METHOD FOR PURIFYING NITROGEN TRIFLUORIDE GAS BY TREATING RAW NITROGEN TRIFLUORIDE(NF3) GAS CONTAINING OXIDATIVE IMPURITIES USING AQUEOUS REDUCING AGENT SOLUTION HAVING pH RANGE OF 8 TO 12

摘要

PURPOSE: To economically prepare high purity nitrogen trifluoride in which oxidative impurities such as OF2 and F2 exist in extremely small quantities, and which does not contain CO2, NO and NO2 at all by treating nitrogen trifluoride with an aqueous reducing agent solution in a pH range of 8 to 12, thereby effectively removing oxidative impurities. CONSTITUTION: A purification method of nitrogen trifluoride(NF3) gas is characterized in that nitrogen trifluoride gas containing oxidative impurities is treated with an aqueous reducing agent solution in a pH range of 8 to 12, wherein the aqueous reducing agent solution is an aqueous solution containing 0.1 to 20 wt.% of a reducing agent elected from Na2S2O3, Na2SO3, HI, K2S2O3, K2SO3 and a mixture thereof, wherein purified nitrogen trifluoride contains 0.05 ppm or less of oxidative impurities, wherein the oxidative impurities are OF2, F2, CO2, NO, NO2 or a mixture thereof, and wherein nitrogen trifluoride containing oxidative impurities is derived from a process of reacting the prepared fluorine with ammonia or ammonium salts such as ammonium fluorides after preparing fluorine(F2) by electrolyzing hydrofluoric acid(HF) or a process of directly electrolyzing fluorides of ammonia(NH3).