Treatment method of waste catalyst in pentafluoroethane production

Abstract

The invention relates to the technical field of chemical engineering, and discloses a treatment method of a waste catalyst in pentafluoroethane production, which comprises the following steps: 1, collecting the waste catalyst; step 2, pretreatment; step 3, ultrasonic-assisted separation; 4, solid residue treatment; and 5, metal recovery. According to the treatment method for the waste catalyst in pentafluoroethane production, on the treatment effect, efficient treatment of the waste catalyst is achieved by improving the metal recovery rate and the organic impurity removal rate, and waste can be effectively recycled and purified. And in the aspect of process flexibility, a relatively large adjustment space is provided for actual operation no matter selection of solutions and additives or setting of process parameters, and different production conditions and waste catalyst characteristics can be adapted. And from the perspective of environmental protection and economy, the pollution to the environment is reduced, and economic value is brought to enterprises.

Description

Technical Field

[0001] The invention relates to the technical field of chemical industry, in particular to a method for treating a waste catalyst in the production of pentafluoroethane. Background Art

[0002] Pentafluoroethane (HFC-125), as an important hydrofluorocarbon refrigerant, is widely used in refrigeration, air conditioning and other industries. In the production process of pentafluoroethane, catalysts containing metal fluorides such as chromium, aluminum, and nickel are often used. However, as production proceeds, these catalysts will gradually deactivate and become waste catalysts. These waste catalysts contain not only metal fluorides, but also organic impurities. If not properly handled, they will cause a series of serious problems.

[0003] Traditional treatment methods often fail to effectively recycle the metal components in waste catalysts. For example, some companies may directly landfill or simply incinerate waste catalysts as waste, which results in the waste of valuable metal resources such as chromium, aluminum, and nickel in the waste catalysts. These metals have important application values ​​in many fields such as electronics and metallurgy, and their waste is undoubtedly a huge loss of resources.

[0004] If the organic impurities in the waste catalyst are simply landfilled, they may seep out with rainwater during the landfill process, polluting the soil and groundwater. Moreover, if incineration is used, incomplete combustion of organic impurities may produce harmful gases, such as dioxins, which will cause serious pollution to the atmospheric environment.

[0005] If the metal fluorides in the spent catalysts are not properly handled, they may release fluoride ions. Fluoride ions are highly toxic. Excessive fluoride entering the soil or water will affect the ecological balance of the soil, inhibit the growth of aquatic organisms and plants, and may even cause harm to human health through accumulation in the food chain.

[0006] In the traditional waste catalyst treatment process, the separation of solid and liquid components in the waste catalyst is often inefficient. For example, it is difficult to quickly and effectively separate the solid residues and the solution containing metal ions in the waste catalyst by simply relying on natural sedimentation or conventional filtration methods, which makes the entire treatment process time-consuming and increases the treatment cost.

[0007] Traditional treatment methods lack precise process parameter control at each stage of the treatment process. For example, when treating impurities in spent catalysts, there is no clear optimization of parameters such as solution concentration, treatment temperature and time, which leads to unstable treatment effects and makes it difficult to ensure that the treated products meet environmental protection and resource recovery requirements. Summary of the invention

[0008] 1. Technical issues to be resolved

[0009] In view of the deficiencies in the prior art, the present invention provides a method for treating waste catalyst in pentafluoroethane production to solve the above problems.

[0010] (II) Technical solution

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

[0012] Step 1: Collection of spent catalysts: collecting spent catalysts from a pentafluoroethane production unit;

[0013] Step 2: Pretreatment: the collected waste catalyst is placed in a reaction container, and an alkaline solution is first 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, placing the pretreated mixture in an ultrasonic field, and performing solid-liquid separation at the same time to obtain a solid residue and an acidic solution containing metal ions;

[0015] Step 4: solid residue treatment, mixing the solid residue with a specific additive and then subjecting it to microwave roasting treatment to convert the remaining metal fluoride into metal oxide;

[0016] Step 5: Metal recovery: using electrolysis to recover the metals from the acidic solution containing metal ions.

[0017] Preferably, in the pretreatment of step 2, 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°C; 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 immersion time is 2-6 hours, and the immersion temperature is 40-80°C.

[0018] Preferably, in the pretreatment of step 2, 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 ultrasound-assisted separation in step three, the ultrasound frequency is 20-60 kHz and the ultrasound time is 0.5-2 hours.

[0020] Preferably, in the solid residue treatment of step 4, 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°C, and the roasting time is 1-4 hours.

[0021] Preferably, the microwave roasting process is carried out under a nitrogen atmosphere, and the nitrogen gas volume fraction is 80%-95%.

[0022] Preferably, in the metal recovery of step five, the inert electrode is used as the anode, the 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° C. 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] 1. Improved overall processing effect

[0026] Improved metal recovery efficiency

[0027] In the treatment method of the present invention, the recovery rate of metals in the waste catalyst 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, which is a significant improvement over 70.2% in the comparative example. This means that more metal resources can be recycled and reused, reducing the waste of resources, which is of great significance for the sustainable utilization of metal resources.

[0028] This efficient metal recovery benefits from the treatment of the waste catalyst with alkaline and acidic solutions in the pretreatment step, which enables 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] The treatment method has a significant effect on the removal of organic impurities. In Examples 1-3, the organic impurity removal rates reached 85.2%, 82.6% and 83.8% respectively, while the organic impurity removal rate in the comparative example was only 65.5%.

[0031] The alkaline solution preliminary treatment and acid solution soaking treatment in the pretreatment, as well as the ultrasound-assisted separation step, are all helpful in removing organic impurities. The alkaline solution can react with some organic impurities, the acid solution further removes organic impurities, and the ultrasound-assisted separation promotes the separation of organic impurities from solids and liquids through physical vibration and impact, thereby improving the overall treatment effect and making the treated product purer.

[0032] 2. Enhanced process flexibility

[0033] Flexibility in choice of solutions and additives

[0034] In the claims, the alkaline solution, acidic solution and additive are defined broadly, which provides more options for practical operation. For example, the alkaline solution can be a variety of strong alkaline solutions, rather than just a specific alkali, which allows the most suitable alkaline solution to be selected for pretreatment under different production environments and cost considerations.

[0035] The additive is a mixture of carbonates, and its mass ratio and ratio to the solid residue also have a certain range. This flexibility helps to make adjustments based on the actual waste catalyst composition and treatment requirements, thereby improving the adaptability of the process.

[0036] Wide range 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 wide range of parameters enables the treatment method to adapt to different waste catalyst conditions. Under different production scales, equipment conditions and initial conditions of waste catalysts, adjustments can be made within these parameter ranges to achieve the best treatment effect, reducing the process's dependence on specific conditions and improving the versatility of the process.

[0039] 3. Environmental protection and economic value

[0040] Environmental benefits

[0041] Efficient waste catalyst treatment helps reduce environmental pollution caused by waste. If the metal fluorides and organic impurities contained in the waste catalyst are not properly treated, they may cause pollution to the soil, water and other environments. Through this treatment method, the metals can be recovered and the organic impurities can be effectively removed, greatly reducing the environmental harm of the waste.

[0042] For example, it reduces the risk of metal fluoride leakage 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 obvious economic value. Recovered metals can be reused in the production process or sold, reducing the company's raw material costs. At the same time, efficient treatment methods also reduce the cost of waste disposal, because there is no need to use more complex and expensive waste treatment methods to deal with spent catalysts that are not effectively treated.

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

[0046] The method for treating waste catalysts in pentafluoroethane production of the present invention has many significant advantages. In terms of treatment effect, by improving the metal recovery rate and the organic impurity removal rate, efficient treatment of waste catalysts is achieved, so that waste can be effectively recycled and purified. In terms of process flexibility, whether it is the selection of solutions and additives or the setting of process parameters, a large adjustment space is given to actual operations, which can adapt to different production conditions and waste catalyst characteristics. From an environmental and economic perspective, it not only reduces pollution to the environment, but also brings economic value to the enterprise, which helps the enterprise find a balance between environmental protection and economic benefits and achieve sustainable development. This treatment method has broad application prospects in the pentafluoroethane production industry and can provide strong technical support for the green development and resource recycling of the industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 The figure is a schematic diagram of the process steps of the present invention. DETAILED DESCRIPTION

[0048] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. Obviously, the described embodiments are only part of the embodiments of the invention, rather than all of the embodiments. In the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other. Based on the embodiments in the invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the invention.

[0049] See also Figure 1 ,

[0050] Example 1

[0051] A method for treating a waste catalyst in pentafluoroethane production comprises the following steps:

[0052] 1. Collection of spent catalyst

[0053] Spent catalyst is collected from a pentafluoroethane production unit.

[0054] 2. Preprocessing

[0055] Initial treatment with alkaline solution

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

[0057] Acid solution immersion treatment

[0058] Prepare a mixed acid solution with a hydrochloric acid concentration of 2 mol / L and a hydrofluoric acid concentration of 1 mol / L. Add the spent catalyst that has been preliminarily treated with the alkaline solution to the acid solution at a mass ratio of 1:6. Place the mixed solution in a 60°C thermostat and soak for 4 hours.

[0059] 3. Ultrasonic assisted separation

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

[0061] 4. Solid residue treatment

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

[0063] The solid residue and the additive were fully mixed according to a mass ratio of the solid residue to the additive of 1:0.4.

[0064] The mixture was placed in a microwave roasting device and microwave roasted in a nitrogen atmosphere with a volume fraction of 90%, a microwave roasting power of 800 W, a roasting temperature of 550° C., and a roasting time of 2.5 hours.

[0065] 5. Metal recycling

[0066] The metal ions in the acid solution are electrolyzed for metal recovery. The platinum electrode is used as the anode and the copper electrode is used as the cathode. The electrolysis voltage is set to 5V and the electrolysis time is set to 2 hours. The metal precipitate obtained by electrolysis is filtered and then washed with deionized water. Finally, the washed metal precipitate is placed in a drying oven at 80°C and dried for 1 hour to obtain a dry metal recovery.

[0067] Example 2

[0068] A method for treating a waste catalyst in pentafluoroethane production comprises the following steps:

[0069] 1. Collection of spent catalyst

[0070] Same as Example 1.

[0071] 2. Preprocessing

[0072] Initial treatment with alkaline solution

[0073] Prepare a potassium hydroxide solution with a mass concentration of 2 mol / L. Place the collected waste catalyst in a reaction vessel at a mass ratio of 1:3 between the waste catalyst and the alkaline solution, and then add the potassium hydroxide solution. Place the reaction vessel in a constant temperature water bath at 30°C for 2 hours.

[0074] Acid solution immersion treatment

[0075] Prepare a mixed acid solution with a hydrochloric acid concentration of 1 mol / L and a hydrofluoric acid concentration of 0.5 mol / L. Add the spent catalyst that has been preliminarily treated with the alkaline solution to the acid solution at a mass ratio of 1:4. Place the mixed solution in a 40°C constant temperature box and soak for 6 hours.

[0076] 3. Ultrasonic assisted separation

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

[0078] 4. Solid residue treatment

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

[0080] The solid residue and the additive are fully mixed according to a mass ratio of the solid residue to the additive of 1:0.2.

[0081] The mixture was placed in a microwave roasting device and microwave roasted in a nitrogen atmosphere with a volume fraction of 80%, a microwave roasting power of 500 W, a roasting temperature of 400° C., and a roasting time of 4 hours.

[0082] 5. Metal recycling

[0083] The acidic solution containing metal ions is electrolyzed for metal recovery. A graphite electrode is selected as the anode and a nickel electrode is selected as the cathode. The electrolysis voltage is set to 3V and the electrolysis time is set to 3 hours. The metal precipitate obtained by electrolysis is filtered and then washed with deionized water. Finally, the washed metal precipitate is placed in a drying oven at 60°C for 2 hours to obtain a dry metal recovery.

[0084] Example 3

[0085] A method for treating a waste catalyst in pentafluoroethane production comprises the following steps:

[0086] 1. Collection of spent catalyst

[0087] Same as Example 1.

[0088] 2. Preprocessing

[0089] Initial treatment with alkaline solution

[0090] Prepare a barium hydroxide solution with a mass concentration of 6 mol / L. Place the collected waste catalyst in a reaction vessel at a mass ratio of 1:8 between the waste catalyst and the alkaline solution, and then add the barium hydroxide solution. Place the reaction vessel in a constant temperature water bath at 70°C for 0.5 hours.

[0091] Acid solution immersion treatment

[0092] Prepare a mixed acid solution with a hydrochloric acid concentration of 3 mol / L and a hydrofluoric acid concentration of 1.5 mol / L. Add the spent catalyst that has been preliminarily treated with the alkaline solution to the acid solution at a mass ratio of 1:10. Place the mixed solution in a thermostat at 80°C and soak for 2 hours.

[0093] 3. Ultrasonic assisted separation

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

[0095] 4. Solid residue treatment

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

[0097] The solid residue and the additive were fully mixed according to a mass ratio of the solid residue to the additive of 1:0.6.

[0098] The mixture was placed in a microwave roasting device and microwave roasted in a nitrogen atmosphere with a volume fraction of 95%, a microwave roasting power of 1000 W, a roasting temperature of 700° C., and a roasting time of 1 hour.

[0099] 5. Metal recycling

[0100] The acidic solution containing metal ions is electrolyzed for metal recovery. A platinum electrode is selected as the anode and a copper electrode is selected as the cathode. The electrolysis voltage is set to 8V and the electrolysis time is 1 hour. The metal precipitate obtained by electrolysis is filtered and then washed with deionized water. Finally, the washed metal precipitate is placed in a drying oven at 100°C and dried for 0.5 hours to obtain a dry metal recovery.

[0101] Comparative Example

[0102] The waste catalyst was treated according to a conventional waste catalyst treatment method, without using the specific steps and parameters of the pretreatment, ultrasound-assisted separation, solid residue treatment and metal recovery of the present invention.

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

[0104] Treatment Metal recovery rate (%) Organic impurities 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] It can be seen from the above experimental data that the method for treating waste catalyst in pentafluoroethane production of the present invention is significantly superior to 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 replacements, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

[0107] It will be apparent to those skilled in the art that the 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 the spirit or essential features of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations falling within the meaning and scope of the equivalent elements of the claims be included in the invention. Any reference numeral in a claim should not be considered as limiting the claim to which it relates.

[0108] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for treating spent catalyst in pentafluoroethane production, characterized in that: The following steps are involved: Step 1: Collection of spent catalysts: collecting spent catalysts from a pentafluoroethane production unit; Step 2: Pretreatment: the collected waste catalyst is placed in a reaction container and initially treated with an alkaline solution to remove some organic impurities; Then, an acid solution is added for soaking treatment to dissolve part of the metal fluoride and further remove organic impurities; Step 3: Ultrasonic assisted separation, placing the pretreated mixture in an ultrasonic field, and performing solid-liquid separation at the same time, to obtain a solid residue and an acidic solution containing metal ions; Step 4: solid residue treatment, mixing the solid residue with a specific additive and then subjecting it to microwave roasting treatment to convert the remaining metal fluoride into metal oxide; Step 5: Metal recovery: using electrolysis to recover the metals from the acidic solution containing metal ions.

2. A method for treating waste catalyst in pentafluoroethane production according to claim 1: in the pretreatment of step 2, 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°C; 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 immersion time is 2-6 hours, and the immersion temperature is 40-80°C.

3. The method for treating waste catalyst in pentafluoroethane production according to claim 1, characterized in that: In the pretreatment of step 2, 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 waste catalyst in pentafluoroethane production according to claim 1, characterized in that: In the ultrasound-assisted separation of step three, the ultrasound frequency is 20-60 kHz, and the ultrasound time is 0.5-2 hours.

5. The method for treating waste catalyst in pentafluoroethane production according to claim 2, characterized in that: In the solid residue treatment of step 4, 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°C, and the roasting time is 1-4 hours.

6. The method for treating waste catalyst in pentafluoroethane production according to claim 5, characterized in that: The microwave roasting process is carried out in a nitrogen atmosphere, and the nitrogen gas volume fraction is 80%-95%.

7. The method for treating waste catalyst in pentafluoroethane production according to claim 1, characterized in that: In the metal recovery of step 5, the inert electrode is used as the anode, the metal electrode is used as the cathode, the electrolysis voltage is 3-8V, and the electrolysis time is 1-3 hours.

8. The method for treating waste catalyst in pentafluoroethane production according to claim 1, characterized in that: The drying temperature after the metal recovery is 60-100° C., and the drying time is 0.5-2 hours.

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