Preparation method of double metal cyanide catalyst for preparing polycarbonate-ether

Abstract

The invention relates to a method for producing a double metal cyanide catalyst for producing polycarbonate ethers from epoxides and carbon dioxide, wherein the method comprises the steps of: (a) mixing a metal salt selected from the group consisting of zinc (II) metal salts, iron (II) metal salts, cobalt (II) metal salts, nickel (II) metal salts, a metal cyanide salt with a first complexing agent selected from the group consisting of alcohol compounds, ketone and diketone compounds, ketone-ester compounds, ether compounds or mixtures thereof for a predetermined time and temperature, thereby obtaining a double metal cyanide catalyst precursor; and (b) reacting the double metal cyanide catalyst precursor obtained in step (a) with a second complexing agent selected from an aliphatic carbonyl compound, an aliphatic ester ether compound or a mixture thereof in water or an organic solvent for a predetermined time and temperature, thereby obtaining the double metal cyanide catalyst.

Description

Technical Field

[0001] The invention relates to a method for preparing a double metal cyanide catalyst for preparing polycarbonate-ether. Background Art

[0002] Greenhouse gas emissions, particularly carbon dioxide (CO), continue to increase. This is the primary cause of global warming, which is driving rising temperatures and thus climate change. Consequently, many business sectors around the world are collaborating to promote decarbonization within environmental policies. The overarching goal is net-zero emissions. Developing catalysts for the production of linear or aliphatic polycarbonates offers an alternative approach to generating value from CO.

[0003] Polycarbonates are classified as thermoplastic polymers containing carbonate functional groups (-O(CO)O-) as a chemical component. Aliphatic polycarbonates are important biodegradable polymers with a wide range of applications, depending on the polycarbonate type. For example, poly(propylene carbonate) is used in coatings, biomedical applications, and packaging.

[0004] Typically, linear polycarbonates can be synthesized by ring-opening copolymerization of epoxy compounds such as propylene oxide and carbon dioxide under catalytic conditions. Commonly used catalysts can be divided into two categories: homogeneous catalysts containing complexes of chromium (III), cobalt (III), aluminum (III) and zinc (II); and

[0005] Heterogeneous catalysts such as zinc gluconate and double metal cyanide catalysts.

[0006] However, the preparation of homogeneous catalysts is more complex than that of heterogeneous catalysts and requires more steps. Furthermore, the resulting polymer may be contaminated with metals that are difficult to remove. This can be observed from the color of the resulting polymer. Therefore, heterogeneous catalysts are suitable for the industrial production of polycarbonates due to their colorlessness, ease of handling, reusability, and low production costs.

[0007] Double metal cyanide heterogeneous catalysts are effective catalysts for the production of polycarbonates from epoxides and carbon dioxide. Typically, these catalysts are prepared by reacting metal salts such as zinc chloride (ZnCl2) with metal cyanide salts such as potassium hexacyanocobalt(III)ate. However, double metal cyanide catalysts, also known as Prussian blue, without complexing agents are inefficient in ring-opening copolymerization. Therefore, the development of metal cyanide catalysts requires complexing agents as a component.

[0008] Wang et al. (European Polymer Journal 2011, 47, 2152-2157) disclose the preparation of zinc hexacyanocobaltate with tert-butyl alcohol as a complexing agent for the ring-opening copolymerization of propylene oxide and carbon dioxide. A 10-hour reaction experiment at 90°C under a carbon dioxide pressure of 40 bar revealed that the catalyst produced a yield of 60 kg of polymer per gram of catalyst. The resulting polypropylene carbonate-ether had an average molecular weight of 130 kg / mol. The carbonate content of the polymer ranged from 34% to 49%. The by-product propylene carbonate was also found to be less than 1.0% by weight.

[0009] Zhang et al. (Polymer 2011, 52, 5494-5502) disclose the use of tert-butyl alcohol as a complexing agent to prepare a nano-layered zinc hexacyanocobaltate catalyst for the ring-opening copolymerization of propylene oxide and carbon dioxide to produce polypropylene carbonate. A 10-hour reaction experiment at 60°C under a carbon dioxide pressure of 50 bar revealed a yield of 6.05 kg polymer per 1 g catalyst. The average molecular weight (M) of the resulting polypropylene carbonate-ether was 1.37 mmol / L. n ) is 36.5 kg / mol. The molecular weight distribution is 2.0. The carbonate content in the polymer is as high as 72.6%.

[0010] Darbha et al. (Applied Catalysis A: General 2014, 482, 300-308) disclose the use of tert-butyl alcohol as a complexing agent to prepare a zinc hexacyanocobaltate catalyst for the ring-opening copolymerization of cyclohexene oxide and carbon dioxide to produce polycyclohexene carbonate. A reaction experiment conducted at 75°C under a carbon dioxide pressure of 30 bar for 11 hours revealed that the catalyst produced a yield of 52.8 kg of polymer per 1 g of catalyst, with no induction period. The resulting polymer had an average molecular weight of 20.9 kg / mol and a molecular weight distribution of 1.8. The carbonate content of the polymer was 86%.

[0011] US Pat. No. 5,482,908 B2 discloses the preparation of a highly catalytic double metal cyanide catalyst for the polymerization of epoxides. The method comprises preparing a zinc hexacyanocobaltate double metal cyanide catalyst in the presence of tert-butyl alcohol as a complexing agent and a polyether having an average molecular weight greater than 500 g / mol as a co-complexing agent to facilitate phase development and reduce catalyst crystallization. The resulting solid double metal cyanide catalyst contains approximately 5% to 80% by weight of the polyether.

[0012] US9605111B2 discloses the preparation of a double metal cyanide catalyst having a high reaction rate for use in the polymerization synthesis of polyether polyols. The method comprises: a) synthesizing a solid double metal cyanide catalyst in the presence of an organic complexing agent and a polyether polyol ligand having an average molecular weight of less than 2000 g / mol; and b) washing the resulting catalyst with an aqueous solution containing 90 to 100 weight percent water and 0 to 10 weight percent polyether polyol, wherein the aqueous solution does not contain an organic complexing agent.

[0013] US Patent No. 10619006B2 discloses the preparation of a double metal cyanide catalyst for use in the polymerization of polycarbonate polyols. The method comprises preparing a zinc hexacyanocobaltate double metal cyanide catalyst in the presence of a complexing agent having acetate and tartrate groups. The weight ratio of the metal salt to the complexing agent is 1:5 to 1:10. The polyether polyol ligand is present in an amount of 0.1 to 30 parts by weight relative to the weight of the double metal cyanide catalyst. The catalyst obtained by this invention achieves high polycarbonate production efficiency while using an environmentally friendly complexing agent. The reaction proceeds rapidly and has a short induction time. However, the catalyst obtained by this invention and Korean Patent No. 10-

[0014] The catalyst using a lactate compound as a complexing agent disclosed in 2012-0042796 and the catalyst using a ketone- and alcohol-containing compound as a complexing agent disclosed in Korean Patent No. 10-2014-0042167 cannot control the specificity of polycarbonate synthesis at a high level.

[0015] In summary, the use of tert-butyl alcohol as a complexing agent for the preparation of double metal cyanide catalysts is suitable and effective. Attempts have been made to improve catalyst performance by using co-complexing agents such as polyether polyols or other complexing agents instead of tert-butyl alcohol, but to date, these approaches have been less effective in achieving the induction times and high polymer specificity achieved when using tert-butyl alcohol as a complexing agent. Furthermore, previously disclosed techniques require the mixing of complexing agents and / or co-complexing agents with the double metal cyanide catalyst. This complicates catalyst development and preparation, as changing the complexing agent requires restarting all synthesis steps.

[0016] The present invention provides a method for preparing a double metal cyanide catalyst for producing polycarbonate-ethers from epoxides and carbon dioxide, which facilitates the use of a complexing agent. Furthermore, the present invention provides a novel method for improving the performance of catalysts prepared using tert-butyl alcohol as the first complexing agent by using a second complexing agent. This method facilitates catalyst improvement, provides a variety of catalyst structures, and improves the efficiency of polycarbonate-ether production in terms of yield, induction time, and specificity in controlling polymer synthesis. Summary of the Invention

[0017] The present invention relates to a method for preparing a double metal cyanide catalyst for producing polycarbonate-ether from epoxide and carbon dioxide, which method is easy to adjust the complexing agent and is more efficient in producing polycarbonate-ether from epoxide and carbon dioxide.

[0018] Next steps:

[0019] (a) mixing a metal salt selected from zinc (II) metal salts, iron (II) metal salts, cobalt (II) metal salts, nickel (II) metal salts, metal cyanide salts and a first complexing agent selected from alcohol compounds, ketone and diketone compounds, ketone-ester compounds, ether compounds or mixtures thereof for a predetermined time and temperature to obtain a double metal cyanide catalyst precursor; and

[0020] (b) reacting the double metal cyanide catalyst precursor obtained in step (a) with a second complexing agent selected from aliphatic carbonyl compounds, aliphatic ester ether compounds or mixtures thereof in water or an organic solvent for a predetermined time and temperature to obtain a double metal cyanide catalyst. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Graphs showing analysis of the catalysts by X-ray diffraction (XRD) technique: a) Comparative Catalyst 1; b) Comparative Catalyst 2; c) Comparative Catalyst 3; d) Catalyst 1 according to the present invention; e) Catalyst 2 according to the present invention; and f) Catalyst 3 according to the present invention. DETAILED DESCRIPTION

[0022] The present invention relates to a method for preparing a double metal cyanide catalyst for producing polycarbonate-ethers from epoxides and carbon dioxide, wherein the method facilitates adjustment of a complexing agent. The catalyst of the present invention can effectively catalyze the production of polycarbonate-ethers from epoxides and carbon dioxide. The preparation method according to the present invention can be described as follows.

[0023] Unless otherwise stated, any aspect described herein is intended to encompass other applications of the invention.

[0024] Unless otherwise defined, technical or scientific terms used herein have the same definitions as those commonly used in this field.

[0025] Any tools, devices, methods or chemicals referred to herein are tools, devices, methods or chemicals commonly used by those skilled in the art, unless otherwise specified that these tools, devices, methods or chemicals are only tools, devices, methods or chemicals specific to the present invention.

[0026] In the claims or the specification, a singular noun or pronoun used with "comprising" means "a", "one", "more than one", "at least one" and "one or more than one".

[0027] Even if not specifically described in the claims, all compositions and / or methods disclosed in this application and the claims are intended to cover any actions, behaviors, modifications or adjustments that can be made by a person of ordinary skill in the art without any experiment significantly different from the present invention and can achieve the same purpose and results as the embodiments of the present invention. Therefore, alternatives or similar embodiments of the present invention, including any minor modifications or adjustments that are obvious to those skilled in the art, should be interpreted as still within the spirit, scope and concept of the present invention as recorded in the appended claims.

[0028] Throughout this application, the term "about" means that any number stated or shown herein may vary or be subject to deviation due to any error in the equipment, method, or person using the equipment or method.

[0029] The following illustrates embodiments of the present invention and is not intended to limit any scope of the invention.

[0030] The present invention relates to a method for preparing a double metal cyanide catalyst for efficiently producing polycarbonate-ether from epoxide and carbon dioxide, and more particularly to the formation of polycarbonate-ether. The catalyst preparation method comprises the following steps:

[0031] (a) mixing a metal salt selected from zinc (II) metal salts, iron (II) metal salts, cobalt (II) metal salts, nickel (II) metal salts, metal cyanide salts and a first complexing agent selected from alcohol compounds, ketone and diketone compounds, ketone-ester compounds, ether compounds or mixtures thereof for a predetermined time and temperature to obtain a double metal cyanide catalyst precursor; and

[0032] (b) reacting the double metal cyanide catalyst precursor obtained in step (a) with a second complexing agent selected from aliphatic carbonyl compounds, aliphatic ester ether compounds or mixtures thereof in water or an organic solvent for a predetermined time and temperature to obtain a double metal cyanide catalyst.

[0033] In one aspect of the present invention, the first complexing agent is tert-butyl alcohol.

[0034] In one aspect of the present invention, the second complexing agent is selected from 2,5-hexanedione, methyl methoxyacetate, methyl 3-methoxypropionate, or a mixture thereof.

[0035] In one aspect of the present invention, the metal salt is selected from zinc (II) chloride, zinc (II) bromide, zinc (II) acetate, zinc (II) acetylacetonate, zinc (II) nitrate, iron (II) sulfate, iron (II) bromide, cobalt (II) chloride, cobalt (II) thiocyanate, nickel (II) nitrate or a mixture thereof.

[0036] In one aspect of the invention, the metal salt is zinc(II) chloride (ZnCl2).

[0037] In one aspect of the present invention, the metal cyanide salt is selected from potassium hexacyanocobaltate (III), potassium hexacyanoferrate (III), calcium hexacyanocobaltate (III), or mixtures thereof.

[0038] In one aspect of the present invention, the metal cyanide salt is potassium hexacyanocobaltate (III).

[0039] In one aspect of the present invention, the molar ratio of the metal salt to the metal cyanide salt in step (a) is from 1:1 to 20:1.

[0040] In one aspect of the present invention, the molar ratio of the metal salt to the metal cyanide salt in step (a) is from 5:1 to 10:1.

[0041] In one aspect of the present invention, the preparation method is operated at a temperature of 20°C to 100°C, preferably 40°C to 70°C.

[0042] In some aspects of the present invention, the method for preparing a polycarbonate-ether comprises the following steps:

[0043] (a) placing the double metal cyanide catalyst according to any one of claims 1 to 11 in a reactor, adding a polymer polyol, an epoxide and carbon dioxide at a predetermined pressure, heating at a temperature of 50° C. to 120° C., and pressurizing the carbon dioxide to 1 bar to 40 bar; and

[0044] (b) removing the mixture obtained in step (a) from the reactor and isolating the polycarbonate-ether product from the mixture.

[0045] In some aspects of the invention, the polycarbonate-ether synthesis process is operated at a temperature of 70°C to 100°C and a carbon dioxide pressure of 5 bar to 20 bar.

[0046] In some aspects of the invention, the molar ratio of polymer polyol to epoxide is from 1:5 to 1:4,000.

[0047] Generally, one skilled in the art can adjust the ring-opening copolymerization between the epoxide and carbon dioxide to suit the type and composition of the catalyst.

[0048] The following examples are only used to illustrate one aspect of the present invention and are not intended to limit the scope of the present invention in any way.

[0049] Catalyst preparation

[0050] The catalyst can be prepared as follows.

[0051] Comparative Catalyst 1

[0052] Comparative Catalyst 1 can be prepared by mixing a zinc(II) chloride solution (manufactured by DAEJUNG) and an aqueous potassium hexacyanocobalt(III) solution (manufactured by ACROS ORGANICS) at a molar ratio of 8:1. The solution is then vigorously stirred at a temperature of 40°C to 70°C. The white precipitate is separated and dried. Comparative Catalyst 1 is obtained as a white solid.

[0053] Comparative Catalyst 2

[0054] Comparative catalyst 2 was prepared according to the procedure disclosed by Srinivas et al. (see Applied Catalysis A: General, 2014, 482, 300-308).

[0055] Comparative Catalyst 2 was prepared by mixing a 50:50 solution of tert-butyl alcohol in water (manufactured by LOBA CHEMIE PVT) at a molar ratio of 8:1 with Comparative Catalyst 1 at a temperature of 40° C. to 70° C. The white precipitate was separated and dried to obtain Comparative Catalyst 2 as a white solid.

[0056] Comparative Catalyst 3

[0057] Comparative catalyst 3 was prepared according to the procedures disclosed by Kim et al. (see Catalysis Today, 2021, 375, 335-342).

[0058] Comparative Catalyst 3 was prepared by mixing a zinc(II) chloride solution (manufactured by DAEJUNG) and a 2,5-hexanedione compound (manufactured by Sigma-Aldrich) in water at a molar ratio of 2.25:1. Then, an aqueous potassium hexacyanocobalt(III) solution (manufactured by ACROS ORGANICS) was mixed into the solution at a temperature of 50°C. The molar ratio of zinc(II) chloride to potassium hexacyanocobalt(III) was 6:1. A mixture containing Pluronic (P-123) (manufactured by SIGMA-ALDRICH) and the 2,5-hexanedione compound was added at a molar ratio of 1:460. The white precipitate was separated and dried. Comparative Catalyst 3 was obtained as a white solid.

[0059] Catalyst 1 according to the present invention

[0060] Catalyst 1 according to the present invention can be prepared by adding 2,5-hexanedione (manufactured by SIGMA-ALDRICH) in distilled water (concentration: 0.9 M) at a ratio of 1 g of catalyst to 20 mL of complexing agent solution at a temperature of 50°C. The white precipitate is then separated and dried. Catalyst 1 according to the present invention is obtained as a white solid.

[0061] Catalyst 2 according to the present invention

[0062] Catalyst 2 according to the present invention can be prepared by the method according to Catalyst 1 according to the present invention, except that methyl methoxyacetate (manufactured by Tokyo Chemical Industry) is used as a complexing agent.

[0063] Catalyst 3 according to the present invention

[0064] Catalyst 3 according to the present invention can be prepared by the method according to Catalyst 1 according to the present invention, except that methyl 3-methoxypropionate (manufactured by Tokyo Chemical Industry) is used as a complexing agent.

[0065] Testing of the polymerization efficiency in the production of polycarbonate-ethers

[0066] The comparative catalysts and the catalysts according to the invention were tested for their ability to produce polycarbonate-ethers. The test conditions are as follows.

[0067] The catalyst shown in Table 1 is added to the reactor. Adding molecular weight is polypropylene glycol (manufactured by SIGMA-ALDRICH) and propylene oxide (manufactured by SIGMA-ALDRICH) of 425g / mol, the molar ratio of polypropylene glycol to propylene oxide being 1:200. Then, carbon dioxide is added until the pressure reaches 10 bar. The temperature is heated to about 80 ℃ to 100 ℃, and continues for 1 hour to 3 hours. The reaction is monitored by nuclear magnetic resonance to quantify the content of the by-product cyclic carbonate. When the reaction finishes, the temperature is cooled to room temperature. The resulting polymer is washed with water to remove propylene carbonate and dried to obtain polycarbonate-ether.

[0068] Table 1 shows the production of polycarbonate-ethers from carbon dioxide and epoxides by reactions using comparative catalysts and catalysts according to the invention.

[0069]

[0070] a Experimental conditions: temperature 90 °C, carbon dioxide pressure 10 bar, and propylene oxide to polypropylene glycol precursor ratio of 200;

[0071] b calculated by proton nuclear magnetic resonance spectroscopy;

[0072] c Results obtained by gel permeation chromatography (GPC) technique using polystyrene as a reference standard.

[0073] Detection using proton nuclear magnetic resonance spectroscopy

[0074] 10 mg of the polymer was dissolved in chloroform-d solution and analyzed by nuclear magnetic resonance (Bruker, AVIII HD-600 MHz). The obtained pattern was compared with the reference chemical shift (δ) of the residual protons of chloroform-d (δ = 7.26 ppm).

[0075] Detection by gel permeation chromatography

[0076] 15 mg of polymer was dissolved in 5 mL of tetrahydrofuran (THF) solution. They were then filtered through a 0.22 μm polytetrafluoroethylene filter (PTFE filter) and analyzed using a gel permeation chromatograph (Malvern, Viscotek GPCmax TDA 305) connected to a 300 mm x 8.0 mm ID column containing a porous styrene divinylbenzene copolymer. The test conditions were as follows: a flow rate of 1.0 mL / min and a temperature of 35°C. Tetrahydrofuran was used as the mobile phase. The resulting molecular weight and molecular weight dispersion were compared with polystyrene standards ranging from 1,200 to 300,000 Daltons.

[0077] Detection by powder X-ray diffraction (XRD)

[0078] The samples were ground into powder using a ceramic mortar and pressed into a silicon mold to give it a smooth surface, and then analyzed using a powder X-ray diffractometer (Bruker, D8 ADVANCE). Cu Kα was used as the radiation source. Start at 5 degrees and increase by 0.02 degrees at a rate of 1 degree per minute until it reaches 70 degrees.

[0079] Catalyst test results

[0080] Table 1 shows the results for the comparative catalyst and the catalyst according to the present invention. The conversion of propylene oxide shows that the catalyst according to the present invention has a higher reaction rate than the comparative catalyst. The catalyst according to the present invention provides a higher conversion rate than the comparative catalyst.

[0081] Furthermore, a comparison of Catalyst 1 according to the present invention with Comparative Catalyst 3, which also used 2,5-hexanedione as a complexing agent but had a different catalyst preparation step, revealed that the catalyst according to the present invention provided superior efficiency in the synthesis of polycarbonate-ethers. Both its propylene oxide conversion percentage and polymer yield per gram of catalyst were higher than those of the comparative catalyst. The formation of the byproduct cyclic carbonate was also significantly reduced (5.3% for Catalyst 1 according to the present invention and 36.5% for Comparative Catalyst 3).

[0082] In addition, powder X-ray diffraction (such as Figure 1 As shown in Figure 2, all three catalysts according to the present invention underwent a phase change in molecular structure compared to the catalyst before treatment (Comparative Catalyst 2). Furthermore, these results differed depending on the type of complexing agent, demonstrating that the method according to the present invention can modify the internal structure of the catalyst depending on the selected complexing agent.

[0083] In summary, this demonstrates that the present invention's method for preparing a double metal cyanide catalyst using a secondary complexing agent to improve catalyst performance is simple and easy to implement, and allows for convenient substitution of alternative complexing agents. Compared to previously disclosed methods, the present invention reduces catalyst preparation time and requires only a small amount of complexing agent. Furthermore, the present invention can improve polycarbonate-ether production efficiency compared to conventional catalysts, both in terms of yield and high polymer specificity.

[0084] Preferred embodiments of the present invention

[0085] Preferred embodiments of the present invention are as described in the present specification.

Claims

1. A method for preparing a double metal cyanide catalyst for preparing polycarbonate-ether, wherein the method comprises the following steps: (a) mixing a metal salt selected from zinc (II) metal salts, iron (II) metal salts, cobalt (II) metal salts, nickel (II) metal salts, metal cyanide salts and a first complexing agent selected from alcohol compounds, ketone and diketone compounds, ketone-ester compounds, ether compounds or mixtures thereof for a predetermined time and temperature to obtain a double metal cyanide catalyst precursor; as well as (b) reacting the double metal cyanide catalyst precursor obtained in step (a) with a second complexing agent selected from aliphatic carbonyl compounds, aliphatic ester ether compounds or mixtures thereof in water or an organic solvent for a predetermined time and temperature to obtain the double metal cyanide catalyst.

2. The method for preparing a catalyst according to claim 1, wherein the first complexing agent is tert-butyl alcohol.

3. The method for preparing a catalyst according to claim 1, wherein the second complexing agent is selected from 2,5-hexanedione, methyl methoxyacetate, methyl 3-methoxypropionate or a mixture thereof.

4. The method for preparing a catalyst according to claim 1, wherein the metal salt is selected from zinc chloride (II), zinc bromide (II), zinc acetate (II), zinc acetylacetonate (II), zinc nitrate (II), iron sulfate (II), iron bromide (II), cobalt chloride (II), cobalt thiocyanate (II), nickel nitrate (II), or a mixture thereof.

5. The method for preparing a catalyst according to claim 1, wherein the metal salt is zinc (II) chloride (ZnCl2).

6. The method for preparing a catalyst according to claim 1, wherein the metal cyanide salt is selected from potassium hexacyanocobaltate (III), potassium hexacyanoferrate (III), calcium hexacyanocobaltate (III) or a mixture thereof.

7. The method for preparing a catalyst according to claim 1, wherein the metal cyanide salt is potassium hexacyanocobaltate (III).

8. The method for preparing a catalyst according to claim 1, wherein the molar ratio of the metal salt to the metal cyanide salt in step (a) is 1:1 to 20:

1.

9. The method for preparing a catalyst according to claim 1, wherein the molar ratio of the metal salt to the metal cyanide salt in step (a) is 5:1 to 10:

1.

10. The method for preparing a catalyst according to claim 1, wherein the method is operated at a temperature of 20°C to 100°C.

11. The method for preparing a catalyst according to claim 1, wherein the method is operated at a temperature of 40°C to 70°C.

12. A method for producing a polycarbonate-ether, wherein the method comprises the following steps: (a) placing the double metal cyanide catalyst according to any one of claims 1 to 11 in a reactor, adding a polymer polyol, an epoxide and carbon dioxide at a predetermined pressure, heating at a temperature of 50° C. to 120° C., and pressurizing the carbon dioxide to 1 bar to 40 bar; and (b) removing the mixture obtained in step (a) from the reactor and isolating the polycarbonate-ether product from the mixture.

13. The process for producing polycarbonate-ether according to claim 12, wherein the reaction is operated at a temperature of 70 to 100°C and a pressure of carbon dioxide of 5 to 20 bar.

14. The method for producing polycarbonate-ether according to claim 12, wherein the molar ratio of the polymer polyol to the epoxide is 1:5 to 1:4,000.

15. A catalyst obtained by the method for preparing a catalyst according to any one of claims 1 to 11.

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