Preparation method of phosphazene catalyst and application of phosphazene catalyst in field of preparation of polyether polyol

Abstract

The invention discloses a preparation method of a phosphazene catalyst and application of the phosphazene catalyst in the field of preparation of polyether polyols, phosphorus pentachloride is uniformly dispersed in a solvent under the action of a fatty acid amide dispersing agent and reacts with an amine monomer to obtain an inorganic phosphazene catalyst solution, and the inorganic phosphazene catalyst solution reacts with alkali to obtain an organic phosphazene catalyst solution; according to the method, side reactions can be greatly reduced, and the purity of the synthesized phosphazene catalyst reaches 99.5% or above, so that the phosphazene catalyst does not need to be purified, the production technological process is greatly reduced, the loss of the phosphazene catalyst in the purification process is reduced, and the yield can reach 99% or above. The polyether polyol synthesized by the catalyst not only has higher catalytic activity, but also can greatly reduce the occurrence of side reactions in the reaction process of epoxypropane, so that the prepared polyether polyol has the advantages of low degree of unsaturation, low odor and low aldehyde content.

Description

Technical Field

[0001] This invention belongs to the field of polyether polyol catalyst synthesis, specifically relating to a method for preparing a phosphazene catalyst and its application in the preparation of polyether polyols. Background Technology

[0002] Polyether polyols are an important raw material for the synthesis of polyurethanes and are widely used in industries such as textiles, synthetic leather, adhesives, foam plastics, and elastomers. Catalysts for producing polyether polyols mainly include potassium hydroxide, bimetallic cyanide complexes (DMC), and phosphazene catalysts. Potassium hydroxide is inexpensive and widely used industrially; however, when catalyzing the ring-opening polymerization of propylene oxide, a side reaction occurs that isomerizes propylene oxide, generating polyethers containing unsaturated double bonds. DMC catalysts have very high catalytic activity and are widely used in propylene oxide polymerization or propylene oxide / ethylene oxide copolymerization systems. However, when using DMC to catalyze the homopolymerization of ethylene oxide, it causes ethylene oxide to polymerize on a single molecular chain, generating polyethylene oxide with a large molecular weight, affecting product performance. Therefore, it cannot be used to synthesize highly active (primary hydroxyl-terminated) polyethers. Phosphazene catalysts can perfectly solve the above problems, exhibiting fewer side reactions and lower polyether unsaturation when catalyzing propylene oxide. They can also catalyze the homopolymerization of ethylene oxide. However, phosphazene catalysts have complex production processes and extremely high costs, making them difficult to apply industrially.

[0003] Patent CN1287563A discloses a method for preparing polyoxyethylene polyols and their derivatives. This method synthesizes a catalyst containing P=N bonds and uses it in the preparation of polyoxyethylene polyols. However, the purification process for this catalyst is complex, requiring multiple extractions and multi-step reactions to obtain a high-purity catalyst. This cumbersome process makes industrial production difficult. Patent CN1021171272A discloses a catalyst containing a salt of phosphazene onium cations and active hydrogen compound anions. This catalyst can effectively produce polyalkylene glycols without residual metal components in the product. However, the synthesis of this catalyst requires repeated dissolution, filtration, and extraction using various solvents, which not only causes catalyst loss and reduces yield but also increases the production cost, severely hindering the industrial application of phosphazene catalysts.

[0004] The reason why the phosphazene catalyst in the above invention needs to be purified is that a large number of side reactions occur during the catalyst synthesis process, resulting in low purity of the phosphazene compound, which cannot be directly used for the catalytic synthesis of polyether polyols. Therefore, it is of great significance to invent a method for preparing a phosphazene catalyst with high purity and few side reactions. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides a method for preparing a phosphazene catalyst. By adding a dispersant during the synthesis of the phosphazene catalyst, the dispersant can be adsorbed onto the surface of phosphorus pentachloride, reducing the interfacial tension between phosphorus pentachloride and the solvent. This results in a more uniform distribution of phosphorus pentachloride and the generated solid products within the system, reducing the occurrence of side reactions. It also reduces the need for purification processes, significantly decreasing the number of steps in the synthesis of the phosphazene catalyst and lowering economic costs.

[0006] Another objective of this invention is to provide the application of the above-mentioned phosphazene catalyst in the preparation of polyether polyols, which can significantly reduce the occurrence of side reactions during the propylene oxide reaction, and the prepared polyether polyols have the advantages of low unsaturation, low odor, and low aldehyde content.

[0007] A method for preparing a phosphazene catalyst includes the following steps:

[0008] (1) Under a nitrogen atmosphere, phosphorus pentachloride is dispersed in a solvent, a dispersant is added, the system temperature is cooled to -70 to 20°C, preferably -70 to -30°C, a compound with the general formula (1) is added to the reaction system, the reaction temperature is maintained at -70 to 20°C, preferably -70 to -30°C, and then the temperature is raised to 100 to 160°C to continue the reaction, and the inorganic phosphazene catalyst solution is obtained by filtration.

[0009]

[0010] In the formula, R is an alkyl group with 1 to 10 carbon atoms or an aryl group with 6 to 10 carbon atoms.

[0011] The general structural formula of inorganic phosphazene catalysts is (PR1)4 + X -

[0012] In the formula, the structure of R1 is:

[0013]

[0014] X represents chloride ions.

[0015] Optionally, (2) the base is added to the inorganic phosphazene catalyst, the reaction temperature is maintained at 20-60℃, and the reaction is carried out for 1-5 hours. The solution of the organic phosphazene catalyst is then obtained by filtration.

[0016] The general structural formula of organophosphorus nitrile catalysts is (PR1)4 + Y -

[0017] In the formula, the structure of R1 is:

[0018]

[0019] Y is a hydroxyl group or an alkoxy group with 1 to 4 carbon atoms.

[0020] Preferably, the dispersant in step (1) has the structural formula shown in (2), and the molar ratio of the dispersant to phosphorus pentachloride is 1:1 to 1:100, preferably 1:10 to 1:30.

[0021]

[0022] In the formula, R2 is an alkane group, olefin group, or alkyne group with 8 to 20 carbon atoms.

[0023] Preferably, the dispersant is N,N-dimethyldodecanoamide, N,N-dimethylhexadecanoamide, or (Z)-N,N-dimethyloctadec-9-enamide.

[0024] Preferably, in step (1), the molar ratio of phosphorus pentachloride to the compound with the general formula (2) is 1:6 to 1:12, more preferably 1:8 to 1:10.

[0025] Preferably, the solvent in step (1) is selected from ethers, halogenated hydrocarbons, halogenated aromatic hydrocarbons, ketones, etc.; preferably, it is an ether or cyclic ether containing 2 to 6 carbons, a halogenated hydrocarbon containing 1 to 3 carbons, a halogenated benzene containing 6 to 8 carbons, or a ketone containing 2 to 6 carbons; more preferably, it is one or more of dichloromethane, dioxane, acetone, chlorobenzene, and o-dichlorobenzene.

[0026] Preferably, the solvent water content in step (1) is less than 100 ppm, more preferably less than 30 ppm; the water content of the compound with the general formula (1) is less than 100 ppm, more preferably less than 30 ppm; and the purity of phosphorus pentachloride needs to be greater than 99%, more preferably greater than 99.5%, and more preferably greater than 99.9%. Controlling the water content and the purity of phosphorus pentachloride is beneficial to reducing the impurity content in the reaction and further improving the purity of the product.

[0027] Preferably, the alkali in step (2) is an inorganic alkali metal compound or an alkali metal alkoxide containing 1 to 4 carbon atoms, preferably one or more of sodium hydroxide, potassium hydroxide, sodium methoxide, potassium methoxide, etc.; the molar ratio of the inorganic phosphazene catalyst to the alkali is 0.9 to 1:1.

[0028] The present invention also provides the application of the phosphazene catalyst in the preparation of polyether polyols, which is used as a catalyst for the ring-opening polymerization of epoxides to prepare polyether polyols.

[0029] Preferably, the polyether polyol is prepared by ring-opening polymerization of an active hydrogen compound and an epoxide alkane in the presence of the organophosphorus nitrile catalyst described in this invention.

[0030] Alternatively, the polyether polyol can be prepared by ring-opening polymerization of a potassium-containing initiator with an epoxide alkane in the presence of the inorganic phosphazene catalyst described in this invention.

[0031] Preferably, the active hydrogen compound is selected from organic compounds containing -OH or organic compounds containing -NH-. More preferably, the active hydrogen compound is a polyol containing 1 to 8 hydroxyl groups and having 2 to 10 carbon atoms, or a polyepoxyalkane polyol containing 1 to 8 hydroxyl groups and having a molecular weight of 500 to 5000.

[0032] Preferably, the potassium-containing initiator is a product of an active hydrogen compound containing -OH in which the hydrogen atoms in the -OH group are replaced by potassium atoms.

[0033] Among them, the active hydrogen compound containing -OH is a polyol with 2 to 10 carbon atoms containing 1 to 8 hydroxyl groups, or a polyepoxide polyol with a molecular weight of 500 to 5000 containing 1 to 8 hydroxyl groups.

[0034] For example, the potassium-containing initiator has the following structural formula:

[0035] R2-o - K +

[0036] R2 is a polyol containing 1 to 5 hydroxyl groups and having 2 to 10 carbon atoms, or a polyepoxide polyol containing 1 to 5 hydroxyl groups and having a molecular weight of 500 to 5000.

[0037] The epoxide alkane is selected from one or more of ethylene oxide, propylene oxide, 1,2-epoxide butane, etc.

[0038] Preferably, the amount of the organophosphorus nitrile catalyst added is 300-20000 ppm, more preferably 500-10000 ppm.

[0039] Preferably, the mass ratio of the active hydrogen compound to the epoxide is 0.001 to 10:1, more preferably 0.01 to 1:1.

[0040] Preferably, the inorganic phosphazene catalyst is added in an amount of 300-20000 ppm, more preferably 500-10000 ppm.

[0041] Preferably, the mass ratio of the potassium-containing initiator to the epoxide is 0.001 to 10:1, more preferably 0.01 to 1:1.

[0042] Preferably, the ring-opening reaction temperature of alkyl epoxides is 60–150°C, more preferably 70–140°C.

[0043] Compared with the prior art, the present invention has the following advantages:

[0044] (1) In the synthesis of phosphazene catalyst, a dispersant is added. The dispersant can be adsorbed on the surface of phosphorus pentachloride, reducing the interfacial tension between phosphorus pentachloride and solvent, so that phosphorus pentachloride and the generated solid products are more evenly distributed in the system, and reducing the occurrence of side reactions.

[0045] (2) The phosphazene catalyst synthesized by the present invention has high purity, which can reduce the purification steps of the phosphazene catalyst, greatly reduce the production process, and reduce the loss of phosphazene catalyst during the purification process.

[0046] (3) The present invention uses only one solvent in the process of synthesizing phosphazene catalyst, which greatly reduces the production cost of the catalyst.

[0047] (4) The phosphazene catalyst prepared by this invention has high purity. It not only has high catalytic activity when synthesizing polyether polyols, but also can significantly reduce the occurrence of side reactions during the propylene oxide reaction. Therefore, the prepared polyether polyols have the advantages of low unsaturation, low odor and low aldehyde content.

[0048] (5) The present invention can use potassium-containing polyether polyols as initiators to synthesize polyether polyols under inorganic phosphazene catalysis. In industrial production, the process of synthesizing organic phosphazene catalysts and removing potassium ions from polyethers can be omitted.

[0049] Specific implementation methods

[0050] The present invention is further illustrated below with reference to embodiments, but these embodiments do not constitute any limitation.

[0051] All chemical reagents used in the examples are commercially available and of analytical grade.

[0052] Odor test method for polyether polyol: Take 100mL of polyether polyol and put it into a 200mL glass bottle. Place it in an 80℃ oven for 2 hours. After taking it out, have 5 or more people smell the polyether polyol and give an odor evaluation. Finally, take the average value of all evaluations as the final result.

[0053] The national standard for unsaturation testing is GB / T 12008.6-2010.

[0054] The odor evaluation criteria are shown in the table below:

[0055]

[0056] Iminotris(dimethylamino)phosphine and iminotris(dipropylamino)phosphine were synthesized in the laboratory. See Schwesinger R, Schlemper H, Hasenfratz C, et al. Extremely strong, uncharged auxiliary bases; monomeric and polymer-supported polyaminophosphazenes (P2–P5)[J]. Liebigs Annalen, 1996, 1996(7):1055-1081. The synthesis method is shown on pages 1066-1067 of the literature.

[0057] Tetramethylguanidine can be purchased from Beijing Innocare Technology Co., Ltd.

[0058] N,N-Dimethyldodecanoamide (CAS No. 3007-53-2), N,N-Dimethylhexadecanoamide (CAS No. 3886-91-7), and (Z)-N,N-Dimethyloctadec-9-enamide (CAS No. 2664-42-8) were purchased from Aladdin.

[0059] Potassium-containing polyether polyols: Polyether intermediates produced by the equipment can be sampled directly from the equipment or synthesized in the laboratory. Synthesis method: Mix polyether polyols with KOH solution, the mass fraction of KOH is 0.01% to 5%, heat to above 100°C and dehydrate under vacuum until the water content is <500ppm.

[0060] Example 1

[0061] 20 g of phosphorus pentachloride and 521 g of chlorobenzene were added to a reaction vessel, along with 2.18 g of dispersant N,N-dimethyldodecylamide. The system temperature was lowered to -70 °C, and the mixture was stirred for 1 h. 153.7 g of iminotris(dimethylamino)phosphine was slowly added, maintaining the reaction temperature at -70 °C. After the addition was complete, the temperature was raised to 140 °C, and the reaction continued for 12 h. The mixture was then cooled to below 50 °C and filtered to obtain a chlorobenzene solution with an inorganic phosphazene catalyst.

[0062] 5.94 g of solid potassium hydroxide was added to the solution, and the reaction was carried out at 60 °C for 1 h. The precipitate was removed by filtration, and the solvent was removed under reduced pressure at 100 °C to obtain 72.15 g of organophosphorus nitrile catalyst A, with a yield of 99.5%.

[0063] Example 2

[0064] 20 g of phosphorus pentachloride and 1073 g of dioxane were added to a reaction vessel, along with 1.36 g of dispersant N,N-dimethylhexadecanoamide. The system temperature was lowered to -50 °C, and the mixture was stirred for 1 h. 337.7 g of iminotris(dipropylamino)phosphine was slowly added, maintaining the reaction temperature at -50 °C. After the addition was complete, the temperature was raised to 160 °C, and the reaction continued for 10 h. The mixture was then cooled to below 50 °C and filtered to obtain a dioxane solution with an inorganic phosphazene catalyst.

[0065] 7.02 g of potassium methoxide solid was added to the solution, and the reaction was carried out at 40 °C for 2 h. The precipitate was removed by filtration, and the solvent was removed under reduced pressure at 100 °C to obtain 139.6 g of organophosphorus nitrile catalyst B, with a yield of 99.3%.

[0066] Example 3

[0067] 20 g of phosphorus pentachloride and 325 g of dichloromethane were added to a reaction vessel, along with 0.99 g of dispersant (Z)-N,N-dimethyloctadec-9-enamide. The system temperature was lowered to -30 °C, and the mixture was stirred for 1 h. 88.2 g of tetramethylguanidine was slowly added, maintaining the reaction temperature at -30 °C. After the addition was complete, the temperature was raised to 100 °C, and the reaction continued for 8 h. The mixture was then cooled to below 50 °C and filtered to obtain a dichloromethane solution containing an inorganic phosphazene catalyst.

[0068] 8.12 g of potassium ethoxide solid was added to the solution, and the reaction was carried out at 20 °C for 4 h. The precipitate was removed by filtration, and the solvent was removed under reduced pressure at 100 °C to obtain 49.5 g of organophosphorus nitrile catalyst C with a yield of 99.6%.

[0069] Comparative Example 1

[0070] 20 g of phosphorus pentachloride and 325 g of dichloromethane were added to a reaction vessel, and the system temperature was lowered to -30 °C and stirred for 1 h. 88.2 g of tetramethylguanidine was slowly added, maintaining the reaction temperature at -30 °C. After the addition was complete, the temperature was raised to 100 °C and the reaction continued for 8 h. The mixture was cooled to below 50 °C and filtered to obtain a dichloromethane solution containing an inorganic phosphazene catalyst. The dichloromethane phase was extracted three times with 100 g of water, and the two phases were combined. Distillation of the dichloromethane yielded 37.6 g of a white powder, with a yield of 75%.

[0071] The white solid was dissolved in 100g of ethanol, and 6.12g of potassium ethoxide solid was added. The mixture was reacted at 20°C for 4h. The precipitate was removed by filtration, and the solvent was removed under reduced pressure at 100°C to obtain 37.2g of organophosphorus nitrile catalyst D.

[0072] Example 4

[0073] 20g of glycerol and 1.63g of organophosphorus nitrile catalyst A were added to a high-pressure reactor. After complete purging with nitrogen, volatile substances were removed from the reactor under vacuum, and the temperature inside the reactor was maintained at 100℃. Vacuuming was stopped after 1 hour. 1365.9g of propylene oxide was continuously introduced into the reactor. After the propylene oxide was completely added, the reaction continued until the pressure inside the reactor no longer changed. Unreacted propylene oxide was removed using a vacuum pump. 244.5g of ethylene oxide was then introduced into the reactor. After the ethylene oxide was completely added, the reaction continued until the pressure inside the reactor no longer changed. Unreacted ethylene oxide was removed using a vacuum pump. After the reaction was completed, the crude polyether polyol was neutralized with phosphoric acid, adsorbed by magnesium silicate, dehydrated, and filtered to obtain purified polyether polyol. The product had a hydroxyl value of 24.5mgKOH / g, an unsaturation degree of 0.018mmol / g, and an odor grade of 1.5.

[0074] Example 5

[0075] Following the procedure described in Example 4, organophosphazene catalyst A was replaced with organophosphazene catalyst B to obtain purified polyether polyol. The product had a hydroxyl value of 24.3 mg KOH / g, an unsaturation degree of 0.015 mmol / g, and an odor grade of 2.

[0076] Example 6

[0077] Following the procedure described in Example 4, organophosphazene catalyst A was replaced with organophosphazene catalyst C to obtain purified polyether polyol. The product had a hydroxyl value of 24.6 mg KOH / g, an unsaturation degree of 0.019 mmol / g, and an odor grade of 1.

[0078] Comparative Example 2

[0079] Following the procedure described in Example 4, organophosphazene catalyst A was replaced with organophosphazene catalyst D to obtain purified polyether polyol. The product had a hydroxyl value of 24.8 mg KOH / g, an unsaturation degree of 0.03 mmol / g, and an odor rating of 4.

[0080] Example 7

[0081] A chlorobenzene solution of an inorganic phosphazene catalyst was prepared according to the method in Example 1. The solvent was removed by vacuum distillation at 100°C to obtain a white solid. 200g of potassium-containing polyether polyol (functionality 3, molecular weight 800), with a potassium ion concentration of 0.15%, was added to a high-pressure reactor. 1.5g of the aforementioned white solid was added, and after complete nitrogen purging, volatile substances were removed from the reactor under vacuum. The reactor temperature was maintained at 100°C, and vacuuming was stopped after 1 hour. 1030g of propylene oxide was continuously introduced into the reactor. After the propylene oxide was completely added, the reaction continued until the pressure inside the reactor no longer changed. Unreacted propylene oxide was removed using a vacuum pump. 270g of ethylene oxide was then introduced into the reactor. After the ethylene oxide was completely added, the reaction continued until the pressure inside the reactor no longer changed. Unreacted ethylene oxide was removed using a vacuum pump. After the reaction, the crude polyether polyol was neutralized with phosphoric acid, adsorbed by magnesium silicate, dehydrated, and filtered to obtain purified polyether polyol. The product has a hydroxyl value of 29.1 mgKOH / g, an unsaturation degree of 0.014 mmol / g, and an odor grade of 1.

[0082] Example 8

[0083] A chlorobenzene solution of the inorganic phosphazene catalyst was prepared according to the method in Example 2. The solvent was removed by vacuum distillation at 100°C to obtain a white solid. 100g of potassium-containing polyether polyol (functionality 2, molecular weight 400), with a potassium ion concentration of 0.2%, was added to a high-pressure reactor. 1.25g of the aforementioned white solid was added, and after complete nitrogen purging, volatile substances were removed from the reactor under vacuum. The reactor temperature was maintained at 100°C, and vacuuming was stopped after 1 hour. 950g of propylene oxide was continuously introduced into the reactor. After the propylene oxide was completely added, the reaction continued until the pressure inside the reactor no longer changed. Unreacted propylene oxide was removed using a vacuum pump. 200g of ethylene oxide was then introduced into the reactor. After the ethylene oxide was completely added, the reaction continued until the pressure inside the reactor no longer changed. Unreacted ethylene oxide was removed using a vacuum pump. After the reaction, the crude polyether polyol was neutralized with phosphoric acid, adsorbed by magnesium silicate, dehydrated, and filtered to obtain purified polyether polyol. The product has a hydroxyl value of 23.8 mgKOH / g, an unsaturation degree of 0.016 mmol / g, and an odor grade of 1.5.

[0084] Example 9

[0085] A chlorobenzene solution of the inorganic phosphazene catalyst was prepared according to the method in Example 3. The solvent was removed by vacuum distillation at 100°C to obtain a white solid. 200g of potassium-containing polyether polyol (functionality 6, molecular weight 2000), with a potassium ion concentration of 0.1%, was added to a high-pressure reactor. 1.2g of the aforementioned white solid was added, and after complete nitrogen purging, volatile substances were removed from the reactor under vacuum. The reactor temperature was maintained at 100°C, and vacuuming was stopped after 1 hour. 520g of propylene oxide was continuously introduced into the reactor. After the propylene oxide was completely added, the reaction continued until the pressure inside the reactor no longer changed. Unreacted propylene oxide was removed using a vacuum pump. 480g of ethylene oxide was then introduced into the reactor. After the ethylene oxide was completely added, the reaction continued until the pressure inside the reactor no longer changed. Unreacted ethylene oxide was removed using a vacuum pump. After the reaction, the crude polyether polyol was neutralized with phosphoric acid, adsorbed by magnesium silicate, dehydrated, and filtered to obtain purified polyether polyol. The product has a hydroxyl value of 29.7 mgKOH / g, an unsaturation degree of 0.018 mmol / g, and an odor grade of 1.5.

Claims

1. A method for preparing a phosphazene catalyst, characterized in that, Includes the following steps: (1) Under an inert atmosphere, phosphorus pentachloride is dispersed in a solvent, a dispersant is added, and a compound with the general formula (1) is added to the reaction system. The reaction is carried out at a low temperature first, and then the temperature is raised to 100-160℃ to continue the reaction. The inorganic phosphazene catalyst solution is obtained by filtration. In the formula, R is an alkyl group with 1 to 10 carbon atoms or an aryl group with 6 to 10 carbon atoms; The general structural formula of inorganic phosphazene catalysts is (PR1)4 + X - ; In the formula, the structure of R1 is: X is a chloride ion; Preferably, the compound with the general formula (1) is added to the system at -70 to 20°C, and more preferably the system temperature is -70 to -30°C; Preferably, the low-temperature reaction temperature is -70 to 20°C, and more preferably -70 to -30°C.

2. The preparation method according to claim 1, characterized in that, The preparation method also includes step (2) adding the base to the inorganic phosphazene catalyst to react and obtain an organic phosphazene catalyst solution; The general structural formula of organophosphorus nitrile catalysts is (PR1)4 + Y - ; In the formula, the structure of R1 is: Y is a hydroxyl group or an alkoxy group with 1 to 4 carbon atoms; Preferably, the reaction temperature is 20–60°C and the reaction time is 1–5 h.

3. The preparation method according to claim 1, characterized in that, The dispersant structure in step (1) is shown in (2), and the molar ratio of the dispersant to phosphorus pentachloride is 1:1 to 1:100, preferably 1:10 to 1:

30. In the formula, R2 is an alkane group, alkene group, or alkyne group with 8 to 20 carbon atoms; Preferably, the dispersant is N,N-dimethyldodecanoamide, N,N-dimethylhexadecanoamide, or (Z)-N,N-dimethyloctadec-9-enamide; Preferably, in step (1), the molar ratio of phosphorus pentachloride to the compound with the general formula (2) is 1:6 to 1:12, more preferably 1:8 to 1:

10.

4. The preparation method according to any one of claims 1-3, characterized in that, The solvent in step (1) is selected from ethers, halogenated hydrocarbons, halogenated aromatic hydrocarbons, and ketones; preferably ethers or cyclic ethers containing 2 to 6 carbons, halogenated hydrocarbons containing 1 to 3 carbons, halogenated benzenes containing 6 to 8 carbons, and ketones containing 2 to 6 carbons; more preferably one or more of dichloromethane, dioxane, acetone, chlorobenzene, and o-dichlorobenzene. And / or, the water content of the solvent in step (1) is less than 100 ppm, preferably less than 30 ppm; And / or, the water content of the compound with the general formula (1) structure is less than 100 ppm, preferably less than 30 ppm; And / or, the purity of phosphorus pentachloride is greater than 99%, preferably greater than 99.5%, more preferably greater than 99.9%.

5. The preparation method according to any one of claims 1-3, characterized in that, The alkali mentioned in step (2) is an inorganic alkali metal compound or an alkali metal alkoxide containing 1 to 4 carbon atoms, preferably one or more of sodium hydroxide, potassium hydroxide, sodium methoxide, and potassium methoxide; Preferably, the molar ratio of the inorganic phosphazene catalyst to the base is 0.9 to 1:

1.

6. The application of the phosphazene catalyst according to any one of claims 1-5 in the field of polyether polyol preparation, wherein it is used as a catalyst for the ring-opening polymerization of epoxides to prepare polyether polyols.

7. A method for preparing a polyether polyol, characterized in that: In the presence of the organophosphazene catalyst according to any one of claims 1-5, the active hydrogen compound is subjected to ring-opening polymerization with an epoxide alkane; Alternatively, in the presence of the inorganic phosphazene catalyst according to any one of claims 1-5, a potassium-containing initiator is subjected to ring-opening polymerization with an epoxide alkane.

8. The preparation method according to claim 7, characterized in that, The active hydrogen compound is selected from organic compounds with a structural formula containing -OH or organic compounds containing -NH-. Preferably, the active hydrogen compound is a polyol containing 1 to 8 hydroxyl groups and having 2 to 10 carbon atoms, or a polyepoxyalkane polyol containing 1 to 8 hydroxyl groups and having a molecular weight of 500 to 5000. Preferably, the potassium-containing initiator is a product in which the hydrogen in the -OH group of an active hydrogen compound containing -OH is replaced by potassium atoms; wherein, the active hydrogen compound containing -OH is a polyol containing 1 to 8 hydroxyl groups and having 2 to 10 carbon atoms, or a polyepoxyalkane polyol containing 1 to 8 hydroxyl groups and having a molecular weight of 500 to 5000. Preferably, the epoxide is selected from one or more of ethylene oxide, propylene oxide, 1,2-epoxide butane, etc.

9. The preparation method according to claim 7 or 8, characterized in that, The amount of the organophosphorus nitrile catalyst added is 300-20000 ppm, preferably 500-10000 ppm; Preferably, the mass ratio of the active hydrogen compound to the epoxide is: 0.001 to 10:1, preferably 0.01 to 1:1; Preferably, the amount of the inorganic phosphazene catalyst added is 300-20000 ppm, more preferably 500-10000 ppm; Preferably, the mass ratio of the potassium-containing initiator to the epoxide is: 0.001 to 10:1, preferably 0.01 to 1:1; Preferably, the ring-opening reaction temperature of alkyl epoxides is 60–150°C, more preferably 70–140°C.

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