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CN-117658167-B - Quaternary ammonium salt modified molecular sieve for adsorbing and purifying electronic gas octafluoropropane as well as preparation method and application thereof

CN117658167BCN 117658167 BCN117658167 BCN 117658167BCN-117658167-B

Abstract

The invention discloses a quaternary ammonium salt modified molecular sieve for adsorbing and purifying electronic gas octafluoropropane, and a preparation method and application thereof. The synthesis method comprises the steps of adding ZSM-5 molecular sieve powder into a quaternary ammonium salt aqueous solution, stirring for a second preset time at a second preset temperature, filtering with water, and drying to obtain the quaternary ammonium salt modified molecular sieve. According to the preparation method, the TMAZ microporous material with uniform pore diameter is prepared by carrying out accurate quaternary ammonium salt single ion exchange on the ZSM-5 molecular sieve, so that the material has higher adsorption capacity on chloropentafluoroethane and can obviously inhibit the adsorption on octafluoropropane. The material has higher separation factor of chloropentafluoroethane/octafluoropropane, so that the adsorption and purification of trace chloropentafluoroethane in octafluoropropane can be realized.

Inventors

  • XIAO JING
  • ZHOU XIAOYING
  • HUANG JIAWU
  • MIAO GUANG
  • YANG CUITING

Assignees

  • 华南理工大学

Dates

Publication Date
20260505
Application Date
20231103

Claims (8)

  1. 1. A preparation method of a quaternary ammonium salt modified molecular sieve for adsorbing and purifying electronic gas octafluoropropane is characterized by comprising the following steps of (1) carrying out primary activation treatment on a ZSM-5 molecular sieve, wherein the activation treatment comprises the steps of heating the ZSM-5 molecular sieve to 550-650 ℃ at a rate of 10-110 ℃ in a programmed manner, keeping the temperature for 5 hours, then carrying out programmed cooling to 100 ℃ at a rate of 10-min, (2) adding quaternary ammonium salt into an aqueous solution, stirring for 20-50 minutes at a first preset temperature of 25-55 ℃ until the quaternary ammonium salt is completely dissolved, obtaining a clarified quaternary ammonium salt aqueous solution, (3) adding the activated ZSM-5 molecular sieve powder obtained in the step (1) into the quaternary ammonium salt aqueous solution obtained in the step (2), continuously stirring in a water bath at a second preset temperature of 50-110 ℃ for 3-9 hours, then filtering, washing a filter cake with a sufficient amount of water to remove residual ammonium salt, and finally drying, wherein the quaternary ammonium salt is obtained through the cross-modified ZSM-5 molecular sieve and the quaternary ammonium salt is subjected to cation exchange with a cation channel of a porous channel of a quaternary ammonium salt in a molecular sieve, and the modified ZSM-5.5 molecular sieve is subjected to cation exchange according to a ratio of a cation channel of the quaternary ammonium salt to a cation channel of a direct-5-cation channel of a porous sieve.
  2. 2. The method according to claim 1, wherein in the step (2), the quaternary ammonium salt is any one of tetramethylammonium chloride, choline chloride, tetraethylammonium chloride.
  3. 3. The preparation method of claim 1, wherein in the step (2), the concentration of the quaternary ammonium salt aqueous solution is 5-55 g/L.
  4. 4. The method according to claim 1, wherein in the step (3), the amount of the ZSM-5 molecular sieve powder is 0.016 to 0.024 g/mL of the aqueous quaternary ammonium salt solution.
  5. 5. The method according to claim 1, wherein in the step (3), the drying operation comprises heating the filtered and washed product to 100 ℃ to 110 ℃ at a rate of 5 ℃ per minute, maintaining for 2 hours, heating to 195 ℃ to 205 ℃ at a rate of 5 ℃ per minute, maintaining for 4 hours, and finally cooling to 30 ℃ to 35 ℃ at a rate of 5 ℃ per minute.
  6. 6. A quaternary ammonium salt modified molecular sieve made by the method of any one of claims 1-5.
  7. 7. The use of the quaternary ammonium salt modified molecular sieve according to claim 6 for adsorbing and purifying electronic gas octafluoropropane.
  8. 8. The use according to claim 7, wherein the quaternary ammonium salt modified molecular sieve is used for treating a crude octafluoropropane gas containing 100 ppm chloropentafluoroethane, enabling the octafluoropropane to have a purity of 99.99999% (7N grade), and 61.83 litres of 7N grade octafluoropropane product per kg of the quaternary ammonium salt modified molecular sieve.

Description

Quaternary ammonium salt modified molecular sieve for adsorbing and purifying electronic gas octafluoropropane as well as preparation method and application thereof Technical Field The invention relates to the field of gas adsorption separation materials, in particular to a quaternary ammonium salt modified molecular sieve for adsorbing and purifying electronic gas octafluoropropane, and a preparation method and application thereof. Background Octafluoropropane is an important electron gas widely used in semiconductor manufacturing processes such as cleaning and etching. For example, a mixture of octafluoropropane and oxygen is used as a plasma etching material that selectively reacts with the metal matrix of the silicon wafer. In the octafluoropropane preparation process, chloropentafluoroethane impurity (100 ppm) is inevitably generated, and the precision of the semiconductor etching process is seriously affected by the extremely low concentration of chloropentafluoroethane impurity, so that the ultra-high purity octafluoropropane (7N) is of great significance for manufacturing an extremely large-scale integrated circuit. In addition, capturing chloropentafluoroethane from octafluoropropane is an indispensable step in promoting the greening of the electronics industry, considering its high Ozone Depletion Potential (ODP) and its greenhouse effect potential (GHP). The current octafluoropropane purification method mostly adopts a low-temperature high-pressure rectification method. According to the purifying method of the octafluoropropane disclosed by the patent CN103664502A, octafluoropropane raw material gas is subjected to rectification twice at the temperature of-37 ℃ to 10 ℃ and the pressure adsorption for a plurality of times at the temperature of 1-6 bar, and finally, the chlorine-containing fluorocarbon impurities in the target product are less than or equal to 1ppm. However, the method requires multiple times of rectification, has high energy consumption, needs to be matched with a low-temperature/pressure adsorption process, and is complex to operate. Under the actual working condition, the boiling point difference of the octafluoropropane and the chloropentafluoroethane is only 1.1 ℃, so that a low-boiling azeotrope is very easy to form, the separation and purification of the mixture become difficult, the energy consumption is high, and the cost is high. The adsorption separation process has the advantages of low energy consumption, low cost, simple operation, high efficiency, environmental protection, cyclic operation and the like, so that the method has scientific significance and industrial value if the adsorption separation process with more environmental protection and low energy consumption can be adopted to realize the high-efficiency purification of the octafluoropropane at room temperature. In practice, for gases which are difficult to separate, thermodynamic separation of the two gases can be achieved as long as the resulting adsorbent differs in the forces acting on the two gases, and kinetic separation of the two gases can be achieved if the resulting adsorbent differs in the diffusion of the two gases. If the aperture of the prepared adsorbent is between two gas molecules, the separation of the two gases can be realized according to the principle of 'sucking small and exhausting large'. The three mechanisms are widely applied to separation of near gas molecules such as ethylene ethane, propylene propane and the like, but have not been reported in the field of purification of electronic gas octafluoropropane. The patent CN1220548C discloses an adsorbent for purifying perfluorocarbon, a production method thereof, high-purity octafluoropropane and octafluorocyclobutane and application thereof, wherein the carbon-based adsorbent can be used for removing 10-10000 ppm of chloropentafluoroethane in crude octafluoropropane and comprises the steps of (1) pickling raw carbon, then washing with water, (2) deoxidizing the raw carbon in an inert gas flow with the temperature of 50-250 ℃, 3) re-carbonizing the raw carbon under the inert gas flow with the temperature of 500-700 ℃, and (4) activating the raw carbon in a mixed gas flow containing inert gas, carbon dioxide and water vapor. The adsorbent has complex synthesis steps, low yield caused by multiple high-temperature calcination, and can generate toxic and harmful substances such as greenhouse gas during calcination. Disclosure of Invention In order to overcome the defects of the prior art, the invention provides a simple and easy-to-synthesize adsorption separation material for realizing normal-temperature deep removal of trace azeotropic impurities in octafluoropropane, and particularly relates to a quaternary ammonium salt modified molecular sieve for adsorbing and purifying electronic gas octafluoropropane, and a preparation method and application thereof. The method for synthesizing the adsorption material is to introduce a large volume