A method for treating spent catalyst in the production of pentafluoroethane

Abstract

The application relates to the chemical technology field and discloses a treatment method for waste catalysts in the production of pentafluoroethane, which comprises the following steps: step one, waste catalyst collection; step two, pretreatment; step three, ultrasonic-assisted separation; step four, solid residue treatment; and step five, metal recovery. The treatment method for waste catalysts in the production of pentafluoroethane has the advantages of high treatment efficiency, high metal recovery rate and high organic impurity removal rate, so that the waste catalysts can be effectively treated, and the waste can be effectively recycled and purified. In terms of flexibility, the selection of the solution and the additive and the setting of the process parameters can be adjusted to adapt to different production conditions and waste catalyst characteristics. From the environmental protection and economic perspectives, the treatment method can reduce the environmental pollution and bring economic value to enterprises.

Description

Technical Field

[0001] This invention relates to the field of chemical technology, specifically to a method for treating waste catalysts in the production of pentafluoroethane. Background Technology

[0002] Pentafluoroethane (HFC-125), as an important hydrofluorocarbon refrigerant, has wide applications in the refrigeration and air conditioning industries. The production process of pentafluoroethane often uses catalysts containing metallic fluorides such as chromium, aluminum, and nickel. However, as production progresses, these catalysts gradually deactivate and become spent catalysts. These spent catalysts not only contain metallic fluorides but also organic impurities, and if not properly handled, they will cause a series of serious problems.

[0003] Traditional treatment methods often fail to effectively recover and utilize the metal components in spent catalysts. For example, some companies may directly treat spent catalysts as waste, resorting to landfilling or simple incineration. This results in the waste of valuable metal resources such as chromium, aluminum, and nickel. These metals have important applications in many fields, including electronics and metallurgy, and their waste undoubtedly represents a significant depletion of resources.

[0004] If organic impurities in spent catalysts are simply landfilled, they may seep out with rainwater during the landfill process, polluting the soil and groundwater. Furthermore, if incinerated, incomplete combustion of these organic impurities may produce harmful gases such as dioxins, causing serious air pollution.

[0005] Improper handling of spent catalysts can release fluoride ions from metal fluorides. Fluoride ions are highly toxic, and excessive fluoride entering soil or water can disrupt the ecological balance of the soil, inhibit the growth of aquatic organisms and plants, and may even accumulate in the food chain, posing a threat to human health.

[0006] In traditional spent catalyst treatment processes, the separation of solid and liquid components is often inefficient. For example, relying solely on natural sedimentation or conventional filtration methods makes it difficult to quickly and effectively separate solid residues from solutions containing metal ions, resulting in a lengthy treatment process and increased costs.

[0007] Traditional treatment methods lack precise control over process parameters at each stage of the process. For example, when treating impurities in spent catalysts, the lack of clear optimization of parameters such as solution concentration, treatment temperature, and time leads to unstable treatment results and makes it difficult to ensure that the treated products meet environmental protection and resource recycling requirements. Summary of the Invention

[0008] (a) Technical problems to be solved

[0009] To address the shortcomings of existing technologies, this invention provides a method for treating waste catalysts in pentafluoroethane production, thereby solving the aforementioned problems.

[0010] (II) Technical Solution

[0011] To achieve the above objectives, the present invention provides the following technical solution: a method for treating spent catalyst in pentafluoroethane production, comprising the following steps:

[0012] Step 1: Collection of spent catalysts. The spent catalysts from the pentafluoroethane production unit will be collected.

[0013] Step 2: Pretreatment. The collected waste catalyst is placed in a reaction vessel. First, an alkaline solution is added for preliminary treatment to remove some organic impurities. Then, an acidic solution is added for soaking treatment to dissolve some metal fluorides and further remove organic impurities.

[0014] Step 3: Ultrasonic-assisted separation. The pretreated mixture is placed in an ultrasonic field, and solid-liquid separation is performed simultaneously to obtain solid residue and an acidic solution containing metal ions.

[0015] Step 4: Solid residue treatment. The solid residue is mixed with specific additives and then microwave roasted to convert the remaining metal fluorides into metal oxides.

[0016] Step 5: Metal recovery. Electrolysis is used to recover the metals from the acidic solution containing metal ions.

[0017] Preferably, in the pretreatment of step two, the alkaline solution is a strong alkaline solution with a mass concentration of 2-6 mol / L, the treatment time is 0.5-2 hours, and the treatment temperature is 30-70℃; the acidic solution is a mixed solution of hydrochloric acid and hydrofluoric acid, wherein the concentration of hydrochloric acid is 1-3 mol / L, the concentration of hydrofluoric acid is 0.5-1.5 mol / L, the soaking time is 2-6 hours, and the soaking temperature is 40-80℃.

[0018] Preferably, in the pretreatment step two, the mass ratio of the waste catalyst to the alkaline solution is 1:3-1:8, and the mass ratio of the waste catalyst to the acidic solution is 1:4-1:10.

[0019] Preferably, in the ultrasonic-assisted separation in step three, the ultrasonic frequency is 20-60 kHz and the ultrasonic time is 0.5-2 hours.

[0020] Preferably, in the solid residue treatment in step four, the additive is a mixture of carbonates, the mass ratio of solid residue to additive is 1:0.2-1:0.6, the microwave roasting power is 500-1000W, the roasting temperature is 400-700℃, and the roasting time is 1-4 hours.

[0021] Preferably, the microwave roasting process is carried out under a nitrogen atmosphere, with a nitrogen gas integral of 80%-95%.

[0022] Preferably, in the metal recovery step five, an inert electrode is used as the anode, a metal electrode is used as the cathode, the electrolysis voltage is 3-8V, and the electrolysis time is 1-3 hours.

[0023] Preferably, the drying temperature after metal recovery is 60-100℃, and the drying time is 0.5-2 hours.

[0024] Compared with the prior art, the present invention provides a method for treating waste catalyst in pentafluoroethane production, which has the following beneficial effects:

[0025] I. Improved overall processing effect

[0026] Improved metal recycling efficiency

[0027] In the processing method of this invention, the recovery rate of metals from spent catalysts is significantly improved through carefully designed steps and reasonable parameter ranges. For example, in Examples 1-3, the metal recovery rates reached 90.5%, 88.7%, and 89.3%, respectively, a substantial increase compared to the 70.2% in the comparative example. This means that more metal resources can be recycled and reused, reducing resource waste and having significant implications for the sustainable utilization of metal resources.

[0028] This highly efficient metal recovery benefits from the treatment of the spent catalyst with alkaline and acidic solutions in the pretreatment step, which allows the metal fluorides to be better dissolved and converted, creating favorable conditions for subsequent electrolytic recovery. At the same time, the microwave roasting step in the solid residue treatment converts the remaining metal fluorides into metal oxides, further improving the efficiency of metal recovery.

[0029] Effective removal of organic impurities

[0030] This treatment method is highly effective in removing organic impurities. In Examples 1-3, the removal rates of organic impurities reached 85.2%, 82.6%, and 83.8%, respectively, while the removal rate of organic impurities in the comparative example was only 65.5%.

[0031] Pre-treatment with alkaline solution, soaking in acidic solution, and ultrasonic-assisted separation all contribute to the removal of organic impurities. The alkaline solution reacts with some organic impurities, the acidic solution further removes them, and ultrasonic-assisted separation promotes the separation of organic impurities from solids and liquids through physical vibration and impact, thereby improving the overall treatment effect and resulting in a purer product.

[0032] II. Enhanced process flexibility

[0033] Flexibility in the selection of solutions and additives

[0034] The claims provide a broad definition of alkaline solutions, acidic solutions, and additives, offering more options for practical application. For example, an alkaline solution can be a variety of strong alkali solutions, not just a specific one. This allows for the selection of the most suitable alkaline solution for pretreatment, taking into account different production environments and cost considerations.

[0035] The additives are a mixture of carbonates, and their mass ratio and proportion to solid residue also have certain ranges. This flexibility helps to adjust according to the actual composition of the spent catalyst and treatment requirements, thus improving the adaptability of the process.

[0036] Broadness of process parameters

[0037] The process parameters in each processing step are set within a certain range, such as temperature and time in pretreatment, ultrasonic frequency and time in ultrasonic-assisted separation, microwave roasting power, temperature and time in solid residue treatment, and electrolysis voltage and time in metal recovery.

[0038] This broad parameter range allows the treatment method to adapt to different conditions of spent catalyst. Adjustments can be made within these parameter ranges to achieve optimal treatment results under varying production scales, equipment conditions, and initial states of spent catalyst, reducing the process's dependence on specific conditions and improving its versatility.

[0039] III. Environmental and Economic Value

[0040] Environmental benefits

[0041] Efficient spent catalyst treatment helps reduce environmental pollution from waste. Metal fluorides and organic impurities contained in spent catalysts, if not properly treated, can pollute soil, water bodies, and other environments. This treatment method can recover the metals and effectively remove organic impurities, significantly reducing the environmental hazards of the waste.

[0042] For example, it reduces the risk of metal fluorides leaching into the environment, avoids the decomposition of organic impurities in the natural environment to produce harmful substances, meets environmental protection requirements, and helps enterprises achieve green production.

[0043] Economic value

[0044] The recycling and reuse of metals has significant economic value. Recycled metals can be reused in production processes or sold, reducing raw material costs for businesses. At the same time, efficient processing methods also reduce waste disposal costs, as more complex and expensive waste treatment methods are not required to handle ineffectively treated spent catalysts.

[0045] In the long run, this environmentally friendly and economical method of treating spent catalysts will help companies improve their competitiveness and achieve better economic benefits on the path of sustainable development.

[0046] The method for treating spent catalysts in pentafluoroethane production presented in this invention offers several significant advantages. In terms of treatment efficiency, it achieves highly efficient treatment of spent catalysts by improving metal recovery and organic impurity removal rates, enabling effective resource recovery and purification of the waste. Regarding process flexibility, it provides considerable room for adjustment in both solution and additive selection and process parameter settings, adapting to different production conditions and the characteristics of spent catalysts. From an environmental and economic perspective, it reduces environmental pollution while generating economic value for enterprises, helping them find a balance between environmental protection and economic benefits, and achieving sustainable development. This treatment method has broad application prospects in the pentafluoroethane production industry and can provide strong technical support for the industry's green development and resource recycling. Attached Figure Description

[0047] Figure 1 This is a schematic diagram of the processing steps of the present invention. Detailed Implementation

[0048] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only a part of the embodiments of the invention, and not all of them. Unless otherwise specified, the embodiments and features described in this application can be combined with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0049] Please see Figure 1 ,

[0050] Example 1

[0051] A method for treating spent catalyst in pentafluoroethane production, comprising the following steps:

[0052] 1. Collection of spent catalysts

[0053] Collect spent catalysts from pentafluoroethane production units.

[0054] 2. Pretreatment

[0055] Preliminary treatment of alkaline solution

[0056] Prepare a 4 mol / L sodium hydroxide solution. Place the collected spent catalyst in a reaction vessel at a mass ratio of 1:5 (used catalyst to alkaline solution), and then add the sodium hydroxide solution. Place the reaction vessel in a 50°C constant temperature water bath for 1 hour.

[0057] Acidic solution soaking treatment

[0058] Prepare a mixed acidic solution with a hydrochloric acid concentration of 2 mol / L and a hydrofluoric acid concentration of 1 mol / L. Add the spent catalyst, after preliminary treatment with an alkaline solution, to the acidic solution at a mass ratio of 1:6. Place the mixed solution in a constant temperature incubator at 60℃ and soak for 4 hours.

[0059] 3. Ultrasonic-assisted separation

[0060] The pretreated mixture was placed in an ultrasonic field with an ultrasonic frequency of 40 kHz and an ultrasonic treatment time of 1.5 hours. During the ultrasonic process, solid-liquid separation, such as filtration or centrifugation, was performed simultaneously to obtain solid residue and an acidic solution containing metal ions.

[0061] 4. Solid residue treatment

[0062] Prepare an additive, which is a mixture of sodium carbonate and potassium carbonate in a mass ratio of 2:1.

[0063] Mix the solid residue and additive thoroughly according to a mass ratio of 1:0.4.

[0064] The mixture was placed in a microwave calcination apparatus and calcined under a nitrogen atmosphere. The nitrogen volume fraction was 90%, the microwave calcination power was set to 800W, the calcination temperature to 550℃, and the calcination time to 2.5 hours.

[0065] 5. Metal recycling

[0066] Metals containing metal ions were recovered from acidic solutions using electrolysis. A platinum electrode was selected as the anode, and a copper electrode as the cathode. The electrolysis voltage was set to 5V, and the electrolysis time was 2 hours. The metal precipitate obtained from electrolysis was filtered, washed with deionized water, and finally dried in an 80℃ drying oven for 1 hour to obtain dried metal recovery.

[0067] Example 2

[0068] A method for treating spent catalyst in pentafluoroethane production, comprising the following steps:

[0069] 1. Collection of spent catalysts

[0070] Same as Example 1.

[0071] 2. Pretreatment

[0072] Preliminary treatment of alkaline solution

[0073] Prepare a 2 mol / L potassium hydroxide solution. Place the collected spent catalyst in a reaction vessel at a mass ratio of 1:3 (used catalyst to alkaline solution), then add the potassium hydroxide solution. Place the reaction vessel in a 30°C water bath for 2 hours.

[0074] Acidic solution soaking treatment

[0075] Prepare a mixed acidic solution with a hydrochloric acid concentration of 1 mol / L and a hydrofluoric acid concentration of 0.5 mol / L. Add the spent catalyst, after preliminary treatment with an alkaline solution, to the acidic solution at a mass ratio of 1:4. Place the mixed solution in a constant temperature incubator at 40℃ and soak for 6 hours.

[0076] 3. Ultrasonic-assisted separation

[0077] The pretreated mixture was placed in an ultrasonic field with an ultrasonic frequency of 20 kHz and an ultrasonic treatment time of 2 hours. During the ultrasonic process, solid-liquid separation was performed simultaneously to obtain a solid residue and an acidic solution containing metal ions.

[0078] 4. Solid residue treatment

[0079] Prepare an additive, which is a mixture of sodium carbonate and potassium carbonate in a mass ratio of 1:1.

[0080] Mix the solid residue and additive thoroughly according to a mass ratio of 1:0.2.

[0081] The mixture was placed in a microwave roasting apparatus and roasted under a nitrogen atmosphere. The nitrogen volume fraction was 80%, the microwave roasting power was set to 500W, the roasting temperature to 400℃, and the roasting time to 4 hours.

[0082] 5. Metal recycling

[0083] Metals containing metal ions were recovered from acidic solutions using electrolysis. A graphite electrode was selected as the anode, and a nickel electrode as the cathode. The electrolysis voltage was set to 3V, and the electrolysis time to 3 hours. The metal precipitate obtained from electrolysis was filtered, washed with deionized water, and finally dried in a 60℃ drying oven for 2 hours to obtain dried metal recovery.

[0084] Example 3

[0085] A method for treating spent catalyst in pentafluoroethane production, comprising the following steps:

[0086] 1. Collection of spent catalysts

[0087] Same as Example 1.

[0088] 2. Pretreatment

[0089] Preliminary treatment of alkaline solution

[0090] Prepare a 6 mol / L barium hydroxide solution. Place the collected spent catalyst in a reaction vessel at a mass ratio of 1:8 (used catalyst to alkaline solution), and then add the barium hydroxide solution. Place the reaction vessel in a 70°C water bath for 0.5 hours.

[0091] Acidic solution soaking treatment

[0092] Prepare a mixed acidic solution with a hydrochloric acid concentration of 3 mol / L and a hydrofluoric acid concentration of 1.5 mol / L. Add the spent catalyst, after preliminary treatment with an alkaline solution, to the acidic solution at a mass ratio of 1:10. Place the mixed solution in an 80℃ constant temperature incubator and soak for 2 hours.

[0093] 3. Ultrasonic-assisted separation

[0094] The pretreated mixture was placed in an ultrasonic field with an ultrasonic frequency of 60 kHz and an ultrasonic treatment time of 0.5 hours. During the ultrasonic process, solid-liquid separation was performed simultaneously, yielding a solid residue and an acidic solution containing metal ions.

[0095] 4. Solid residue treatment

[0096] Prepare an additive, which is a mixture of sodium carbonate and potassium carbonate in a mass ratio of 3:1.

[0097] Mix the solid residue and additive thoroughly according to a mass ratio of 1:0.6.

[0098] The mixture was placed in a microwave roasting apparatus and roasted under a nitrogen atmosphere. The nitrogen volume fraction was 95%, the microwave roasting power was set to 1000W, the roasting temperature to 700℃, and the roasting time to 1 hour.

[0099] 5. Metal recycling

[0100] Metals containing metal ions were recovered from acidic solutions using electrolysis. A platinum electrode was selected as the anode, and a copper electrode as the cathode. The electrolysis voltage was set to 8V, and the electrolysis time to 1 hour. The metal precipitate obtained from electrolysis was filtered, washed with deionized water, and finally dried in a 100℃ drying oven for 0.5 hours to obtain dried metal recovery.

[0101] Comparative Example

[0102] The waste catalyst was treated using conventional methods, without employing the specific steps and parameters of the present invention, including pretreatment, ultrasonic-assisted separation, solid residue treatment, and metal recovery.

[0103] By comparing the treatment effects of Examples 1-3 and the comparative example, the advantages of the waste catalyst treatment method in pentafluoroethane production of the present invention in terms of metal recovery rate and organic impurity removal rate were evaluated. Specific experimental data are shown in the table below:

[0104] processing method Metal recovery rate (%) Organic impurity removal rate (%) Example 1 90.5 85.2 Example 2 88.7 82.6 Example 3 89.3 83.8 Comparative Example 70.2 65.5

[0105] The experimental data above show that the waste catalyst treatment method in the production of pentafluoroethane of the present invention is significantly better than conventional treatment methods in terms of metal recovery rate and organic impurity removal rate, and has significant technical advantages and practical value.

[0106] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

[0107] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0108] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A method for treating spent catalyst in pentafluoroethane production, characterized in that, Includes the following steps: Step 1: Collection of spent catalysts. The spent catalysts from the pentafluoroethane production unit will be collected. Step 2: Pretreatment. The collected waste catalyst is placed in a reaction vessel and an alkaline solution is added for preliminary treatment to remove some organic impurities. Then, an acidic solution is added for soaking treatment to dissolve some of the metal fluorides and further remove organic impurities; Step 3: Ultrasonic-assisted separation. The pretreated mixture is placed in an ultrasonic field, and solid-liquid separation is performed simultaneously to obtain solid residue and an acidic solution containing metal ions. Step 4: Solid residue treatment. The solid residue is mixed with specific additives and then microwave roasted to convert the remaining metal fluoride into metal oxide. The additives are a mixture of carbonates. Step 5: Metal recovery. Electrolysis is used to recover the metals from the acidic solution containing metal ions.

2. A method for treating spent catalyst in pentafluoroethane production according to claim 1: In the pretreatment step two, the alkaline solution is a strong alkaline solution with a mass concentration of 2-6 mol / L, the treatment time is 0.5-2 hours, and the treatment temperature is 30-70℃; the acidic solution is a mixed solution of hydrochloric acid and hydrofluoric acid, wherein the concentration of hydrochloric acid is 1-3 mol / L, the concentration of hydrofluoric acid is 0.5-1.5 mol / L, the soaking time is 2-6 hours, and the soaking temperature is 40-80℃.

3. The method for treating spent catalyst in pentafluoroethane production according to claim 1, characterized in that: In the pretreatment of step two, the mass ratio of the waste catalyst to the alkaline solution is 1:3-1:8, and the mass ratio of the waste catalyst to the acidic solution is 1:4-1:

10.

4. The method for treating spent catalyst in pentafluoroethane production according to claim 1, characterized in that: In step three, the ultrasonic-assisted separation uses an ultrasonic frequency of 20-60 kHz and an ultrasonic duration of 0.5-2 hours.

5. A method for treating spent catalyst in pentafluoroethane production according to claim 2, characterized in that: In the solid residue treatment in step four, the mass ratio of solid residue to additive is 1:0.2-1:0.6, the microwave roasting power is 500-1000W, the roasting temperature is 400-700℃, and the roasting time is 1-4 hours.

6. A method for treating spent catalyst in pentafluoroethane production according to claim 5, characterized in that: The microwave roasting process is carried out under a nitrogen atmosphere, with a nitrogen gas integral of 80%-95%.

7. The method for treating spent catalyst in pentafluoroethane production according to claim 1, characterized in that: In the metal recovery step five, an inert electrode is used as the anode and a metal electrode as the cathode. The electrolysis voltage is 3-8V and the electrolysis time is 1-3 hours.

8. The method for treating spent catalyst in pentafluoroethane production according to claim 1, characterized in that: The metal is dried at a temperature of 60-100℃ for 0.5-2 hours after recovery.

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