Refrigerant waste catalyst treatment method
Through the low-temperature and low-pressure gradient separation-deep antimony removal coupling process, the problems of precious metal waste and environmental pollution in the treatment of refrigerant waste catalysts are solved, efficient recovery and purification are achieved, energy consumption is reduced, and it is in line with the concept of sustainable development.
Patent Information
- Application Number
- CN202510966008.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-14
- Publication Date
- 2025-10-10
AI Technical Summary
The existing methods for treating waste refrigerant catalysts result in waste of precious metal resources and environmental pollution, and have low recovery rates and purity, as well as high energy consumption.
A low-temperature, low-pressure gradient separation-deep antimony removal coupling process is adopted, including ceramic membrane filtration, intermittent distillation tower separation, adsorption tower separation and other steps, combined with anti-coking agents and specific catalyst treatment to achieve efficient separation and purification of antimony-based catalysts and methane chloride.
The recovery rate of antimony-based catalysts was increased to over 99.0%, the purity of methane chloride reached over 95.0%, steam energy consumption was reduced, and resource recycling and environmental protection were achieved.
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of refrigerant waste catalyst recovery, and in particular to a method for treating refrigerant waste catalyst. Background Art
[0002] Freon is a common refrigerant, and there are many types, the most common of which are R22, R32, R134a, etc., and in the current production process of R22 and R32 refrigerants, the amount of waste catalysts generated exceeds 100,000 tons per year. Traditional methods of treating these waste catalysts include incineration and landfilling, which not only leads to the waste of precious metal resources, but also causes environmental pollution by dioxins. There are some problems with the existing solvent extraction method, such as the recovery rate of methane chloride is less than 85%, and the entrainment of antimony compounds reaches or exceeds 500ppm, which can lead to catalyst deactivation. In addition, the conventional distillation process has high energy consumption, with steam consumption exceeding 3.5 tons per ton of product, and the residual amount of catalyst in the tower kettle exceeds 15%, which can cause coking of the device and needs to be improved. Summary of the Invention
[0003] The problem to be solved by the present invention is to provide a method for treating waste refrigerant catalysts in response to the above-mentioned shortcomings in the prior art. The method adopts a low-temperature, low-pressure gradient separation-deep antimony removal coupling process to treat the waste catalysts. The recovery rate of the antimony-based catalyst after treatment is ≥99.0%, and the purity of methane chloride is ≥95.0%. It has the advantages of avoiding deactivation of the antimony-based catalyst, improving recovery efficiency, efficient recycling and reuse, and saving raw material costs.
[0004] The above-mentioned object of the present invention is achieved through the following technical solutions: A method for treating waste refrigerant catalyst comprises the following steps: S1 adds an anti-coking agent to the slurry of the refrigerant waste catalyst and uses a ceramic filter membrane to remove particulate matter; S2: feeding the slurry obtained in S1 into a batch distillation tower for a first low-temperature and low-pressure distillation treatment to separate the light components containing methane chloride and antimony-based catalyst from the heavy components to obtain a first overhead distillate; S3: feeding the first overhead distillate obtained in S2 into a batch distillation tower for a second low-temperature and low-pressure distillation to purify the methane chloride and obtain a second overhead distillate; S4: adding the second overhead distillate obtained in S3 into an adsorption tower with Fe3O4@SiO2-SH filler to complete the separation of methane chloride and antimony-based catalyst to obtain methane chloride; S5: using the methane chloride obtained in S4 to prepare refrigerants, carbon tetrachloride, methylchlorosilane, chlorofluorocarbons, or chlorinated aromatic hydrocarbons.
[0005] Furthermore, in the above S1, an anti-coking agent is added to the refrigerant waste catalyst slurry in an amount of 0.3-1.5 wt% of the slurry.
[0006] Furthermore, in the S1, the anti-coking agent is 0.1-0.5 wt% of polyether-modified siloxane.
[0007] Furthermore, in S1, the filtration accuracy of the ceramic filter membrane is controlled to be 0.05-0.20 μm.
[0008] Furthermore, in S2, the pressure of the first low-temperature and low-pressure distillation is controlled to be 1.0-3.0 kPa, the tower bottom temperature is 80-100°C, and the tower top temperature is 15-30°C to complete the separation of light components (CH3Cl, antimony-based catalyst) and heavy components (CCl4, HCl), and the CH3Cl purity is ≥93%.
[0009] Furthermore, in S3, the pressure of the second low-temperature and low-pressure distillation is controlled to be 3.0-5.0 kPa, the tower bottom temperature is 60-90°C, and the tower top temperature is 40-50°C to complete the purification of methane chloride, and the CH3Cl purity is ≥96.5%.
[0010] Furthermore, in S2 and S3, the intermittent distillation tower is provided with plate corrugated packing, the tower bottom temperature is controlled at 120-140°C, the tower bottom reboiler adopts a falling film form to reduce the metal wall temperature, and after the top gas phase is condensed by the condenser, a small amount of HF and HCl entrained with part of the CMS is discharged as non-condensable gas, and the tower top condensation temperature is controlled below 20°C.
[0011] Furthermore, in S4, the steam of the second overhead distillate passes through the adsorption tower at a flow rate of 1-3 BV / h, the bed height is controlled to be 1.8 m, and the temperature difference of the tower plates is ≤3°C.
[0012] Furthermore, in S5, the methane chloride obtained in S4 is reacted with hydrogen fluoride under the action of the adsorbed antimony-based catalyst to obtain a refrigerant.
[0013] Furthermore, in the step S5, the methane chloride obtained in step S4 is reacted under the action of a supported catalyst (γ-Al2O3 supported TiO2) to obtain carbon tetrachloride.
[0014] Furthermore, in S5, the methane chloride obtained in S4 is vaporized and reacted with silicon powder (Si), and after the reaction is completed, it is post-treated to obtain methylchlorosilane.
[0015] Furthermore, in S5, the methane chloride obtained in S4 and carbon tetrachloride are sequentially subjected to azeotropic distillation, catalytic dehydrogenation, and transesterification to obtain chlorofluorocarbons (CFCs).
[0016] Furthermore, in S5, the methane chloride obtained in S4 is reacted with benzene in the presence of a FeCl3 catalyst, and after completion of the reaction, the reaction is post-treated to obtain chlorinated aromatic hydrocarbons.
[0017] In summary, the beneficial technical effects of the present invention are: 1. The low-temperature, low-pressure gradient separation-deep antimony removal coupling process effectively improves the treatment efficiency of spent catalysts. By precisely controlling the distillation conditions and adsorption process, steam energy consumption is reduced to below 2.2t / t, achieving efficient separation and purification of antimony-based catalysts and methane chloride. 2. The recovery rate of the antimony-based catalyst is as high as over 99.0%, significantly reducing the waste of precious metal resources. At the same time, the purity of methane chloride has reached over 95.0%, providing high-quality raw materials for subsequent chemical synthesis. 3. The method of the present invention not only avoids the environmental pollution problems caused by traditional methods of treating spent catalysts and realizes the recycling of resources, but also ensures the efficient reuse of methane chloride, increases the production of refrigerants, carbon tetrachloride, methylchlorosilane, chlorofluorocarbons, and chlorinated aromatic hydrocarbons, and conforms to the concept of sustainable development. DETAILED DESCRIPTION
[0018] In order to make the technical means, creative features, objectives and functions achieved by the present invention clearer and easier to understand, the present invention is further elaborated below in conjunction with specific implementation methods.
[0019] Example 1: A method for treating waste refrigerant catalyst disclosed in the present invention comprises the following steps: S1 adds an anti-coking agent to the slurry of the refrigerant waste catalyst and uses a ceramic filter membrane to remove particulate matter; S2: feeding the slurry obtained in S1 into a batch distillation tower for a first low-temperature and low-pressure distillation treatment to separate the light components containing methane chloride and antimony-based catalyst from the heavy components, thereby obtaining a first overhead distillate; S3: The first overhead distillate obtained in S2 is fed into a batch distillation tower for a second low-temperature and low-pressure distillation to purify the methane chloride and obtain a second overhead distillate; S4 feeds the second overhead distillate obtained in S3 into an adsorption tower with Fe3O4@SiO2-SH filler to complete the separation of methane chloride and antimony-based catalyst to obtain methane chloride; S5 uses the methane chloride obtained in S4 to prepare refrigerants, carbon tetrachloride, methylchlorosilane, chlorofluorocarbons, or chlorinated aromatic hydrocarbons.
[0020] Example 2: This is a method for treating waste refrigerant catalysts disclosed in the present invention. The difference from Example 1 is that the specific implementation method of S1 is to add an anti-coking agent accounting for 0.3~1.5wt% of the slurry dosage to the refrigerant waste catalyst slurry at room temperature with stirring. In this embodiment, 1.2wt% of polyether modified silicone is preferred. Then, a 0.05~0.20μm ceramic filter membrane is used to filter and remove particles with a particle size greater than 5μm. In this embodiment, a 0.15μm ceramic filter membrane is preferred to obtain a filtered slurry.
[0021] Example 3: A method for treating waste refrigerant catalysts disclosed in the present invention is different from Example 2 in that S2 is specifically implemented by feeding the slurry obtained in S1 into a batch distillation tower for a first low-temperature, low-pressure distillation treatment, controlling the pressure of the first low-temperature, low-pressure distillation to 3.0 kPa, the bottom temperature to 80°C, and the top temperature to 30°C to complete the separation of light components (CH3Cl, antimony-based catalyst) from heavy components (CCl4, HCl), and the purity of CH3Cl is ≥93%, thereby obtaining a first top distillate; wherein, the batch distillation tower is provided with plate corrugated packing, the bottom temperature is controlled at 130°C, the bottom reboiler adopts a falling film form to reduce the metal wall temperature, and after the top gas phase is condensed by the condenser, a small amount of HF and HCl are entrained with part of CMS and discharged as non-condensable gas, and the top condensation temperature is controlled below 20°C.
[0022] Example 4: A method for treating a waste refrigerant catalyst disclosed in the present invention is different from Example 2 in that S3 is specifically implemented by feeding the first overhead distillate obtained in S2 into a batch distillation tower for a second low-temperature, low-pressure distillation treatment, controlling the pressure of the second low-temperature, low-pressure distillation to 4.0 kPa, the bottom temperature to 90°C, and the top temperature to 50°C to complete the purification of methane chloride, and the CH3Cl purity is ≥96.5%, thereby obtaining a second overhead distillate; wherein, the batch distillation tower is provided with a plate corrugated packing, the bottom temperature is controlled at 140°C, the bottom reboiler adopts a falling film form to reduce the metal wall temperature, and after the top gas phase is condensed by the condenser, a small amount of HF and HCl are entrained with part of the CMS and discharged as non-condensable gas, and the top condensation temperature is controlled below 20°C.
[0023] Example 5: A method for treating waste refrigerant catalyst disclosed in the present invention. The method differs from Example 3 in that S4 is specifically implemented by adding the second overhead distillate obtained in S3 to an adsorption tower with Fe3O4@SiO2-SH filler, and the steam of the second overhead distillate passes through the Fe3O4@SiO2-SH filler at a flow rate of 2BV / h, controlling the bed height to 1.8m and the plate temperature difference to ≤3°C to complete the separation of methane chloride and antimony-based catalyst to obtain methane chloride; wherein the methane chloride yield is ≥99.5%, the CH3Cl purity is 96.8%, Sb is not detected in the methane chloride (<0.5ppm), the antimony-based catalyst yield is ≥99.3%, the coking amount is <0.01%, and the steam unit consumption is 2.05t / t.
[0024] Example 6: A method for treating spent refrigerant catalyst disclosed herein differs from Example 4 in that S5 is implemented by preparing refrigerant from the methane chloride collected in Example 4. The recovered methane chloride is returned to the reactor and reacted according to the formula CHCl₃ + 2HF = CHClF₂ + 2HCl at a temperature of 100°C ± 2°C and a pressure of 2 MPa. An antimony-based catalyst is used. A mixture of recycled CHCl₃ and fresh CHCl₃ is introduced into the synthesis reactor in a molar ratio of total CHCl₃ to HF of 1:3. After 12 hours of reaction, the discharged material is analyzed and tested. Results show an 82% molar yield of refrigerant R₂2 (83% recovery of fresh feedstock) and a 98% conversion rate of CH₃Cl. Energy consumption is 1.2 kWh / t of refrigerant R₂2, compared to 1.45 kWh / t for a conventional process that does not recover CH₃Cl.
[0025] Example 6: This invention discloses a method for treating spent refrigerant catalysts. This method differs from Example 4 in that S5 is implemented by using the methane chloride collected in Example 4 to prepare electronic-grade carbon tetrachloride (CCl4). This reaction is carried out at 500°C in the presence of a supported catalyst (γ-Al2O3-supported TiO2). The resulting CCl4 achieves a purity of 99.9% and a yield of 98%, a 20% improvement over conventional processes.
[0026] Example 6: This is a method for treating waste refrigerant catalysts disclosed herein. This method differs from Example 4 in that S5 is implemented by preparing methylchlorosilane (CH3SiCl3) from the methane chloride collected in Example 4. The recovered CH3Cl is vaporized and then mixed with silicon powder (Si) in a 10:1 molar ratio before entering a fluidized bed reactor. The mixture reacts at 650°C under nitrogen to produce a methylchlorosilane mixture, which is then washed and fractionated to obtain a high-purity monomer. Analytical testing results indicate a 15% increase in methylchlorosilane yield. The dimethyldichlorosilane (DMDC) content in the product is reduced from 8% in conventional processes to 2%, significantly improving monomer selectivity.
[0027] Example 6: This is a method for treating spent refrigerant catalysts disclosed herein. This method differs from Example 4 in that S5 is implemented by using the methane chloride collected in Example 4 to produce chlorofluorocarbons (CFCs). CCl4 and CH3Cl are introduced into an azeotropic distillation column in a ratio of 3:1 to separate a high-purity mixed refrigerant (e.g., R-410A or an R-32 / R-125 mixture). The resulting mixed refrigerant has a GWP (global warming potential) that is over 70% lower than that of traditional CFCs, meeting international environmental regulations, such as the Kigali Amendment, for HFC control.
[0028] Example 6: This is a method for treating spent refrigerant catalysts disclosed herein. This method differs from Example 4 in that S5 is implemented by using the methane chloride collected in Example 4 to produce chlorinated aromatic hydrocarbons. Chlorobenzenes (such as chlorobenzene) and dichlorobenzenes are important intermediates for dyes and pesticides. Their production requires chlorination using benzene or toluene as raw materials. The recovered CH3Cl can be used as a low-cost chlorinating agent to replace chlorine (Cl2).
[0029] CH3Cl reacts with benzene in the presence of an FeCl3 catalyst at 60°C to produce chlorobenzene and HCl as a byproduct. Chlorobenzene is purified by distillation and used in downstream synthesis, while HCl is recycled back into the distillation system. Results demonstrate a CH3Cl molar conversion of 92%, a 30% improvement over the Cl2 method (due to the absence of free radical side reactions). The risk of chlorine gas leakage is eliminated, wastewater emissions are reduced by 75%, and chlorinating agent costs are reduced by 60% (CH3Cl costs approximately one-fifth of Cl2).
[0030] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limiting. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the purpose and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.
Claims
1. A method for treating waste refrigerant catalyst, characterized by: The following steps are included: S1 adds an anti-coking agent to the slurry of the refrigerant waste catalyst and uses a ceramic filter membrane to remove particulate matter; S2: feeding the slurry obtained in S1 into a batch distillation tower for a first low-temperature and low-pressure distillation treatment to separate the light components containing methane chloride and antimony-based catalyst from the heavy components to obtain a first overhead distillate; S3: feeding the first overhead distillate obtained in S2 into a batch distillation tower for a second low-temperature and low-pressure distillation to purify the methane chloride and obtain a second overhead distillate; S4: adding the second overhead distillate obtained in S3 into an adsorption tower with Fe3O4@SiO2-SH filler to complete the separation of methane chloride and antimony-based catalyst to obtain methane chloride; S5: using the methane chloride obtained in S4 to prepare refrigerants, carbon tetrachloride, methylchlorosilane, chlorofluorocarbons, or chlorinated aromatic hydrocarbons.
2. The method for treating waste refrigerant catalyst according to claim 1, wherein: In the step S1, an anti-coking agent is added to the refrigerant waste catalyst slurry in an amount of 0.3-1.5 wt % of the slurry.
3. The method for treating waste refrigerant catalyst according to claim 2, wherein: In the S1, the anti-coking agent is 0.1-0.5 wt% of polyether-modified siloxane.
4. The method for treating waste refrigerant catalyst according to claim 1, wherein: In the step S1 , the filtration accuracy of the ceramic filter membrane is controlled to be 0.05-0.20 μm.
5. The method for treating waste refrigerant catalyst according to claim 1, wherein: In S2, the pressure of the first low-temperature and low-pressure distillation is controlled to be 1.0-3.0 kPa, the bottom temperature is 80-100°C, and the top temperature is 15-30°C to complete the separation of light components and heavy components, and the purity of CH3Cl is ≥93%.
6. The method for treating waste refrigerant catalyst according to claim 1, wherein: In S3, the pressure of the second low-temperature and low-pressure distillation is controlled to be 3.0-5.0 kPa, the tower bottom temperature is 60-90°C, and the tower top temperature is 40-50°C to complete the purification of methane chloride, and the CH3Cl purity is ≥96.5%.
7. The method for treating waste refrigerant catalyst according to claim 1, wherein: In S2 and S3, the intermittent distillation tower is provided with plate corrugated packing, the tower bottom temperature is controlled at 120-140°C, the tower bottom reboiler adopts a falling film form to reduce the metal wall temperature, and after the top gas phase is condensed by the condenser, a small amount of HF and HCl entrained with part of the CMS is discharged as non-condensable gas, and the tower top condensation temperature is controlled below 20°C.
8. The method for treating waste refrigerant catalyst according to claim 1, wherein: In the step S4, the steam of the second overhead distillate passes through the adsorption tower at a flow rate of 1-3 BV / h, the bed height is controlled to be 1.8 m, and the temperature difference of the tower plates is ≤3°C.
9. The method for treating waste refrigerant catalyst according to claim 1, wherein: In S5, the methane chloride obtained in S4 is reacted with hydrogen fluoride under the action of the adsorbed antimony-based catalyst to obtain a refrigerant.
10. The method for treating waste refrigerant catalyst according to claim 1, characterized in that: In S5, the methane chloride obtained in S4 and carbon tetrachloride are sequentially subjected to azeotropic distillation, catalytic dehydrogenation, and transesterification to obtain chlorofluorocarbons.