Inactivated DMC catalyst regeneration method based on mechanochemical method, regenerated DMC catalyst and application

Abstract

The invention belongs to the technical field of industrial catalyst recovery, and particularly relates to an inactivated DMC catalyst regeneration method based on a mechanochemical method, a regenerated DMC catalyst and application. Comprising the following steps: pretreatment cleaning: mixing an inactivated DMC catalyst with a polar organic solvent, carrying out ultrasonic treatment, removing organic residues on the surface, and carrying out centrifugal drying; mechanochemical activation: mixing the pretreated catalyst with a metal salt and a complexing auxiliary agent, and carrying out high-energy ball milling in an inert atmosphere; and post-processing and drying: washing the ball-milled product, and drying in vacuum to obtain the regenerated DMC catalyst. A crystallization phase of the deactivated catalyst is destroyed through high-energy ball milling, meanwhile, a high-activity amorphous structure is reconstructed through the coordination effect of tert-butyl alcohol and metal salt, and metal loss and structure collapse caused by traditional acid pickling or high-temperature roasting are avoided; zinc salt is dynamically supplemented in the ball milling process, Co < 2 + > is oxidized to Co < 3 + >, and the complexing ability of the catalyst to a substrate is recovered.

Description

Technical Field

[0001] The invention belongs to the technical field of industrial catalyst recovery, and in particular relates to a deactivated DMC catalyst regeneration method based on a mechanochemical method, a regenerated DMC catalyst and an application thereof. Background Art

[0002] Double metal cyanide (DMC) catalyst is a type of heterogeneous catalyst formed by the coordination of transition metal ions and cyanide ligands, such as Zn 2+ 、Co 2+ 、Co 3+ With [Co(CN)6] 3- . This type of catalyst was first developed by General Electric in the 1960s and was initially used for the ring-opening polymerization of propylene oxide (PO) and ethylene oxide (EO) to produce polyether polyols (PPG / PEG). Due to its unique coordination structure and the synergistic effect of surface acidic-basic sites, DMC catalysts exhibit extremely high catalytic activity and selectivity, can precisely control the molecular weight distribution of polymers, and effectively inhibit side reactions such as chain transfer and cyclization. Compared with traditional alkaline catalysts (such as KOH), DMC catalysts have significant advantages such as high activity, narrow molecular weight distribution, and environmental friendliness. No neutralization treatment is required after the reaction, reducing waste salt emissions.

[0003] Currently, Zn-Co DMC catalysts, due to their high catalytic efficiency and simplicity, have become the mainstream catalyst for producing low-unsaturation polyether polyols (used in high-resilience foams, elastomers, etc.). In recent years, with the rise of green chemistry and sustainable chemical engineering concepts, the application of DMC catalysts has expanded beyond traditional applications, finding significant applications in CO2 copolymerization to produce polycarbonates, polymerization of bio-based epoxy compounds, and synthesis of high-performance specialty polyethers.

[0004] Despite the promising application prospects of DMC catalysts, their industrialization faces two major challenges. First, high industrial costs are associated with the catalyst preparation, which involves the use of precious metals such as Co and complex processes such as coprecipitation and aging. Second, deactivation is a problem. During the continuous reaction process, the catalyst is easily deactivated by organic deposition, crystallization, or changes in metal valence. For example, in propylene oxide polymerization, the activity of deactivated catalysts decreases by more than 50%, and simple regeneration is difficult to restore. Currently, industrial disposal of deactivated catalysts often involves landfilling or incineration, which not only results in the loss of metals such as Zn and Co, resulting in resource waste, but also in the leakage of cyanide, posing environmental risks. Therefore, the development of efficient and low-cost regeneration technologies to achieve the recycling of DMC catalysts has become a focus of both academia and industry. From a technical and economic perspective, if the cost of regenerating deactivated catalysts can be kept within 30% of the cost of fresh catalyst preparation, and the activity recovery rate can exceed 90%, this technology has the potential for large-scale application in the polyurethane industry, reducing tens of thousands of tons of heavy metal waste annually and significantly lowering production costs.

[0005] The deactivation of double metal cyanide catalysts is a complex multi-factor process involving changes at the physical, chemical and structural levels. Its deactivation mainly stems from the following aspects: 1) Surface organic matter deposition: In the polymerization reaction of epoxy compounds (such as propylene oxide and ethylene oxide), the growth of polymer chain segments may not be fully controlled, resulting in incompletely dissociated monomers or oligomers covering the active centers on the catalyst surface through physical adsorption. As the reaction proceeds, the polymer chains entangle on the catalyst surface to form a "dead zone", which hinders the diffusion of new monomers to the active sites and causes a significant decrease in the reaction rate; 2) Changes in the valence state and coordination environment of the metal active center: The high activity of DMC catalysts depends on the special electronic configuration of transition metals (such as Zn 2+ -Co 3+ electron pairs), but Co 3+ Reduction of Zn 2+ 3) Crystallization and phase transition: The activity of DMC catalysts is closely related to their amorphous structure, but long-term use can lead to localized crystallization. Furthermore, trace impurities (acidic substances and halide ions) in the raw materials or reaction environment can cause irreversible damage to the catalyst.

[0006] US Patent No. 48779067 discloses a method for removing double metal cyanide composite catalysts from polyether polyols. The residual catalyst is precipitated using an alkali metal compound and a phosphorus compound, and then removed by filtration. This method requires a filter aid (diatomaceous earth) to improve catalyst recovery efficiency. US Patent No. 50990756 discloses a method for removing double metal cyanide composite catalyst residues from polyols. The method comprises the following steps, performed after the polyol is formed: (a) contacting the polyol containing the catalyst residue with an effective amount of an oxidizing agent to form an insoluble residue that is insoluble in the polyol; and (b) separating the insoluble residue from the polyol. This method achieves the separation of the DMC catalyst from the polyether polyol. Although this method can efficiently separate the catalyst from the reaction system, it suffers from the drawback that the recovered catalyst cannot be directly reused in the catalytic reaction, significantly increasing the cost of the catalytic reaction. Patent DE19809539A1 reports a method for recovering DMC catalysts using a soluble polymer as an aid. The core of this method involves reacting a DMC catalyst with a soluble polymer acid (such as polyacrylic acid) to form insoluble agglomerates, which are then separated by filtration. The agglomerates can then be regenerated into active DMC catalyst using an acid solution. Patent CN116730401A describes a method for highly selectively recovering cobalt from DMC catalyst sludge by adsorption. This method utilizes a "cloverleaf" polymer resin adsorbent, combined with an optimized process flow, to achieve highly efficient and selective recovery of cobalt and zinc from DMC catalyst sludge with a specific composition. A techno-economic evaluation of this regeneration method revealed that the greatest challenge in current DMC catalyst recovery and regeneration processes is catalyst deactivation. Therefore, reactivating deactivated catalysts is a key issue that needs to be addressed. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention provides a mechanochemical regeneration method for deactivated DMC catalysts. This method utilizes controlled ball milling combined with metal salts and complexing agents to restore the catalyst's amorphous structure and regenerate its active sites. This method can reduce processing costs and carbon emissions, promote the recycling of DMC catalysts, reduce heavy metal waste, and enhance production sustainability in industries such as polyurethane.

[0008] The principle of mechanochemistry is to induce physical and chemical changes in substances through mechanical force. Unlike traditional wet chemistry or high-temperature treatment, mechanochemistry has three core advantages: first, there is no solvent or low solvent requirement, which greatly reduces waste liquid emissions; second, it is usually carried out at room temperature or mild conditions to avoid structural damage caused by high temperature; third, mechanical energy acts directly on chemical bonds, with a high energy efficiency conversion rate.

[0009] The present invention also provides a regenerated DMC catalyst, the activity recovery rate of the regenerated DMC catalyst reaches more than 90%, and the number of cycles is increased to 3-5 times.

[0010] The present invention also provides its application, and the regenerated DMC catalyst can be reused in the epoxy compound polymerization reaction process.

[0011] The method for regenerating a deactivated DMC catalyst based on a mechanochemical method of the present invention comprises the following steps: (1) Pretreatment cleaning: The deactivated DMC catalyst is mixed with a polar organic solvent, subjected to ultrasonic treatment for 10-30 minutes to remove organic residues on the surface, and then centrifuged to dry; (2) Mechanochemical activation: The pretreated catalyst is mixed with a metal salt and a complexing agent, and subjected to high-energy ball milling under an inert atmosphere, with zinc salt being added in batches during the ball milling process; (3) Post-treatment drying: The ball-milled product was washed and vacuum-dried to obtain a regenerated DMC catalyst.

[0012] The polar organic solvent in step (1) is at least one of acetone, ethanol or methanol.

[0013] The metal salt in step (2) is a mixture of ZnCl2 and K3[Co(CN)6] in a mass ratio of (1-3):1, and the added amount is 10%-50% of the mass of the deactivated DMC catalyst; the additional batch supplementation of zinc salt is adding zinc salt three times, and the total amount of zinc salt added is 10% of the mass of the deactivated DMC catalyst. The additional batch supplementation process is accompanied by inert gas, and the zinc salt is ZnCl2.

[0014] The complexing aid in step (2) is tert-butanol, and the added amount is 10%-20% of the mass of the deactivated DMC catalyst.

[0015] The rotation speed of the high-energy ball mill in step (2) is 300-800 rpm, the ball milling time is 2-6 hours, and the high-energy ball mill uses a planetary ball mill with a ball-to-material ratio of 10:1-20:1.

[0016] The inert atmosphere in step (2) is nitrogen (N2) or argon (Ar).

[0017] The vacuum drying temperature in step (3) is 60-80°C, and the drying time is 4-12 hours.

[0018] The washing in step (3) is performed using deionized water and acetone, and the number of washing times is 2-4 times.

[0019] The regenerated DMC catalyst of the present invention is used for polymerization of epoxy compounds, including polymerization of propylene oxide, ethylene oxide or a mixture thereof.

[0020] The catalytic activity of the regenerated DMC catalyst in the polymerization reaction of propylene oxide or ethylene oxide is restored to more than 90% of that of the fresh catalyst.

[0021] The catalytic activity can be regenerated at least three times, and after each regeneration, the catalytic activity is still maintained at more than 80% of the initial activity, wherein the first and second regeneration activities are more than 90%, and the third regeneration activity is more than 80%.

[0022] Compared with the prior art, the present invention has the following beneficial effects: (1) This invention is the first to apply high-energy ball milling technology in conjunction with metal salts / complexing agents to the regeneration of DMC catalysts, establishing a new "mechanical force-chemical action" synergistic regeneration mechanism, developing a mild regeneration process without strong acid or high temperature, using polar organic solvents (acetone / ethanol / methanol) to replace traditional hydrochloric acid / sulfuric acid cleaning, completely eliminating heavy metal wastewater pollution, and designing a ball milling system protected by an inert atmosphere (N2 / Ar, O2 <50ppm) to prevent oxidation of active components.

[0023] (2) The present invention precisely controls the ball milling parameters and utilizes mechanical energy to selectively destroy the catalyst crystalline phase, thereby reducing the crystallinity detected by XRD from 20-30% at the time of deactivation to below 8%, thereby restoring the amorphous active structure.

[0024] (3) The present invention introduces tert-butyl alcohol as a complexing regulator, which reacts with Zn 2+ / Co 3+ Formation of stable Zn 2+ - t BuOH-Co 3+ The ternary complex dynamically protects the active sites under mechanical force, avoiding the structural collapse problem of traditional regeneration methods.

[0025] (4) The present invention achieves the synergistic effect of mechanical cleaning and chemical activation, and simultaneously completes the removal of surface organic matter. Mass comparison analysis and ICP analysis show that the surface organic matter removal rate is >90%, and the catalyst crystal structure is repaired, and the specific surface area is restored to more than 85% of the initial level.

[0026] (5) The present invention selects K3[Co(CN)6] as an oxidation-supplementation dual-functional additive to convert the inactivated Co 2+ Oxidized to active Co 3+, and at the same time, cyanide ligands are supplemented to repair coordination defects; through dynamic supplementation of ZnCl2 and mechanochemical dispersion, the catalyst activity recovery rate of the present invention is significantly improved compared with the traditional acid washing method; the present invention establishes a quantitative relationship between ball milling energy input (rotation speed 300-800rpm) and metal valence state conversion, realizes precise regulation of the electronic structure of the catalyst, and restores the substrate complexing ability of the regenerated catalyst to more than 90% of that of the fresh catalyst.

[0027] (6) The washing process of the present invention improves the drying efficiency of the catalyst. Compared with the traditional method which takes 100-120 hours, the present invention only takes 4-12 hours, thus saving production costs.

[0028] (7) The regeneration method of the present invention can regenerate the DMC catalyst more than three times, and the regeneration activity of the catalyst in the first two times is greater than 90%, and the regeneration activity of the third time is greater than 80%, breaking through the technical bottleneck of the traditional method of regeneration times not exceeding 2 times. The TOF value of the regenerated catalyst in propylene oxide polymerization reaches 2000h -1 The above fully meets the production requirements of high-end polyether polyols. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 1 is the XRD pattern of the DMC catalyst before and after regeneration in Example 1; Figure 2 1 is an XPS graph of the DMC catalyst before and after regeneration in Example 1; Figure 3 is the XRD pattern of the DMC catalyst after regeneration in Example 5; Figure 4 This is the XPS graph of the DMC catalyst after regeneration in Example 5. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the examples.

[0031] Unless otherwise specified, all raw materials used in the examples are commercially available.

[0032] Example 1 The deactivated DMC catalyst regeneration method based on the mechanochemical method comprises the following steps: (1) Pretreatment cleaning: 100 g of deactivated DMC catalyst was placed in a 500 mL polytetrafluoroethylene beaker, 300 mL of acetone (water content < 0.1%) was added, and the mixture was treated in a 40 kHz ultrasonic cleaner for 20 minutes (ultrasonic frequency 20 kHz, temperature 35°C) to remove organic residues on the surface. The suspension was transferred to a centrifuge tube and centrifuged at 4000 rpm for 10 minutes. The supernatant was discarded and the solid was placed in a vacuum drying oven and dried at 80°C for 2 hours (vacuum degree -0.095 MPa); (2) Mechanochemical activation: 95.2 g of the pretreated catalyst was mixed with 15 g of anhydrous ZnCl2, 10 g of K3[Co(CN)6] (ACS reagent grade), and 15.76 g of tert-butyl alcohol (analytical grade). The mixture was placed in a 500 mL zirconia ball mill, and 5 mm diameter zirconia grinding balls (ball-to-material ratio of 15:1) were added. The mill was connected to the air inlet and high-purity nitrogen (99.999%) was introduced for displacement three times to ensure that the oxygen content was less than 50 ppm. Maintain a positive pressure of 0.05 MPa and run the planetary ball mill at 500 rpm for 4 hours. During the operation, add a total of 10 g of anhydrous ZnCl2 in three times (each time with an interval of 20 minutes, 3.33 g each time). During the addition, nitrogen is continuously introduced into the ball mill. The external temperature of the tank is monitored in real time (35 ± 2 °C). (3) Post-treatment drying: The ball-milled product was transferred to a sand-core funnel, washed once with 200 mL of deionized water, and then washed twice with 200 mL of acetone, stirring for 5 minutes each time; the washed solid was placed in a vacuum drying oven and dried at 70°C for 10 hours (vacuum degree -0.098 MPa) to obtain a regenerated DMC catalyst.

[0033] Test results: The color of the catalyst changed from gray-brown before regeneration to gray-white.

[0034] Agglomeration rate after ball milling: measured by passing through a 2 mm sieve, the mass of solids that do not pass through the sieve divided by the mass of the activated catalyst is the agglomeration rate; the agglomeration rate is 2.1%.

[0035] Karl Fischer water content: 0.13%.

[0036] The effectiveness of the pre-treatment cleaning in step (1) in removing organic residues was tested and evaluated: Organic matter removal rate = the amount of organic matter in the solid after pretreatment and cleaning tested by mass comparison method / the amount of residual organic matter in the deactivated DMC catalyst based on ICP test × 100%; The organic matter removal rate was 91.4%.

[0037] in: The amount of residual organic matter in the deactivated DMC catalyst based on ICP testing was 12.36 wt.%; The process and calculation method of testing the amount of organic matter by comparing the solid mass after pretreatment and cleaning: Methods: Heating and weighing were performed in stages to gradually remove different components. After each step, the sample was cooled to room temperature (approximately 30 minutes in a nitrogen-filled desiccator) and weighed using a high-precision balance (0.0001 mg, Balance XPR2U). The weight was recorded to the nearest 0.0001 mg.

[0038] Step 1: Initial weighing (total weight, including water, organic matter, and inorganic framework). Place the empty crucible on a balance and return it to zero. Add the sample and distribute it evenly with tweezers. Weigh to obtain the initial mass m0.

[0039] Step 2: Remove moisture and weakly adsorbed substances (low-temperature stage, <= 100°C). Place the sample in a vacuum drying oven and heat to 100°C under a nitrogen atmosphere for 2 hours to evaporate water and low-boiling-point solvents. Cool and weigh to obtain m1. Moisture loss = m0 − m1.

[0040] Step 3: Remove surface organic matter (intermediate temperature stage, 150-400°C). Transfer the sample to a muffle furnace and slowly increase the temperature (5°C / min) to 350-400°C under nitrogen protection. Hold for 2 hours. Cool and weigh to obtain m2. Organic matter loss = m1 − m2.

[0041] Step 4: Verify inorganic residues (high temperature stage, >500°C). Heat to 500-600°C, hold for 1 hour, and weigh to obtain m3. This loss includes cyanide, etc., but is not included in the organic residue and is only used to confirm the total loss.

[0042] Step 5: Calculation, the formula is as follows: The solids after pretreatment and cleaning were tested by mass comparison method to determine the amount of organic matter (wt.%) = (m1-m2) / m0×100%.

[0043] Repeat: The deactivated DMC catalyst and the solid sample after pretreatment and cleaning were run three times each and the average value was taken.

[0044] The DMC catalyst before and after regeneration was subjected to XRD test (Cu, Kα radiation), and the results are as follows: Figure 1 As shown: 2θ = 15-25° presents a typical amorphous broad peak, and the surface metal valence state is mainly Zn 2+ and Co 3+ Mainly, the crystallinity dropped from 25% before regeneration to 4.8%.

[0045] XPS test (Al, Kα source) was performed on the DMC catalyst before and after regeneration. The results are shown in the figure. Figure 2 shown.

[0046] A fresh catalyst (DMC bimetallic catalyst from Changzhou Runtianyuan New Materials Co., Ltd.) and a catalyst regenerated from Example 1 (regenerated according to the method of Example 1 after each use, and cycled for 3 times, with the same reaction conditions for each evaluation) were used to evaluate propylene oxide polymerization: Weigh 10g of polyoxypropylene glycol (PPG400, hydroxyl value 280mgKOH / g) and a catalyst (50 ppm), mix and stir until uniform. Incubate at 150°C under vacuum for 1 hour. Propylene oxide is introduced, maintaining a pressure of 0.1-0.3MPa. Once the reaction begins, continue feeding (maintaining pressure ≤0.1MPa and temperature 150°C). After feeding stops and the pressure reaches ≤10Pa, remove small molecules, cool, and discharge the product.

[0047] The calculation formula of polymerization activity TOF is: TOF = moles of reactant converted / moles of active sites × reaction time; The TOF and activity recovery test results of the fresh catalyst and the catalyst regenerated in Example 1 are shown in Table 1 below: Table 1 TOF and activity recovery test results of fresh catalyst and catalyst regenerated in Example 1

[0048] Example 2 The deactivated DMC catalyst regeneration method based on the mechanochemical method comprises the following steps: (1) Pretreatment cleaning: 100 g of deactivated DMC catalyst was placed in a 500 mL polytetrafluoroethylene beaker, and 300 mL of anhydrous ethanol (water content < 0.1%) was added. The mixture was treated in a 40 kHz ultrasonic cleaner for 20 minutes (ultrasonic frequency 20 kHz, temperature 35°C) to remove organic residues on the surface. The suspension was transferred to a centrifuge tube and centrifuged at 4000 rpm for 10 minutes. The supernatant was discarded and the solid was placed in a vacuum drying oven and dried at 80°C for 2 hours (vacuum degree -0.095 MPa). (2) Mechanochemical activation: 95.2 g of the pretreated catalyst was mixed with 7.5 g of anhydrous ZnCl₂, 2.5 g of K₃[Co(CN)₆] (ACS reagent grade), and 20 g of tert-butyl alcohol (analytical grade). The mixture was placed in a 500 mL zirconia ball mill, and 5 mm diameter zirconia grinding balls (ball-to-batch ratio of 10:1) were added. The mill was connected to the air inlet and high-purity nitrogen (99.999%) was introduced three times to ensure that the oxygen content was less than 50 ppm. The positive pressure was maintained at 0.05 MPa. The mill was operated at 300 rpm for 6 h. During this operation, a total of 10 g of anhydrous ZnCl₂ was added in three additions (each addition was 20 minutes apart, 3.33 g each time). Nitrogen was continuously introduced into the mill during the addition process, and the external temperature of the mill was monitored in real time (35 ± 2°C). (3) Post-treatment drying: The ball-milled product was transferred to a sand core funnel, washed once with 200 mL of deionized water and then washed once with 200 mL of acetone, stirring for 5 minutes each time; the washed solid was placed in a vacuum drying oven and dried at 60°C for 12 hours (vacuum degree -0.098 MPa) to obtain a regenerated DMC catalyst.

[0049] Test data: activity recovery rate 91.2%, TOF value 2098h -1 .

[0050] Example 3 The deactivated DMC catalyst regeneration method based on the mechanochemical method comprises the following steps: (1) Pretreatment cleaning: 100 g of deactivated DMC catalyst was placed in a 500 mL polytetrafluoroethylene beaker, 300 mL of methanol (water content <0.1%) was added, and the mixture was treated in a 40 kHz ultrasonic cleaner for 20 minutes (ultrasonic frequency 20 kHz, temperature 35°C) to remove organic residues on the surface. The suspension was transferred to a centrifuge tube and centrifuged at 4000 rpm for 10 minutes. The supernatant was discarded and the solid was placed in a vacuum drying oven and dried at 80°C for 2 hours (vacuum degree -0.095 MPa); (2) Mechanochemical activation: 95.2 g of the pretreated catalyst was mixed with 35 g of anhydrous ZnCl2, 15 g of K3[Co(CN)6] (ACS reagent grade), and 15.76 g of tert-butyl alcohol (analytical grade). The mixture was placed in a 500 mL zirconia ball mill, and 5 mm diameter zirconia grinding balls (ball-to-material ratio 20:1) were added. The mill was connected to the air inlet and high-purity nitrogen (99.999%) was introduced for displacement three times to ensure that the oxygen content was less than 50 ppm. Maintain a positive pressure of 0.05 MPa and run the planetary ball mill at 800 rpm for 2 hours. During the operation, add a total of 10 g of anhydrous ZnCl2 in three times (each time with an interval of 20 minutes, 3.33 g each time). During the addition, nitrogen is continuously introduced into the ball mill. The external temperature of the tank is monitored in real time (35 ± 2 °C). (3) Post-treatment drying: The ball-milled product was transferred to a sand-core funnel, washed once with 200 mL of deionized water, and then washed three times with 200 mL of acetone, stirring for 5 minutes each time; the washed solid was placed in a vacuum drying oven and dried at 80°C for 4 hours (vacuum degree -0.098 MPa) to obtain a regenerated DMC catalyst.

[0051] Test data: activity recovery rate 91.8%, TOF value 2111h -1 .

[0052] Example 4 The same as Example 1, except that the amount of tert-butyl alcohol in step (2) was reduced to 10 g. Slight agglomeration of the material occurred during the ball milling process.

[0053] Test results: The color of the catalyst changed from gray-brown before regeneration to gray-white.

[0054] Agglomeration rate after ball milling: measured by passing through a 2 mm sieve, the mass of solids that do not pass through the sieve divided by the mass of the activated catalyst is the agglomeration rate; the agglomeration rate is 4.9%.

[0055] Propylene oxide polymerization evaluation was the same as in Example 1, with a polymerization activity TOF of 2107 h. -1 , activity recovery rate was 91.6%.

[0056] Example 5 Same as Example 1, except that the processing capacity is amplified 10 times.

[0057] Test results: The regenerated DMC catalyst was subjected to XRD test (Cu, Kα radiation), and the results are as follows: Figure 3 As shown: 2θ=15-25° presents a typical amorphous broad peak, and the degree of crystallinity drops from 25% before regeneration to 5.6%.

[0058] The regenerated DMC catalyst was subjected to XPS test (Al, Kα source), and the results are as follows Figure 4 shown.

[0059] Agglomeration rate after ball milling: measured by passing through a 2 mm sieve, the mass of solids that do not pass through the sieve divided by the mass of the activated catalyst is the agglomeration rate; the agglomeration rate is 2.0%.

[0060] Karl Fischer water content: 0.15%.

[0061] Propylene oxide polymerization evaluation was the same as in Example 1, with a polymerization activity TOF of 2082 h. -1 , activity recovery rate 90.5%.

[0062] Example 6 Same as Example 1, except that the rotation speed in step (2) is 200 rpm.

[0063] Propylene oxide polymerization evaluation was the same as in Example 1, with a polymerization activity TOF of 1872 h. -1 , activity recovery rate was 81.4%.

[0064] Example 7 Same as Example 1, except that the complexing auxiliary agent is isopropyl alcohol.

[0065] Polymerization activity TOF = 1939h -1 , activity recovery rate was 84.3%.

[0066] Example 8 Same as Example 1, except that in step (3), deionized water was used for washing three times.

[0067] The drying time needs to be extended to 24 hours.

[0068] Agglomeration rate after ball milling: measured by passing through a 2 mm sieve, the mass of solids that do not pass through the sieve divided by the mass of the activated catalyst is the agglomeration rate; the agglomeration rate is 8.7%.

[0069] The catalyst washed with acetone in Example 1 was in a flour-like state after passing through the sieve, while the catalyst washed with only deionized water in this example was in a sand-like state after drying even after passing through the sieve, which affected its solubility in the solvent.

[0070] Propylene oxide polymerization evaluation was the same as in Example 1, with a polymerization activity TOF of 1962 h. -1 , activity recovery rate was 85.3%.

[0071] Comparative Example 1 Same as Example 1, except that: (2) Mechanochemical activation: Add 10 g ZnCl2 added in batches during the ball milling process to the metal salt mixture: 25g anhydrous ZnCl2, 10g K3[Co(CN)6] (ACS reagent grade), no batch replenishment.

[0072] Propylene oxide polymerization evaluation was the same as in Example 1, with polymerization activity TOF = 1990 h -1 , activity recovery rate was 86.5%.

[0073] Comparative Example 2 The deactivated DMC catalyst regeneration method based on the acid washing method comprises the following steps: (1) Pretreatment cleaning: 100 g of deactivated DMC catalyst was placed in a 500 mL polytetrafluoroethylene beaker, 300 mL of acetone (water content < 0.1%) was added, and the mixture was treated in a 40 kHz ultrasonic cleaner for 20 minutes (ultrasonic frequency 20 kHz, temperature 35°C) to remove organic residues on the surface. The suspension was transferred to a centrifuge tube and centrifuged at 4000 rpm for 10 minutes. The supernatant was discarded and the solid was placed in a vacuum drying oven and dried at 80°C for 2 hours (vacuum degree -0.095 MPa); (2) Pickling activation method: Weigh 95.2 g of the pretreated catalyst and mix it with 15.76 g of tert-butyl alcohol (analytical grade). Dissolve it in 500 mL of 1 wt.% hydrochloric acid solution. Then add 25 g of anhydrous ZnCl2 and 10 g of K3[Co(CN)6] (ACS reagent grade) to the above solution. Pass high-purity nitrogen (99.999%) through the solution three times to ensure that the oxygen content is less than 50 ppm. Then stir (300 rpm) for 60 minutes, and monitor the external temperature of the reactor in real time (35 ± 2°C). (3) Post-treatment drying: The acid-washed product was transferred to a sand core funnel, washed once with 200 mL of deionized water, and then washed twice with 200 mL of acetone, stirring for 5 minutes each time; the washed solid was placed in a vacuum drying oven and dried at 70°C for 10 hours (vacuum degree -0.098 MPa) to obtain a regenerated DMC catalyst.

[0074] The TOF and activity recovery test results of the fresh catalyst and the catalyst regenerated in Comparative Example 2 are shown in Table 2 below: Table 2 TOF and activity recovery test results of fresh catalyst and catalyst regenerated in Comparative Example 2

[0075] The activity recovery rate of the catalyst activated by the acid washing method is much lower than that of the catalyst activated by the mechanochemical method described in the present invention.

Claims

1. A method for regenerating a deactivated DMC catalyst based on a mechanochemical method, characterized in that: The following steps are involved: (1) Pretreatment cleaning: The deactivated DMC catalyst was mixed with a polar organic solvent, subjected to ultrasonic treatment to remove organic residues on the surface, and then centrifuged to dry. (2) Mechanochemical activation: The pretreated catalyst is mixed with a metal salt and a complexing agent, and subjected to high-energy ball milling under an inert atmosphere, with zinc salt being added in batches during the ball milling process; (3) Post-treatment drying: The ball-milled product was washed and vacuum-dried to obtain a regenerated DMC catalyst.

2. The method for regenerating a deactivated DMC catalyst based on a mechanochemical method according to claim 1, characterized in that: The polar organic solvent in step (1) is at least one of acetone, ethanol or methanol.

3. The method for regenerating a deactivated DMC catalyst based on a mechanochemical method according to claim 1, characterized in that: The metal salt in step (2) is a mixture of ZnCl2 and K3[Co(CN)6], and the added amount is 10%-50% of the mass of the deactivated DMC catalyst; the additional batch supplementation of zinc salt is adding zinc salt three times, and the total amount of zinc salt added is 10% of the mass of the deactivated DMC catalyst, and the additional batch supplementation process is accompanied by inert gas.

4. The method for regenerating a deactivated DMC catalyst based on a mechanochemical method according to claim 1, characterized in that: The complexing aid in step (2) is tert-butanol, and the added amount is 10%-20% of the mass of the deactivated DMC catalyst.

5. The method for regenerating a deactivated DMC catalyst based on a mechanochemical method according to claim 1, wherein: The rotation speed of the high-energy ball mill in step (2) is 300-800 rpm, the ball milling time is 2-6 hours, and the high-energy ball mill uses a planetary ball mill with a ball-to-material ratio of 10:1-20:

1.

6. The method for regenerating a deactivated DMC catalyst based on a mechanochemical method according to claim 1, characterized in that: The inert atmosphere in step (2) is nitrogen or argon.

7. The method for regenerating a deactivated DMC catalyst based on a mechanochemical method according to claim 1, characterized in that: The vacuum drying temperature in step (3) is 60-80°C, and the drying time is 4-12 hours.

8. The method for regenerating a deactivated DMC catalyst based on a mechanochemical method according to claim 1, characterized in that: The washing in step (3) is performed with water and acetone, and the number of washing times is 2-4 times.

9. A regenerated DMC catalyst obtained by a mechanochemical method for regenerating a deactivated DMC catalyst, characterized in that: The product is prepared by the regeneration method according to any one of claims 1 to 8.

10. Use of the regenerated DMC catalyst according to claim 9, characterized in that: Used in epoxy compound polymerization reactions, including polymerization of propylene oxide, ethylene oxide or their mixtures.

Images