Double-metal cyanide complex catalyst as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of catalyst preparation, and discloses a double-metal cyanide complex catalyst as well as a preparation method and application thereof. The preparation method comprises the following steps: dispersing a metal precursor in a first solvent to obtain a solution A; dispersing metal cyanide in a second solvent to obtain a solution B; immersing a high-shear mixer into the solution A, dropwise adding the solution B into the solution A for reaction, then adding the solution C for continuous reaction, and filtering to remove filtrate to obtain a precipitate; and carrying out constant-temperature slurrying on the precipitate by using the solution D, and finally carrying out solid-liquid separation to obtain a solid product. At least one of 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 method has the characteristics of short catalytic induction time, narrow molecular weight distribution of prepared polyether polyol and the like when being used for ring-opening polymerization of epoxy compounds.

Description

Technical Field

[0001] The invention belongs to the technical field of catalyst preparation, and specifically 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. At present, alkaline catalysts and double metal cyanide complex catalysts (DMC) are mainly used in the industry to produce polyether polyols. Compared with the alkaline catalysts used in the traditional ring-opening polymerization of epoxy compounds, DMC has the advantages of less dosage, high catalytic activity, and no need for post-treatment. The obtained polyether polyols have the advantages of high molecular weight, low unsaturation, high average functionality, and narrow molecular weight distribution. In recent years, DMC has also been widely used in the preparation of polycarbonates from epoxides and carbon dioxide. Therefore, it is also a meaningful work to prepare DMC catalysts with better performance.

[0003] The most widely used DMC catalyst is synthesized from K3[Co(CN)6] and ZnCl2, with Zn3[Co(CN)6]2 as the main skeleton and organic ligands as the coordination. The most common organic ligand is tert-butyl alcohol. In addition, organic substances with different functional groups, such as ethers, polyethers, ketones, etc., are added according to different reaction requirements. There are also some studies on doping or loading DMC catalysts and adding some auxiliary components to achieve the ideal catalytic effect.

[0004] According to previous research results, it is proved that the ring-opening polymerization mechanism of the DMC catalytic system belongs to weak cationic coordination polymerization. The catalytic mechanism is that the initiator first activates the catalyst. In this process, the bimetallic complex provides active sites, each active center is connected to the initiator, and the oxygen-containing groups in the initiator are exchanged with the oxygen-containing organic ligands in the catalyst to form active centers on the surface; ethylene oxide and propylene oxide as polymerization monomers are continuously inserted between zinc and oxygen in the catalyst to achieve ring-opening polymerization to achieve chain growth; finally, the reaction is terminated by chain transfer. The real active center is the zinc ion coordinated with the oxygen atom, so the catalytic activity is closely related to the active sites exposed in the catalyst. Improving the uniformity of the particle size of DMC, making its average particle size small, and exposing more active sites can achieve the effect of short catalytic induction time and narrow product distribution.

[0005] In recent years, the preparation technology of DMC has been continuously improved and perfected, and is basically based on mechanical stirring paddles or magnetic stirring. The time from the formation of crystal nuclei to the growth of crystals prepared by traditional mechanical stirring paddles and magnetic stirring is quite different, so the prepared particle size is not uniform, so there are few exposed active sites, which seriously affects the catalytic effect and makes the molecular weight distribution of the prepared polyether product wider.

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

[0007] The present invention aims to solve 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 and a preparation method and application thereof. The double metal cyanide complex catalyst prepared by the present invention has a short catalytic induction time and a narrow molecular weight distribution of the prepared product.

[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 speed of 4000-8000 r / min for reaction, then adding a solution C prepared with a third solvent and containing or not containing a ligand compound, and continuing the reaction. After the reaction is completed, filtering the filtrate 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 obtain 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 between 10 wt% and 40 wt%.

[0019] Preferably, 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 halogen ion, hydroxide, sulfate, bisulfate, carbonate, bicarbonate, cyanide, thiocyanate, isocyanate, cyanate, carboxylate, oxalate, nitrate or nitrite; a is 1 to 4, b is 1 to 4, and the stoichiometric numbers a and b are such that M1 a X b The compound represented is electrically neutral.

[0020] Preferably, 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; c is 1 to 4, d is 4 to 8, e is 1 to 4, and the stoichiometric numbers c, d, e make M2 c [M3(CN) d ] e The compound represented by is electrically neutral; the M1 and the M3 may be the same or different.

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

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

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

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

[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, isopropanol, 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.; 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, wherein the double metal cyanide complex catalyst has the structural formula M1 c [M3(CN) d ] e g M1 a X b ·fL1·kH2O, the values ​​of a, b, c are 1 to 4 respectively, the value of d is 4 to 8, the value of e is 1 to 4, the values ​​of f, g, k are 1 to 10 respectively, where L1 represents an organic ligand.

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

[0033] Specifically, the double metal cyanide complex catalyst is used 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, and the large shear rate formed in the shear gap 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, and the material is sucked into the rotor part from the axial direction, and then is quickly thrown to the shear gap under the action of the rotor centrifugal force. The material is subjected to strong shearing 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 more, so 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 controls its rotation speed. The prepared DMC catalyst has uniform size and a small average particle size; more active ions (such as zinc ions) that can be coordinated with oxygen are exposed, which makes the catalyst structure more disordered, has low crystallinity, and has more active sites. In the catalytic process, the double metal cyanide complex catalyst provided by the present invention can greatly shorten the catalytic induction time and make the molecular weight distribution of the prepared product narrow.

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

[0038] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0039] The reagents used in the following examples and comparative examples are from Aladdin reagents with a purity of 99%. Other raw materials or devices, unless otherwise specified, 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 zinc chloride in 180g ultrapure water, add 40g tert-butyl alcohol, stir and pre-mix for 15min to obtain solution A; dissolve 6g potassium cobalt cyanide in 100g water to obtain solution B; place a high shear mixer in solution A, adjust the speed to 6000r / min, use a radial flow rotor, and drip solution B near the high shear mixer, and drip it within 8min; then add a mixture of 60g tert-butyl alcohol and 60g dimethyl phthalate, and stir at a constant temperature of 30℃ for 20min. Then filter and collect the precipitate, and mix the precipitate with a mixture of 60g tert-butyl alcohol, 60g dimethyl phthalate and 60g water at a constant temperature of 30℃ for 20min, and repeat this process twice; finally, use a mixture of 60g tert-butyl alcohol and 30g dimethyl phthalate to mix at a constant temperature of 30℃ for 20min. 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 zinc chloride in 140g ultrapure water, add 30g tert-butyl alcohol, stir and pre-mix for 15min to obtain solution A; dissolve 6g potassium cobalt cyanide in 100g water to obtain solution B; place the high shear mixer in solution A, adjust the speed to 5000r / min, use the jet flow rotor, drip solution B near the high shear mixer, and drip it within 10min; then add a mixture of 60g tert-butyl alcohol and 50g dimethyl phthalate, and stir at a constant temperature of 30℃ for 30min. Then filter and collect the precipitate, and stir the precipitate with a mixture of 60g tert-butyl alcohol, 50g dimethyl phthalate and 50g water at a constant temperature of 30℃ for 30min, and repeat this process twice; finally, use a mixture of 60g tert-butyl alcohol and 30g dimethyl phthalate to perform high shear pulping at a constant temperature of 30℃. 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 zinc chloride in 140g ultrapure water, add 36g tert-butyl alcohol, stir and pre-mix for 15min to obtain solution A; dissolve 6g potassium cobalt cyanide in 160g water to obtain solution B; place the high shear mixer in solution A, adjust the speed to 7000r / min, use a jet flow rotor, drip solution B near the high shear mixer, and drip it within 10min; then add a mixture of 60g tert-butyl alcohol and 50g dimethyl phthalate, and stir at a constant temperature of 40℃ for 20min. Then filter and collect the precipitate, stir the precipitate with a mixture of 60g tert-butyl alcohol, 50g dimethyl phthalate and 50g water at a constant temperature of 40℃ for 30min, and repeat this process twice; finally, use a mixture of 60g tert-butyl alcohol and 60g dimethyl phthalate to pulp at a constant temperature of 40℃ for high shear. 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-butyl alcohol, stir and pre-mix for 15min 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, adjust the speed to 6000r / min, use an axial flow rotor, and drip solution B near the high shear mixer within 10min; then add a mixture of 60g of tert-butyl alcohol and 60g of PPG polyether with a molecular weight of 1000, and stir at constant temperature and high shear for 30min at 30℃. Then filter and collect the precipitate, stir the precipitate with a mixture of 80g of tert-butyl alcohol and 50g of water at constant temperature and high shear for 30min at 30℃, and repeat this process twice; finally, use 80g of tert-butyl alcohol at 30℃ and high shear for pulping. 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] Dissolve 36g of zinc chloride in 180g of ultrapure water, add 20g of a mixture of PPG polyether with a molecular weight of 1000, stir and pre-mix for 15min 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, adjust the speed to 7000r / min, use an axial flow rotor, and drip solution B near the high shear mixer within 10min; then add 60g of tert-butyl alcohol, and stir at a constant temperature of 30℃ for 30min. Then filter and collect the precipitate, and mix the precipitate with a mixture of 80g of tert-butyl alcohol, 60g of PPG polyether with a molecular weight of 1000 and 60g of water, and stir at a constant temperature of 30℃ for 30min, and repeat this process twice; finally, use 80g of tert-butyl alcohol at a constant temperature of 30℃ for high shear pulping. 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 within 8 minutes under the action of a mechanical stirring paddle 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 within 10 min under the action of a mechanical stirring paddle 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 within 10 min under the action of a mechanical stirring paddle 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 within 10 min under the action of a mechanical stirring paddle at a rotation speed of 600 r / min. Other operations are the same as those 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 within 10 min under the action of a mechanical stirring paddle at a rotation speed of 600 r / min. Other operations are the same as those in Example 5.

[0065] Comparative Example 6

[0066] The difference between this 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 this comparative example and Example 4 is that the high-speed shear mixer is placed in solution B, the rotation speed is adjusted to 6000 r / min, solution A is dripped at a position near the high-shear mixer and the dripping is completed within 10 minutes. Other operations are the same as in Example 4.

[0069] Comparative Example 8

[0070] The difference between this comparative example and Example 4 is that the rotation speed of the high shear mixer is controlled to be 2000 r / min, and the other operations are the same as those in Example 4.

[0071] Application Examples

[0072] The polyether polyols were prepared using the double metal cyanide complex catalysts provided in the above examples and comparative examples.

[0073] The specific process is as follows: 200g of polypropylene glycol PPG400 and 0.04g of the above catalyst are added to the reactor, and the nitrogen is replaced several times and then vacuumed and heated to 120°C for dehydration. After dehydration, the temperature is lowered to 80°C, 0.04g of the above catalyst is added, the temperature is raised to 140°C, and 50g of propylene oxide is slowly added for activation. The activation time (i.e., catalytic induction time) is recorded. After activation, the feed rate is 5g / min, and 850g of propylene oxide is introduced. After the reaction is completed, the temperature is lowered and the material is discharged to obtain a polyether product. 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 can be seen from the data in Table 1, the double metal cyanide complex catalyst prepared by the high shear mixer in the embodiment of the present invention has a short catalytic induction time, a high reaction effect, and a narrower molecular weight distribution of the product obtained by catalysis, compared with the catalyst prepared by the traditional mechanical stirring method. In addition, by comparing Example 4 with Comparative Examples 6, 7, and 8, it can be seen that controlling the order of adding the solutions and the speed of the high shear mixer rotor during the preparation process are crucial to preparing a high-performance catalyst.

[0078] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached 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 speed of 4000-8000 r / min for reaction, then adding a solution C prepared with a third solvent and containing or not containing a ligand compound, and continuing the reaction. After the reaction is completed, filtering the filtrate 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 obtain 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 dripped into the solution A at a rotation speed of 4500-8000 r / min to react.

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 halogen ion, 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; the value of c is 1 to 4, the value of d is 4 to 8, and the value of 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 5-20; the molar ratio of the M3 to the ligand compound is 10-50.

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-butyl alcohol, glycerol, isopropyl alcohol, methyl ethyl ketone, 3-pentanone, ethylene glycol dimethyl ether, tetrahydrofuran, diethylene glycol dimethyl ether, 1,4-dioxane, benzaldehyde, isobutylaldehyde, 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 respectively, the value of d is 4 to 8, the value of e is 1 to 4, the values ​​of f, g, k are 1 to 10 respectively, 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.

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