A method for the preparation of a catalyst for the synthesis of high activity bio-based polyols

Abstract

The application provides a preparation method of a catalyst for high-activity bio-based polyol synthesis, comprising the following steps: 1) mixing a ligand polymer with an alcohol compound to obtain a catalyst ligand; 2) synchronously and slowly adding the catalyst ligand obtained in the step 1) and a potassium hexacyanocobaltate aqueous solution into a zinc salt aqueous solution to carry out a reaction, and obtaining a solid precipitate, which is a catalyst crude product; 3) washing the catalyst crude product with a weak acid aqueous solution, then washing with desalted water, filtering water, and then carrying out post-treatment to obtain the catalyst. The catalyst can be used for the synthesis of high-activity castor oil polyether polyol, the prepared castor oil polyether polyol has a content of primary hydroxyl groups higher than 80%, and has the advantages of no ester group chain breaking and narrow molecular weight distribution.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of catalyst synthesis, and in particular, the present application relates to a preparation method of a catalyst for high-activity bio-based polyol synthesis. BACKGROUND

[0002] High resilience foam is a kind of soft polyurethane foam with excellent resilience performance, which is widely used in furniture, vehicle seats, experience equipment and other fields. The preparation of high resilience foam takes high-activity polyether polyol and isocyanate as main raw materials, wherein the high-activity polyether polyol is an EO-terminated polyether polyol product with a primary hydroxyl content of >80%. The high primary hydroxyl content provides high reactivity of polyether and isocyanate.

[0003] The development of vegetable oil polyol is considered to be an effective way for the development of bio-based materials, which is a molecular structure derived from chemical modification of vegetable oil as raw material, and is an important renewable resource. When reacting with isocyanate compounds, it is a good alternative raw material for petroleum-based polyols. The hydroxyl functionality of castor oil is 2.7, which meets the application requirements of soft foam polyether, and is an ideal initiator for soft foam polyether. Patents CN10112 1784A and CN103694465A disclose a preparation method for synthesizing castor oil-based polyether polyol using DMC catalyst. However, DMC catalyst is not suitable for the polymerization of pure ethylene oxide, so the primary hydroxyl content of the prepared bio-based polyether polyol is much lower than 80%. Alkali metal catalysts such as potassium hydroxide can catalyze the polymerization of PO and EO, but the reaction of alkali metal catalysts with ester groups in castor oil causes chain scission, resulting in a wide molecular weight distribution of the prepared polyether polyol, which affects the application performance of the final product.

[0004] In summary, it is crucial to develop a catalyst that can overcome the above problems and be suitable for the synthesis of high-activity castor oil polyether polyol. SUMMARY

[0005] In view of the problems existing in the prior art, the purpose of the present application is to provide a preparation method of a catalyst for high-activity bio-based polyol synthesis. The catalyst prepared by the method of the present application can realize the catalytic polymerization of EO to prepare high-activity bio-based polyether polyol, and at the same time, will not cause chain scission by reacting with ester groups, and has the advantage of narrow molecular weight distribution.

[0006] To achieve the purpose, the present application adopts the following technical solutions:

[0007] A preparation method of a catalyst for high-activity bio-based polyol synthesis, comprising the following steps:

[0008] 1) mixing the ligand polymer and the alcohol compound uniformly to obtain a catalyst ligand;

[0009] 2) The catalyst ligand obtained in step 1) is slowly added into the zinc salt aqueous solution synchronously to react, and a solid precipitate is obtained, which is the crude catalyst;

[0010] 3) The crude catalyst is washed with weak acid aqueous solution, and then with desalination water, filtered to remove water, and then post-treated to obtain the catalyst.

[0011] According to the preparation method, in step 1), the structure of the ligand polymer is as follows:

[0012]

[0013] wherein a:b = 10:1-20:1, a:c = 1:1-1:3, 50≤m+n≤100, m:n = 1:1-1:10.

[0014] According to the preparation method, in step 1), the alcohol compound is one or more of isopropyl alcohol, tert-butyl alcohol, propylene glycol and ethylene glycol, preferably isopropyl alcohol.

[0015] According to the preparation method, in step 1), the mass ratio (g / g) of the ligand polymer to the alcohol compound is 1:(10-15).

[0016] According to the preparation method, in step 2), the zinc salt includes one of zinc sulfate, zinc chloride, zinc acetate and zinc nitrate, preferably zinc chloride.

[0017] According to the preparation method, in step 2),

[0018] The concentration of the zinc salt aqueous solution ranges from 10wt% to 30wt%;

[0019] The concentration of the potassium hexacyanocobaltate aqueous solution ranges from 10wt% to 30wt%;

[0020] The mass ratio (g / g) of the potassium hexacyanocobaltate aqueous solution to the catalyst ligand is 1:10-1:40, preferably 1:20-1:30;

[0021] The mass ratio (g / g) of the potassium hexacyanocobaltate aqueous solution to the zinc salt aqueous solution is 1:3-1:10, preferably 1:5-1:8.

[0022] According to the preparation method, in step 2), the reaction temperature is 20-40℃, and the reaction time is 1h-5h, preferably the reaction temperature is 25-35℃, and the time is 2h-4h.

[0023] According to the preparation method, in step 3), the weak acid is one of lactic acid, acetic acid and formic acid, preferably acetic acid; and the pH of the aqueous weak acid solution is 5-6.8, preferably 5.5-6.5.

[0024] According to the preparation method, in step 3), the post-treatment comprises drying and grinding treatment, wherein the drying temperature is 40-60°C, and the drying time is 8-24 hours.

[0025] According to the preparation method, the ligand polymer is prepared by the following steps:

[0026] S1: dissolving styrene sulfonic acid, allyl alcohol polyether and ligand polymer monomers in an organic solvent to form a monomer solution;

[0027] S2: adding an initiator to the monomer solution to perform a polymerization reaction;

[0028] S3: removing the organic solvent in the reaction solution to obtain the ligand polymer.

[0029] According to the preparation method, in step S1, the concentration of the monomer solution is 4-20 wt%, preferably 5-17 wt%.

[0030] According to the preparation method, in step S1, the organic solvent is one or more of toluene, o-xylene and m-xylene.

[0031] According to the preparation method, in step S1, the mass ratio of styrene sulfonic acid, allyl alcohol polyether and ligand polymer monomers is 1:(1-6): (1.1-4), preferably 1:(1.05-5.5):(1.2-3.6).

[0032] According to the preparation method, in step S1,

[0033] The structure of the allyl alcohol polyether is:

[0034]

[0035] wherein m and n are as defined above;

[0036] The structure of the ligand polymer monomer is:

[0037]

[0038] According to the preparation method, in step S2, the initiator is one or more of azobisisobutyronitrile, benzoyl peroxide, azobisisoheptyl nitrile and lauroyl peroxide, preferably azobisisobutyronitrile.

[0039] According to the preparation method of the present application, in step S2, the amount of initiator added is 0.15-0.30wt%, preferably 0.18-0.27wt% of the monomer solution.

[0040] According to the preparation method of the present application, in step S2, the reaction temperature is 80-120℃, and the reaction time is 2-5h.

[0041] According to the preparation method of the present application, in step S3, the organic solvent in the reaction solution is removed under vacuum at -0.095-0.100MPaG, preferably at 100-120℃.

[0042] Compared with the prior art, the present application has the following advantages:

[0043] The present application designs to synthesize a comb-shaped ligand polymer, introduces a stereoscopic N heterocyclic structure in the comb-shaped chain, and when forming a catalyst with zinc and cobalt, can effectively reduce the crystallinity of the catalyst and improve the catalytic activity of the catalyst. At the same time, the protonic acid provided by the sulfonic acid group in the ligand polymer combines with the N heterocyclic structure to form a quaternary ammonium salt cation, which can effectively strengthen the ring-opening treatment effect of ethylene oxide in cooperation with the complex metal ion catalysis. The catalyst of the present application can be used for the synthesis of high-activity castor oil polyether polyol, and the prepared castor oil polyol has a primary hydroxyl content of >80% and no ester group chain scission, and has the advantages of narrow molecular weight distribution. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 The GPC spectrum of the polyether polyol prepared in Example 4 of the present application is shown.

[0045] Figure 2 The GPC spectrum of the polyether polyol prepared in Comparative Example 1 is shown.

[0046] Figure 3 The GPC spectrum of the polyether polyol prepared in Comparative Example 2 is shown. DETAILED DESCRIPTION

[0047] The technical solutions in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments. All other embodiments obtained by those skilled in the art based on the embodiments in the present application belong to the scope of protection of the present application.

[0048] Unless otherwise defined, all professional terms used herein have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the scope of protection of the present application.

[0049] Gel permeation chromatography test conditions: tested using a Waters 515 liquid chromatograph, the chromatographic column is HR-3, HR-4, HR-6, the detector is a refractive index detector waters 2414, the mobile phase is tetrahydrofuran, the flow rate is 1 mL / min, the column temperature is 40℃, the sample concentration is 5 mg / mL, and narrow distribution polyethylene glycol is used as a sample.

[0050] Raw material sources:

[0051] The reagents used in the examples have no special description and can be purchased from reagent manufacturers. The product purity is chemical purity.

[0052] The allyl alcohol polyether used to prepare the ligand polymer can be prepared by a conventional method. The preparation method of the allyl alcohol polyether of the present application is described as follows.

[0053] Preparation Example 1: Preparation of allyl alcohol polyether a

[0054] Into a 10L reactor, 100g of allyl alcohol and 10g of sodium metal were added. The temperature was maintained at 40℃ under stirring at 200rpm for 1h, then the temperature was increased to 110℃. The flow rate was controlled to keep the pressure in the reactor less than 0.3MPaG. 3500g of propylene oxide was continuously fed into the reactor. After the feeding was completed, the reaction was continued for 1.5h. The flow rate was controlled to keep the pressure in the reactor less than 0.3MPaG. 2655g of ethylene oxide was continuously fed into the reactor. After the feeding was completed, the reaction was continued for 1.5h. The unreacted propylene oxide and ethylene oxide were removed by reducing the pressure to-0.098MPaG at 110℃. 50.2g of phosphoric acid and 300g of water were added to the reaction solution for neutralization for 1h. 3g of adsorbent was added for adsorption for 1h. The water content was reduced to less than 0.05% by dehydration. Filtration gave allyl alcohol polyether a (m=25, n=25).

[0055] The allyl alcohol polyether b of Preparation Example 2 and the allyl alcohol polyether c of Preparation Example 3 were obtained by the same preparation method as Preparation Example 1. The reaction conditions were the same as those of Preparation Example 1, except that the feeding ratio was different. The feeding amount of allyl alcohol polyether b and allyl alcohol polyether c was as shown in Table 1.

[0056] Table 1

[0057] Allyl alcohol (g) Sodium metal (g) Propylene oxide (g) Ethylene oxide (g) Phosphoric acid (g) Water (g) Allyl alcohol polyether b 100 10 5000 379 50.2 300 Allyl alcohol polyether c 100 10 7500 1137 50.2 300

[0058] The structure of the prepared allyl alcohol polyether b is m=5, n=50; and the structure of the allyl alcohol polyether c is m=15, n=75.

[0059] The following examples use ligand polymer monomer A to prepare ligand polymers, which can be prepared by referring to patent CN 111440180B. The structure of ligand polymer monomer A is as follows:

[0060]

[0061] Embodiment

[0062] Preparation of catalyst a in example 1

[0063] Synthesis of ligand polymer a: 50 g of styrene sulfonic acid, 90.7 g of allyl alcohol polyether a, and 90 g of monomer A were dissolved in 800 g of toluene to form a solution, 2.70 g of azobisisobutyronitrile was added to the solution, and the solution was heated to 100°C under stirring at 500 rpm. The reaction was continued for 3 h at 100°C, and toluene in the reaction solution was removed under the condition of a vacuum degree of -0.098 MPaG and a temperature of 100°C. The product was placed in a dialysis bag for dialysis purification, and water in the purified product was removed under the condition of a vacuum degree of -0.098 MPaG and a temperature of 100°C. Ligand polymer a (the number average molecular weight was 34200, the PDI was 1.46, m = 25, n = 25, a:b:c = 10:1:10) was obtained.

[0064] The ligand polymer a was stirred with 100 g of isopropyl alcohol to prepare a catalyst ligand. The catalyst ligand and 5 g of an aqueous solution of potassium hexacyanocobaltate (30 wt%) were simultaneously added dropwise to 15 g of an aqueous solution of zinc chloride (30 wt%) under stirring. The dropwise addition was completed in 1 h, and the reaction was continued for 1 h after the dropwise addition. The temperature was maintained at 20°C throughout the process. After the reaction, a solid precipitate was obtained by filtration, which was the crude catalyst. The crude catalyst was washed with 500 mL of an aqueous acetic acid solution (pH 5) in three times. After the washing, the water was removed by filtration, and then the catalyst was dried in a vacuum environment at 40°C for 24 h. The catalyst product a was obtained by grinding.

[0065] Preparation of catalyst b in example 2

[0066] Synthesis of ligand polymer b: 50 g of styrene sulfonic acid, 53 g of allyl alcohol polyether b, and 178 g of monomer A were dissolved in 800 g of m-xylene to form a solution, 1.9 g of azobisisobutyronitrile was added to the solution, and the solution was heated to 100°C under stirring at 500 rpm. The reaction was continued for 3 h at 100°C, and m-xylene in the reaction solution was removed under the condition of a vacuum degree of -0.098 MPaG and a temperature of 100°C. The product was placed in a dialysis bag for dialysis purification, and water in the purified product was removed under the condition of a vacuum degree of -0.098 MPaG and a temperature of 100°C. Ligand polymer b (the number average molecular weight was 35600, the PDI was 1.39, m = 5, n = 50, a:b:c = 15:1:30) was obtained.

[0067] The 100 g ligand polymer b is stirred and mixed with 1200 g propylene glycol to prepare catalyst ligand b. The catalyst ligand b and 51 g of an aqueous potassium hexacyanocobaltate solution (10 wt%) are simultaneously added dropwise to 510 g of an aqueous zinc sulfate solution (10 wt%) under stirring, and the dropping is completed in 1 h. After the dropping is completed, the stirring is continued for 5 h, and the temperature is maintained at 40°C throughout the process. After the reaction is completed, a solid precipitate is obtained by filtration, which is the catalyst crude product. The catalyst crude product is washed with 2000 mL of an aqueous lactic acid solution (pH 6.8) in three times. After the washing, the water is removed by filtration, and then the catalyst product b is obtained by drying at 60°C in a vacuum environment for 8 h and then grinding.

[0068] Preparation of the catalyst c of Example 3

[0069] Synthesis of the ligand polymer c: 50 g of styrene sulfonic acid, 268 g of allyl alcohol polyether c, and 63 g of monomer A are dissolved in 800 g of toluene to prepare a solution. 3.2 g of azobisisobutyronitrile is added to the solution. The solution is stirred at 500 rpm and heated to 100°C. The reaction is continued at 100°C for 3 h. The toluene in the reaction solution is removed at a vacuum degree of -0.098 MPaG and a temperature of 100°C. The product is placed in a dialysis bag for purification by dialysis. The water in the purified product is removed at a vacuum degree of -0.098 MPaG and a temperature of 100°C. The ligand polymer c is obtained (the number average molecular weight is 35600, the PDI is 1.39, m = 15, n = 75, a:b:c = 20:1:60, as determined by gel permeation chromatography).

[0070] The 10 g ligand polymer c is stirred and mixed with 150 g of tert-butyl alcohol to prepare a catalyst ligand. The catalyst ligand and 5.3 g of an aqueous potassium hexacyanocobaltate solution (20 wt%) are simultaneously added dropwise to 32 g of an aqueous zinc nitrate solution (20 wt%) under stirring, and the dropping is completed in 1 h. After the dropping is completed, the stirring is continued for 3 h, and the temperature is maintained at 30°C throughout the process. After the reaction is completed, a solid precipitate is obtained by filtration, which is the catalyst crude product. The catalyst crude product is washed with 1000 mL of an aqueous formic acid solution (pH 6) in three times. After the washing, the water is removed by filtration. Then, the catalyst product c is obtained by drying at 50°C in a vacuum environment for 12 h and then grinding.

[0071] Synthesis of the polyether polyol

[0072] 900g castor oil as a starting agent mixed with 0.10g catalyst a in the above example, heated to 100℃, stirred until the material was evenly dispersed, kept the temperature at 100℃, stirred under vacuum for 2h; heated to 140℃, added 50g propylene oxide, activated; when the pressure dropped to-0.09MPaG, 1900g of propylene oxide was continuously added to the reaction vessel again, the reaction temperature was controlled at 140℃ and the pressure was not higher than 0.3MPaG during the reaction, after the feeding was completed, the reaction was continued for 30min, then the reaction vessel was filled with nitrogen to raise the pressure to 0.1MPaG, 450g of ethylene oxide was continuously added to the reaction vessel again, the reaction temperature was controlled at 140℃ and the pressure was not higher than 0.3MPaG during the reaction, after the feeding was completed, the reaction was continued for 30min, then the unreacted ethylene oxide was removed by controlling the vacuum degree to-0.098MPaG and the temperature to 140℃ under reduced pressure, and 3000g of polyether polyol product was obtained.

[0073] Example 5 Synthesis of polyether polyol

[0074] The difference between Example 5 and Example 4 is that catalyst b in Example 2 is used, and the rest of the conditions are the same. The GPC spectrum of the polyether polyol prepared in Example 5 is consistent with that of Example 4.

[0075] Example 6 Synthesis of polyether polyol

[0076] The difference between Example 6 and Example 4 is that catalyst c in Example 3 is used, and the rest of the conditions are the same. The GPC spectrum of the polyether polyol prepared in Example 6 is consistent with that of Example 4.

[0077] Comparative Example 1 Synthesis of polyether polyol

[0078] The difference between Comparative Example 1 and Example 4 is that KOH is used as a catalyst, and the amount of catalyst used is 18g, and the rest of the conditions are the same.

[0079] Comparative Example 2 Synthesis of polyether polyol

[0080] The difference between Comparative Example 2 and Example 4 is that the bimetallic catalyst used in the preparation of polyether polyol in this comparative example is a commercially available product from Huai'an Bad Polyurethane Technology Co., Ltd., and the rest of the conditions are the same.

[0081] The polyether polyols prepared in Examples 4-6, the polyether polyols prepared in Comparative Examples 1 and 2, were tested for hydroxyl value, viscosity, and appearance according to GB / T12008.3-2009 Plastics-Polyether Polyols. Gel permeation chromatography was used to test the molecular weight distribution of the samples, and nuclear magnetic resonance was used to test the content of primary hydroxyl groups. The results are shown in Table 2.

[0082] Table 2

[0083]

[0084]

[0085] From the test data in Table 2, the molecular weight distribution of the sample of Examples 4-6 is about 1.18, and the primary hydroxyl content is about 84%. Compared with the sample of Comparative Example 1, the molecular weight distribution of the sample of Examples is obviously smaller than that of the sample of Comparative Example 1, which proves that the ester groups are not broken. Compared with the samples of Comparative Examples 1 and 2, the primary hydroxyl content of the sample of Examples is obviously higher than that of the samples of Comparative Examples 1 and 2, which proves that the catalyst of the present application is suitable for the polymerization of EO and can produce a product with high primary hydroxyl content. The catalyst of the present application can be used for the synthesis of high-activity castor oil polyether polyol, and the castor oil polyol produced has a primary hydroxyl content higher than 80% and no ester group breakage, and has the advantage of narrow molecular weight distribution.

Claims

1. A method for preparing a catalyst for the synthesis of highly active bio-based polyols, comprising the following steps: 1) The ligand polymer is mixed with an alcohol compound to obtain a catalyst ligand, wherein the structure of the ligand polymer is as follows: Where, a:b=10:1-20:1, a:c=1:1-1:3, 50≤m+n≤100, m:n=1:1-1:10; 2) The catalyst ligand obtained in step 1) is simultaneously and slowly added dropwise to the zinc salt aqueous solution to carry out the reaction, and the solid precipitate obtained is the crude catalyst. 3) The crude catalyst was washed with a weak acid aqueous solution, then washed with demineralized water, filtered to remove water, and then post-treated to obtain the catalyst.

2. The preparation method according to claim 1, wherein, In step 1), The alcohol compound is one or more of isopropanol, tert-butanol, propylene glycol, and ethylene glycol; The mass ratio of the ligand polymer to the alcohol compound is 1:(10-15).

3. The preparation method according to claim 1 or 2, wherein, In step 2), The zinc salt includes one of zinc sulfate, zinc chloride, zinc acetate, and zinc nitrate; The concentration range of zinc salt aqueous solution is 10-30 wt%. The concentration range of potassium hexacyanocobalamin aqueous solution is 10-30 wt%. The mass ratio of potassium hexacyanocobalaate aqueous solution to catalyst ligand is 1:10-1:40; The mass ratio of potassium hexacyanocobalamin aqueous solution to zinc salt aqueous solution is 1:3-1:10; The reaction temperature is 20–40℃, and the reaction time is 1–5 h.

4. The preparation method according to claim 3, wherein, In step 2), The mass ratio of potassium hexacyanocobalaate aqueous solution to catalyst ligand is 1:20-1:30; The mass ratio of potassium hexacyanocobaltate aqueous solution to zinc salt aqueous solution is 1:5-1:

8.

5. The preparation method according to claim 1 or 2, wherein, In step 3), The weak acid is one of lactic acid, acetic acid, or formic acid; the pH of an aqueous solution of a weak acid is 5-6.

8. Post-processing includes drying and grinding, with the drying temperature being 40–60℃ and the drying time being 8–24 hours.

6. The preparation method according to claim 1 or 2, wherein, The ligand polymer is prepared by the following steps: S1: Prepare a monomer solution by dissolving styrene sulfonic acid, allyl alcohol polyether, and ligand polymer monomer in an organic solvent; S2: Add an initiator to the monomer solution to initiate the polymerization reaction; S3: Remove the organic solvent from the reaction solution to obtain the ligand polymer.

7. The preparation method according to claim 6, wherein, In step S1, The concentration of the monomer solution is 4-20 wt%. The organic solvent is one or more of toluene, o-xylene, and m-xylene; The mass ratio of styrene sulfonic acid, allyl alcohol polyether, and ligand polymer monomer is 1:(1-6):(1.1-4).

8. The preparation method according to claim 6, wherein, In step S1, The structure of allyl alcohol polyether is as follows: Wherein, m and n are as defined in claim 1; The structure of the ligand polymer monomer is as follows:

9. The preparation method according to claim 6, wherein, In step S2, The initiator is one or more of azobisisobutyronitrile, benzoyl peroxide, azobisisoheptanenitrile, and dodecanoyl peroxide; The amount of initiator added is 0.15-0.30 wt% of the monomer solution; The reaction temperature is 80-120℃, and the reaction time is 2-5 hours.

10. The preparation method according to claim 6, wherein, In step S3, Organic solvents in the reaction solution are removed under vacuum conditions of -0.095 to -0.100 MPaG.

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