Process for refining nitrogen trifluoride gas using alkali earth metal exchanged zeolite 4A

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PURPOSE : A process for refining nitrogen trifluoride gas using zeolite 4A ion-exchanged with alkali earth metal is provided to selectively adsorb NF3 only from NF3 containing CF4 by ion-exchanging zeolite 4A with a proper amount of alkali earth metal, and a nitrogen trifluoride adsorbent formed of 4A zeolite used in the process is provided. CONSTITUTION : A process for refining nitrogen trifluoride gas comprises a step of recovering pure nitrogen trifluoride after selectively adsorbing nitrogen fluoride only and ventilating carbon tetrafluoride by flowing nitrogen trifluoride(NF3) gas containing carbon tetrafluoride(CF4) through a column packed with zeolite 4A ion-exchanged with alkali earth metal, wherein an amount of the ion-exchanged alkali earth metal is 20 to 95 wt.% of the total metal weight in zeolite, wherein the alkali earth metal is magnesium(Mg), calcium(Ca), strontium(Sr) or barium(Ba), wherein the nitrogen trifluoride(NF3) gas containing carbon tetrafluoride(CF4) flows through a packing layer packed with an adsorbent at a temperature of -100 to 50 deg.C, wherein the nitrogen trifluoride(NF3) gas containing carbon tetrafluoride(CF4) flows through the packing layer along with 20 to 80 vol.% of an inert gas of argon, helium or nitrogen, and wherein adsorption and recovery of nitrogen trifluoride gas using zeolite 4A ion-exchanged with alkali earth metal are repeatedly performed two or more times. © KIPO 2006