NITROGEN TRIFLUORIDE PRODUCTION PROCESS Russian patent published in 2008 - IPC C01B21/83 

FIELD: industrial inorganic synthesis.

SUBSTANCE: invention relates to processes of producing nitrogen trifluoride, which can be used as source of fluorine for synthesis of fluoroolefines, as oxidant for high-energy fuels in rocket engineering, and as dry etching substance for semiconductors, silicon plates, and large integrated circuits in electronic industry. Process of invention comprises nitrogen trifluoride synthesis stage accomplished via fluorine-mediated fluorination of ammonium difluoride melt and synthesized nitrogen trifluoride purification stage including alkali solution-assisted absorption extraction of impurities and removal of moisture from gas stream. Process further comprises fluorine purification stage involving thermal decomposition of oxygen fluoride at 300-350°C on developed-surface nickel packing and removal of hard-volatile impurities via cryogenic condensation at temperature from -170 to -180°C followed by cryogenic rectification at pressure 0.15-0.17 MPa. Nitrogen trifluoride comprises thermal decomposition of nitrogen fluoride by-products and removal of volatile impurities via cryogenic condensation at pressure 0.3-0.5 MPa. From the results of analytical control, summary impurity level in desired product does not exceed 90 ppm, in particular tetrafluoromethane level does not exceed 28 ppm. Fluorine-based yield of nitrogen trifluoride is at least 80%.

EFFECT: increased yield of desired product.

5 cl, 1 dwg, 3 tbl