A dmc catalyst and a method for producing the same

Abstract

The application discloses a DMC catalyst and a preparation method thereof, and belongs to the technical field of catalysts, which comprises the following steps: S1, a first metal precursor is added into a first solvent containing a ligand compound, and is dispersed by stirring to obtain a first solution; S2, a metal cyanide is added into a second solvent to obtain a second solution; S3, the first solution and the second solution are simultaneously poured into a colloid mill for rapid nucleation; a ligand compound is added into the colloid for crystallization, and first precipitates are obtained through suction filtration and separation; S4, the first precipitates are repeatedly constant-temperature slurried by using a mixed solution composed of the ligand compound and water, second precipitates are obtained through suction filtration and separation, and drying is performed, so that the DMC catalyst is obtained. The DMC catalyst is prepared by using a nucleation and crystallization isolation method, rapid nucleation is realized by using a colloid mill, the colloid is crystallized under specific conditions, the crystal grain size is uniform and controllable, the active sites are increased, the induction time is short, and the prepared polyether polyol has the advantages of narrow molecular weight distribution.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a DMC catalyst and its preparation method. Background Technology

[0002] Polyether polyols, also known as polyoxyolefin polyols, are important chemical raw materials widely used in polyurethane products such as polyurethane foams, adhesives, and elastomers. Currently, industrially, alkaline catalysts and dimetallic cyanide complex catalysts (DMC) are mainly used to produce polyether polyols. Compared with the alkaline catalysts used in the traditional ring-opening polymerization of epoxides, DMC has advantages such as lower dosage, higher 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 narrow molecular weight distribution.

[0003] Currently, the most widely used DMC catalysts are synthesized from K3[Co(CN)6] and ZnCl2 as raw materials to form the main framework Zn3[Co(CN)6]2, which is then coordinated with organic ligands such as tert-butanol. Organic compounds with different functional groups, such as ethers, polyethers, and ketones, can also be added according to different reaction requirements. In recent years, the preparation technology of DMC has been continuously improved and perfected. Currently, there are three methods for preparing DMC catalysts: The first method involves first preparing a metal salt solution containing organic ligands, then gradually adding a metal cyanide solution to the metal salt solution. After the addition is complete, mechanical stirring is continued for a certain period of time, followed by filtration to separate the precipitate. The precipitate is then slurried with an organic ligand-water mixture, and the slurry and filtration operations are repeated several times. Finally, a slurry is slurried with pure organic ligands, and the precipitate is filtered and separated. The precipitate is then vacuum dried to obtain the final product. The second method involves gradually adding a metal salt solution to a metal cyanide solution while mechanically stirring, then adding a certain amount of organic ligand, and repeating the stirring, filtration, and slurry preparation operations of the first method. The third method involves adding the organic ligand to the metal salt solution and the metal cyanide solution respectively, and then repeating the above steps. The above preparation methods mostly employ mechanical or magnetic stirring to prepare bimetallic catalysts. However, when the resulting DMC catalysts are applied to the synthesis of polyether polyols, they suffer from long induction times and difficulties in induction. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide a method for preparing DMC catalyst. This method uses a nucleation crystallization isolation method to prepare DMC catalyst. By using a colloid mill to achieve rapid nucleation, the nucleated colloid is then crystallized under specific conditions to make the crystal size uniform and controllable and increase the number of active sites. The polyether polyol produced by the catalyst prepared by this method has the advantages of short induction time and narrow molecular weight distribution.

[0005] To solve the above problems, the technical solution adopted by the present invention is as follows: A method for preparing a DMC catalyst, comprising the following steps: S1. The first metal precursor is added to a first solvent containing a ligand compound and stirred to disperse, thus obtaining a first solution; S2. Add the metal cyanide to the second solvent and disperse to obtain the second solution; S3. The first and second solutions are simultaneously poured into a colloid mill with a rotation speed of 3000~6000 r / min for rapid nucleation to obtain a colloid; a ligand compound is added to the colloid to carry out a crystallization reaction; after the reaction is completed, the first precipitate is obtained by filtration and separation. S4. The first precipitate is repeatedly subjected to isothermal slurrying with a mixed solution of ligand compound and water, and then the ligand compound is added for isothermal slurrying. After filtration and separation, the second precipitate is obtained and dried to obtain the DMC catalyst.

[0006] In a preferred embodiment of the present invention, in step S1, the weight percentage of the first metal precursor in the first solution is 5-40 wt%, and the weight percentage of the ligand compound in the first solution is 10-30 wt%; the stirring time is 5-20 min.

[0007] In a preferred embodiment of the present invention, the molecular formula of the first metal precursor is M. 1 a X b Among them, M 1 Zn 2+ Ni 2+ Fe 2+ Fe 3+ Cr 3+ Co 3+ One of the following; X is selected from one of the following: halide ion, hydroxide ion, sulfate ion, bisulfate ion, carbonate ion, bicarbonate ion, cyanide ion, thiocyanate ion, isocyanate ion, cyanate ion, carboxylate ion, oxalate ion, nitrate ion, or nitrite ion; the molecular formula of the metal cyanide is M. 2 c [M 3 (CN) d ] e Among them, M 2 M is an alkali metal. 3 For Fe 2+ Fe 3+ Co 2+ Co 3+ Mn 2+ Mn 3+ Ni 2+ Cr 2+ One of them.

[0008] In a preferred embodiment of the present invention, in step S2, the metal cyanide in the second solution accounts for 0.5~20 wt%, and M 1 With M 3 The molar ratio is 5~20.

[0009] In a preferred embodiment of the present invention, the amount of ligand compound used in step S3 is 20-40 wt% of the colloid mass.

[0010] In a preferred embodiment of the present invention, the content of the ligand compound in the DMC catalyst in step S4 is 10~40wt%.

[0011] In a preferred embodiment of the present invention, the stirring time for adding the ligand compound in steps S3 and S4 is 20-60 min, and the reaction temperature is 20-50℃; the number of times the slurry is washed in step S4 is 2-3 times.

[0012] In a preferred embodiment of the present invention, the ligand compound is one of tert-butanol, dimethyl phthalate, or polyether.

[0013] In a preferred embodiment of the present invention, the first solvent and the second solvent are both selected from water, tert-butanol, 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, polyether, polyester, and starch.

[0014] Another aspect of the present invention is to provide a DMC catalyst prepared by the above-described preparation method. Further, the general formula of the DMC catalyst is M... 1 c [M 3 (CN) d ] e ·gM 1 a X b ·f L1·k H2O, where L is a ligand compound.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: The preparation method of this invention employs a nucleation / crystallization isolation method to prepare DMC catalysts. A colloid mill is used to instantaneously nucleate the solution during the reaction process. Due to the extremely rapid nucleation rate, crystal growth in the colloid mill is negligible. The nucleated colloid is then subjected to isothermal crystallization, allowing the crystal nuclei to grow synchronously under the same conditions, resulting in uniform and controllable crystal size. Furthermore, the DMC catalyst prepared by the nucleation / crystallization isolation method has more defect sites, exposing more active centers of metal ions coordinated with oxygen atoms in the organic ligands. This leads to a more disordered catalyst structure, lower crystallinity, and an increase in active sites, resulting in better catalytic performance. Consequently, the polyether polyols produced using the DMC catalyst prepared by this invention have the advantages of short induction time and narrow molecular weight distribution. Detailed Implementation

[0016] The present invention will be further described in detail below with reference to specific embodiments.

[0017] A method for preparing a DMC catalyst, comprising the following steps: S1. The first metal precursor is added to a first solvent containing a ligand compound, and the mixture is stirred and dispersed for 5-20 minutes to obtain a first solution; the weight percentage of the first metal precursor in the first solution is 5-40 wt%, and the weight percentage of the ligand compound in the first solution is 10-30 wt%. S2. Add the metal cyanide to the second solvent and disperse to obtain the second solution; S3. Simultaneously pour the first and second solutions into a colloid mill at a speed of 3000-6000 r / min for rapid nucleation to obtain a colloid. Add a ligand compound to the colloid and stir for crystallization for 20-60 min at a reaction temperature of 20-50℃. After the reaction, filter and separate to obtain the first precipitate. The amount of the ligand compound used is 20-40 wt% of the colloid mass. S4. The first precipitate is subjected to a first isothermal slurrying process using a mixed solution of the ligand compound and water. The stirring time for each slurrying process is 20-60 min, the reaction temperature is 20-50℃, and the slurry is washed 2-3 times. Then, the ligand compound is added again, and a second isothermal slurrying process is performed under the same conditions. The second precipitate is obtained by filtration and separation, and then dried to obtain the DMC catalyst. Specifically, the ligand compound added in the first isothermal slurrying process accounts for 60%-80% of the weight of the mixed solution of the ligand compound and water, and the amount of ligand compound used in the second isothermal slurrying process is 60-120% of the total amount of ligand compound used in the first isothermal slurrying process. The content of the ligand compound in the DMC catalyst is 10-40 wt%.

[0018] In the above method, the molecular formula of the first metal precursor is M. 1 a Xb Among them, M 1 Zn 2+ Ni 2+ Fe 2+ Fe 3+ Cr 3+ Co 3+ One of the following; X is selected from one of the following: halide ion, hydroxide ion, sulfate ion, bisulfate ion, carbonate ion, bicarbonate ion, cyanide ion, thiocyanate ion, isocyanate ion, cyanate ion, carboxylate ion, oxalate ion, nitrate ion, or nitrite ion. The molecular formula of metal cyanide is M. 2 c [M 3 (CN) d ] e Among them, M 2 M is an alkali metal. 3 For Fe 2+ Fe 3+ Co 2+ Co 3+ Mn 2+ Mn 3+ Ni 2+ Cr 2+ One of them. The metal cyanide accounts for 0.5~20 wt% of the weight in the second solution, and M 1 With M 3 The molar ratio is 5-20. The ligand compound is one of tert-butanol, dimethyl phthalate, or polyether. The first and second solvents are both one of water, tert-butanol, 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, polyether, polyester, or starch.

[0019] The reagents used in the following embodiments and comparative examples of the present invention are from Aladdin reagents and have a purity of 99%.

[0020] Example 1 A method for preparing a DMC catalyst, comprising the following steps: S1. Dissolve 36g of zinc chloride in 160g of ultrapure water, add 40g of tert-butanol, stir and mix for 15min to obtain the first solution; S2. Dissolve 6g of potassium cobalt cyanate in 100g of water and disperse to obtain a second solution; S3. The first and second solutions are simultaneously poured into a colloid mill at a speed of 6000 r / min and reacted for 3 min to rapidly nucleate and obtain a milky white colloid. It is then transferred to a beaker, and a mixture of 60 g of tert-butanol and 60 g of dimethyl phthalate is added. The mixture is stirred at 30 °C for 30 min to crystallize. After the reaction is completed, the mixture is filtered and separated to collect the first precipitate. S4. The first precipitate is mixed with a mixture of 60g tert-butanol, 60g dimethyl phthalate and 60g water and stirred at 30°C for 30min. This process is repeated twice. Finally, a mixture of 60g tert-butanol and 30g dimethyl phthalate is added and stirred at 30°C for 30min. After filtration and separation, the second precipitate is collected and dried in a vacuum oven with a cold trap at 80°C for 48h to obtain the DMC catalyst.

[0021] Example 2 A method for preparing a DMC catalyst, comprising the following steps: S1. Dissolve 20g of zinc chloride in 140g of ultrapure water, add 30g of tert-butanol, stir and mix for 15min to obtain the first solution; S2. Dissolve 6g of potassium cobalt cyanate in 100g of water and disperse to obtain a second solution; S3. The first and second solutions are simultaneously poured into a colloid mill at a speed of 5000 r / min and reacted for 3 min to rapidly nucleate and obtain a milky white colloid. It is then transferred to a beaker, and a mixture of 60 g of tert-butanol and 50 g of dimethyl phthalate is added. The mixture is stirred at 30 °C for 30 min to crystallize. After the reaction is completed, the mixture is filtered and separated to collect the first precipitate. S4. The first precipitate is mixed with a mixture of 60g tert-butanol, 50g dimethyl phthalate and 50g water and stirred at 30°C for 30min. This process is repeated twice. Finally, a mixture of 60g tert-butanol and 30g dimethyl phthalate is added and stirred at 30°C for 30min. After filtration and separation, the second precipitate is collected and dried in a vacuum oven with a cold trap at 80°C for 48h to obtain the DMC catalyst.

[0022] Example 3 A method for preparing a DMC catalyst, comprising the following steps: S1. Dissolve 36g of zinc chloride in 140g of ultrapure water, add 36g of tert-butanol, stir and mix for 15min to obtain the first solution; S2. Dissolve 6g of potassium cobalt cyanate in 160g of water and disperse to obtain a second solution; S3. The first and second solutions were simultaneously poured into a colloid mill at a speed of 6000 r / min and reacted for 4 min to rapidly nucleate and obtain a milky white colloid. It was then transferred to a beaker, and a mixture of 60 g tert-butanol and 50 g dimethyl phthalate was added. The mixture was stirred at 40 °C for 30 min to crystallize. After the reaction was completed, the mixture was filtered and separated to collect the first precipitate. S4. The first precipitate is mixed with a mixture of 60g tert-butanol, 50g dimethyl phthalate and 50g water and stirred at 40°C for 30min. This process is repeated twice. Finally, a mixture of 60g tert-butanol and 60g dimethyl phthalate is added and stirred at 40°C for 30min. After filtration and separation, the second precipitate is collected and dried in a vacuum oven with a cold trap at 80°C for 48h to obtain the DMC catalyst.

[0023] Example 4 A method for preparing a DMC catalyst, comprising the following steps: S1. Dissolve 36g of zinc chloride in 160g of ultrapure water, add 60g of tert-butanol, stir and mix for 15min to obtain the first solution; S2. Dissolve 5g of potassium cobalt cyanate in 100g of water and disperse to obtain a second solution; S3. The first and second solutions are simultaneously poured into a colloid mill at a speed of 5000 r / min and reacted for 4 min to rapidly nucleate and obtain a milky white colloid. It is then transferred to a beaker, and a mixture of 60 g of tert-butanol and 60 g of PPG polyether with a molecular weight of 1000 is added. The mixture is stirred at 30 °C for 30 min to crystallize. After the reaction is completed, the mixture is filtered and separated to collect the first precipitate. S4. The first precipitate is mixed with 80g of tert-butanol and 50g of water and stirred at 30°C for 30min. This process is repeated twice. Finally, 80g of tert-butanol is added and stirred at 40°C for 30min. After filtration and separation, the second precipitate is collected and dried in a vacuum oven with a cold trap at 80°C for 48h to obtain the DMC catalyst.

[0024] Example 5 A method for preparing a DMC catalyst, comprising the following steps: S1. Dissolve 36g of zinc chloride in 160g of ultrapure water, and add 20g of PPG polyether with a molecular weight of 1000. Stir and mix for 15 minutes to obtain the first solution. S2. Dissolve 5g of potassium cobalt cyanate in 100g of water and disperse to obtain a second solution; S3. The first and second solutions are simultaneously poured into a colloid mill at a speed of 4000 r / min and reacted for 5 min to rapidly nucleate and obtain a milky white colloid. It is then transferred to a beaker, and 60 g of tert-butanol is added. The mixture is stirred at 30 °C for 30 min to crystallize. After the reaction is completed, the mixture is filtered and separated to collect the first precipitate. S4. The first precipitate is mixed with 80g of tert-butanol, 60g of PPG polyether with a molecular weight of 1000 and 50g of water and stirred at 30°C for 30min. This process is repeated twice. Finally, 80g of tert-butanol is added and stirred at 30°C for 30min. After filtration and separation, the second precipitate is collected and dried in a vacuum oven with a cold trap at 80°C for 48h to obtain the DMC catalyst.

[0025] Comparative Example 1 The difference between this comparative example and Example 1 is that the second solution was added dropwise to the first solution within 10 minutes under mechanical stirring, while the other operations were the same.

[0026] Comparative Example 2 The difference between this comparative example and Example 2 is that the second solution was added dropwise to the first solution within 10 minutes under mechanical stirring, while the other operations were the same.

[0027] Comparative Example 3 The difference between this comparative example and Example 3 is that the second solution was added dropwise to the first solution within 10 minutes under mechanical stirring, while the other operations were the same.

[0028] Comparative Example 4 The difference between this comparative example and Example 4 is that the second solution was added dropwise to the first solution within 10 minutes under mechanical stirring, while the other operations were the same.

[0029] Comparative Example 5 The difference between this comparative example and Example 5 is that the second solution was added dropwise to the first solution within 10 minutes under mechanical stirring, while the other operations were the same.

[0030] Comparative Example 6 The difference between this comparative example and Example 1 is that 50g of zinc chloride was used, the colloid mill speed was 8000r / min, and other operations were the same.

[0031] Comparative Example 7 The difference between this comparative example and Example 2 is that in step S4, the first precipitate is mixed with a mixture of 120g tert-butanol, 100g dimethyl phthalate and 50g water and stirred at 30°C for 30 minutes to form a slurry. Other operations are the same.

[0032] Comparative Example 8 The difference between this comparative example and Example 3 is that the crystallization and slurry-forming temperatures are both 70°C, while other operations are the same.

[0033] Comparative Example 9 The difference between this comparative example and Example 4 is that the first precipitate was mixed with a mixture of 30g tert-butanol and 50g water and stirred at 30°C for 30 minutes to form a slurry. This process was repeated twice, and the other operations were the same.

[0034] Performance comparison test The DMC catalysts prepared in Examples 1-5 and Comparative Examples 1-9 were applied to the preparation of polyether polyols. The specific procedures were as follows: 200g of polypropylene glycol PPG400 and 0.04g of DMC catalyst were added to a reactor, the reactor was evacuated and heated to 140°C, and then 900g of propylene oxide was added at a feed rate of 50g / min. After the reaction was completed, the reactor was cooled and discharged. The induction time and molecular weight distribution coefficient of the resulting polyether polyols were measured, and the results are shown in Table 1.

[0035] Table 1 Comparison of induction time and molecular weight distribution coefficient of polyether polyols

[0036] As shown in Table 1, the DMC catalyst prepared by the present invention using the nucleation / crystallization isolation method for the preparation of polyether polyols has a shorter induction time and a narrower molecular weight distribution of the polyether polyol product compared to the DMC catalyst prepared by conventional mechanical stirring.

[0037] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a DMC catalyst, characterized in that: Includes the following steps: S1. The first metal precursor is added to a first solvent containing a ligand compound and stirred to disperse, thus obtaining a first solution; S2. Add the metal cyanide to the second solvent and disperse to obtain the second solution; S3. Simultaneously pour the first solution and the second solution into a colloid mill with a rotation speed of 4000~6000r / min for rapid nucleation to obtain a colloid; A ligand compound was added to the colloid and the mixture was stirred for 20-60 minutes to crystallize it at a temperature of 20-50°C. After the reaction was completed, the first precipitate was obtained by filtration and separation. The amount of ligand compound used is 20-40 wt% of the colloid mass; S4. The first precipitate is subjected to a first isothermal slurrying with a mixed solution of ligand compound and water. The stirring time for each slurrying is 20-60 min, the reaction temperature is 20-50℃, and the slurry washing is performed 2-3 times. Then, the ligand compound is added and a second isothermal slurrying is performed under the same conditions. The second precipitate is obtained by filtration and separation, and then dried to obtain the DMC catalyst. The ligand compound added in the first isothermal slurrying accounts for 60%-80% of the weight of the mixed solution of ligand compound and water, and the amount of ligand compound used in the second isothermal slurrying is 60-120% of the total amount of ligand compound used in the first isothermal slurrying. The content of ligand compound in DMC catalyst is 10-40 wt%.

2. The method for preparing the DMC catalyst according to claim 1, characterized in that: In step S1, the weight percentage of the first metal precursor in the first solution is 5-40 wt%, and the weight percentage of the ligand compound in the first solution is 10-30 wt%; the stirring time is 5-20 min.

3. The method for preparing the DMC catalyst according to claim 1 or 2, characterized in that: The molecular formula of the first metal precursor is M 1 a X b ; Among them, M 1 Zn 2+ Ni 2+ Fe 2+ Fe 3+ Cr 3+ Co 3+ One of the following; X is selected from one of the following: halide ion, hydroxide ion, sulfate ion, bisulfate ion, carbonate ion, bicarbonate ion, cyanide ion, thiocyanate ion, isocyanate ion, cyanate ion, carboxylate ion, oxalate ion, nitrate ion, or nitrite ion; the molecular formula of the metal cyanide is M. 2 c [M 3 (CN) d ] e Among them, M 2 M is an alkali metal. 3 For Fe 2+ Fe 3+ Co 2+ Co 3+ Mn 2+ Mn 3+ Ni 2+ Cr 2+ One of them.

4. The method for preparing the DMC catalyst according to claim 3, characterized in that: In step S2, the metal cyanide in the second solution accounts for 0.5~20 wt%, and M 1 With M 3 The molar ratio is 5~20.

5. The method for preparing the DMC catalyst according to claim 1, characterized in that: The ligand compound is one of tert-butanol, dimethyl phthalate, or polyether.

6. The method for preparing the DMC catalyst according to claim 1, characterized in that: The first solvent and the second solvent are both selected from water, tert-butanol, 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, polyether, polyester, and starch.

7. A DMC catalyst, characterized in that: It is prepared by the preparation method described in any one of claims 1 to 6.

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