A method for recovering cesium fluoride, a failed catalyst in the synthesis of perfluorohexanone
By employing a secondary high-temperature thermal decomposition and precision filtration method, combined with high-temperature distillation and vacuum drying, the problems of adhesion and impurity introduction in the recovery of exhausted cesium fluoride catalysts have been solved, achieving high-purity and high-efficiency cesium fluoride recovery and improving catalytic performance and safety.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GANSU RUISIKE NEW MATERIAL CO LTD
- Filing Date
- 2024-06-19
- Publication Date
- 2026-07-21
AI Technical Summary
In the synthesis of perfluorohexanone, the degraded cesium fluoride catalyst is difficult to recover, resulting in high production costs and environmental harm. Furthermore, existing recovery methods are prone to introducing impurities that affect purity and catalytic performance.
High-purity cesium fluoride powder was prepared by using a two-stage high-temperature thermal decomposition and precision filtration method, combined with high-temperature distillation and vacuum drying. Oily substances and impurities were removed by multiple calcinations and dissolution filtrations, and finally, white powdered cesium fluoride was prepared.
It achieves efficient recovery of depleted cesium fluoride, increasing purity by 0.0046%-0.0048%, with catalytic effect superior to standard samples, and the catalytic cycle can be used up to 3 times, avoiding side reactions and safety hazards.
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of cesium fluoride recovery technology, specifically a method for recovering cesium fluoride catalysts that have failed during the synthesis of perfluorohexanone. Background Technology
[0002] Perfluorohexanone (FK-5-1-12), chemically known as perfluoro-2-methyl-3-pentanone, is a fire extinguishing agent introduced by 3M Corporation in the United States to replace halon and Freon. Perfluorohexanone has a boiling point of 49°C, is highly vaporized, leaves no residue after release, has a short atmospheric residence time (5 days), does not deplete the ozone layer (ODP=0), has a low global warming potential (GWP=1), and poses almost zero harm to the environment and humans. It is a new type of clean and environmentally friendly fire extinguishing agent with comprehensive advantages such as high fire extinguishing efficiency, environmental friendliness, high safety margin, good insulation performance, and no damage to precision electronic equipment. It has been recognized by the international fire protection community and is widely used in important locations such as aerospace, data centers, libraries, military equipment, and subways. It is currently recognized as a substitute for hydrofluorocarbon fire extinguishing agents such as heptafluoropropane, with huge market demand and broad market prospects.
[0003] Currently, there are various methods for synthesizing perfluorohexanone, most of which use hexafluoropropylene as a raw material, and almost every step uses a fluorine-containing inorganic catalyst. In the perfluorohexanone synthesis experiments, the applicant found that cesium fluoride exhibits significantly better catalytic performance than other fluorine-containing catalysts. However, when using cesium fluoride as a catalyst, it becomes deactivated after three consecutive uses, rendering it unusable. Cesium fluoride is expensive, costing approximately 1.2 million yuan per ton. To produce 1,000 tons of perfluorohexanone annually, approximately 3 tons of cesium fluoride would be needed, requiring 3.6 million yuan. Failure to recycle the deactivated cesium fluoride catalyst would significantly increase the production cost of perfluorohexanone, and the untreated deactivated cesium fluoride is also solid waste, impacting the environment. Therefore, recycling the deactivated cesium fluoride catalyst generated during the perfluorohexanone production process has significant economic and social benefits.
[0004] Based on the above, the applicant employs a two-stage thermal decomposition method. The exhausted cesium fluoride catalyst is placed in a platinum crucible, and the oily substance coating the surface of the cesium fluoride is ingeniously decomposed into black slag using high temperature. Then, taking advantage of the fact that the black slag is insoluble in water while cesium fluoride is soluble in water, the oily substance affecting the catalytic effect is removed, yielding blocky cesium fluoride. However, the blocky cesium fluoride obtained by the two-stage high-temperature thermal decomposition method is not yet usable as a catalyst and requires further processing to prepare it into powdered cesium fluoride with catalytic effects. Two problems exist in preparing powdered cesium fluoride: First, the blocky cesium fluoride obtained by pyrometallurgical solvent evaporation easily adheres to the bottom of the platinum crucible and is difficult to remove. Strong mechanical force is required to peel it off from the platinum crucible wall, which results in the loss of cesium fluoride, leading to a decrease in yield. Furthermore, because cesium fluoride is highly toxic, this process is extremely likely to cause harm to humans, leading to safety accidents. Secondly, the cesium fluoride removed from the crucible using strong mechanical force is easily deliquesced into small droplets upon prolonged exposure to air, also reducing the cesium fluoride yield. Therefore, the applicant employs a method of pulverizing in a closed space to remove the blocky cesium fluoride from the platinum crucible wall and prepare it into powdered cesium fluoride, ensuring a high cesium fluoride yield. However, the applicant conducted a full elemental analysis on the spent cesium fluoride treated using the above method. The results showed that the content of impurity ions (mainly sodium and potassium ions) increased by approximately 2000 ppm compared to a purchased standard cesium fluoride sample with a purity of 99.5%. The applicant's experiments verified that the introduction of impurities triggers other side reactions, thereby reducing the purity of the prepared product by approximately 1.553%. Furthermore, using strong mechanical force to separate the obtained cesium fluoride in blocky form from the container wall can easily deform the container, and over time it can easily break. It can also knock down metal from the container wall and mix it into the cesium fluoride, resulting in a decrease in the purity of the recovered cesium fluoride and affecting subsequent synthesis reactions. Summary of the Invention
[0005] This invention provides a method for recovering the degraded catalyst cesium fluoride during the synthesis of perfluorohexanone. The aim is to address the technical problem that during the recovery of degraded cesium fluoride, the blocky cesium fluoride obtained from pyrometallurgical solvent evaporation tends to adhere to the bottom, making it difficult to remove. This requires strong mechanical force (using a strong mechanical force to grind the walls of the dryer to introduce impurities) to peel it off, followed by pyrometallurgical solvent drying (enriching impurity ions in the solvent) and pulverization in a confined space (high-speed friction between the blocky cesium fluoride and the walls and blades of the pulverizer to introduce impurities), which can lead to side reactions and affect product purity.
[0006] To achieve its purpose, the present invention adopts the following technical solution:
[0007] This invention provides a method for recovering cesium fluoride, a degraded catalyst, during the synthesis of perfluorohexanone, comprising the following steps:
[0008] (1) The exhausted catalyst cesium fluoride was placed in a platinum crucible and calcined under an air flow of 400-450℃ to obtain calcined cesium fluoride;
[0009] (2) Dissolve the calcined cesium fluoride obtained in step (1) in water to obtain a mixed solution of cesium fluoride containing black slag;
[0010] (3) The mixed solution obtained in step (2) is first coarsely filtered with filter paper, and then finely filtered with a filter membrane to obtain a pale yellow cesium fluoride aqueous solution;
[0011] (4) Transfer the cesium fluoride aqueous solution obtained in step (3) into a platinum crucible, and then calcine it for 3-4 hours under an air flow of 200-250℃, and then calcine it for 3-4 hours under an air flow of 400-450℃. After calcineation, cool it to room temperature to obtain solid cesium fluoride.
[0012] (5) The solid cesium fluoride obtained in step (4) is further dissolved in water to obtain a secondary aqueous solution of cesium fluoride. The secondary aqueous solution of cesium fluoride is first coarsely filtered with filter paper and then finely filtered with a filter membrane to obtain a clear and transparent aqueous solution of cesium fluoride.
[0013] (6) Continue to place the clear and transparent cesium fluoride aqueous solution obtained in step (5) into a platinum crucible and calcine it for 3-4 hours under an air flow of 200-250°C. Then raise the temperature to 400-450°C and continue calcining under a nitrogen flow until blocky cesium fluoride crystals are obtained.
[0014] (7) The blocky cesium fluoride crystals obtained in step (6) are further dissolved in ultrapure water or methanol to obtain an aqueous solution of cesium fluoride or a methanol solution of cesium fluoride;
[0015] (8) Place the cesium fluoride aqueous solution or cesium fluoride methanol solution obtained in step (7) into a platinum round-bottom flask (if glass products are used, the cesium fluoride solution will react with the glass, resulting in a significant increase in the content of calcium ions, potassium ions, sodium ions, silicon, etc. in the cesium fluoride obtained, which will affect the performance of the regenerated cesium fluoride and may also cause abnormalities in the subsequent synthesis of perfluorohexanone), add mechanical stirring, and distill at 120°C until the volume of the solution in the round-bottom flask is reduced to 1 / 3. The distilled solvent is condensed into the recovery device and returned to step (7) to dissolve the blocky cesium fluoride crystals. Stop heating, cool the solution to room temperature while stirring, and then separate the solid and liquid to obtain wet cesium fluoride crystals.
[0016] (9) The wet cesium fluoride obtained in step (8) is placed in a vacuum drying oven for drying and cooled to room temperature to obtain white powdered cesium fluoride.
[0017] As a further preferred embodiment of the technical solution of the present invention, in step (1), the calcination time is 3-4 hours.
[0018] Furthermore, in step (2), the solid-liquid mass ratio of cesium fluoride to water after calcination is 1:3-5.
[0019] Furthermore, in steps (3) and (5), the filter paper for coarse filtration has a pore size of 1 μm, and the filter membrane for precision filtration has a pore size of 0.2 μm.
[0020] Furthermore, in step (5), the solid-liquid mass ratio of cesium fluoride solid to water is 1:3-5.
[0021] Furthermore, in step (6), the calcination time under nitrogen gas flow is 3-4 hours, more preferably 4 hours.
[0022] Furthermore, in step (7), the concentration of the cesium fluoride aqueous solution is 3300-3500 g / L, and the concentration of the cesium fluoride methanol solution is 1200-1400 g / L.
[0023] Furthermore, in step (8), the mechanical stirring speed is 600-800 r / min.
[0024] Furthermore, in step (9), the drying temperature is 120-150℃ and the drying time is 2-3h.
[0025] The beneficial effects of this invention are as follows:
[0026] 1. The surface of the degraded cesium fluoride catalyst is covered with a large amount of yellow oily substance.
[0027] wrap( Figure 1 Firstly, this prevents the reaction substrate from contacting the active sites of the catalyst, thus halting the reaction. Secondly, it poisons the catalyst, causing it to lose its catalytic effect and fail to react with the substrate. This invention cleverly utilizes high temperature to thermally decompose the oily substance coating the surface of cesium fluoride into black slag. Then, taking advantage of the fact that the black slag is insoluble in water while cesium fluoride is soluble, the oily substance affecting the catalytic effect is removed. Furthermore, this invention employs a two-stage high-temperature thermal decomposition, eliminating the problem of incomplete decomposition that can occur with single thermal decomposition, leading to the recovery of cesium fluoride catalyst containing some oily coating, thus affecting the whiteness and purity of the recovered cesium fluoride and consequently impacting subsequent catalytic performance.
[0028] 2. The method of this invention eliminates the presence of [certain substances] during the production of perfluorohexanone.
[0029] The catalytically active cesium fluoride regained its catalytic effect, and the number of times cesium fluoride could be recycled as a catalyst was the same as that of the purchased standard cesium fluoride sample with a purity of 99.5%, with the same number of catalytic cycles reaching 3 times.
[0030] 3. This invention employs the method of dissolving blocky cesium fluoride followed by high-temperature distillation and vacuum drying.
[0031] This invention prepares catalytically active powdered cesium fluoride using a method where, due to the high-temperature distillation process, crystals continuously precipitate in the liquid phase. The high shear force caused by high-speed rotation results in very fine-grained cesium fluoride crystals precipitated in the solvent. Subsequent vacuum drying directly yields powdered cesium fluoride with excellent catalytic effects. The entire process avoids the introduction of impurities, ensuring product purity. Specifically, because crystallization occurs in the solvent phase, the prepared cesium fluoride does not exhibit impurity ion enrichment, preventing side reactions when used as a catalyst in the synthesis reaction. Conversely, the reaction in solution dissolves trace amounts of impurity ions, further improving the purity of the prepared cesium fluoride. A comparison of the full analytical results of cesium fluoride obtained using this method and standard cesium fluoride shows that the content of some impurity ions decreased, with the total impurity ion content decreasing by approximately 46-48 ppm, and the purity increasing by 0.0046%-0.0048%.
[0032] 4. Comparison of the gas chromatograms of the products synthesized from cesium fluoride treated by the method of this invention and from standard cesium fluoride shows that, after the reaction, cesium fluoride treated by the method of this invention, as a catalyst, produced a peak of hexafluoropropylene dimer in the gas chromatogram of the synthesized phase, accounting for 93.282%; while cesium fluoride, as a catalyst, produced a peak of hexafluoropropylene dimer in the gas chromatogram of the synthesized phase, accounting for 92.665%. This indicates that the content of the target product in the synthesized phase increased by 0.617% after the reaction was catalyzed by cesium fluoride treated by the method of this invention, and the catalytic effect was better than that of standard cesium fluoride. Attached Figure Description
[0033] Figure 1 Photograph of degraded cesium fluoride;
[0034] Figure 2 This is a photograph of the cesium fluoride aqueous solution calcined at 200°C under airflow conditions in Example 1;
[0035] Figure 3 This is a photograph of the cesium fluoride aqueous solution calcined under an air stream at 400°C in Example 1.
[0036] Figure 4 Photograph of the clear and transparent cesium fluoride aqueous solution obtained after filtration of the secondary aqueous solution of cesium fluoride in Example 1;
[0037] Figure 5 A photograph of the clear and transparent cesium fluoride aqueous solution from Example 1 calcined under airflow at 200°C;
[0038] Figure 6 This is a photograph of the clear and transparent cesium fluoride aqueous solution from Example 1, which was calcined under an air stream at 200°C and then cooled to room temperature.
[0039] Figure 7 Photograph of the blocky white cesium fluoride crystals obtained by calcining the clear and transparent aqueous solution of cesium fluoride in Example 1 under a nitrogen flow at 400°C;
[0040] Figure 8 Photograph of the white powdery fluoride obtained in Example 1;
[0041] Figure 9 The image shows the gas chromatogram of the synthesized phase after the cesium fluoride catalytic reaction, obtained by the method of Example 1 of this invention, is completed.
[0042] Figure 10 This is the gas chromatogram of the synthesized phase after the catalytic reaction involving the standard cesium fluoride. Detailed Implementation
[0043] The recycling method of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.
[0044] In the following examples, the methanol used is analytical grade methanol.
[0045] Example 1
[0046] This embodiment provides a method for recovering cesium fluoride, a degraded catalyst, during the synthesis of perfluorohexanone, comprising the following steps:
[0047] (1) Take 50g of expired cesium fluoride ( Figure 1 The cesium fluoride was placed in a platinum crucible and calcined for 3 hours under an air flow of 400°C to obtain calcined cesium fluoride.
[0048] (2) The calcined cesium fluoride obtained in step (1) was dissolved in ultrapure water at a solid-liquid mass ratio of 1:3 to obtain a mixed solution of cesium fluoride containing a large amount of black slag.
[0049] (3) The mixed solution obtained in step (2) is first coarsely filtered using filter paper with a pore size of 1 μm, and then finely filtered using a filter membrane with a pore size of 0.2 μm to obtain a pale yellow cesium fluoride aqueous solution.
[0050] (4) Transfer the cesium fluoride aqueous solution obtained in step (3) into a platinum crucible, and then calcine it for 3 hours under an air flow at 200°C (see photo after calcination). Figure 2 Then, it was calcined in air at 400℃ for 4 hours (see photo after calcination). Figure 3 After calcination, the mixture was cooled to room temperature to obtain a pale yellow cesium fluoride solid.
[0051] (5) The cesium fluoride solid obtained in step (4) is further dissolved in ultrapure water at a solid-liquid mass ratio of 1:3 to obtain a secondary aqueous solution of cesium fluoride mixed with small black residue. The secondary aqueous solution of cesium fluoride is first coarsely filtered using filter paper with a pore size of 1 μm, and then finely filtered using a filter membrane with a pore size of 0.2 μm to obtain a clear and transparent aqueous solution of cesium fluoride. Figure 4 );
[0052] (6) Continue to place the clear and transparent cesium fluoride aqueous solution obtained in step (5) into a platinum crucible and calcine it for 3 hours under an air flow of 200°C (see the photo of the aqueous solution during calcination). Figure 5 Photographs of the aqueous solution cooled to room temperature after calcination are shown below. Figure 6 The temperature was then raised to 400℃, and calcination was continued for 4 hours under a nitrogen flow until blocky white cesium fluoride crystals were obtained. Figure 7 );
[0053] (7) Dissolve the blocky cesium fluoride obtained in step (6) in ultrapure water to obtain an aqueous solution of cesium fluoride with a concentration of 3400 g / L;
[0054] (8) Place the cesium fluoride aqueous solution obtained in step (7) into a platinum round-bottom flask, add a mechanical stirrer (stirring speed 800 r / min), and distill at 120°C until the volume of the solution in the round-bottom flask drops to 1 / 3. Stop heating, cool the solution to room temperature while stirring, and then separate the solid and liquid to obtain wet cesium fluoride crystals.
[0055] (9) The wet cesium fluoride obtained in step (8) was placed in a vacuum drying oven and dried at 150°C for 2 hours. After cooling to room temperature, white powdered cesium fluoride was obtained. Figure 8 The results of its elemental analysis are shown in Table 1.
[0056]
[0057] Using the powdered cesium fluoride obtained by the method in this embodiment as a catalyst, the gas chromatogram of the synthesized phase after the catalytic reaction (refer to patent CN112830863A) is as follows. Figure 9 As shown.
[0058] Figure 9 The gas chromatogram showed a peak of hexafluoropropylene dimer (D1), accounting for 93.282%, indicating that the cesium fluoride obtained after treatment by the method of this embodiment has catalytic activity.
[0059] The standard cesium fluoride was used as a catalyst in the catalytic reaction (refer to patent CN112830863A). The gas chromatogram of the synthesized phase after the reaction was completed is shown below. Figure 10 As shown, Figure 10A peak of hexafluoropropylene dimer was observed, accounting for 92.665%.
[0060] Comparing the gas chromatograms of the products obtained after cesium fluoride treatment using the method of this embodiment and the standard cesium fluoride after participating in the catalytic reaction, the proportions of hexafluoropropylene dimer in the synthesized products were 93.282% and 92.665%, respectively, indicating that the cesium fluoride treated by this invention is more effective than the standard cesium fluoride.
[0061] Example 2
[0062] This embodiment provides a method for recovering cesium fluoride, a degraded catalyst, during the synthesis of perfluorohexanone, comprising the following steps:
[0063] (1) Take 100g of expired cesium fluoride and place it in a platinum crucible. Calcine it for 3 hours under an air flow of 400℃ to obtain calcined cesium fluoride.
[0064] (2) The calcined cesium fluoride obtained in step (1) was dissolved in ultrapure water at a solid-liquid mass ratio of 1:3 to obtain a mixed solution of cesium fluoride containing a large amount of black slag.
[0065] (3) The mixed solution obtained in step (2) is first coarsely filtered using filter paper with a pore size of 1 μm, and then finely filtered using a filter membrane with a pore size of 0.2 μm to obtain a pale yellow cesium fluoride aqueous solution.
[0066] (4) The cesium fluoride aqueous solution obtained in step (3) is transferred into a platinum crucible and then calcined at 200°C for 3 hours under air flow conditions, and then calcined at 400°C under air flow conditions for 4 hours. After calcination, the temperature is lowered to room temperature to obtain a light yellow cesium fluoride solid.
[0067] (5) The solid cesium fluoride obtained in step (4) is dissolved in ultrapure water at a solid-liquid mass ratio of 1:3 to obtain a secondary aqueous solution of cesium fluoride mixed with small black residue. The secondary aqueous solution of cesium fluoride is first coarsely filtered with filter paper with a pore size of 1 μm, and then finely filtered with filter membrane with a pore size of 0.2 μm to obtain a clear and transparent aqueous solution of cesium fluoride.
[0068] (6) Continue to place the clear and transparent cesium fluoride aqueous solution obtained in step (5) into a platinum crucible and calcine it for 3 hours under an air flow of 200°C. Then raise the temperature to 400°C and continue to calcine it for 4 hours under a nitrogen flow until blocky white cesium fluoride crystals are obtained.
[0069] (7) Dissolve the blocky cesium fluoride obtained in step (6) in methanol to obtain a cesium fluoride methanol solution with a concentration of 1300 g / L;
[0070] (8) Place the cesium fluoride aqueous solution obtained in step (7) into a platinum round-bottom flask, add a mechanical stirrer (stirring speed 800 r / min), and distill at 120°C until the volume of the solution in the round-bottom flask drops to 1 / 3. Stop heating, cool the solution to room temperature while stirring, and then separate the solid and liquid to obtain wet cesium fluoride crystals.
[0071] (9) The wet cesium fluoride obtained in step (8) was placed in a vacuum drying oven and dried at 120°C for 3 hours. After cooling to room temperature, white powdered cesium fluoride was obtained. The results of its elemental analysis are shown in Table 2.
[0072]
[0073] The full analysis results of the 99.5% cesium fluoride standard sample are shown in Table 3.
[0074]
[0075] As shown in Tables 1-3, the elemental analysis of cesium fluoride treated using the method of this invention revealed that the content of some impurity ions was lower than that of the standard sample after treatment, while the content of the remaining impurity ions was the same as that of the standard sample, and no increase in impurity ion content was observed. Therefore, compared with the standard cesium fluoride sample, the cesium fluoride recovered after treatment using this invention has higher purity, with a decrease in total impurity ions of approximately 46-48 ppm and an increase in purity of 0.0046-0.0048%.
[0076] Example 3
[0077] Example 3 is the same as Example 1 in all other steps, except that the calcination temperature in step (1) is changed from 400℃ to 450℃. After calcination at 450℃, a pale yellow solution is still obtained, with a color similar to that obtained after calcination at 400℃. Considering the energy consumption of calcination, 400℃ is the preferred calcination temperature.
[0078] Example 4
[0079] Example 4 is the same as Example 1 in all other steps, except that the calcination time in step (1) is changed from 3 hours to 4 hours. After calcination for 4 hours, a pale yellow solution is still obtained, with a color similar to that obtained after calcination for 3 hours. Considering the energy consumption of calcination, a calcination time of 3 hours is preferred.
[0080] Example 5
[0081] Example 5 is the same as Example 1 in all other steps, except that the solid-liquid mass ratio in step (2) is changed from 1:3 to 1:5. Both solid-liquid mass ratios of 1:3 and 1:5 can dissolve the deactivated cesium fluoride after high-temperature treatment. Considering the liquid volume, a solid-liquid mass ratio of 1:3 is preferred.
[0082] Example 6
[0083] Example 6 is the same as Example 1 in all other steps, except that the calcination temperature in step (4) is changed from 200℃ to 250℃. Both calcination at 200℃ and 250℃ for 3 hours can evaporate all the moisture, resulting in a pale yellow amorphous substance. Considering energy consumption, the preferred calcination temperature for the first step is 200℃.
[0084] Example 7
[0085] Example 7 follows the same steps as the other examples, except that the calcination time in step (4) is changed from 3 hours to 4 hours. Both 3 and 4 hours of calcination can evaporate the moisture, resulting in a pale yellow amorphous substance. Considering energy consumption, a calcination time of 3 hours is preferred for the first step.
[0086] Example 8
[0087] Example 8 is the same as Example 1 in all other steps, except that the calcination temperature in step (4) is changed from 400℃ to 450℃. Both calcination at 400℃ and 450℃ yields a colorless and transparent cesium fluoride aqueous solution after water solubility. Considering energy consumption, 400℃ is the preferred calcination temperature for the second step.
[0088] Example 9
[0089] Example 9 is the same as Example 1 in all other steps, except that the second calcination time in step (4) is changed from 4 hours to 3 hours. A colorless and transparent cesium fluoride aqueous solution cannot be obtained with a calcination time of 3 hours; the obtained cesium fluoride solution is slightly yellow. Considering the issues of color and purity of the obtained cesium fluoride, a second calcination time of 4 hours is preferred.
[0090] Example 10
[0091] Example 10 is the same as Example 1 in all other steps, except that the solid-liquid mass ratio in step (5) is changed from 1:3 to 1:5. Both solid-liquid mass ratios of 1:3 and 1:5 can dissolve the deactivated cesium fluoride after high-temperature treatment. Considering the liquid volume, a solid-liquid mass ratio of 1:3 is preferred.
[0092] Example 11
[0093] Example 11 is the same as Example 1 in all other steps, except that the calcination temperature in step (6) is changed from 200℃ to 250℃. Both calcination at 200℃ and 250℃ for 3 hours can evaporate all the moisture, resulting in a white amorphous substance. Considering energy consumption, the preferred calcination temperature for the first step is 200℃.
[0094] Example 12
[0095] Example 12 is the same as Example 1 in all other steps, except that the calcination time in step (6) is changed from 3 hours to 4 hours. Both 3 and 4 hours of calcination can evaporate the moisture to obtain a white amorphous substance. Considering energy consumption, a calcination time of 3 hours is preferred for the first step.
[0096] Example 13
[0097] Example 13 is the same as Example 1 in all other steps, except that the calcination temperature in step (6) is changed from 400℃ to 450℃. Both calcination at 400℃ and 450℃ yields white, blocky cesium fluoride crystals after water solubility. Considering energy consumption, 400℃ is the preferred calcination temperature for the second step.
[0098] Example 14
[0099] Example 14 is the same as Example 1 in all other steps, except that the second calcination time in step (6) is changed from 4 hours to 3 hours. Since a calcination time of 3 hours is insufficient to completely transform the calcined cesium fluoride into blocky white crystals, a second calcination time of 4 hours is preferred.
[0100] Examples 15-16
[0101] Examples 15 and 16 are identical to Example 1 in all other steps, except for the concentration of the cesium fluoride aqueous solution in step (7), which is changed from 3400 g / L to 3300 g / L and 3500 g / L, respectively. The subsequent full analysis results of cesium fluoride are essentially the same when the concentration of the cesium fluoride aqueous solution is 3300 g / L and 3500 g / L. Therefore, a concentration of 3300 g / L to 3500 g / L of the cesium fluoride aqueous solution is acceptable.
[0102] Examples 17-18
[0103] Examples 17 and 18 are identical to Example 2 in all other steps, except for the concentration of the cesium fluoride aqueous solution in step (7), which is changed from 1300 g / L to 1200 g / L and 1400 g / L, respectively. The subsequent full analysis results of cesium fluoride are essentially the same when the concentration of the cesium fluoride aqueous solution is 1200 g / L and 1400 g / L. Therefore, a concentration of 1200 g / L to 1400 g / L of the cesium fluoride aqueous solution is acceptable.
Claims
1. A method for recovering cesium fluoride catalyst degraded during the synthesis of perfluorohexanone, characterized in that, Includes the following steps: (1) The exhausted catalyst cesium fluoride was placed in a platinum crucible and calcined under an air flow of 400-450℃ to obtain calcined cesium fluoride; (2) Dissolve the calcined cesium fluoride obtained in step (1) in water to obtain a mixed solution of cesium fluoride containing black slag; (3) The mixed solution obtained in step (2) is first coarsely filtered with filter paper, and then finely filtered with a filter membrane to obtain a pale yellow cesium fluoride aqueous solution; (4) Transfer the cesium fluoride aqueous solution obtained in step (3) into a platinum crucible, and then calcine it for 3-4 hours under an air flow of 200-250℃, and then calcine it for 3-4 hours under an air flow of 400-450℃. After calcineation, cool it to room temperature to obtain solid cesium fluoride. (5) The solid cesium fluoride obtained in step (4) is further dissolved in water to obtain a secondary aqueous solution of cesium fluoride. The secondary aqueous solution of cesium fluoride is first coarsely filtered with filter paper and then finely filtered with a filter membrane to obtain a clear and transparent aqueous solution of cesium fluoride. (6) Continue to place the clear and transparent cesium fluoride aqueous solution obtained in step (5) into a platinum crucible and calcine it for 3-4 hours under an air flow of 200-250°C. Then raise the temperature to 400-450°C and continue calcining under a nitrogen flow until blocky cesium fluoride crystals are obtained. (7) The blocky cesium fluoride crystals obtained in step (6) are further dissolved in ultrapure water or methanol to obtain an aqueous solution of cesium fluoride or a methanol solution of cesium fluoride; (8) Place the cesium fluoride aqueous solution or cesium fluoride methanol solution obtained in step (7) into a platinum round-bottom flask, add a mechanical stirrer, and distill at 120°C until the volume of the solution in the round-bottom flask is reduced to 1 / 3. The distilled solvent is condensed into the recovery device and returned to step (7) to dissolve the blocky cesium fluoride crystals. Stop heating, cool the solution to room temperature while stirring, and then separate the solid and liquid to obtain wet cesium fluoride crystals. (9) The wet cesium fluoride obtained in step (8) is placed in a vacuum drying oven for drying and cooled to room temperature to obtain white powdered cesium fluoride.
2. The degraded catalyst fluorine in the perfluorohexanone synthesis process as described in claim 1 The method for recovering cesium oxide is characterized by, In step (1), the calcination time is 3-4 hours.
3. The degraded catalyst fluorine in the perfluorohexanone synthesis process as described in claim 1 The method for recovering cesium oxide is characterized by, In step (2), the solid-liquid mass ratio of cesium fluoride to water after calcination is 1:3-5.
4. The method for recovering degraded cesium fluoride catalyst during the synthesis of perfluorohexanone as described in claim 1, characterized in that, In steps (3) and (5), the filter paper for coarse filtration has a pore size of 1 μm, and the filter membrane for precision filtration has a pore size of 0.2 μm.
5. The method for recovering degraded cesium fluoride catalyst during the synthesis of perfluorohexanone as described in claim 1, characterized in that, In step (5), the solid-liquid mass ratio of cesium fluoride solid to water is 1:3-5.
6. The method for recovering degraded cesium fluoride catalyst during the synthesis of perfluorohexanone as described in claim 1, characterized in that, In step (6), the calcination time under nitrogen gas flow is 3-4 hours.
7. The method for recovering the degraded catalyst cesium fluoride during the synthesis of perfluorohexanone as described in claim 6, characterized in that, In step (6), the calcination time under nitrogen gas flow is 4 hours.
8. A method for recovering cesium fluoride catalyst degraded during the synthesis of perfluorohexanone as described in any one of claims 1-7, characterized in that, In step (7), the concentration of the cesium fluoride aqueous solution is 3300-3500 g / L, and the concentration of the cesium fluoride methanol solution is 1200-1400 g / L.
9. A method for recovering cesium fluoride catalyst depleted during the synthesis of perfluorohexanone as described in any one of claims 1-7, characterized in that, In step (8), the mechanical stirring speed is 600-800 r / min.
10. A method for recovering cesium fluoride catalyst degraded during the synthesis of perfluorohexanone as described in any one of claims 1-7, characterized in that, In step (9), the drying temperature is 120-150℃ and the drying time is 2-3h.