A double metal cyanide complex catalyst, its preparation method and application

Abstract

The application belongs to the technical field of catalyst preparation, and discloses a double metal cyanide complex catalyst, a preparation method and application thereof. The preparation method is as follows: metal precursors are dispersed in a first solvent to obtain solution A; metal cyanide is dispersed in a second solvent to obtain solution B; a high-shear mixer is immersed in solution A, solution B is added dropwise into solution A for reaction, then solution C is added, the reaction is continuously carried out, and then the filtrate is removed through filtration to obtain a precipitate; the precipitate is constant-temperature thickened using solution D, and finally solid-liquid separation is carried out to obtain a solid product; and the solution A, the solution B, the solution C or the solution D contains a ligand compound. The double metal cyanide complex catalyst prepared by the application has the characteristics of short catalytic induction time and narrow molecular weight distribution of the prepared polyether polyol when used for ring-opening polymerization of an epoxy compound.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation, and particularly relates to a double metal cyanide complex catalyst and a preparation method and application thereof. Background Art

[0002] Polyether polyols are widely used in polyurethane products such as polyurethane foams, adhesives, and elastomers. Currently, alkaline catalysts and double metal cyanide complex catalysts (DMC) are primarily used in the industry to produce polyether polyols. Compared to the alkaline catalysts used in traditional ring-opening polymerizations of epoxy compounds, DMC has the advantages of low dosage, high catalytic activity, and no need for post-treatment. Furthermore, the resulting polyether polyols have advantages such as high molecular weight, low unsaturation, high average functionality, and a narrow molecular weight distribution. In recent years, DMC has also been widely used in the preparation of polycarbonates from epoxides and carbon dioxide. Therefore, the preparation of DMC catalysts with superior performance is a significant undertaking.

[0003] The most widely used DMC catalyst is synthesized from K₃[Co(CN)₆] and ZnCl₂. Its structure is based on a Zn₃[Co(CN)₆]₂ backbone, which is then coordinated with an organic ligand. The most common organic ligand is tert-butyl alcohol. Organic compounds with different functional groups, such as ethers, polyethers, and ketones, are also added depending on the reaction requirements. Other studies have also explored doping or loading DMC catalysts with additives to achieve optimal catalytic performance.

[0004] Previous research has demonstrated that the ring-opening polymerization mechanism of the DMC catalytic system is a weak cationic coordination polymerization. The catalytic mechanism begins with the initiator activating the catalyst. During this process, the bimetallic complex provides active sites. Each active site connects to the initiator, and oxygen-containing groups in the initiator exchange with oxygen-containing organic ligands in the catalyst, forming active sites on the surface. Ethylene oxide and propylene oxide, the monomers, continuously insert between the zinc and oxygen atoms in the catalyst, causing ring-opening polymerization and chain growth. The reaction is terminated by chain transfer. The true active site is the zinc ion coordinated to the oxygen atom, and therefore catalytic activity is closely related to the exposed active sites in the catalyst. Improving the uniformity of DMC particle size, resulting in a small average particle size and more exposed active sites, can achieve a short catalytic induction time and a narrow product distribution.

[0005] In recent years, DMC preparation technology has been continuously improved and refined, primarily relying on mechanical or magnetic stirring. Products prepared using traditional mechanical or magnetic stirring methods experience significant variations in the time it takes for nuclei to form and crystals to grow. This results in uneven particle size, resulting in fewer exposed active sites, severely impacting catalytic performance and leading to a broad molecular weight distribution in the resulting polyether product.

[0006] Therefore, there is an urgent need to provide a double metal cyanide complex catalyst that has a short catalytic induction time and can produce a product with a narrow molecular weight distribution. Summary of the Invention

[0007] The present invention aims to address at least one of the technical problems existing in the above-mentioned prior art. To this end, the present invention provides a double metal cyanide complex catalyst, a preparation method, and applications thereof. The double metal cyanide complex catalyst prepared by the present invention has a short catalytic induction time and produces a product with a narrow molecular weight distribution.

[0008] The invention provides a method for preparing a double metal cyanide complex catalyst.

[0009] Specifically, a method for preparing a double metal cyanide complex catalyst comprises the following steps:

[0010] (1) dispersing a metal precursor in a first solvent to obtain a solution A;

[0011] (2) dispersing the metal cyanide in a second solvent to obtain a solution B;

[0012] (3) immersing the high shear mixer in the solution A, adding the solution B dropwise to the solution A at a rotation speed of 4000-8000 r / min to react, then adding the solution C prepared with a third solvent with or without a ligand compound, and continuing the reaction. After the reaction is completed, the filtrate is filtered to obtain a precipitate;

[0013] (4) using a solution D prepared with a fourth solvent and containing or not containing a ligand compound to slurry the precipitate prepared in step (3) at a constant temperature, and finally obtaining a solid product by solid-liquid separation to prepare a double metal cyanide complex catalyst;

[0014] At least one of the solution A, the solution B, the solution C, or the solution D contains a ligand compound.

[0015] Preferably, in step (3), the solution B is dripped into the solution A at a rotation speed of 4500-8000 r / min for reaction; further preferably, in step (3), the solution B is dripped into the solution A at a rotation speed of 5000-8000 r / min for reaction.

[0016] Preferably, the high shear mixer comprises a rotor, and the rotor is selected from one of a radial flow rotor, a jet flow rotor, and an axial flow rotor.

[0017] Preferably, the ligand compound is selected from at least one of tert-butyl alcohol, dimethyl phthalate or polyether.

[0018] Preferably, the content of the ligand compound in the catalyst is 10wt%-40wt%.

[0019] Preferably, the metal precursor is M1 a X b , wherein M1 is Zn 2+ , Ni 2+ , Fe 2+ , Fe 3+ , Cr 3+ , Co 3+ ; X is selected from one or more of halogen ion, hydroxyl ion, sulfate ion, hydrogen sulfate ion, carbonate ion, hydrogen carbonate ion, cyanide ion, thiocyanate ion, isocyanate ion, cyanate ion, carboxylate ion, oxalate ion, nitrate ion or nitrite ion; a is 1-4, b is 1-4, and the stoichiometric numbers a, b make M1 a X b electrically neutral.

[0020] Preferably, the metal cyanide is M2 c [M3(CN) d ] e , wherein M2 is an alkali metal, and M3 is at least one of Fe 2+ , Fe 3+ , Co 2+ , Co 3+ , Mn 2+ , Mn 3+ , Ni 2+ , Cr 2+ ; c is 1-4, d is 4-8, e is 1-4, and the stoichiometric numbers c, d, e make M2 c [M3(CN) d ] e electrically neutral; and M1 and M3 are the same or different.

[0021] Preferably, the molar ratio of M1 to M3 is 5-20.

[0022] Preferably, the molar ratio of M3 to the ligand compound is 10-50.

[0023] Preferably, the mass percentage of the metal precursor in the solution A is 5wt%-40wt%.

[0024] Preferably, the mass percentage of the metal cyanide in the solution B is 0.05wt%-20wt%.

[0025] Preferably, the first solvent, the second solvent, the third solvent, and the fourth solvent are independently selected from at least one of water, glycerol, isopropyl alcohol, methyl ethyl ketone, 3-pentanone, ethylene glycol dimethyl ether, tetrahydrofuran, diethylene glycol dimethyl ether, 1,4-dioxane, benzaldehyde, isobutyraldehyde, amide, urea, nitrile, sulfide, and polyester.

[0026] Preferably, in step (3), the dropping speed is 7 to 20 mL / min.

[0027] Preferably, in step (3), the reaction temperature is 20°C to 50°C.

[0028] Preferably, in steps (3) and (4), after adding the solution C or the solution D, stirring is continued for 20 to 60 minutes.

[0029] Preferably, in step (4), the temperature of the constant temperature pulping is 20° C. to 50° C.; and the number of constant temperature pulping is 2-6 times.

[0030] The invention provides a double metal cyanide complex catalyst.

[0031] Specifically, a double metal cyanide complex catalyst is prepared by the above preparation method, and the structural formula of the double metal cyanide complex catalyst is M1 c [M3(CN) d ] e ·g M1 a X b ·fL1·kH2O, the values ​​of a, b, c are 1 to 4, d is 4 to 8, e is 1 to 4, f, g, k are 1 to 10, where L1 represents an organic ligand.

[0032] The present invention also provides application of the double metal cyanide complex catalyst.

[0033] Specifically, the use of the double metal cyanide complex catalyst in the preparation of polyether polyols.

[0034] The present invention uses a high shear mixer and utilizes its high rotation speed, high terminal linear velocity, large shear rate formed in the shear gap and other characteristics to prepare a DMC catalyst. The core components of the high shear mixer are the stator and the high-speed rotor and the gap between the two. The high-speed rotating rotor generates a strong centrifugal force, forming a low-pressure area in the center of the rotor. The material is sucked into the rotor part from the axial direction and then quickly thrown into the shear gap under the action of the rotor centrifugal force. The material is subjected to strong shear under the action of the high-speed rotating rotor and can be nucleated instantly. The material subjected to high shear is further evenly dispersed in the container through the stator pores. The product particle size after high shear is small and uniformly distributed, and the exposed zinc ions that can be coordinated with oxygen are relatively large. Therefore, the structure of the catalyst is more disordered, the crystallinity is low, and the active sites are increased.

[0035] Compared with the prior art, the present invention has the following beneficial effects:

[0036] (1) The present invention uses a high-shear mixer to prepare a double metal cyanide complex catalyst, and its rotational speed is controlled. The prepared DMC catalyst has uniform size and a small average particle size. A large number of active ions (such as zinc ions) that can coordinate with oxygen are exposed, resulting in a more disordered structure, low crystallinity, and more active sites. During the catalytic process, the double metal cyanide complex catalyst provided by the present invention can significantly shorten the catalytic induction time and narrow the molecular weight distribution of the prepared product.

[0037] (2) The double metal cyanide complex catalyst prepared by the present invention has the characteristics of short catalytic induction time and narrow molecular weight distribution of the prepared polyether polyol when used for the ring-opening polymerization of epoxy compounds. DETAILED DESCRIPTION

[0038] In order to make the technical solution of the present invention more clearly understood by those skilled in the art, the following examples are given for illustration. It should be noted that the following examples do not limit the scope of protection claimed by the present invention.

[0039] The reagents used in the following examples and comparative examples are Aladdin reagents with a purity of 99%. Unless otherwise specified, other raw materials or devices can be obtained from conventional commercial sources or by existing known methods.

[0040] Example 1

[0041] A method for preparing a double metal cyanide complex catalyst comprises the following steps:

[0042] Dissolve 40g of zinc chloride in 180g of ultrapure water, add 40g of tert-butyl alcohol, and pre-mix with stirring for 15 minutes to obtain Solution A. Dissolve 6g of potassium cobalt cyanide in 100g of water to obtain Solution B. Place a high-shear mixer in Solution A at a speed of 6000 rpm. Using a radial flow rotor, add Solution B dropwise near the high-shear mixer over 8 minutes. Then, add a mixture of 60g of tert-butyl alcohol and 60g of dimethyl phthalate, and stir at a constant temperature of 30°C for 20 minutes. The precipitate is collected by suction filtration and slurried with a mixture of 60g of tert-butyl alcohol, 60g of dimethyl phthalate, and 60g of water at a constant temperature of 30°C for 20 minutes. This process is repeated twice. Finally, slurry is slurried at a constant temperature of 30°C using a mixture of 60g of tert-butyl alcohol and 30g of dimethyl phthalate. The mixture obtained by high shear pulping was filtered, and the precipitate was collected and placed in a vacuum oven with a cold trap device, and dried at 80° C. for 48 hours to obtain a double metal cyanide complex catalyst.

[0043] Example 2

[0044] A method for preparing a double metal cyanide complex catalyst comprises the following steps:

[0045] Dissolve 20g of zinc chloride in 140g of ultrapure water, add 30g of tert-butyl alcohol, and stir premix for 15 minutes to obtain solution A. Dissolve 6g of potassium cobalt cyanide in 100g of water to obtain solution B. Place a high-shear mixer in solution A at a speed of 5000 rpm. Using a Jet Flow rotor, add solution B dropwise near the high-shear mixer over 10 minutes. Then, add a mixture of 60g of tert-butyl alcohol and 50g of dimethyl phthalate, and stir at a constant temperature of 30°C for 30 minutes. The precipitate is collected by suction filtration and slurried with a mixture of 60g of tert-butyl alcohol, 50g of dimethyl phthalate, and 50g of water at a constant temperature of 30°C for 30 minutes. Repeat this process twice. Finally, slurry the mixture of 60g of tert-butyl alcohol and 30g of dimethyl phthalate at a constant temperature of 30°C for high shear stirring. The mixture obtained by high shear pulping was filtered, and the precipitate was collected and placed in a vacuum oven with a cold trap device, and dried at 80° C. for 48 hours to obtain a double metal cyanide complex catalyst.

[0046] Example 3

[0047] A method for preparing a double metal cyanide complex catalyst comprises the following steps:

[0048] Dissolve 40g of zinc chloride in 140g of ultrapure water, add 36g of tert-butyl alcohol, and stir premix for 15 minutes to obtain solution A. Dissolve 6g of potassium cobalt cyanide in 160g of water to obtain solution B. Place a high-shear mixer in solution A at a speed of 7000 rpm. Using a Jet Flow rotor, add solution B dropwise near the high-shear mixer over 10 minutes. Then, add a mixture of 60g of tert-butyl alcohol and 50g of dimethyl phthalate, and stir at a constant temperature of 40°C for 20 minutes. The precipitate is collected by suction filtration and slurried with a mixture of 60g of tert-butyl alcohol, 50g of dimethyl phthalate, and 50g of water at a constant temperature of 40°C for 30 minutes. Repeat this process twice. Finally, slurry the mixture of 60g of tert-butyl alcohol and 60g of dimethyl phthalate at a constant temperature of 40°C for 30 minutes. The mixture obtained by high shear pulping was filtered, and the precipitate was collected and placed in a vacuum oven with a cold trap device, and dried at 80° C. for 48 hours to obtain a double metal cyanide complex catalyst.

[0049] Example 4

[0050] A method for preparing a double metal cyanide complex catalyst comprises the following steps:

[0051] Dissolve 36g of zinc chloride in 160g of ultrapure water, add 60g of tert-butanol, and pre-mix with stirring for 15 minutes to obtain Solution A. Dissolve 5g of potassium cobalt cyanide in 100g of water to obtain Solution B. Place a high-shear mixer in Solution A at 6000 rpm using an axial-flow rotor. Add Solution B dropwise near the high-shear mixer over 10 minutes. Then, add a mixture of 60g of tert-butanol and 60g of PPG polyether with a molecular weight of 1000. Continue stirring at 30°C for 30 minutes. The precipitate is collected by suction filtration and slurried with a mixture of 80g of tert-butanol and 50g of water at 30°C for 30 minutes under high-shear stirring. Repeat this process twice. Finally, slurry is continued with 80g of tert-butanol at 30°C under high-shear stirring. The mixture obtained by high shear pulping was filtered, and the precipitate was collected and placed in a vacuum oven with a cold trap device, and dried at 80° C. for 48 hours to obtain a double metal cyanide complex catalyst.

[0052] Example 5

[0053] A method for preparing a double metal cyanide complex catalyst comprises the following steps:

[0054] 36g of zinc chloride was dissolved in 180g of ultrapure water, and a mixture of 20g of a 1000 molecular weight PPG polyether was added. The mixture was stirred and pre-mixed for 15 minutes to obtain Solution A. 5g of potassium cobalt cyanide was dissolved in 100g of water to obtain Solution B. A high-shear mixer was placed in Solution A at a speed of 7000 rpm. Using an axial flow rotor, Solution B was added dropwise near the high-shear mixer over a period of 10 minutes. 60g of tert-butyl alcohol was then added, and high-shear stirring was maintained at 30°C for 30 minutes. The precipitate was collected by filtration and slurried with a mixture of 80g of tert-butyl alcohol, 60g of a 1000 molecular weight PPG polyether, and 60g of water at 30°C for 30 minutes under high-shear stirring. This process was repeated twice. Finally, high-shear slurrying was performed using 80g of tert-butyl alcohol at 30°C. The mixture obtained by high shear pulping was filtered, and the precipitate was collected and placed in a vacuum oven with a cold trap device, and dried at 80° C. for 48 hours to obtain a double metal cyanide complex catalyst.

[0055] Comparative Example 1

[0056] The difference between this comparative example and Example 1 is that solution B is added dropwise to solution A under the action of a mechanical stirring blade within 8 minutes at a rotation speed of 600 r / min. Other operations are the same as in Example 1.

[0057] Comparative Example 2

[0058] The difference between this comparative example and Example 2 is that solution B is added dropwise to solution A under the action of a mechanical stirring blade within 10 minutes at a rotation speed of 600 r / min. Other operations are the same as in Example 2.

[0059] Comparative Example 3

[0060] The difference between this comparative example and Example 3 is that solution B is added dropwise to solution A under the action of a mechanical stirring blade within 10 minutes at a rotation speed of 600 r / min. Other operations are the same as in Example 3.

[0061] Comparative Example 4

[0062] The difference between this comparative example and Example 4 is that solution B is added dropwise to solution A under the action of a mechanical stirring blade within 10 minutes at a rotation speed of 600 r / min. Other operations are the same as in Example 4.

[0063] Comparative Example 5

[0064] The difference between this comparative example and Example 5 is that solution B is added dropwise to solution A under the action of a mechanical stirring blade within 10 minutes at a rotation speed of 600 r / min. Other operations are the same as in Example 5.

[0065] Comparative Example 6

[0066] The difference between the present comparative example and example 4 is that solution B is quickly poured into solution A, and other operations are the same as those in example 4.

[0067] Comparative example 7

[0068] The difference between the present comparative example and example 4 is that a high-speed shearing mixer is placed in solution B, the rotating speed is adjusted to 6000 r / min, solution A is added dropwise near the high-speed shearing mixer, and the dropping is completed within 10 min, and other operations are the same as those in example 4.

[0069] Comparative example 8

[0070] The difference between the present comparative example and example 4 is that the rotating speed of the high-speed shearing mixer is controlled to 2000 r / min, and other operations are the same as those in example 4.

[0071] Application example

[0072] The double metal cyanide complex catalyst provided by the above examples and comparative examples is used to prepare polyether polyol.

[0073] The specific process is as follows: 200 g of polypropylene glycol PPG400 and 0.04 g of the above catalyst are added to a reaction kettle, the nitrogen is replaced for multiple times, vacuum is applied, and the temperature is raised to 120 DEG C for dehydration. After dehydration, the temperature is lowered to 80 DEG C, 0.04 g of the above catalyst is added, the temperature is raised to 140 DEG C, 50 g of propylene oxide is slowly added, and activation is performed. The activation time (i.e. catalytic induction time) is recorded. After activation, the feeding speed is 5 g / min, 850 g of propylene oxide is introduced, the temperature is lowered after the reaction is completed, and the product is discharged. The molecular weight distribution of the polyether product is tested by GPC. The test results are shown in Table 1.

[0074] Table 1

[0075]

[0076]

[0077] As shown in Table 1, the double metal cyanide complex catalyst prepared by using the high-speed shearing mixer in the present example has a shorter catalytic induction time, a higher reaction effect, and a narrower molecular weight distribution of the product, as compared with the catalyst prepared by the traditional mechanical stirring method. In addition, it can be seen from the comparison between example 4 and comparative examples 6, 7 and 8 that the order of adding the solutions and the rotating speed of the high-speed shearing mixer rotor are crucial for preparing a high-performance catalyst.

[0078] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A method for preparing a double metal cyanide complex catalyst, characterized in that: The following steps are involved: (1) dispersing a metal precursor in a first solvent to obtain a solution A; (2) dispersing the metal cyanide in a second solvent to obtain a solution B; (3) immersing the high shear mixer in the solution A, adding the solution B dropwise to the solution A at a rotation speed of 4000-8000 r / min to react, then adding the solution C prepared with a third solvent with or without a ligand compound, and continuing the reaction. After the reaction is completed, the filtrate is filtered to obtain a precipitate; (4) using a solution D prepared with a fourth solvent and containing or not containing a ligand compound to slurry the precipitate prepared in step (3) at a constant temperature, and finally obtaining a solid product by solid-liquid separation to prepare a double metal cyanide complex catalyst; At least one of the solution A, the solution B, the solution C, or the solution D contains a ligand compound.

2. The preparation method according to claim 1, characterized in that In step (3), the solution B is dropped into the solution A at a rotation speed of 4500-8000 r / min to carry out a reaction.

3. The preparation method according to claim 1 or 2, characterized in that The ligand compound is selected from at least one of tert-butyl alcohol, dimethyl phthalate or polyether.

4. The preparation method according to claim 3, characterized in that The metal precursor is M1 a X b , where M1 is Zn 2+ 、Ni 2+ 、Fe 2+ 、Fe 3+ Cr 3+ 、Co 3+ One of; X is selected from one or more of halide, hydroxide, sulfate, bisulfate, carbonate, bicarbonate, cyanide, thiocyanate, isocyanate, cyanate, carboxylate, oxalate, nitrate or nitrite; a is 1 to 4, and b is 1 to 4.

5. The preparation method according to claim 4, characterized in that The metal cyanide is M2 c [M3(CN) d ] e , where M2 is an alkali metal and M3 is Fe 2+ 、Fe 3+ 、Co 2+ 、Co 3+ 、Mn 2+ 、Mn 3+ 、Ni 2+ Cr 2+ At least one of the following: c is 1 to 4, d is 4 to 8, and e is 1 to 4.

6. The preparation method according to claim 5, characterized in that The molar ratio of the M1 to the M3 is 5 to 20; the molar ratio of the M3 to the ligand compound is 10 to 50.

7. The preparation method according to any one of claims 1, 2, 4, 5 and 6, characterized in that: The first solvent, the second solvent, the third solvent, and the fourth solvent are independently selected from at least one of water, tert-butanol, glycerol, isopropyl alcohol, methyl ethyl ketone, 3-pentanone, ethylene glycol dimethyl ether, tetrahydrofuran, diethylene glycol dimethyl ether, 1,4-dioxane, benzaldehyde, isobutyraldehyde, amide, urea, nitrile, sulfide, polyether, polyester or starch.

8. The preparation method according to claim 7, characterized in that In step (4), the temperature of the constant temperature pulping is 20° C. to 50° C.; the number of constant temperature pulping is 2-6 times.

9. A double metal cyanide complex catalyst, characterized in that Prepared by the preparation method according to any one of claims 1 to 8, the double metal cyanide complex catalyst has the structural formula M1 c [M3(CN) d ] e gM1 a X b ·fL1·kH2O, the values ​​of a, b, c are 1 to 4, d is 4 to 8, e is 1 to 4, f, g, k are 1 to 10, where L1 represents an organic ligand.

10. Use of the double metal cyanide complex catalyst according to claim 9 in the preparation of polyether polyols.

Images