Method for producing nitrogen trifluoride by gas-solid reaction

A method for producing nitrogen trifluoride, said method comprising:

• providing a vessel filled with a particulate solid of an ammonium complex of a metal fluoride;
• introducing a fluorine-containing gas into said vessel to allow said fluorine-containing gas to flow upwardly through said vessel such that said fluorine-containing gas has an upward superficial velocity through said vessel of not less than 1 cm/s, wherein the superficial velocity is defined as O/A where Q is the volume of said fluorine-containing gas introduced into said vessel per unit amount of time at 25° C. and 1 atmosphere and A is the cross-sectional area of said vessel perpendicular to the flow of said fluorine-containing gas through said vessel, and
• agitating said particulate solid during said introducing,
• such that fluorine of said fluorine-containing gas is reacted with said particulate solid in said vessel, thereby to obtain a reaction gas containing nitrogen trifluoride;
• and
• separating said nitrogen trifluoride from said reaction gas.