| 摘要 |
PURPOSE: A method for preparing nitrogen trifluoride gas of high purity by effectively removing moisture and impurities including HF, N2F2 and OF2 contained in the gas from NF3 synthetic gas produced as reaction and synthesis results of nitrogen trifluoride gas is provided. CONSTITUTION: In a method for preparing nitrogen trifluoride (NF3) gas of high purity by removing the impurities and moisture from NF3 synthetic gas containing impurities such as HF, N2F2, OF2, N2O, CO2 and SO2F2 and moisture, the method comprises a step (a) of removing the KF salt by treating NF3 synthetic gas containing impurities of HF, N2F2, OF2, N2O, CO2 and SO2F2 and moisture using a KOH aqueous solution, thereby converting HF in the synthetic gas in the form of KF salt by neutralization reaction; a step (b) of pyrolyzing N2F2 into nitrogen and fluorine gases at a temperature of 240 to 300 deg.C; a step (c) of reducing and removing OF2 and F2 by adding a reducing agent of K2S2O3 to the NF3 synthetic gas; a step (d) of primarily removing moisture existing in the NF3 synthetic gas by condensing the NF3 synthetic gas at the freezing point using ethylene glycol based refrigerant; a step (e) of secondarily removing moisture in the NF3 synthetic gas at a temperature of -80 deg.C or less using a moisture adsorbent of zeolite; a step (f) of removing trace of N2O, CO2 and SO2F2 existing in the NF3 synthetic gas at an ordinary temperature using molecular sieve as an adsorbent; and a step (g) of obtaining NF3 of high purity by exhausting N2 and O2 gases generated by the above steps and condensing NF3 gas.
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