keep the temperature constant for 8h, and finally cool it to room temperature under a nitrogen atmosphere to obtain a silver-modified molecular sieve.

[0063] 5.49 g of anhydrous zinc chloride was weighed and added to 21.95 g of anhydrous ethanol. After mixing, 9.14 g of modified molecular sieve was weighed and added to the above solution. After thorough stirring, the mixture was allowed to stand for 8 h. The mixture was dried in a rotary kiln at 100°C until the mass was constant. The mixture was calcined at 270°C for 4 h to obtain 11.7 g of modified molecular sieve-supported Lewis acid catalyst B, with an anhydrous magnesium chloride loading of 26.25 wt%;

[0064] TCPP flame retardant synthesis:

[0065] 154.1 g of phosphorus oxychloride (purity 99.5%) and 1.2 g of catalyst B were added to a four-necked flask, and the temperature was slowly raised to 40°C. 176.3 g of propylene oxide was added dropwise to the flask, and the reaction temperature was controlled at 40°C. After the addition of propylene oxide was completed, the reaction was continued for 3 hours to obtain 331.5 g of crude TCPP. The crude TCPP was filtered through a sand core funnel to separate the catalyst, the filtrate was sampled and analyzed, and the catalyst was recycled. The experimental results are listed in Table 2.

[0066] Example 3

[0067] Synthesis of supported catalysts:

[0068] Weigh 2.94g of silver perchlorate and add it to 150ml of isopropanol, stir until completely dissolved, weigh 10g of MCM-50 molecular sieve and immerse it in the above solution, stir evenly, let it stand at room temperature for 2 days, and then dry it at 130℃ for 10h. Then place the sample in a quartz boat and place it in a tube furnace. Under a nitrogen atmosphere, first increase the temperature to 550℃ at a rate of 10℃ / min, keep the temperature constant for 8h, and finally cool it to room temperature under a nitrogen atmosphere to obtain a silver-modified molecular sieve.

[0069] 3.50 g of anhydrous magnesium chloride was weighed and added to 31.47 g of anhydrous ethanol. After mixing, 11.65 g of modified molecular sieve was weighed and added to the above solution. After thorough stirring, the mixture was allowed to stand for 8 h. The mixture was dried in a rotary kiln at 100 ° C until the mass was constant. The mixture was calcined at 270 ° C for 4 h to obtain 11.6 g of modified molecular sieve-supported Lewis acid catalyst C, with an anhydrous magnesium chloride loading of 16.15 wt%;

[0070] TCPP flame retardant synthesis:

[0071] 154.1 g of phosphorus oxychloride (purity 99.5%) and 3.8 g of catalyst C were added to a four-necked flask, and the temperature was slowly raised to 60° C. 177.5 g of propylene oxide was added dropwise to the flask, and the reaction temperature was controlled at 60° C. After the addition of propylene oxide was completed, the reaction was continued for 3 h to obtain 335.3 g of crude TCPP. The crude TCPP was filtered through a sand core funnel to separate the catalyst, the filtrate was sampled and analyzed, and the catalyst was recycled. The experimental results are listed in Table 2.

[0072] Example 4

[0073] Synthesis of supported catalysts:

[0074] Weigh 0.16g of silver nitrate and add it to 100ml of methanol, stir until completely dissolved, weigh 20g of MCM-48 molecular sieve and immerse it in the above solution, stir evenly, let it stand at room temperature for 2 days, and then dry it at 130℃ for 10h. Then put the sample in a quartz boat and place it in a tube furnace. Under a nitrogen atmosphere, first increase the temperature to 550℃ at a rate of 10℃ / min, keep the temperature constant for 8h, and finally cool it to room temperature under a nitrogen atmosphere to obtain a silver-modified molecular sieve.

[0075] 1.83 g of anhydrous aluminum chloride was weighed and added to 10.38 g of anhydrous methanol. After mixing, 18.14 g of modified molecular sieve was weighed and added to the above solution. After thorough stirring, the mixture was allowed to stand for 8 h. The mixture was dried in a rotary kiln at 100 ° C until the mass was constant. The mixture was calcined at 270 ° C for 4 h to obtain 16.0 g of modified molecular sieve-supported Lewis acid catalyst D, with an anhydrous magnesium chloride loading of 6.36 wt%;

[0076] TCPP flame retardant synthesis:

[0077] 154.1 g of phosphorus oxychloride (purity 99.5%) and 12.1 g of catalyst D were added to a four-necked flask, and the temperature was slowly raised to 30° C. 175.7 g of propylene oxide was added dropwise to the flask, and the reaction temperature was controlled at 30° C. After the addition of propylene oxide was completed, the reaction was continued for 3 h to obtain 341.8 g of crude TCPP. The crude TCPP was filtered through a sand core funnel to separate the catalyst, the filtrate was sampled and analyzed, and the catalyst was recycled. The experimental results are listed in Table 2.

[0078] Example 5

[0079] Synthesis of supported catalysts:

[0080] Weigh 3.18g of silver nitrate and add it to 200ml of ethanol, stir until completely dissolved, weigh 10g of MCM-48 molecular sieve and immerse it in the above solution, stir evenly, let it stand at room temperature for 2 days, and then dry it at 130℃ for 10h. Then put the sample in a quartz boat and place it in a tube furnace. Under a nitrogen atmosphere, first increase the temperature to 550℃ at a rate of 10℃ / min, keep the temperature constant for 8h, and finally cool it to room temperature under a nitrogen atmosphere to obtain a silver-modified molecular sieve.

[0081] 9.68 g of anhydrous ferric chloride was weighed and added to 54.87 g of isopropanol. After mixing, 11.86 g of modified molecular sieve was weighed and added to the above solution. After thorough stirring, the mixture was allowed to stand for 8 h. The mixture was dried in a rotary kiln at 100 ° C until the mass was constant. The mixture was calcined at 270 ° C for 4 h to obtain 17.2 g of modified molecular sieve-supported Lewis acid catalyst E, with an anhydrous magnesium chloride loading of 30.83 wt%;

[0082] TCPP flame retardant synthesis:

[0083] 154.1 g of phosphorus oxychloride (purity 99.5%) and 0.5 g of catalyst E were added to a four-necked flask, and the temperature was slowly raised to 80° C. 178.0 g of propylene oxide was added dropwise to the flask, and the reaction temperature was controlled at 80° C. After the addition of propylene oxide was completed, the reaction was continued for 3 h to obtain 332.6 g of crude TCPP. The crude TCPP was filtered through a sand core funnel to separate the catalyst, the filtrate was sampled and analyzed, and the catalyst was recycled. The experimental results are listed in Table 2.

[0084] Comparative Example 1

[0085] Compared with Example 1, the catalyst was replaced with AlCl3, and the other reaction conditions were exactly the same.

[0086] 154.1 g of phosphorus oxychloride (99.5% purity) and 0.46 g of AlCl3 catalyst were added to a four-necked flask, which was slowly heated to 50°C. 176.9 g of propylene oxide was added dropwise to the flask, and the reaction temperature was controlled at approximately 50°C. After the addition of propylene oxide, the reaction was continued for 3 hours to obtain 331.4 g of crude TCPP. The sampling and analysis results are listed in Table 2. Since the catalyst could not be recovered, it could not be reused.

[0087] Comparative Example 2

[0088] Compared with Example 1, the molecular sieve was prepared by gold modification, and the other reaction conditions were exactly the same.

[0089] Synthesis of supported catalysts:

[0090] Weigh 1.24g of gold trichloride and add it to 120ml of isopropanol, stir until completely dissolved, weigh 10g of MCM-48 molecular sieve and immerse it in the above solution, stir evenly, let it stand at room temperature for 2 days, and then dry it at 130℃ for 10h. Then put the sample in a quartz boat and place it in a tube furnace. Under a nitrogen atmosphere, first increase the temperature to 550℃ at a rate of 10℃ / min, keep the temperature constant for 8h, and finally cool it to room temperature in a nitrogen atmosphere to obtain a gold-modified molecular sieve.

[0091] 4.05 g of anhydrous magnesium chloride was weighed and added to 22.96 g of anhydrous ethanol. After mixing, 10.12 g of modified molecular sieve was weighed and added to the above solution. After thorough stirring, the mixture was allowed to stand for 8 h. The mixture was dried in a rotary kiln at 100°C until the mass was constant. The mixture was calcined at 270°C for 4 h to obtain 11.3 g of modified molecular sieve-supported Lewis acid catalyst F with an anhydrous magnesium chloride loading of 19.99 wt%;

[0092] TCPP flame retardant synthesis:

[0093] 154.1 g of phosphorus oxychloride (purity 99.5%) and 2.3 g of catalyst F were added to a four-necked flask, and the temperature was slowly raised to 50° C. 176.9 g of propylene oxide was added dropwise to the flask, and the reaction temperature was controlled at 50° C. After the addition of propylene oxide was completed, the reaction was continued for 3 h to obtain 333.2 g of crude TCPP. The crude TCPP was filtered through a sand core funnel to separate the catalyst, the filtrate was sampled and analyzed, and the catalyst was recycled. The experimental results are listed in Table 2.

[0094] Comparative Example 3

[0095] Compared with Example 1, the molecular sieve was prepared by modification with palladium, and the other reaction conditions were exactly the same.

[0096] Synthesis of supported catalysts:

[0097] Weigh 1.36g of palladium chloride and add it to 120ml of isopropanol, stir until completely dissolved, weigh 10g of MCM-48 molecular sieve and immerse it in the above solution, stir evenly, let it stand at room temperature for 2 days, and then dry it at 130℃ for 10h. Then put the sample in a quartz boat and place it in a tube furnace. Under a nitrogen atmosphere, first increase the temperature to 550℃ at a rate of 10℃ / min, keep the temperature constant for 8h, and finally cool it to room temperature under a nitrogen atmosphere to obtain a palladium-modified molecular sieve.

[0098] 4.09 g of anhydrous magnesium chloride was weighed and added to 23.20 g of anhydrous ethanol. After mixing, 10.22 g of modified molecular sieve was weighed and added to the above solution. After thorough stirring, the mixture was allowed to stand for 8 h. The mixture was dried in a rotary kiln at 100 ° C until the mass was constant. The mixture was calcined at 270 ° C for 4 h to obtain 11.5 g of modified molecular sieve-supported Lewis acid catalyst G, with an anhydrous magnesium chloride loading of 19.99 wt%;

[0099] TCPP flame retardant synthesis:

[0100] 154.1 g of phosphorus oxychloride (purity 99.5%) and 2.3 g of catalyst G were added to a four-necked flask, and the temperature was slowly raised to 50° C. 176.9 g of propylene oxide was added dropwise to the flask, and the reaction temperature was controlled at 50° C. After the addition of propylene oxide was completed, the reaction was continued for 3 h to obtain 333.2 g of crude TCPP. The crude TCPP was filtered through a sand core funnel to separate the catalyst, the filtrate was sampled and analyzed, and the catalyst was recycled. The experimental results are listed in Table 2.

[0101] Comparative Example 4

[0102] Compared with Example 1, the raw material molecular sieve was changed to SBA-15 mesoporous molecular sieve, and the other reaction conditions were exactly the same.

[0103] Synthesis of supported catalysts:

[0104] Weigh 1.27g of silver nitrate and add it to 120ml of isopropanol, stir until completely dissolved, weigh 10g of SBA-15 molecular sieve and immerse it in the above solution, stir evenly, let it stand at room temperature for 2 days, and then dry it at 130℃ for 10h. Then place the sample in a quartz boat and place it in a tube furnace. Under a nitrogen atmosphere, first increase the temperature to 550℃ at a rate of 10℃ / min, keep the temperature constant for 8h, and finally cool it to room temperature in a nitrogen atmosphere to obtain a silver-modified molecular sieve.

[0105] 3.84 g of anhydrous magnesium chloride was weighed and added to 21.74 g of anhydrous ethanol. After mixing, 9.58 g of modified molecular sieve was weighed and added to the above solution. After thorough stirring, the mixture was allowed to stand for 8 h. The mixture was dried in a rotary kiln at 100°C until the mass was constant. The mixture was calcined at 270°C for 4 h to obtain 10.7 g of modified molecular sieve-supported Lewis acid catalyst H with an anhydrous magnesium chloride loading of 19.99 wt%;

[0106] TCPP flame retardant synthesis:

[0107] 154.1 g of phosphorus oxychloride (purity 99.5%) and 2.3 g of catalyst H were added to a four-necked flask, and the temperature was slowly raised to 50° C. 176.9 g of propylene oxide was added dropwise to the flask, and the reaction temperature was controlled at 50° C. After the addition of propylene oxide was completed, the reaction was continued for 3 h to obtain 333.2 g of crude TCPP. The crude TCPP was filtered through a sand core funnel to separate the catalyst, the filtrate was sampled and analyzed, and the catalyst was recycled. The experimental results are listed in Table 2.

[0108] Table 2 Catalyst recycling results of various examples and comparative examples

[0109]

[0110]

Claims

1. A method for preparing a TCPP flame retardant, characterized in that: The method comprises the following steps: S1: adding a soluble silver salt to a solvent and stirring until completely dissolved, adding a molecular sieve, allowing to stand, drying, and calcining to prepare a silver-modified molecular sieve carrier; S2: dissolving the Lewis acid in a solvent, adding the modified molecular sieve support of S1, allowing to stand, drying, and calcining to prepare a modified molecular sieve-supported Lewis acid catalyst; S3: The supported catalyst of S2 is dispersed in phosphorus oxychloride, and propylene oxide is introduced into the reaction to obtain the flame retardant TCPP; Wherein, the molecular sieve described in S1 is M41S mesoporous molecular sieve.

2. The preparation method according to claim 1, characterized in that The soluble silver salt in S1 is one or more of silver nitrate, silver acetate, and silver perchlorate; And / or, the molecular sieve in S1 is one or more of MCM-41, MCM-48, and MCM-50; and / or, the solvent in S1 is a C1-C4 saturated aliphatic alcohol; and / or, the standing time in S1 is 1 to 3 days; And / or, the drying in S1 is drying in a rotary kiln at 100-150° C. for 8-12 hours; And / or, the calcination in S1 is performed at 450-650° C. for 5-10 hours.

3. The preparation method according to claim 2, characterized in that The soluble silver salt described in S1 is silver nitrate; And / or, the molecular sieve in S1 is MCM-48 molecular sieve; And / or, the solvent in S1 is one or more of methanol, ethanol, and isopropanol; The volume of the solvent in S1 is 5 to 20 ml / g based on the mass of the molecular sieve; the mass of the silver element contained in the soluble silver salt is 0.5% to 20.0% of the mass of the molecular sieve.

4. The preparation method according to claim 3, characterized in that The solvent in S1 is isopropyl alcohol; The volume of the solvent in S1 is 10-15 ml / g based on the mass of the molecular sieve; the mass of the silver element contained in the soluble silver salt is 1.0%-15.0% of the mass of the molecular sieve.

5. The preparation method according to claim 1 or 2, characterized in that The Lewis acid in S2 is a chloride of a transition metal; and / or, the solvent in S2 is a C1-C4 saturated aliphatic alcohol; And / or, the mass ratio of the Lewis acid to the modified molecular sieve in S2 is (0.1-0.8):1; And / or, the standing time in S2 is 5-10 hours; And / or, the drying in S2 is drying in a rotary kiln at 80-120° C.; And / or, the calcination in S2 is performed at 200-300° C. for 3-5 hours.

6. The preparation method according to claim 5, characterized in that The Lewis acid in S2 is one or more of anhydrous magnesium chloride, anhydrous zinc chloride, anhydrous aluminum chloride, and anhydrous ferric chloride; And / or, the solvent in S2 is one or more of methanol, ethanol, and isopropanol; The mass fraction of the solvent in S2 is 80-90%, calculated as the ethanol solution containing the Lewis acid; And / or, the mass ratio of the Lewis acid to the modified molecular sieve in S2 is (0.3-0.6):

1.

7. The preparation method according to claim 6, characterized in that The Lewis acid in S2 is anhydrous magnesium chloride and / or anhydrous zinc chloride; And / or, the solvent in S2 is ethanol.

8. The preparation method according to claim 1, characterized in that The mass ratio of Lewis acid to phosphorus oxychloride in the supported catalyst S3 is (0.001-0.005):1; And / or, the molar ratio of propylene oxide to phosphorus oxychloride in S3 is (3.01-3.05):1; And / or, the reaction temperature of phosphorus oxychloride and propylene oxide in S3 is 30-80°C.

9. The preparation method according to claim 8, characterized in that The mass ratio of Lewis acid to phosphorus oxychloride in the supported catalyst of S3 is (0.002-0.004):1; And / or, the molar ratio of propylene oxide to phosphorus oxychloride in S3 is (3.02-3.04):1; And / or, the reaction temperature of phosphorus oxychloride and propylene oxide in S3 is 40-60°C.

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