Zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide in trifluoroacetyl fluoride and preparation method of zinc-based modified molecular sieve adsorbent

Abstract

The invention discloses a zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide in trifluoroacetyl fluoride and a preparation method of the zinc-based modified molecular sieve adsorbent, and belongs to the technical field of fluorine-containing fine chemical purification and multi-phase adsorption materials. Comprising the following steps: (1) soaking a molecular sieve carrier in an ammonium fluoride aqueous solution for treatment; (2) dispersing the product in the step (1) in absolute ethyl alcohol, and adding methyltrimethoxysilane for reaction to obtain a pretreated molecular sieve; (3) putting the pretreated molecular sieve into a zinc source aqueous solution, and stirring for reaction; (4) roasting the dried product in an air atmosphere; and (5) cyclically carrying out the steps (1)-(4) for 1-5 times to obtain a finished product. The adsorbent provided by the invention has the advantages of good thermal stability, excellent regeneration performance, template-free synthesis, low cost and the like, and is suitable for an industrial continuous adsorption process environment for purifying electronic-grade trifluoroacetyl fluoride.

Description

A zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride and its preparation method. Technical Field

[0001] This application relates to a zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride and its preparation method, belonging to the technical field of fluorine-containing fine chemical purification and multiphase adsorption materials. Background Technology

[0002] Trifluoroacetyl fluoride (CFCO2F) is considered a potential environmentally friendly electronic etching gas and low-temperature refrigerant due to its low ozone depletion potential (ODP) and global warming potential (GWP). However, industrial-grade trifluoroacetyl fluoride often contains approximately 0.01-0.2% hexafluoropropylene oxide, severely limiting its application in high-end fields such as semiconductor manufacturing. Currently, conventional distillation is difficult to achieve efficient separation due to the close boiling points of the two (trifluoroacetyl fluoride: -59°C; hexafluoropropylene oxide: -30°C). Existing adsorbents such as activated carbon or ordinary molecular sieves exhibit poor selectivity, insufficient thermal stability, and are easily corroded and deactivated by fluorine-containing components. Although some studies have used metal-organic frameworks (MOFs) or modified silica gel for separation, these methods suffer from high costs, poor hydrothermal stability, and difficulty in regeneration.

[0003] While molecular sieve adsorption is the mainstream approach for removing HFPO, the high-strain ternary epoxy structure of HFPO is highly susceptible to ring-opening polymerization in acidic environments, generating polyethers that clog the pores. Existing technologies use zinc-based modification techniques to modify molecular sieve adsorbents, but these techniques have significant drawbacks: the strong Brønsted acid centers introduced by traditional zinc chloride exchange directly catalyze HFPO polymerization, leading to rapid adsorbent deactivation; furthermore, the lack of pore shape-selective modification means that once polymerization occurs, permanent damage is caused.

[0004] Therefore, there is an urgent need to develop a new type of adsorbent to completely eliminate the polymerization caused by strong acids while achieving precise control of the pore microenvironment, thus breaking through the bottlenecks of existing technologies in terms of stability and selectivity. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride. This adsorbent eliminates the strong acid centers that induce polymerization by replacing surface hydroxyl groups with ammonium fluoride, constructs anti-clogging shape-selective channels using methyltrimethoxysilane pore modification, and introduces highly selective Lewis active sites by combining a weak acid zinc source. This enables the efficient separation of hexafluoropropylene oxide and trifluoroacetyl fluoride.

[0006] According to the first aspect of this application, this application provides a method for preparing a zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride, comprising the following steps: (1) immersing the molecular sieve carrier in an ammonium fluoride aqueous solution, treating it at 40-60℃ for 2-4h, and washing and drying it; (2) dispersing the product of step (1) in anhydrous ethanol, adding 1-5% of methyltrimethoxysilane by mass of the product, reacting for 4-8h to obtain a pretreated molecular sieve; (3) placing the pretreated molecular sieve in an aqueous zinc source solution, stirring and reacting at 70-90℃ for 12-24h, and washing and drying it after the reaction is completed; (4) calcining the dried product in an air atmosphere for 4-6h; (5) repeating steps (1)-(4) 1-5 times to obtain the product.

[0007] This application utilizes ammonium fluoride for mild fluorination treatment, specifically replacing the strong Brønsted acid hydroxyl groups on the surface to block the ring-opening polymerization pathway of hexafluoropropylene oxide; simultaneously, methyltrimethoxysilane is introduced to modify the steric hindrance of the pores, constructing shape-selective channels that allow only inflow and outflow to inhibit polymer blockage; finally, a zinc source exchange process is used to precisely anchor highly dispersed Zn within the channels. 2+ Lewis acid active centers.

[0008] Because the kinetic diameter of hexafluoropropylene oxide (approximately 0.58 nm) is larger than that of trifluoroacetyl fluoride (approximately 0.46 nm), and because its molecular structure contains a highly polar epoxy three-membered ring, it has a strong electron-donating ability and can react with Zn introduced into the molecular sieve channels. 2+ Significant coordination occurs at the Lewis acid centers; while trifluoroacetyl fluoride, a linear small molecule, although possessing some polarity, lacks functional groups capable of effectively complexing with Lewis acids, thus exhibiting weaker interactions with the modified active sites. During adsorption, hexafluoropropylene oxide is preferentially and firmly captured within the molecular sieve micropores and mesoporous channels, while trifluoroacetyl fluoride rapidly penetrates the bed, thereby achieving efficient and highly selective separation.

[0009] By calcining at 200-800℃, residual organic solvents and silane byproducts are completely removed, which promotes the transformation of zinc species from amorphous to highly dispersed and stable zinc oxide microcrystals. At the same time, the defects of the molecular sieve framework are repaired, the chemical bonding between the active components and the carrier is enhanced, and the thermal stability and anti-pulverization ability of the adsorbent are significantly improved.

[0010] A cyclical strategy of "pretreatment-modification-loading-calcination" was adopted to achieve multi-layer gradient loading of zinc active components. This process effectively overcomes the problems of surface saturation and pore blockage caused by single impregnation, and significantly increases the zinc loading and active site density per unit mass of adsorbent while keeping the molecular sieve pores unobstructed, thereby multiplying the dynamic adsorption capacity for hexafluoropropylene oxide.

[0011] The inventors discovered that other fluorine sources (such as HF and NaF) either corrode the framework or poison sites during fluorination. However, the fluoride ions provided by ammonium fluoride can selectively interact with aluminum atoms in the molecular sieve framework, thereby removing some aluminum from the framework. This process itself reduces the amount of framework aluminum that generates strong acid centers. Furthermore, this removed aluminum does not completely leave the system but recombines with fluoride ions in the microenvironment created by ammonium ions, forming four-coordinate aluminum-fluorine species (such as AlF). 4- These new species are grafted onto the framework or within the channels of the molecular sieve, interacting with the original strong acid centers (bridged hydroxyl groups) to passivate the excessively strong acidity into a moderate acidity. Simultaneously, ammonium ions slowly decompose during treatment, producing ammonia and hydrogen ions, creating a mild, weakly acidic environment and preventing strong acid shocks. More importantly, when fluoride ions remove aluminum from the framework, they leave behind negatively charged "silanol nests," at which point the NH4+ in the solution... 4+ (or the H produced by its decomposition) + It can compensate for the charge in time, stabilize the etched skeleton structure, and prevent it from collapsing completely.

[0012] Furthermore, the inventors discovered that trimethylchlorosilane or tetraethyl orthosilicate either clog the pores or are unstable during grafting. In contrast, methyltrimethoxysilane, due to the presence of three methoxy groups in its molecule, undergoes hydrolysis during processing to generate silanol groups. These silanol groups can undergo condensation reactions with the silanol groups on the surface (or pores) of the molecular sieve to form three Si-O-Si covalent bonds, which can firmly fix the entire molecule on the surface of the molecular sieve. This ensures that the modified layer is not easily detached under high-temperature reaction or hydrothermal conditions, thus constructing a shape-selective barrier with "moderate steric hindrance and firm anchoring".

[0013] Optionally, the molecular sieve carrier in step (1) is at least one of 5A molecular sieve, ZSM-5 molecular sieve, Beta molecular sieve, and Y-type molecular sieve.

[0014] Optionally, the molecular sieve carrier in step (1) has a mesh size of 20-60.

[0015] Optionally, the ratio of the mass of the molecular sieve support to the volume of the ammonium fluoride aqueous solution in step (1) is 1:(10-30) g / ml.

[0016] Within this ratio range, sufficient contact and moderate etching of fluoride ions with the molecular sieve surface can be achieved, resulting in a pretreated support with abundant surface hydroxyl groups and good framework integrity. If there is too much molecular sieve support, the fluorination effect will be poor, the surface modification will be uneven, and the introduction of active sites will be insufficient. If there is too much ammonium fluoride aqueous solution, it will cause reagent waste, increase the energy consumption of subsequent washing and drying, and may cause the molecular sieve framework to collapse and the specific surface area to decrease due to excessive etching.

[0017] Optionally, the concentration of the ammonium fluoride aqueous solution in step (1) is 0.2-0.8 mol / L.

[0018] Within this concentration range, a balance can be achieved between the appropriate substitution of aluminum species on the molecular sieve surface by fluoride ions and the hydroxylation modification. If the concentration is too low, the driving force of the fluorination reaction is insufficient, the amount of fluoride species introduced on the surface is small, and it is difficult to effectively construct highly dispersed anchoring sites for subsequent zinc components; if the concentration is too high, the etching effect is too strong, resulting in severe dealuminization of the molecular sieve framework, destruction of the crystal structure and a significant reduction in specific surface area, thereby weakening the mechanical strength and adsorption performance of the adsorbent.

[0019] Optionally, the ratio of the volume of anhydrous ethanol in step (2) to the mass of the molecular sieve carrier in step (1) is (10-20): 1 ml / g.

[0020] Dispersing the product in anhydrous ethanol promotes the formation of active silanols from methyltrimethoxysilanes, which then condense with hydroxyl groups on the support surface. Strict anhydrous conditions prevent excessive self-polymerization of silanes that can clog pores, ensuring a high specific surface area and adsorption capacity—a feature that other polar aprotic solvents cannot replicate.

[0021] Optionally, the zinc source in step (3) is at least one of zinc chloride, zinc sulfate, zinc nitrate, and zinc acetate.

[0022] Optionally, the concentration of the zinc source aqueous solution in step (3) is 1-3 mol / L.

[0023] Within this concentration range, a balance can be achieved between efficient loading and high dispersion of the zinc active component within the molecular sieve channels. If the concentration is too low, the loading capacity of a single impregnation will be insufficient, making it difficult to reach the target adsorption capacity, and requiring a significant increase in the number of impregnation cycles, leading to a longer preparation cycle and increased energy consumption. If the concentration is too high, rapid crystallization or agglomeration can easily occur on the outer surface of the molecular sieve, causing pore blockage ("eggshell" distribution), which not only reduces the utilization rate of the internal specific surface area but also forms large particles of zinc oxide during subsequent calcination, weakening the dynamic penetration performance of the adsorbent.

[0024] Optionally, the ratio of the volume of the zinc source aqueous solution in step (3) to the mass of the molecular sieve carrier in step (1) is (10-30): 1 ml / g.

[0025] Within this ratio range, the zinc source solution can achieve sufficient wetting and penetration of the molecular sieve channels, resulting in a modified adsorbent with a qualified loading and uniform distribution. If there is too much molecular sieve, the liquid-to-solid ratio will be too low, leading to insufficient impregnation. The active component will only adhere to the particle surface, resulting in low utilization of the internal channels. If there is too much zinc source aqueous solution, it will not only cause waste of raw materials and a sharp increase in subsequent evaporation energy consumption, but also easily cause the active component to migrate to the surface and agglomerate during the drying process due to slow solvent evaporation, reducing the dispersion.

[0026] Optionally, the roasting temperature in step (4) is 200-800℃.

[0027] Optionally, the heating rate is 10-20℃ / min.

[0028] If the heating rate is too low, it will lead to a long calcination cycle and increased energy consumption. It may also cause the precursor to undergo an unexpected phase transformation or excessive grain growth due to the long low-temperature residence time. If the rate is too fast, it will cause the solvent or decomposition gas (such as NH3, H2O) in the pores to escape rapidly, generating huge internal pressure, which may cause the molecular sieve framework to collapse, the particles to pulverize, or cause local overheating and agglomeration of the active components.

[0029] According to a second aspect of this application, this application provides a zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride, which is prepared by the preparation method of the zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride described in any one of the above claims.

[0030] According to a third aspect of this application, this application provides the application of the zinc-based modified molecular sieve adsorbent described above for removing hexafluoropropylene oxide from trifluoroacetyl fluoride in the purification process of electronic-grade trifluoroacetyl fluoride.

[0031] The beneficial effects of this application include, but are not limited to: 1. According to the preparation method of the zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride in this application, 5A, ZSM-5, Beta, and Y-type molecular sieves are selected as multidimensional carriers. A mild fluorination treatment is performed using ammonium fluoride to specifically replace the strong Brønsted acid hydroxyl groups on the surface, blocking the ring-opening polymerization pathway of hexafluoropropylene oxide. Simultaneously, methyltrimethoxysilane is introduced to modify the steric hindrance of the pores, constructing a "one-way" shape-selective channel to inhibit polymer blockage. Finally, through a zinc source exchange process, highly dispersed Zn is precisely anchored within the pores. 2+ Lewis acid active centers.

[0032] 2. According to the preparation method of the zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride of this application, through Zn 2+ The introduction of Lewis acid active centers can enhance the selective adsorption capacity of molecular sieves for hexafluoropropylene oxide while maintaining low affinity for trifluoroacetyl fluoride, thereby enabling efficient separation of hexafluoropropylene oxide and trifluoroacetyl fluoride.

[0033] 3. The zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride according to this application has significantly better adsorption selectivity for hexafluoropropylene oxide than conventional adsorbents such as unmodified molecular sieves and activated carbon. The adsorption breakthrough time is extended, the single operation cycle is increased by more than 3 times, and the switching frequency and energy consumption are reduced.

[0034] 4. The zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride according to this application has excellent regeneration performance. After five nitrogen purgings combined with vacuum desorption at 150°C, the adsorption capacity retention rate exceeds 90%.

[0035] 5. The zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride according to this application has the advantages of good thermal stability, excellent regeneration performance, template-free synthesis, and low cost, and is suitable for industrial continuous adsorption process environment for the purification of electronic-grade trifluoroacetyl fluoride. Attached Figure Description

[0036] The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments of this application and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings: Figure 1 is a scanning electron microscope image of the zinc-based modified molecular sieve adsorbents prepared in Examples 1-4 of the present invention. Detailed Implementation

[0037] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0038] Unless otherwise specified, the raw materials used in the embodiments and comparative examples of this application were all purchased commercially.

[0039] Unless otherwise specified, the methods used in the embodiments and comparative examples of this application are conventional methods in the prior art.

[0040] Example 1 This example relates to a method for preparing a zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride, comprising the following steps: (1) taking 100g 20-mesh 5A molecular sieve was soaked in 1000ml ammonium fluoride aqueous solution (0.2mol / L), treated at 40℃ for 4h, washed and dried; (2) the product of step (1) was dispersed in 1000ml anhydrous ethanol, 1% of methyltrimethoxysilane was added, and the reaction was carried out under reflux for 4h to obtain pretreated molecular sieve; (3) the pretreated molecular sieve was placed in 1000ml zinc chloride aqueous solution (1mol / L), stirred and reacted at 70℃ for 24h, after the reaction was completed, the solid material was separated by vacuum filtration, and washed repeatedly with deionized water, and then transferred to a forced-air drying oven and dried at 100℃ for 12h; (4) the dried product was placed in a muffle furnace and calcined at 200℃ for 6h at a heating rate of 10℃ / min in air atmosphere, and then cooled to room temperature to obtain the first modified molecular sieve; (5) steps (1)-(4) were repeated 3 times to obtain the product.

[0041] Example 2 This example relates to a method for preparing a zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride, comprising the following steps: (1) 100g of 60-mesh ZSM-5 molecular sieve is soaked in 3000ml of ammonium fluoride aqueous solution (0.8mol / L), treated at 60℃ for 2 h, washed and dried; (2) The product of step (1) is dispersed in 2000ml of anhydrous ethanol, and 2% of methyltrimethoxysilane by mass of the product is added, and the mixture is reacted under reflux for 8 h to obtain a pretreated molecular sieve; (3) The pretreated molecular sieve is placed in 3000ml of zinc sulfate aqueous solution (3mol / L), stirred and reacted at 80℃ for 15 h, and after the reaction is completed, the solid material is separated by filtration and repeatedly washed with deionized water, and then transferred to a forced-air drying oven and dried at 100℃ for 12 h. h; (4) Place the dried product into a muffle furnace and calcine it at 800°C for 4 hours at a heating rate of 20°C / min in air atmosphere. After the calcification, cool it to room temperature to obtain the first modified molecular sieve; (5) Repeat steps (1)-(4) 5 times to obtain the product.

[0042] Example 3 This example relates to a method for preparing a zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride, comprising the following steps: (1) taking 100g 40-mesh Beta molecular sieve was soaked in 2000 ml of ammonium fluoride aqueous solution (0.5 mol / L), treated at 50 °C for 3 h, washed and dried; (2) the product of step (1) was dispersed in 1600 ml of anhydrous ethanol, 1.5% of methyltrimethoxysilane was added, and the reaction was carried out under reflux for 7 h to obtain pretreated molecular sieve; (3) the pretreated molecular sieve was placed in 2000 ml of zinc nitrate aqueous solution (2 mol / L), stirred and reacted at 75 °C for 13 h, after the reaction was completed, the solid material was separated by vacuum filtration and washed repeatedly with deionized water, and then transferred to a forced-air drying oven and dried at 100 °C for 12 h; (4) the dried product was placed in a muffle furnace and calcined at 500 °C for 5 h at a heating rate of 15 °C / min in air atmosphere, and then cooled to room temperature to obtain the first modified molecular sieve; (5) steps (1)-(4) were repeated once to obtain the product.

[0043] Example 4 This example relates to a method for preparing a zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride, comprising the following steps: (1) 100g of 50-mesh Y-type molecular sieve is soaked in 2500ml of ammonium fluoride aqueous solution (0.6mol / L), treated at 40℃ for 4 h, washed and dried; (2) The product of step (1) is dispersed in 1700ml of anhydrous ethanol, and 5% of methyltrimethoxysilane by mass of the product is added, and the mixture is reacted under reflux for 6.5h to obtain a pretreated molecular sieve; (3) The pretreated molecular sieve is placed in 2500ml of zinc acetate aqueous solution (2.5mol / L), stirred and reacted at 90℃ for 12h, and after the reaction is completed, the solid material is separated by vacuum filtration and repeatedly washed with deionized water, and then transferred to a forced-air drying oven and dried at 100℃ for 12 hours. h; (4) Place the dried product into a muffle furnace and calcine it at 600°C for 6 hours at a heating rate of 12°C / min in air atmosphere. After the calcification, cool it to room temperature to obtain the first modified molecular sieve; (5) Repeat steps (1)-(4) 4 times to obtain the product.

[0044] Example 5 The difference between this example and Example 1 is that the volume of the ammonium fluoride aqueous solution in step (1) is 800 ml, and the rest are the same.

[0045] Example 6 The difference between this example and Example 1 is that the concentration of the ammonium fluoride aqueous solution in step (1) is 1 mol / L, and the rest are the same.

[0046] Example 7 The difference between this example and Example 1 is that the volume of anhydrous ethanol in step (2) is 800 ml, and the rest are the same.

[0047] Example 8 The difference between this example and Example 1 is that the concentration of zinc chloride aqueous solution in step (3) is 4 mol / L, and the rest are the same.

[0048] Example 9 The difference between this example and Example 1 is that the volume of the zinc chloride aqueous solution in step (3) is 800 ml, and the rest are the same.

[0049] Example 10 The difference between this example and Example 1 is that the roasting temperature in step (4) is 1000℃, and the rest are the same.

[0050] Example 11 The difference between this example and Example 1 is that the heating rate of the roasting in step (4) is 5℃ / min, and the rest are the same.

[0051] Example 12 The difference between this example and Example 1 is that the heating rate of the roasting in step (4) is 25℃ / min, and the rest are the same.

[0052] Comparative Example 1 differs from Example 1 in that hydrogen fluoride solution (0.2 mol / L) is used instead of ammonium fluoride aqueous solution in step (1), while the rest are the same.

[0053] The difference between Comparative Example 2 and Example 1 is that sodium fluoride aqueous solution (0.2 mol / L) was used instead of ammonium fluoride aqueous solution in step (1), while the rest were the same.

[0054] The difference between Comparative Example 3 and Example 1 is that in step (2), trimethylchlorosilane is used instead of methyltrimethoxysilane, while the rest are the same.

[0055] The difference between Comparative Example 4 and Example 1 is that tetraethyl orthosilicate is used instead of methyltrimethoxysilane in step (2), while the rest are the same.

[0056] The difference between Comparative Example 5 and Example 1 is that step (1) is omitted, while the rest are the same.

[0057] The difference between Comparative Example 6 and Example 1 is that step (2) is not performed, but the rest are the same.

[0058] The difference between Comparative Example 7 and Example 1 is that step (3) is not performed, but the rest are the same.

[0059] The difference between Comparative Example 8 and Example 1 is that step (2) is performed first, followed by step (1), while the rest are the same.

[0060] Test Example 11: The adsorption capacity and regeneration efficiency of the molecular sieve adsorbents prepared in the above examples and comparative examples were tested. The test method is as follows: The prepared molecular sieve adsorbents were packed into a stainless steel fixed-bed adsorbent with an inner diameter of 20 mm and a bed height of 50 cm. Liquid carbonyl fluoride crude product containing 200 ppm (v / v) tetrafluoroethylene impurities was introduced. The operating pressure was 0.8 MPa, the temperature was 25 °C, and the space velocity was 2 h⁻¹. -1 Before adsorption breakthrough, the outlet gas was detected by gas chromatography. After adsorption saturation, regeneration was performed by purging with nitrogen at 120℃ for 4 h. The test results are shown in Table 1.

[0061] The molecular sieve adsorbents prepared in the examples and comparative examples were crushed and sieved, and 40-60 mesh particles were selected. After activation at 150°C under a nitrogen atmosphere for 4 hours, they were ready for use. 2.0 g of the activated adsorbent was weighed and packed into a stainless steel fixed-bed adsorbent with an inner diameter of 10 mm.

[0062] Prepare a simulated carbonyl fluoride process gas containing impurities: Use high-purity nitrogen as the background gas and mix in hexafluoropropylene oxide (HFPO) standard gas, controlling the HFPO concentration to 200 ppm (v / v). Pass the simulated gas into the adsorber, controlling the operating pressure at 0.8 MPa, the adsorption temperature at 25 °C, and the gas hourly space velocity (GHSV) at 2000 h⁻¹. - ¹.

[0063] The concentration of HFPO in the outlet gas was monitored in real time using an online gas chromatograph. The breakthrough time was recorded when the outlet concentration reached 5% of the inlet concentration, and adsorption saturation was considered when it reached 95%. The static adsorption capacity (mg / g) was calculated using the integrated breakthrough curve.

[0064] After adsorption saturation, high-purity nitrogen was switched to purge and regenerate at 120℃ for 4 hours. After cooling to room temperature, a second round of adsorption testing was conducted, and the regeneration efficiency (%) was calculated as the ratio of the second-round adsorption capacity to the first-round adsorption capacity. The test results are shown in Table 1.

[0065] 2. The molecular sieve adsorbents prepared in the above examples and comparative examples were tested for specific surface area, average pore size, and total pore volume. The specific tests are as follows: BET specific surface area, average pore size, and total pore volume data were all obtained using the low-temperature nitrogen adsorption-desorption method. After pretreatment with vacuum degassing at 300℃ for 6 hours, the samples were tested using a fully automated specific surface area and porosity analyzer at 77K liquid nitrogen temperature. The BET specific surface area was calculated based on the BET equation, the total pore volume was determined by the adsorption amount at P / P0≈0.99, and the average pore size was calculated from the desorption branch curve using the BJH model. The test results are shown in Table 2.

[0066] 3. The molecular sieve adsorbents prepared in Examples 1-4 were tested by scanning electron microscopy, and Figure 1 was obtained.

[0067] Table 1

[0068] Table 2

[0069] As shown in Tables 1 and 2 and Figure 1, Examples 1-4 of the present invention maintain a complete and loose particle morphology at the microscopic level (Figure 1), and exhibit a high specific surface area (>690 m²) at the macroscopic level. 2 The high pore volume (Table 2) demonstrates the mild modification effect of process parameters on the molecular sieve framework. This excellent physical structure is the basis for obtaining high adsorption capacity (Table 1). In contrast, Examples 5-12 suffered performance degradation due to pore blockage or framework collapse; while the comparative examples, although possessing high specific surface area, failed to achieve the adsorption effect of this invention due to the lack of a specific hydrophobic layer and synergistic effect with the active center. This fully demonstrates the necessity and inventiveness of the synergistic effect of 'structural regulation' and 'chemical modification' in this invention. The above description is merely an embodiment of this application, and the scope of protection of this application is not limited to these specific embodiments, but is determined by the claims of this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the technical concept and principle of this application should be included within the scope of protection of this application.

Claims

1. A method for preparing a zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride, characterized in that, The process includes the following steps: (1) Immerse the molecular sieve carrier in an aqueous solution of ammonium fluoride and treat it at 40-60℃ for 2-4 h, then wash and dry it; (2) Disperse the product of step (1) in anhydrous ethanol, add 1-5% of methyltrimethoxysilane by mass of the product, and react for 4-8 h to obtain the pretreated molecular sieve; (3) Place the pretreated molecular sieve in an aqueous solution of zinc source and stir it at 70-90℃ for 12-24 h. After the reaction is completed, wash and dry it; (4) Calcine the dried product in an air atmosphere for 4-6 h; (5) Repeat steps (1)-(4) 1-5 times to obtain the final product.

2. The method for preparing the zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride according to claim 1, characterized in that, The molecular sieve carrier mentioned in step (1) is at least one of 5A molecular sieve, ZSM-5 molecular sieve, Beta molecular sieve, and Y-type molecular sieve.

3. The method for preparing the zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride according to claim 1, characterized in that, The ratio of the mass of the molecular sieve support to the volume of the ammonium fluoride aqueous solution in step (1) is 1:(10-30)g / ml.

4. The method for preparing the zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride according to claim 1, characterized in that, The concentration of the ammonium fluoride aqueous solution in step (1) is 0.2-0.8 mol / L.

5. The method for preparing the zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride according to claim 1, characterized in that, The ratio of the volume of anhydrous ethanol in step (2) to the mass of the molecular sieve carrier in step (1) is (10-20): 1 ml / g.

6. The method for preparing the zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride according to claim 1, characterized in that, The zinc source mentioned in step (3) is at least one of zinc chloride, zinc sulfate, zinc nitrate, and zinc acetate.

7. The method for preparing the zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride according to claim 1, characterized in that, The concentration of the zinc source aqueous solution in step (3) is 1-3 mol / L; and / or the ratio of the volume of the zinc source aqueous solution in step (3) to the mass of the molecular sieve carrier in step (1) is (10-30): 1 ml / g.

8. The method for preparing the zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride according to claim 1, characterized in that, The roasting temperature in step (4) is 200-800℃; the heating rate is 10-20℃ / min.

9. A zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride, characterized in that, The zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride, as described in any one of claims 1-8, was prepared using the method described in claims 1-8.

10. The application of the zinc-based modified molecular sieve adsorbent for removing hexafluoropropylene oxide from trifluoroacetyl fluoride as described in claim 9 in the purification process of electronic-grade trifluoroacetyl fluoride.

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