A FAU molecular sieve with a high proportion of supercage Na+ exchange sites and its adsorption and separation application for fluorine-containing electron gases.

Abstract

This invention discloses a method with a high proportion of supercage Na + This paper describes the application of exchange-site FAU molecular sieves for the adsorption and separation of fluorine-containing electron gases. The molecular sieve possesses the FAU molecular sieve configuration recognized by the International Zygotes Association (IZA), with a chemical composition molar ratio of Al₂O₃:mSiO₂:nNa₂O, where the molar ratio m of the oxide SiO₂ / Al₂O₃ ranges from 5 to 20. This molecular sieve is synthesized using an initial gel prepared from an organic template agent, water, silicon source, and aluminum source. FAU seed crystals are added, and the charge density of the organic template agent is adjusted. Different cage structures of the FAU molecular sieve are assembled. Furthermore, through mixing with a solid salt containing Na and solid-phase exchange, Na in the supercage is achieved. + Control of the exchange site ratio. Compared with the commercial molecular sieve USY2.6, this invention has a high proportion of supercage Na. + Exchange-site FAU molecular sieves can be used for the adsorption and separation of fluorine-containing electronic gases in gas-phase systems, especially pentafluorochloroethane C2F5Cl (R115) and hexafluoroethane C2F6 (R116), and the separation effect is good.

Description

Technical Field

[0001] This invention relates to a high proportion of supercage Na + The exchange-site FAU molecular sieve and its adsorption and separation application for fluorine-containing electronic gases can efficiently adsorb and separate pentafluorochloroethane (R115), an impurity gas in hexafluoroethane (R116), which belongs to the field of gas phase adsorption and separation. Background Technology

[0002] Fluorinated electronic gases are high-end products in the electronic gas field, playing a crucial role in semiconductor manufacturing. They are primarily used as cleaning agents, etchants, dopants, and film-forming materials, accounting for approximately 30% of the electronic gas market. In recent years, with the rapid development of the semiconductor industry, the purity requirements for electronic gases have become increasingly stringent. Even trace impurities of one part per million can lead to a rapid increase in the defect rate of electronic products. R116, due to its advantages such as minimal edge lateral erosion, high etching rate, and high precision, solves the problem that conventional wet etching cannot meet the high-precision fine-line etching requirements of deep submicron integrated circuits (0.18-0.25μm), and can perfectly meet the requirements of such small-linewidth processes. Advanced chip manufacturing processes require a purity of 6N or higher; therefore, efficiently removing various impurities from industrial-grade R116 is crucial. Industrial-grade R116 products are mainly derived from the direct fluorination of R115. Industrial products contain various impurities containing fluorine, chlorine, hydrogen, and other compounds, with R115 being the most prevalent. Currently, electronic-grade R116 is mainly purified by distillation, while the removal of chlorine-containing impurities such as R115 is mainly achieved through fluorination-coupled distillation.

[0003] Chinese patent CN1169505A reports the use of HCl and R116 to form an azeotrope, employing azeotropic distillation to obtain 99.9999% pure R116. However, distillation requires low temperature and high pressure, resulting in high energy consumption and demanding equipment requirements. Furthermore, fluorination is highly corrosive, further emphasizing operational and equipment requirements. Adsorption separation, on the other hand, offers milder operating conditions, lower energy consumption, and higher removal depth, demonstrating significant advantages in the industrial production of electronic-grade R116. However, the prerequisite for industrial application is the selection of a highly efficient adsorbent.

[0004] US Patent 6274782B1 discloses a method using an aperture of Carbonaceous adsorbents or molecular sieves with a silica-to-alumina ratio less than 1.5 can remove Freon impurities containing two carbon atoms from R116, but do not remove R115 impurities. However, carbonaceous adsorbents and low silica-to-alumina ratio molecular sieves generally exhibit poor thermal stability during the exothermic adsorption process, which is not conducive to continuous use in industrial processes. US Patent US636138B1 uses a critical mass method to remove non-volatile impurities from R116, with NaX molecular sieve as the adsorbent, but it did not achieve efficient adsorption and removal of R115. Zhang Jinke et al. from the Zhejiang Provincial Chemical Research Institute utilized the difference in polarity between the two, applying NaX to the adsorption and separation of R115 / R116. They found that NaX had a selectivity of 40.9% for C2F5Cl relative to C2F6 at 100 kPa, 10℃, and a total flow rate of 25 mL·min. -1 Under conditions of (R115 / He = 450ppm, R116 / He = 400ppm), it can maintain a breakthrough time difference of 30h (Journal of Shanghai Jiaotong University, 2021, 55(9):9). However, its low silica-alumina ratio limits the strength of the active sites, making it difficult to form a strong adsorption effect on the adsorbate, resulting in a limited adsorption capacity. Therefore, it is urgent to develop high-silica FAU molecular sieve adsorbent materials with high selectivity and stability.

[0005] Zhang Jinke et al. clarified the adsorption separation mechanism by studying the adsorption equilibrium constant and adsorption heat of R116 and its key impurity R115 on NaX molecular sieves. They pointed out that the reason affecting the adsorption separation of R115 and R116 in NaX molecular sieves is not the pore size confinement effect of the molecular sieve, but a certain number of active sites and their intensity (Chinese Journal of Higher Chemical Engineering, 2020, 34(02): 311-317). Meanwhile, Johannes A. Lercher et al. studied the kinetics of the process from hydrogel formation to FAU zeolite lattice using ex-situ and in-situ spectroscopy. 23Na2MAS NMR revealed that Na ions were distributed in a 30:70 ratio within the sodalite cages and supercages during the synthesis of NaX molecular sieves. This demonstrates that the low silica-to-alumina ratio of NaX molecular sieves limits the intensity of active sites, creating a shielding effect and resulting in low utilization of active sites (Chemistry of Materials 2018, 30, 3, 888-897). Meanwhile, molecular sieves with higher silica-to-alumina ratios exhibit stronger active site intensity. Cation exchange sites, as a type of active site, are more abundant in the supercages of high-silica molecular sieves compared to NaX molecular sieves. However, current methods to improve active site exposure primarily involve acid-base post-treatment, which significantly reduces specific surface area and intensity (Journal of Environmental Health Science and Engineering 2021, 19: 1435-1445). Furthermore, defect sites generated during the dealumination process reduce the proportion of cation exchange sites. In contrast, the one-step synthesis method avoids the acidification process, effectively preventing issues such as reduced specific surface area, strength, and defect sites. Furthermore, increasing the silicon content of the molecular sieve helps improve structural stability. Therefore, there is an urgent need to develop novel methods for regulating the active sites of high-silica FAU molecular sieves. Our previous patents reported high… The acid site ratio of FAU molecular sieves was considered, but the Na content in the FAU molecular sieves was not addressed. + Applications of exchange site regulation and electron gas separation (CN116514138A)

[0006] Given the current understanding of targeted regulation of Na within the supercage of high-silica FAU molecular sieves + No synthetic method for exchanging site ratios has been reported. This invention achieves the directional assembly of different cage structures of FAU molecular sieves by adjusting organic template agents with different charge densities, and directly obtains supercage Na with a high proportion through mixing with a solid salt containing Na and solid-phase exchange. + The exchange-site FAU molecular sieve is ultimately applied to the adsorption and separation of fluorine-containing electronic gases, especially the adsorption and separation of R115 and R116. Summary of the Invention

[0007] The following will elaborate on the invention's objective, key features, synthesis process, and specific implementation methods:

[0008] The purpose of this invention is to provide a high-proportion supercage Na + FAU molecular sieve adsorbents with exchange sites are used to directionally assemble different cage structures of FAU molecular sieves by adjusting the composition of organic templates with different charge densities. These structures are then directly obtained through mixing with a solid salt containing Na and solid-phase exchange, resulting in a high proportion of supercage Na. +The exchange-site FAU molecular sieve can achieve effective separation of R115 / R116.

[0009] To achieve the above objectives, this invention successfully synthesized a high proportion of supercage Na+ by adjusting the composition of template agents with different charge densities and selecting appropriate synthesis conditions. + The exchange-site FAU molecular sieve achieves efficient separation of R115 / R116.

[0010] The technical solution adopted in this invention is as follows:

[0011] A type of supercage Na + The exchange-site FAU molecular sieve has the FAU molecular sieve configuration recognized by the International Zygote Association (IZA). Its chemical composition has a molar ratio of Al2O3:mSiO2:nNa2O, and the molar ratio m of the oxide SiO2 / Al2O3 is between 5 and 20. When X-ray diffraction is performed, it has characteristic peaks in at least the following four interplanar spacings d: first interplanar spacing d = 14.4 ± 0.2, second interplanar spacing d = 8.9 ± 0.2, third interplanar spacing d = 7.6 ± 0.2, and fourth interplanar spacing d = 5.8 ± 0.2.

[0012] Furthermore, the aforementioned method has a high proportion of supercage Na + FAU molecular sieves with exchange sites, after 23 Na MAS NMR determination of Na in the supercage of FAU molecular sieve + Content as a percentage of total Na + The ratio of interchangeable parts is 50%-75%, preferably 56%-60%.

[0013] This invention provides a high proportion of supercage Na + FAU molecular sieve adsorbents with exchange sites are used to directionally assemble different cage structures of FAU molecular sieves by adjusting organic templates with different charge densities. These structures are then directly obtained through mixing with a solid salt containing Na and solid-phase exchange, resulting in a high proportion of supercage Na. + The exchange-site FAU molecular sieve, which can efficiently adsorb and separate impurity gas R115 from fluorine-containing electronic gas R116, is synthesized by a hydrothermal method, specifically including the following processes:

[0014] (a) Al source, Si source, NaCl, and organic template agent were dissolved in deionized water, and then FAU seed crystals were added. The mixture was stirred until homogeneous and aged to obtain an initial gel. The gel was then transferred to a pressure-resistant container and sealed. Through hydrothermal synthesis, different cage structures of FAU molecular sieves were assembled under the action of organic template agents with different charge densities, resulting in gels with different NaCl concentrations. + Molecular sieve precursors with exchange site ratios;

[0015] (b) After the reaction in step (a) is completed, the molecular sieve precursor is filtered, washed and dried, and then heated and activated in a muffle furnace to remove the organic matter in the molecular sieve precursor, thus obtaining the calcined matrix.

[0016] (c) The calcination matrix obtained in step (b) is mixed with a solid containing Na elemental solid salt, and the mixture is ground in a mortar. The ground mixture is then calcined in an argon gas flow to obtain the high proportion of supercage Na. + FAU molecular sieve with exchange sites.

[0017] Further, the Al source described in step (a) includes one or more of alkoxyaluminum, aluminum salt, activated alumina, pseudoboehmite or pseudoboehmite, preferably alkoxyaluminum, aluminum salt, activated alumina or pseudoboehmite, more preferably alkoxyaluminum or aluminum salt.

[0018] The Si source includes one or more of silica sol, silica gel, active silica or tetraethyl orthosilicate, preferably silica sol, silica gel or tetraethyl orthosilicate; the molar ratio of Si source in SiO2 form to Al source in Al2O3 form is 10-20:1, preferably 15-16:1.

[0019] The organic template agent comprises two types: the first template agent is TEAOH or TPAOH, and the second template agent is TBAOH or a choline-based compound. The molar ratio of the first template agent to the second template agent is 2-10:1, preferably 5-8:1. The choline-based compound is at least one of choline hydroxide and choline chloride. The molar ratio of the organic template agent to the Al source in the form of Al2O3 is 25-52.5:1, preferably 42.5-52.5:1.

[0020] The molar ratio of NaCl to Al source in the form of Al2O3 is 5-10:1, preferably 7.5-8:1;

[0021] The FAU seed crystals have a SAR value of 50-70, preferably 60, and their mass concentration in the initial gel is 10-30 g / L, preferably 17.5-20 g / L. The SAR is the molar ratio of SiO2 to Al2O3.

[0022] Step (a) The aging time is selected as 12-36h, preferably 20-28h, the temperature of the hydrothermal synthesis reaction is 380-410K, preferably 400-405K, and the reaction time is 30-45h, preferably 35-40h.

[0023] Furthermore, the temperature for heating activation in step (b) is 500-600℃, and the heating activation time is 2-8h.

[0024] Further, in step (c), the Na-containing solid salt includes sodium chloride, sodium nitrate, sodium carbonate, sodium acetate, or disodium ethylenediaminetetraacetate, preferably disodium ethylenediaminetetraacetate; the mass ratio of the Na-containing compound to the calcining matrix is ​​2-8:1, preferably 4-6:1.

[0025] Furthermore, in step (c), the heating temperature is 450-550℃ and the heating time is 10-15h.

[0026] This invention also provides a high proportion of supercage Na. + Application of exchange-site FAU molecular sieves in the adsorption and separation of fluorine-containing electron gases in gas-phase systems.

[0027] Furthermore, the molecular sieve of the present invention is used for the adsorption and separation of pentafluorochloroethane R115 and hexafluoroethane R116. The FAU molecular sieve adsorbs and separates gases at 273-323 K, preferably 293-303 K.

[0028] The beneficial effects achieved by this invention are:

[0029] (1) The FAU molecular sieve synthesis in this invention uses template agents with different charge densities, and the prepared product has a high proportion of supercage Na + The exchange sites can avoid the problem of low effective active site ratio in traditional one-time synthesis of Y molecular sieves, thus improving the adsorption efficiency of the molecular sieve. At the same time, compared with commercial Y molecular sieves, it effectively avoids the decrease in specific surface area and strength and defects caused by acid treatment, so as to avoid the decrease in adsorption activity and regeneration performance, as well as problems such as coking and carbon deposition during the activation process.

[0030] (2) The FAU molecular sieve in this invention has a high silica-alumina ratio, which is used to balance the Na content of the framework charge. + The amount used is small, while the cost of Li and Ag used for ion exchange is high and the amount used is large. Therefore, using the Na-FAU molecular sieve with the best performance in this invention is beneficial to reducing the manufacturing cost of molecular sieves.

[0031] (3) The FAU molecular sieve in this invention has a high silicon-to-aluminum ratio, low polarity, and strong hydrophobicity, which can avoid the high powder loss rate in the adsorbent manufacturing process.

[0032] (4) In this invention, all-Na type FAU molecular sieves can be directly prepared, and the exposure of Na sites can be adjusted. Attached Figure Description

[0033] Figure 1 The adsorption and separation curves of NaY-2.6 molecular sieve for the R115 / R116 system are shown.

[0034] Figure 2It is the adsorption separation measurement curve of NaY-3.3 molecular sieve for the R115 / R116 system;

[0035] Figure 3 It is the adsorption separation measurement curve of NaY-5.0 molecular sieve for the R115 / R116 system;

[0036] Figure 4 It is the adsorption separation measurement curve of NaY-5.6 molecular sieve for the R115 / R116 system;

[0037] Figure 5 It is the adsorption separation measurement curve of NaY-8.0 molecular sieve for the R115 / R116 system;

[0038] Figure 6 It is a schematic diagram of the XRD test results of different molecular sieve adsorbent materials;

[0039] Figure 7 It is the sodium ion distribution diagram of different molecular sieves. Specific implementation mode

[0040] The present invention will be described in detail below by way of examples, but the present invention is not limited to these examples.

[0041]

Instrument characterization

[0042] <X-ray diffraction determination>

[0043] The X-ray diffraction determination instrument is Panalytical X’Pert PRO, the detection light source is Cu Kα, the tube voltage is 40 kV, the tube current is 40 mA, the detection angle range is 5-50°, and the detection time is 10 min. The present invention determines the phase structure of the synthesized molecular sieve by X-ray diffraction. The milled sample powder is added into the square hole on the glass plate, and then the glass plate is inserted into the axis position of the goniometer. Under the irradiation of the Cu Kα light source, the probe rotates at a speed of 2θ / min. In addition, the light source is not limited to CuKα, and Co Kα, Mo Kα, and Ag Kα can also be used as the light source for phase analysis. The raw material form for testing can be powder, emulsion or solid particles.

[0044] <Inductively coupled plasma spectroscopy determination>

[0045] Inductively coupled plasma spectroscopy (ICP) determination is carried out using PerkinElmer Optima8x00. The present invention determines the content of tetravalent element Si, trivalent element Al, and monovalent element or monovalent cation Na in the synthesized molecular sieve by inductively coupled plasma spectroscopy. The standard sample is diluted to make a concentration gradient absorption curve. The sample is dissolved with hydrofluoric acid and then diluted with water, and then the concentration of each element in the sample is determined by measuring the absorption peak intensity.

[0046] <NMR Determination of Molecular Sieves>

[0047] Adopt 23 Na nuclear magnetic resonance ( 23 NaMAS NMR) was used to determine the proportion of the supercage Na exchange sites in the FAU molecular sieve with respect to the total Na exchange sites. The sample was heated to 400 °C (at a rate of 5 °C / min) and held at this temperature for 10 h to achieve dehydration. Experiments were carried out at different magnetic field strengths. A Bruker 500 MHz spectrometer equipped with a triple resonance wide-bore probe was used. The resonance frequency was set to 132.3 MHz, and the sample was rotated at 10 kHz. The π / 20 pulse corresponded to a pulse width of 1.4 μs. Scans were accumulated 5000 times at a rotation speed of 16 kHz, and the pulse delay was 1 s. The signal reference was set to 0 ppm using solid NaCl.

[0048] <R115 / R116 Adsorption Separation Determination>

[0049] In this invention, the gas adsorption capacity was tested by gas adsorption measurement. R115 / R116 was determined at 298 K. Approximately 190 mg of the sample was placed in a U-shaped tube, and then a mixed gas with a total gas flow rate of 90 mL / min and a concentration ratio of R115 / R116 / He of 1:9:90 was introduced. The tail gas after the sample adsorption was introduced into a gas chromatograph for detection. All samples were calcined at 400 - 600 °C for more than 6 h before adsorption.

[0050] In the actual gas adsorption measurement, the calculation formula for the R115 / R116 adsorption selectivity is

[0051]

[0052] Here, S represents selectivity, q represents the saturated adsorption capacity of the molecular sieve for different gases (mmol g -1 ), and p represents the partial pressure of a specific gas in the mixed gas (kPa).

[0053]

Examples

[0054] The FAU seed crystals (SAR = 60) in the examples of this invention were purchased from Tianjin Nanhua Catalyst Co., Ltd., model NKF - 3. ChOH is choline hydroxide, and ChCl is choline chloride.

[0055] Example 1

[0056] ​​​​Aluminum sec-butoxide (AUD) was dissolved in deionized water at a molar ratio of 1.5 NaCl : 0.2 Al₂O₃ (AUD used in Al₂O₃ form) : 8 SiO₂ (Tetraethyl orthosilicate used in SiO₂ form) : 8 TEAOH : 0.5 ChOH : 2 ChCl. The AUD, TEAOH, tetraethyl orthosilicate, ChOH, ChCl, and NaCl were dissolved in deionized water, with the AUD molar concentration in the deionized water determined to be 0.14 mol / L. FAU seed crystals with a final concentration of 17.8 g / L were added, and the mixture was aged for 24 h to obtain an initial gel. The gel mixture was transferred to a pressure-resistant container, sealed, and reacted at 403 K for 36 h. After the hydrothermal reaction, the reaction solution was cooled, filtered, and washed to obtain a crystalline product. The obtained crystals were dried at 373 K for 12 h to obtain a powdered product, i.e., the catalyst precursor.

[0057] The obtained powdered product (catalyst precursor) was calcined in a muffle furnace at 550℃ for 6 h, and then cooled to room temperature. 1 g of the calcined product was ground and mixed with 5 g of disodium ethylenediaminetetraacetate for 1 h. After grinding, the mixture was heated to 500℃ (heating rate 2℃ / min) in an argon gas flow (flow rate 25 mL / min) and held at 500℃ for 12 h. After the reaction was completed, the mixture was cooled in an argon gas flow. The resulting powdered molecular sieve was named NaY-3.3.

[0058] The obtained product NaY-3.3 was subjected to phase analysis by XRD. The interplanar spacings at the characteristic peaks in NaY-3.3 are shown in Table 1. A schematic diagram of the XRD test results is shown in [Figure 1]. Figure 6 This indicates that the synthesized molecular sieve possesses the FAU molecular sieve configuration recognized by the IZA. Elemental composition analysis of the above samples was performed using ICP. The results showed that the SAR value of NaY-3.3 was 6.6, where SAR represents the molar ratio of SiO2 to Al2O3.

[0059] Table 1 Characteristic interplanar spacings of NaY-3.3

[0060] Interplanar spacing (d) 1 14.250 2 8.746 3 7.458 4 5.660 5 4.897 6 4.755 7 4.366 8 3.759

[0061] Example 2

[0062] Example 2: The preparation method of the molecular sieve was the same as in Example 1, except that the molar ratio of all raw materials was replaced with 1.5 NaCl:0.2 Al2O3 (the amount of aluminum sec-butoxide fed was in the form of Al2O3):8 SiO2 (the amount of tetraethyl orthosilicate fed was in the form of SiO2):8 TEAOH:1.0 TBAOH. Aluminum sec-butoxide, TEAOH, TBAOH, tetraethyl orthosilicate and NaCl were dissolved in deionized water, and the molar concentration of aluminum sec-butoxide in deionized water was determined to be 0.14 mol / L and remained unchanged. Other conditions remained unchanged, and the final powdered molecular sieve product was named NaY-5.0.

[0063] The obtained product NaY-5.0 was subjected to phase analysis by XRD. The interplanar spacings at the characteristic peaks in NaY-5.0 are shown in Table 2. A schematic diagram of the XRD test results is shown in [Figure 2]. Figure 6 This indicates that the synthesized molecular sieve possesses the FAU molecular sieve configuration recognized by the IZA. Elemental composition analysis of the above samples was performed using ICP, and the results showed that the SAR value of NaY-5.0 was 10.0.

[0064] Table 2 Characteristic interplanar spacings of NaY-5.0

[0065] Interplanar spacing (d) 1 14.264 2 8.717 3 7.387 4 5.682 5 4.751 6 4.152 7 3.893 8 3.762

[0066] Example 3

[0067] Example 3: The preparation method of the molecular sieve was the same as in Example 1, except that the molar ratio of all raw materials was replaced with 1.5 NaCl:0.2 Al2O3 (the amount of aluminum sec-butoxide fed was in the form of Al2O3):8 SiO2 (the amount of tetraethyl orthosilicate fed was in the form of SiO2):6 TPAOH:2.5 ChCl. Aluminum sec-butoxide, TPAOH, tetraethyl orthosilicate, ChCl, and NaCl were dissolved in deionized water, and the molar concentration of aluminum sec-butoxide in deionized water was determined to be 0.14 mol / L, which remained unchanged. Other conditions remained unchanged, and the final powdered molecular sieve product was named NaY-5.6.

[0068] The obtained product NaY-5.6 was subjected to phase analysis by XRD. The interplanar spacings at the characteristic peaks in NaY-5.6 are shown in Table 3. A schematic diagram of the XRD test results is shown in [Figure 3]. Figure 6 This indicates that the synthesized molecular sieve possesses the FAU molecular sieve configuration recognized by the IZA. Elemental composition analysis of the above samples was performed using ICP, and the results showed that the SAR value of NaY-5.6 was 11.2.

[0069] Table 3 Characteristic interplanar spacings of NaY-5.6

[0070] Interplanar spacing (d) 1 14.274 2 8.773 3 7.492 4 5.688 5 4.762 6 4.380 7 3.915 8 3.774

[0071] Example 4

[0072] Example 4: The preparation method of the molecular sieve was the same as in Example 1, except that the molar ratio of all raw materials was replaced with 1.5 NaCl:0.2 Al2O3 (the amount of aluminum sec-butoxide fed was in the form of Al2O3):8 SiO2 (the amount of tetraethyl orthosilicate fed was in the form of SiO2):8 TBAOH. Aluminum sec-butoxide, TBAOH, tetraethyl orthosilicate, and NaCl were dissolved in deionized water, and the molar concentration of aluminum sec-butoxide in deionized water was determined to be 0.14 mol / L, which remained unchanged. Other conditions remained unchanged, and the final powdered molecular sieve product was named NaY-8.0.

[0073] The obtained product NaY-8.0 was subjected to phase analysis by XRD. The interplanar spacings at the characteristic peaks in NaY-8.0 are shown in Table 4. A schematic diagram of the XRD test results is shown in [Figure 4]. Figure 6 This indicates that the synthesized molecular sieve possesses the FAU molecular sieve configuration recognized by the IZA. Elemental composition analysis of the above samples was performed using ICP, and the results showed that the SAR value of NaY-8.0 was 16.0.

[0074] Table 4 Characteristic interplanar spacings of NaY-8.0

[0075] Interplanar spacing (d) 1 14.345 2 8.817 3 7.529 4 5.716 5 4.786 6 4.380 7 3.933 8 3.793

[0076] Comparative Example 1

[0077] To obtain commercial USY-2.6 molecular sieve, 1g of it is ground and mixed with 5g of disodium ethylenediaminetetraacetate for 1 hour. After grinding, the mixture is heated to 500℃ (heating rate 2℃ / min) in an argon gas flow (flow rate 25mL / min) and maintained at 500℃ for 12 hours. After the reaction is completed, the mixture is cooled in an argon gas flow. The resulting powdered molecular sieve is named NaY-2.6.

[0078] The proportion of supercage Na cation exchange sites to total Na cation exchange sites in different molecular sieves in Examples 1-4 and Comparative Example 1 was determined. The specific procedure is as follows: The sample was heated to 400℃ at a heating rate of 5℃ / min and held at this temperature for 10h to achieve dehydration. Experiments were conducted under different field strengths. A Bruker 500MHz spectrometer equipped with a triple-resonance wide-aperture probe was used. The resonance frequency was set to 132.3MHz, and the sample was rotated at 10kHz. The π / 20 pulse corresponded to a pulse width of 1.4μs. 5000 scans were accumulated at a rotation speed of 16kHz, with a pulse delay of 1s. The signal reference solid NaCl was set to 0ppm. The proportion of supercage Na cation exchange sites to total Na cation exchange sites in different molecular sieves is as follows: Figure 3 As shown in Table 5.

[0079] The adsorption performance of different molecular sieves in Examples 1-4 and Comparative Example 1 was determined: Samples were calcined at 500℃ for at least 6 hours before adsorption, then cooled to room temperature, and subsequently used to test adsorption performance. Approximately 190 mg of molecular sieve was placed in a U-tube, and a mixed gas with a total flow rate of 90 mL / min and a volume concentration ratio of R115 / R116 / He of 1:9:90 was passed through. The tail gas after sample adsorption was then detected by gas chromatography. The adsorption and separation curves of different molecular sieves for the R115 / R116 system are shown below. Figure 1-5 As shown in Table 5, the adsorption capacity of different molecular sieves for R115 and the adsorption selectivity of R115 / R116 are obtained from the results.

[0080] Table 5. Adsorption capacity, R115 / R116 selectivity, and Na+ content within the supercage of molecular sieve adsorbent material R115. + Proportion

[0081]

[0082] As shown in Table 5, FAU molecular sieve synthesis uses template agents with different charge densities. Compared with commercial FAU molecular sieves, the molecular sieve product prepared in this invention has a high proportion of supercage Na+. + Exchange sites (i.e., supercage Na within the molecular sieve) + Exchanged bits account for a total of Na + With a higher exchange site ratio, this method avoids the problem of low effective active site ratio in traditional one-step synthesis of high-silica Y molecular sieves, thus improving the adsorption capacity of the molecular sieve for R115 and the adsorption selectivity of R115 / R116. (Table 5 shows Na...) + The 4(SC) ratio represents the Na+ content within the molecular sieve. + Exchanged bits account for a total of Na + Swap bit ratio.

[0083] The curve was determined by adsorption separation. Figure 1-5 It can be seen that the larger the enclosed area between the two lines in the R115 / R116 adsorption curves, the better the separation effect of the adsorbent material for the two. Table 5 shows the specific values ​​of the molecular sieve adsorbent's adsorption capacity for R115 and its selectivity for R115 / R116. Therefore, it can be found that the high-silica FAU molecular sieves prepared with TEA and TBA co-templating agents and TPA and Ch co-templating agents have a higher proportion of supercage cation exchange sites, resulting in better adsorption and separation effects on the R115 / R116 system. High-silica FAU molecular sieves using TBA as a single template agent also show good adsorption and separation effects on the R115 / R116 system.

[0084] The contents described in this specification are merely an enumeration of the implementation forms of the inventive concept, and the scope of protection of this invention should not be regarded as limited to the specific forms described in the embodiments.

Claims

1. A high proportion of supercage Na + The application of exchange-site FAU molecular sieves in the adsorption and separation of fluorine-containing electron gases in gas-phase systems is characterized by... Molecular sieves are used for the adsorption and separation of pentafluorochloroethane R115 and hexafluoroethane R116. The molecular sieve has the FAU molecular sieve configuration recognized by the International Zygotes Association (IZA), and its chemical composition molar ratio is Al2O3:mSiO2:nNa2O. The molar ratio m of the oxide SiO2 / Al2O3 is between 5 and 20. When X-ray diffraction is performed, it has characteristic peaks in at least the following four interplanar spacings d: first interplanar spacing d = 14.4 ± 0.2, second interplanar spacing d = 8.9 ± 0.2, third interplanar spacing d = 7.6 ± 0.2, and fourth interplanar spacing d = 5.8 ± 0.

2. go through 23 Na MAS NMR determination of Na in the supercage of FAU molecular sieve + Content as a percentage of total Na + The ratio of swapped bits is 50%-75%; The preparation of molecular sieves includes the following processes: (a) Al source, Si source, NaCl, and organic template agent were dissolved in deionized water, and then FAU seed crystals were added. The mixture was stirred until homogeneous and aged to obtain an initial gel. The gel was then transferred to a pressure-resistant container and sealed. Through hydrothermal synthesis, different cage structures of FAU molecular sieves were assembled under the action of organic template agents with different charge densities, resulting in gels with different NaCl concentrations. + Molecular sieve precursors with exchange site ratios; (b) After the reaction in step (a) is completed, the molecular sieve precursor is filtered, washed and dried, and then heated and activated in a muffle furnace to remove organic matter from the molecular sieve precursor, thus obtaining a calcined matrix. (c) The calcination matrix obtained in step (b) is mixed with a solid salt containing Na, and the mixture is ground in a mortar. The ground mixture is then calcined in an argon gas flow to perform solid-phase exchange, thereby obtaining the high-proportion supercage Na. + FAU molecular sieve with exchange sites; The organic template agent includes two types: the first template agent is TEAOH or TPAOH, and the second template agent is TBAOH or a choline compound. The molar ratio of the first template agent to the second template agent is 2-10:1, and the choline compound is at least one of choline hydroxide and choline chloride.

2. The application as described in claim 1, characterized in that... go through 23 Na MAS NMR determination of Na in the supercage of FAU molecular sieve + Content as a percentage of total Na + The ratio of swapped bits is 56-60%.

3. The application as described in claim 1, characterized in that... The Al source mentioned in step (a) includes one or more of alkoxyaluminum, aluminum salts, activated alumina, pseudoboehmite or pseudoboehmite; The Si source includes one or more of silica sol, silica gel, active silica or tetraethyl orthosilicate; the molar ratio of the Si source in the form of SiO2 to the Al source in the form of Al2O3 is 10-20:

1. The molar ratio of the organic template agent to the Al source in the form of Al2O3 is 25-52.5:1; The molar ratio of NaCl to Al source in the form of Al2O3 is 5-10:1; The SAR value of the FAU seed crystal is 50-70, its mass concentration in the initial gel is 10-30 g / L, and the SAR is the molar ratio of SiO2 to Al2O3. Step (a) The aging time is selected as 12-36 h, the temperature of the hydrothermal synthesis reaction is 380-410 K, and the reaction time is 30-45 h.

4. The application as described in claim 3, characterized in that... The Al source mentioned in step (a) is alkoxyaluminum, aluminum salt, activated alumina, or pseudoboehmite; The Si source is silica sol, silica gel, or tetraethyl orthosilicate; the molar ratio of the Si source in the form of SiO2 to the Al source in the form of Al2O3 is 15-16:

1. The molar ratio of the first template agent to the second template agent is 5-8:1, and the molar ratio of the organic template agent to the Al source in the form of Al2O3 is 42.5-52.5:

1. The molar ratio of NaCl to Al source in the form of Al2O3 is 7.5-8:1; The FAU seed crystals have a SAR value of 60 and a mass concentration of 17.5-20 g / L in the initial gel. Step (a) The aging time is selected as 20-28 h, the temperature of the hydrothermal synthesis reaction is 400-405 K, and the reaction time is 35-40 h.

5. The application as described in claim 1, characterized in that... The temperature for heating activation in step (b) is 500-600 ℃, and the heating activation time is 2-8 h.

6. The application as described in claim 1, characterized in that... In step (c), the Na-containing solid salt includes sodium chloride, sodium nitrate, sodium carbonate, sodium acetate, or disodium ethylenediaminetetraacetate; the mass ratio of the Na-containing solid salt to the calcination matrix is ​​2-8:

1.

7. The application as described in claim 6, characterized in that... In step (c), the Na-containing solid salt is disodium ethylenediaminetetraacetate; the mass ratio of the Na-containing solid salt to the calcination matrix is ​​4-6:

1.

8. The application as described in claim 1, characterized in that... In step (c), the heating temperature is 450-550℃ and the heating time is 10-15h.

9. The application as described in claim 1, characterized in that... The FAU molecular sieve adsorbs and separates gases at 273-323 K.

10. The application as described in claim 9, characterized in that... The FAU molecular sieve adsorbs and separates gases at 293-303 K.

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