Supported multimetal cyanide complex catalyst, process for its preparation and use

Abstract

This invention discloses a supported multimetallic cyanide complex catalyst, its preparation method, and its application. The catalyst satisfies the following general formula: Zn3[Co(CN)6]2·Zn3[Fe(CN)6]2·Zn[Ni(CN)4]@MCM-41(OH-)·vZnCl2·xLa(NO3)3·y t BuOH·z Igepal CA-520, where MCM-41(OH-) represents an alkali-treated mesoporous molecular sieve; v = 0.5–3, x = 0–0.01, y = 0.1–2, z = 0–0.1. This catalyst is a multi-metallic cyanide complex catalyst modified with organic ligands and co-complexing agents supported on a support surface. When applied to the preparation of high-molecular-weight polypropylene glycol, this catalyst exhibits high conversion rates, minimal loss of active components, strong catalyst regeneration performance, and a narrow molecular weight distribution and low aldehyde value of the resulting polypropylene glycol product, demonstrating broad application prospects.

Description

Technical Field

[0001] This invention relates to a heterogeneous catalyst, its preparation method and application, and more particularly to a supported polymetallic cyanide complex catalyst, its preparation method and application. Background Technology

[0002] Polyether polyols are a class of polymeric compounds with ether bonds (ROR) and terminal hydroxyl groups (OH groups). They are synthesized by ring-opening polymerization of low molecular weight compounds (such as alcohols and amines) with compounds containing epoxy structures. These synthetic materials have wide applications in various industrial fields, including the preparation of polyurethanes, surfactants, and water-based functional liquids.

[0003] To date, industrial-scale ring-opening polymerization of alkyl epoxides primarily utilizes alkali metal hydroxides as anionic polymerization catalysts, with potassium hydroxide being the most commonly used. However, traditional anionic polymerization methods present several challenges in synthesizing propylene oxide polyether polyols. The first problem is that under strongly alkaline conditions, propylene oxide monomers undergo isomerization, generating allyl alcohol anions. These anions act as new initiation and chain propagation sites, leading to a wider molecular weight distribution of the product, reduced reaction selectivity, and limiting molecular weight growth. The second problem is that homogeneous alkaline catalysis results in complex post-processing of the product, causing environmental pollution and equipment corrosion, and increasing production costs.

[0004] Currently, the most widely used catalyst in the industrial preparation of polyether polyols is the bimetallic cyanide complex catalyst (DMC), but it mainly faces the following problems: (1) long reaction induction period; (2) the polypropylene glycol products prepared by the existing zinc-cobalt bimetallic catalyst contain some by-product propylene ester, and the selectivity needs to be improved; (3) the catalyst and product cannot be separated, resulting in a large amount of metal residue in the product, which affects the performance; (4) the reaction temperature is high and the reaction is exothermic, which is dangerous when operating in a batch reactor and cannot be continuously produced.

[0005] Multimetallic cyanide complex catalysts (MMCs) are highly efficient catalysts for epoxide polymerization. Compared with traditional catalysts such as acids and bases, MMCs have improved catalytic effects, but their catalytic performance still needs further improvement and the induction period needs to be shortened. Summary of the Invention

[0006] Purpose of the invention: The purpose of this invention is to provide a supported multimetallic cyanide complex catalyst with high catalytic activity, minimal loss of active components, and short induction period;

[0007] A second objective of this invention is to provide a method for preparing the above-described supported multimetallic cyanide complex catalyst;

[0008] A third objective of this invention is to provide the application of the above-described supported multimetallic cyanide complex catalyst.

[0009] Technical solution: The supported multimetallic cyanide complex catalyst of the present invention satisfies the following general formula:

[0010] Zn3[Co(CN)6]2·Zn3[Fe(CN)6]2·Zn[Ni(CN)4]@MCM-41(OH-)·vZnCl2·xLa(NO3)3·y t BuOH·z Igepal CA-520, where MCM-41(OH-) represents alkali-treated mesoporous molecular sieve; v = 0.5-3, x = 0-0.01, y = 0.1-2, z = 0-0.1.

[0011] The preparation method of the above-mentioned supported multimetallic cyanide complex catalyst includes the following steps:

[0012] (1) After calcining MCM-41 powder, it is mixed with alkaline solution, stirred, cooled to room temperature, washed, dried and ground into powder; the powder is added to ion exchange solution for ion exchange, washed, filtered and dried to obtain alkaline-treated MCM-41 support, denoted as MCM-41(OH-).

[0013] (2) Dissolve three metal cyanides, K3[Co(CN)6], K3[Fe(CN)6], and K2[Ni(CN)4], respectively, and name the resulting solutions A, B, and C, respectively; disperse MCM-41(OH-) in a solvent to obtain an MCM-41(OH-) solution, and then add ZnCl2, La(NO3)3, t The solution obtained by mixing BuOH and Igepal CA-520 is named solution D.

[0014] (3) Add solutions A, B and C dropwise to solution D and stir to obtain a catalyst slurry; filter, wash and dry the catalyst slurry to obtain the supported polymetallic cyanide complex catalyst.

[0015] In step (1), the MCM-41 molecular sieve support is calcined in air at a temperature of 450-650℃ for 4-6 hours. The concentration of the alkaline solution is 0.05-0.3 mol / L, and the alkaline is preferably NaOH; the solid-liquid ratio (g / mL) of MCM-41 to the alkaline solution is 1:10-20; the concentration of the ion exchange solution is 0.3-0.7 mol / L, and the ion exchange solution is preferably NH4Cl solution; the solid-liquid ratio (g / mL) of the powder to the ion exchange solution is 1:10-20.

[0016] In step (2), the concentration of K3[Co(CN)6] solution is 0.05-0.5 g / ml, and the concentrations of K3[Fe(CN)6] and K2[Ni(CN)4] solutions are 5-20% of the concentration of K3[Co(CN)6] solution, respectively.

[0017] In step (2), the t The mass ratio of BuOH to MCM-41(OH-) solution is 1:1-2, the mass ratio of ZnCl2 to MCM-41(OH-) is 5-1:1, and the mass ratio of the sum of the three metal cyanides to MCM-41(OH-) is 2-1:1. The concentration of the MCM-41(OH-) solution is 0.01-0.1 g / ml, and MCM-41(OH-) is preferably dispersed in deionized water.

[0018] In step (2), the mass ratio of La(NO3)3 to MCM-41(OH-) is 1:5-20; the mass ratio of IgepalCA-520 to MCM-41(OH-) is 2-1:1.

[0019] In step (3), the dripping time is 10-30 min, and the stirring is continued for 30-90 min at a stirring rate of 2500-3500 rpm and a temperature of 30-60℃ to obtain the catalyst slurry.

[0020] In step (3), the filter cake obtained by filtration needs to be washed with an aqueous solution of organic ligands at least three times, and the volume ratio of organic ligands to deionized water gradually increases; the drying temperature of the obtained filter cake is 50-80℃.

[0021] The above-mentioned supported multimetallic cyanide complex catalysts are used in the preparation of high molecular weight polypropylene glycol.

[0022] The reaction temperature is 100-140℃, the pressure is 0.1-0.5MPa, the feed ratio is 8:12-72, specifically 8g:12-72g; the single feed amount is 1-12g.

[0023] The apparatus used to synthesize the polymer polypropylene glycol is an external circulation reactor. The external circulation reactor includes a reactor body, an air inlet system, and an external circulation system. The reactor body is equipped with a stirring device and a heating device for heating the reactor. The stirring device and the heating device are respectively connected to the high-pressure reactor controller. The air inlet system is connected to the reactor body to supply raw material gas and protective gas to the reactor body. The external circulation system includes a plunger pump, which is connected to the external circulation outlet at the bottom of the reactor body and the external circulation inlet at the top of the reactor body through pipelines.

[0024] Invention principle:

[0025] (1) Smaller catalyst size and crystallinity are beneficial to improving catalyst performance. The general formula of polymetallic cyanide complexes, i.e., nanoporous Prussian blue analogues, is M. a 2+ [M b 3+ (CN) c ] d M, composed of an octahedral structure b 3+ (CN) c Through M a 2+ Ion bridges connect the crystals, forming a cubic lattice. This cubic lattice consists of alternating M... a 2+ and M b 3+ Ions form crystals linked together by cyanide linkers, creating "defect-free" pores without any unsaturated metal centers. However, due to M... a 2+ With M b 3+ (CN) c The charge imbalance between structures leads to 1 / 3 of M b 3+ Disordered M appears at the site b 3+ (CN) c Vacancies are present to maintain the electroneutrality of the crystal structure, providing space for the subsequent introduction of metal ions. Therefore, in the zinc-cobalt bimetallic cyanide structure Zn3[Co(CN)6]2, Zn... 2+ The charge balance of the ions results in one-third of [Co(CN)6] being part of the crystal lattice structure. 3 - A vacancy exists at the site, where a new ligand [Fe(CN)6] can be introduced. 3 -and [Ni(CN)6] 3 - This forms Zn3[Fe(CN)6]2 and Zn3[Ni(CN)6]2 structures. The polymerization active center of the polymetallic cyanide complex catalyst (MMC) is chelated metal Zn. 2+The synergistic effect of multiple metal cyanide components increases the content of amorphous components in the catalyst. Furthermore, Zn3[Fe(CN)6]2 and Zn3[Ni(CN)6]2 possess larger specific surface areas and more active sites, thus the multimetallic cyanide complex catalyst (MMC) exhibits higher catalytic activity than the ordinary bimetallic cyanide catalyst (DMC). The electronegativity of zinc decreases with increasing coordination number because the introduction of metals Ni(II) and Fe(III) increases the coordination amount of zinc, reduces the electron contribution of cyanide ligands to zinc, decreases the coordination strength between the central zinc atom and the ligands, and also reduces the crystallinity of the catalyst. Therefore, the introduction of metals Ni(II) and Fe(III) can increase the specific surface area of ​​the catalyst, provide more active sites, and simultaneously reduce the crystallinity of the catalyst, thereby improving the catalyst's activity and selectivity.

[0026] (2) Water molecules in Zn 2+ The resulting cavity is filled in both bound and dissolved states, and the organic ligand can then react with Zn. 2+ The open coordination sites on the ligand interact with each other, generating open coordination sites after replacing bound water molecules, and then interacting to form an active catalyst. Based on previous research, the organic ligand is preferably... t BuOH. In the presence of a co-complexing agent, MMC can be converted into nano-sized MMC through a reverse emulsification reaction. Igepal CA-520 is a nonionic surfactant that assists in emulsification and dispersion at the oil-water interface, thereby promoting the reaction. Igepal CA-520 can react with ZnCl2 and Zn3[Co(CN)6]. 2、 The reaction between Zn[Ni(CN)4] and Zn3[Fe(CN)6]2 allows the oxygen atoms in the co-complexing agent Igepal CA-520 to coordinate with Zn, forming new active centers. At the same time, the co-complexing agent Igepal CA-520 can control the size of MMC particles, synthesizing MMC in the particle size range of 50-100 nm. Smaller MMC particle size is beneficial for loading on the MCM-41(OH-) support and improving catalyst performance.

[0027] (3) Since the amount of MMC catalyst used is small, it is difficult to extract the catalyst residue in the product by conventional filtration method. Therefore, MMC with active ingredients is loaded on MCM-41(OH-) support to achieve easy separation of catalyst and product while ensuring complete contact between catalyst and reactant. This avoids residual metal in product and realizes catalyst regeneration and reuse.

[0028] Beneficial effects: Compared with the prior art, the present invention achieves the following significant effects:

[0029] (1) Based on the traditional zinc-cobalt bimetallic cyanide catalyst (DMC), metals Ni(II) and Fe(III) were introduced to prepare a multimetallic cyanide complex catalyst (MMC), which reduced the crystallinity of the catalyst, increased the specific surface area of ​​the catalyst, improved the catalytic activity of the catalyst, and resulted in a shorter reaction induction period and fewer by-products; (2) Igepal, a co-complexing agent, was added during the preparation of MMC. CA-520 reduced the particle size of the catalyst and increased the number of active sites of the catalyst; (3) MMC catalyst was loaded in MCM-41(OH-) support, which made it easy to separate from the product, the active components were not easily lost, and the catalyst life was long; (4) The obtained high molecular weight polypropylene glycol product had a narrow molecular weight distribution width and low aldehyde value, and had broad application prospects; (5) The continuous synthesis of high molecular weight polypropylene glycol using heterogeneous catalyst in an external circulation reactor was realized. The external circulation promoted the mixing between reactants and products and accelerated the reaction rate; the reaction heat generated during polymerization was removed in time through external circulation, avoiding the phenomenon of "explosive polymerization" caused by excessive local temperature in the reactor, improving the color of the product and improving production safety. Attached Figure Description

[0030] Figure 1 SEM image of the catalyst prepared in Example 1;

[0031] Figure 2 TG-DTG curve of the catalyst prepared in Example 1;

[0032] Figure 3 Example 7 illustrates the effect of reaction temperature on the molecular weight and conversion rate of the product.

[0033] Figure 4 Example 8 illustrates the effect of reaction pressure on the molecular weight and conversion rate of the product.

[0034] Figure 5 The effect of feed ratio on product molecular weight and conversion rate in Example 9;

[0035] Figure 6 Example 10 illustrates the effect of a single monomer addition on the molecular weight and conversion rate of the product.

[0036] Figure 7 The effect of the number of times the catalyst is reused on the molecular weight and conversion rate of the product in Example 11;

[0037] Figure 8 This is a schematic diagram of the external circulation reactor used in the synthesis of polypropylene glycol according to the present invention. Detailed Implementation

[0038] The present invention will now be described in further detail.

[0039] Example 1

[0040] A supported polymetallic cyanide complex catalyst with the molecular formula: Zn3[Co(CN)6]2·Zn3[Fe(CN)6]2·Zn[Ni(CN)4]@MCM-41(OH-)·ZnCl2·La(NO3)3· t BuOH·Igepal CA-520 is prepared by the following steps:

[0041] (1) MCM-41 powder with Si / Al (m / m) = 25 was placed in a muffle furnace and calcined at 550℃ in air atmosphere for 5h. The calcined MCM-41 molecular sieve was mixed with 0.10mol / L NaOH solution at a solid-liquid ratio (g / mL) of 1:20 in a round-bottom flask and stirred at 800rpm at 65℃ for 0.5h. The round-bottom flask was then cooled to room temperature, washed with water and filtered until pH = 7. It was dried at 110℃ for 10h and the resulting solid was ground into powder. The powder was then added to 0.5mol / L NH4Cl solution at a solid-liquid ratio (g / mL) of 1:20 and subjected to ion exchange at 60℃ for 1h and filtration. The above operation was repeated four times. The powder was then washed with deionized water until the filtrate was free of chloride ions and dried in an oven at 110℃ overnight to obtain the alkali-treated MCM-41 support, denoted as MCM-41(OH-).

[0042] (2) Prepare four solutions: Dissolve 1.0g K3[Co(CN)6], 0.1g K3[Fe(CN)6], and 0.1g K2[Ni(CN)4] in 10ml of deionized water to prepare three aqueous solutions of metal cyanides, named solution A, solution B, and solution C respectively; take 1g of alkali-treated MCM-41(OH) - Disperse the solution in 10ml of deionized water, then add 4.0g ZnCl2, 0.1g La(NO3)3, and 15ml of water. t Solution D was prepared by dissolving BuOH and 5.0 g of Igepal CA-520.

[0043] (3) Under the conditions of 80℃ and 3000rpm, solutions A, B and C are simultaneously added to solution D within 20min, and stirring is continued for 1h to obtain catalyst slurry.

[0044] (4) Filter the catalyst slurry five times with deionized water: After the first filtration, use 100ml of deionized water. t The mixture of BuOH and water is used to make a slurry, in which t The volume ratio of BuOH to water is 1:2; after pulping, a second filtration is performed, and 100ml of the filtered solution is used. t The mixture of BuOH and water is used to make a slurry, in whicht The volume ratio of BuOH to water is 1:1; after pulping, a third filtration is performed, and 100ml of the filtered solution is used. t The mixture of BuOH and water is used to make a slurry, in which t The volume ratio of BuOH to water is 2:1; after pulping, a fourth filtration is performed, and 100ml of the filtered solution is used. t BuOH was used for slurry preparation; after slurry preparation, a fifth filtration was performed. The filtered cake was then placed in a vacuum drying oven and dried overnight at 65°C to obtain a supported multi-metallic cyanide complex catalyst: MCM-41(OH-)@Zn3[Co(CN)6]2·Zn3[Fe(CN)6]2·Zn[Ni(CN)4]·ZnCl2·La(NO3)3· t BuOH·Igepal CA-520.

[0045] Figure 1 Here is a SEM image of the catalyst prepared in Example 1, where Figure 1 Figure a in the image is the overall SEM image. Figure 1 Figure b in the image is a partial SEM image, showing the good integration of the support and the active component. The alkali-modified support, MCM-41 molecular sieve, has an enlarged pore size, exposing more active sites, upon which a multi-metal cyanide complex catalyst grows. The prepared MMC exhibits a distinct layered structure, such as... Figure 1 In the b, the sheet-like MMCs aggregate together in a relatively stable environment to form a certain cluster structure.

[0046] Figure 2 The image shows the TG-DTG curve of the catalyst prepared in Example 1. Thermal analysis was used to determine the binding state of the ligands, co-complexing agents, and their main catalyst backbone, zinc hexacyanocobaltate. The supported MMC catalyst complexes two types of organic ligands: small-molecule organic compounds and high-molecular-weight polymers. Its composition and structure are more complex than those of the zinc hexacyanocobaltate sample, and its TG curve is also more complex, lacking obvious steps, indicating that the boundaries between decomposition stages are not very clear and that the ligand binding states are complex. The mass loss can be roughly divided into three stages: first, the rapid removal of physically adsorbed water; second, the removal of free organic ligands and co-complexing agents; and finally, the removal of cyanide ligands.

[0047] Comparative Example 1

[0048] A supported bimetallic cyanide complex catalyst, differing from Example 1 only in that it does not contain Zn3[Fe(CN)6]2 and Zn[Ni(CN)4], has the structural formula: Zn3[Co(CN)6]2@MCM-41(OH-)·ZnCl2·La(NO3)3· t BuOH·Igepal CA-520.

[0049] Comparative Example 2

[0050] A supported multimetallic cyanide complex catalyst, differing from Example 1 only in that it does not contain Zn[Ni(CN)4], has the following structural formula: Zn3[Co(CN)6]2·Zn3[Fe(CN)6]2@MCM-41(OH-)·ZnCl2·La(NO3)3· t BuOH·Igepal CA-520.

[0051] Comparative Example 3

[0052] A supported multimetallic cyanide complex catalyst, differing from Example 1 only in that it does not contain Zn3[Fe(CN)6]2, has the structural formula: Zn3[Co(CN)6]2·Zn[Ni(CN)4]@MCM-41(OH-)·ZnCl2·La(NO3)3· t BuOH·Igepal CA-520.

[0053] Comparative Example 4

[0054] A supported multimetallic cyanide complex catalyst, differing from Example 1 only in that it does not contain Zn3[Fe(CN)6]2 and Zn[Ni(CN)4], but instead contains K4Fe(CN)6, with the structural formula: Zn3[Co(CN)6]2·K4Fe(CN)6@MCM-41(OH-)·ZnCl2·La(NO3)3· t Preparation method of BuOH·Igepal CA-520.

[0055] Comparative Example 5

[0056] A supported multimetallic cyanide complex catalyst, differing from Example 1 only in that it does not contain Ige palCA-520, has the following structural formula: Zn3[Co(CN)6]2·Zn3[Fe(CN)6]2·Zn[Ni(CN)4]@MCM-41(OH-)·ZnCl2·La(NO3)3· t BuOH.

[0057] Catalyst performance testing:

[0058] The catalysts used in Example 1 and Comparative Examples 1-5 were tested for catalyst performance. These catalysts were used in an external circulation reactor to catalyze the polymerization of small-molecule polypropylene glycol and propylene oxide to produce high-molecular-weight polypropylene glycol, with a target molecular weight of 3000. Specific test conditions were as follows: initial reaction pressure of 0.2 MPa, reaction temperature of 120°C; total feed amount of initiator PPG-400 of 8 g, added all at once; total feed amount of propylene oxide of 52 g, with a single feed amount of 3 g, added in small amounts multiple times. After the reaction, the product was collected, and unreacted monomers were separated by rotary evaporation under reduced pressure to obtain the high-molecular-weight polypropylene glycol product. The hydroxyl value of the high-molecular-weight polypropylene glycol product was titrated using the phthalic anhydride method. The results are shown in Table 1.

[0059] Table 1. Comparison of catalyst performance tests in Example 1 and Comparative Examples 1-5

[0060]

[0061] As shown in Table 1, under the same reaction time, the catalytic performance of Example 1 is significantly improved compared with Comparative Examples 1-5. This can be attributed to two reasons: First, the elements Ni(II), Fe(III), and Fe(II) added in Example 1 reduce the crystallinity of the MMC catalyst and increase its specific surface area. Second, the co-complexing agent Igepal CA-520 added in Example 1 enables control over the particle size of the MMC catalyst, synthesizing a nano-scale catalyst. This catalyst reacts with the active components ZnCl2, Zn3[Co(CN)6]2, Zn3[Fe(CN)6]2, Zn[Ni(CN)4], and K4Fe(CN)6, promoting the coordination of Zn with oxygen in Igepal CA-520 and generating new active sites. Both of these factors enhance the catalytic activity of the catalyst.

[0062] Furthermore, Ni(II), Fe(III), and Fe(II) metals all exhibited the strongest catalytic activity. Ni(II) showed superior monometallic catalytic performance compared to Fe(III) and Fe(II), and Ni(II) and Fe(III) showed a synergistic effect in this reaction. This may be due to Ni... 2 + Fe 3+ High specific capacitance and Co 2+ The synergistic effect between the redox-rich valence states of ions improves the structural stability of the four-coordinated nanosheets, thereby promoting the activation of the active centers.

[0063] Example 2

[0064] Two parallel experiments were designed, with the specific preparation method the same as in Example 1, except that: in one group, the amount of K2[Ni(CN)4] added in step (2) was different, with the amounts of K2[Ni(CN)4] added being 0.05g, 0.10g, and 0.15g, respectively; in the other group, the amount of K3[Fe(CN)6] added in step (2) was different, with the amounts of K3[Fe(CN)6] added being 0.05g, 0.10g, and 0.15g, respectively.

[0065] Catalyst performance tests were conducted on catalysts with different amounts of potassium nickel cyanide and potassium ferricyanide, and the hydroxyl value of the products was determined. The results are shown in Tables 2-1 and 2-2, respectively.

[0066] Table 2-1 Comparison of Catalyst Performance Tests with Different Potassium Nickel Cyanide Addition Amounts

[0067]

[0068] Table 2-2 Comparison of Catalyst Performance Tests with Different Potassium Ferricyanide Addition Amounts

[0069]

[0070] As shown in Tables 2-1 and 2-2, with the increase of potassium nickel cyanide and potassium ferricyanide, the catalytic performance of the catalyst first increases and then decreases under the same reaction time. This is because although the introduction of elements Ni(II) and Fe(III) can improve the activity of the catalyst, excessive Ni(II) and Fe(III) will further reduce the crystallinity of MMC, but at the same time, it will also block the active centers of MMC, thus resulting in a relatively longer induction period and a slower reaction rate.

[0071] Example 3

[0072] Four parallel experiments were designed, with the same preparation method as in Example 1, except that the amount of ZnCl2 added in step (2) was different, namely 2.0g, 4.0g, 6.0g, 8.0g and 10.0g. The catalysts synthesized with different amounts of ZnCl2 were tested for catalyst performance, and the hydroxyl value of the products was titrated. The results are shown in Table 3.

[0073] Table 3 Performance test results of catalysts synthesized with different ZnCl2 addition amounts

[0074]

[0075] As shown in Table 3, both excessive and insufficient ZnCl2 addition will affect the catalyst performance. The synthesized catalyst exhibits the best catalytic performance when the ZnCl2 addition amount is 4.0 g.

[0076] Example 4

[0077] Three sets of parallel experiments were designed. The specific preparation method was the same as in Example 1. The difference was that the support in step (1) was different. The supports were MCM-41 with Si / Al (m / m) = 25, Hβ with Si / Al (m / m) = 25, ZSM-5 with Si / Al (m / m) = 70, and SiO2 with Si / Al (m / m) = 25.

[0078] Catalyst performance tests were conducted on catalysts supported on different supports, and hydroxyl value titrations were performed on the products. The results are shown in Table 4.

[0079] Table 4 Performance Test Table of Catalysts with Different Supports

[0080]

[0081] As shown in Table 4, the synthesized catalyst exhibits the best catalytic performance when MCM-41 (Si / Al = 25) is used as the support. This is because MCM-41 (Si / Al = 25) possesses unique acidity and pore structure, providing more active sites.

[0082] Example 5

[0083] Four parallel experiments were designed, and the specific preparation method was the same as in Example 1. The difference was whether NaOH solution was used in step (1) and whether different NaOH solution concentrations were used for alkali treatment. The results were that no NaOH solution was used and NaOH solution concentrations of 0.05 mol / L, 0.10 mol / L, 0.15 mol / L and 0.20 mol / L were used for alkali treatment.

[0084] Catalysts prepared from supports treated with different NaOH solution concentrations were tested for catalyst performance, and the hydroxyl values ​​of the products were titrated. The results are shown in Table 5.

[0085] Table 5. Catalyst Performance Tests at Different NaOH Solution Concentrations

[0086]

[0087] Table 5 shows that the catalyst prepared with a NaOH solution concentration of 0.10 mol / L exhibits the best catalytic effect. This is because the appropriate alkali treatment concentration further increases the pore volume and specific surface area of ​​the support MCM-41 (Si / Al = 25), resulting in more active sites. Conversely, excessively low alkali treatment concentrations have little effect, while excessively high concentrations will damage the pore structure of the molecular sieve, causing pore collapse and reducing the number of active sites.

[0088] Example 6

[0089] Three parallel experiments were designed, and the specific preparation method was the same as in Example 1. The difference was that the co-complexing agents in step (2) were different. The co-complexing agents were Igepal CA-520, PPG-3000, PTMEG and P123.

[0090] Catalyst performance tests were conducted on catalysts with different co-complexing agents, and the hydroxyl value of the products was determined. The results are shown in Table 6.

[0091] Table 6. Catalyst Performance Test Table with Different Co-complexing Agents

[0092]

[0093] Without the addition of a co-complexing agent, the performance of MMC catalysts is relatively low. Therefore, it is necessary to add a suitable co-complexing agent to complex with MMC catalysts and activate their activity in propylene oxide polymerization. As shown in Table 6, compared with polymers PPG-3000, polytetramethylene ether glycol (PTMEG), and triblock polymer P123, Igepal CA-520 has a more significant effect on improving catalyst stability and dispersibility. This may be because ammonia-catalyzed MCM-41(OH-) particles co-condense in the reverse microemulsion of Igepal CA-520, producing a partially condensed nanosphere system, which promotes the dispersion of MMC catalysts, forms smaller nanoscale MMC, and increases the surface area of ​​the catalyst.

[0094] Example 7

[0095] The catalyst and reactants prepared in Example 1 were used to synthesize high-molecular-weight polypropylene glycol. Four parallel experiments were designed to investigate the effect of reaction temperature on the synthesis of high-molecular-weight polypropylene glycol. The reaction temperatures were set at 100℃, 110℃, 120℃, 130℃, and 140℃, respectively. The results are shown in [Figure number missing]. Figure 3 .

[0096] Depend on Figure 3 It can be seen that the conversion rate of propylene oxide and the molecular weight of the product initially increase and then tend to stabilize with increasing reaction temperature. The polymerization rate increases significantly with increasing temperature, but the catalyst performance tends to stabilize after reaching 120℃. Further increasing the temperature leads to more by-products, a darker product color, and increased energy consumption. Therefore, the prepared supported MMC catalyst requires a lower reaction temperature than current MMC catalysts, improving operational safety and reducing energy consumption.

[0097] Example 8

[0098] Four parallel experiments were designed, differing from Example 6 in that the reaction pressures for synthesizing polypropylene glycol were different, set at 0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, and 0.5 MPa, respectively. The results are shown in [Figure Number]. Figure 4 .

[0099] Reaction pressure affects the solubility of propylene oxide in the liquid phase. Within a certain range, higher pressure leads to higher solubility, which in turn increases the probability of effective collisions between propylene oxide, glycerol, and the catalyst. Increased pressure increases the equilibrium constant of the polymerization reaction, propelling the reaction in the forward direction (the direction with fewer gas molecules). Figure 4 It can be seen that the conversion rate of propylene oxide and the molecular weight of polypropylene glycol do not change much with pressure: when the pressure reaches 0.2 MPa, the reaction results gradually stabilize.

[0100] Example 9

[0101] Four parallel experiments were designed, differing from Example 6 in that the feed ratios of the initiator and propylene oxide in the synthesis of polypropylene glycol were different, set to 8g:12g, 8g:32g, 8g:52g, 8g:62g, and 8g:72g, respectively. The target molecular weights of the synthesized polypropylene glycol were 1000, 2000, 3000, 3500, and 4000, respectively. The results are shown in […]. Figure 5 .

[0102] Depend on Figure 5 It can be seen that as the target molecular weight of the synthesized polypropylene glycol increases, the conversion rate also increases, indicating that the catalyst has good application prospects in the synthesis of polypropylene glycol.

[0103] Example 10

[0104] Four parallel experiments were designed, differing from Example 6 in that the single-batch dosage of propylene oxide varied while maintaining a constant initiator dosage. The total dosage of initiator PPG-400 was 8g, added all at once; the total dosage of propylene oxide was 52g, with single-batch dosages of 1g, 3g, 6g, 9g, and 12g, added in small, multiple batches. Results are shown below. Figure 6 .

[0105] Depend on Figure 6 It can be seen that when the total amount of propylene oxide is constant, the amount of propylene oxide added at one time has a particularly significant impact on the distribution width of the high-molecular-weight polypropylene glycol product. The smaller the amount added at one time, the narrower the distribution width, the better the polymerization effect, and the higher the product quality.

[0106] Example 11

[0107] After the reaction, the catalyst from Example 1 was filtered to obtain a solid catalyst. It was then repeatedly washed with tert-butanol and water under vacuum to remove residual small-molecule polypropylene glycol product adhering to the catalyst surface. The recovered catalyst was vacuum dried and reused in synthesis experiments. The obtained catalyst was then used again to test its catalytic activity lifetime and regenerability. This process was repeated 5 times, resulting in 6 sets of performance comparisons. The results are shown in [Figure Number]. Figure 7 .

[0108] Depend on Figure 7 It can be seen that the conversion rate still remains above 94.5% after the catalyst is recycled 5 times, indicating that the prepared supported MMC catalyst has high stability, the active components are not easily lost, and the reusability is good, thus it has good prospects for industrial application.

[0109] Example 12

[0110] like Figure 8 As shown, the present invention provides an external circulation reactor for synthesizing high molecular weight polypropylene glycol, comprising a reactor body, a high-pressure vessel controller 18, an external circulation system, and an air inlet system. The reactor body is equipped with a stirring device and a heating device for heating the reactor.

[0111] The reactor body in this embodiment includes a vessel body fixed on a support, a vessel lid component, and a stirring device, a strong magnetic coupling stirrer 5 fixed on the lid. A thermometer 4 is also fixed on the lid; the thermometer 4 is inserted into the reactor body; the strong magnetic coupling stirrer 5 is connected to a servo speed-regulating motor 1 via a transmission belt 3. The strong magnetic coupling stirrer 5 includes a stirring paddle 9 extending into the reactor body, and a cooling coil 8 is provided on the stirring paddle 9, which is connected to a condensate pipe (not shown in the figure). The reactor body is equipped with a high-temperature, high-pressure needle valve 6 for controlling the pressure inside the reactor body and a pressure gauge 7 for detecting the pressure inside the reactor body. The heating device includes a heating layer 10 located on the inner side wall of the reactor body, an insulation layer 11 located on the outer side wall of the reactor body, and a mesh screen 12 for filtering the catalyst inside the reactor body. The high-pressure reactor controller 18 is electrically connected to the heating layer 10 and the servo speed-regulating motor 1, respectively, and can control the temperature and stirring rate inside the reactor.

[0112] The air intake system of this embodiment includes a nitrogen cylinder 20 and a propylene oxide cylinder 21. An air intake pipeline is connected between the nitrogen cylinder 20 and the propylene oxide cylinder 21 and the vessel body. A three-way valve 19 is provided on the air intake pipeline.

[0113] The external circulation system of this embodiment includes an external circulation outlet 13 located at the bottom of the reactor body, a pump inlet pipe 14 connected to the external circulation outlet 13, a plunger pump 15 connected to the pump inlet pipe 14, a pump outlet pipe 16 connected to the plunger pump 15, and an external circulation inlet 17 located at the top of the reactor body on the pump outlet pipe 16. All pipes and pump fittings are made of 316L stainless steel.

[0114] Working process: Materials and catalysts are added to the reactor to carry out the synthesis reaction of high molecular weight polypropylene glycol. The materials in the reactor are filtered by the catalyst screen and flow out from the external circulation outlet 13. They flow into the plunger pump 15 through the pump inlet pipe 14. The plunger pump 15 then transports the materials through the pump outlet pipe 16 to the external circulation inlet 17 and flows back into the reactor to form an external circulation reaction.

Claims

1. A supported multi-metal cyanide complex catalyst characterised in that, The catalyst satisfies the following general formula: Zn3[Co(CN)6]2·Zn3[Fe(CN)6]2·Zn[Ni(CN)4]@MCM-41(OH-)·vZnCl2·xLa(NO3)3·y t BuOH·z Igepal CA-520, wherein MCM-41(OH-) represents an alkali-treated mesoporous molecular sieve; v = 0.5-3, x = 0-0.01, y = 0.1-2, z = 0-0.

1.

2. A process for the preparation of the supported polymetal cyanide complex catalyst according to claim 1, characterized in that The method comprises the following steps: (1) After roasting the MCM-41 powder, the powder is mixed with an alkali solution, stirred, and cooled to room temperature. The product is washed, dried, and ground into powder. The powder is added to an ion exchange solution for ion exchange, washed, filtered, and dried to obtain an alkali-treated MCM-41 carrier, denoted as MCM-41(OH-); (2) Dissolve K3[Co(CN)6], K3[Fe(CN)6] and K2[Ni(CN)4] to obtain solution A, solution B and solution C, respectively; disperse MCM-41(OH - ) in a solvent to obtain MCM-41(OH - ) solution, then add ZnCl2, La(NO3)3, t BuOH and Igepal CA-520 to obtain solution D; (3) Solution A, solution B and solution C are added dropwise to solution D, and stirred to obtain a catalyst slurry; The catalyst slurry is filtered, washed, and dried to obtain the supported multi-metal cyanide complex catalyst.

3. The process for the preparation of supported multi-metal cyanide complex catalyst according to claim 2, characterized in that, In step (2), the concentration of the K3[Co(CN)6] solution is 0.05-0.5 g / ml, and the concentrations of the K3[Fe(CN)6] and K2[Ni(CN)4] solutions are 5-20% of the concentration of the K3[Co(CN)6] solution.

4. The process for the preparation of supported multi-metal cyanide complex catalyst according to claim 2, characterized in that, In step (2), the t The mass ratio of BuOH to MCM-41(OH-) solution is 1:1-2, the mass ratio of ZnCl2 to MCM-41(OH-) is 5-1:1, and the mass ratio of the sum of the three metal cyanides to MCM-41(OH-) is 2-1:

1.

5. The process for the preparation of supported multi-metal cyanide complex catalyst according to claim 2, characterized in that, In step (2), the mass ratio of the La(NO3)3 to the MCM-41(OH-) is 1:5-20, and the mass ratio of the Igepal CA-520 to the MCM-41(OH-) is 2-1:

1.

6. Use of the supported multi-metal cyanide complex catalyst of claim 1 in the preparation of high-molecular polypropylene glycol.

7. Use of a supported polymetal cyanide complex catalyst according to claim 6 for the preparation of high molecular polypropylene glycol, characterized in that The reaction temperature is 100-140°C, and the pressure is 0.1-0.5 MPa.

8. Use of a supported polymetal cyanide complex catalyst according to claim 6 for the preparation of high molecular polypropylene glycol, characterized in that The feeding ratio is 8:12-72.

9. Use of a supported polymetal cyanide complex catalyst according to claim 6 for the preparation of high molecular polypropylene glycol, characterized in that The device for synthesizing high-molecular polypropylene glycol is an external circulation kettle reactor. The external circulation kettle reactor comprises a reaction kettle body, a gas inlet system, and an external circulation system. The reaction kettle body is provided with a stirring device and a heating device for heating the reaction kettle. The stirring device and the heating device are respectively connected with a high-pressure kettle controller (18). The gas inlet system is connected with the reaction kettle body for conveying raw material gas and protective gas to the reaction kettle body. The external circulation system comprises a plunger pump (15) connected with an external circulation outlet (13) at the lower part of the reaction kettle body and an external circulation inlet (17) at the upper part of the reaction kettle body through pipelines respectively.

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