Purification of Nitrogen Trifluoride By Pressure Swing Absorption

摘要

A pressure-swing adsorption process for producing a purified nitrogen trifluoride (NF3) product gas from a feed gas contaminated with carbon tetrafluoride (CF4) using a column packed with an adsorbent that exhibits selectivity for NF3 over CF4. The process separates the feed gas into a first product gas having a greater concentration of CF4 than the feed gas and a second product gas having a lesser concentration of CF4 without the use of an inert carrier gas while recovering essentially all of the NF3. The process includes filling the column with the feed gas until the column reaches a first pressure, removing the first product gas, and then removing the second product gas, where after the second product gas is removed the column is at a second pressure. A rinse gas of NF3 and CF4 may be used to remove the first product gas or the second product gas.

主权项

1. A method for purifying nitrogen trifluoride (NF3), the method comprising:
filling an adsorption column with a first volume of a feed gas consisting essentially of NF3 and carbon tetrafluoride (CF4) until the adsorption column reaches a first pressure greater than an initial pressure of the adsorption column, wherein the adsorption column includes an adsorbent material that selectively adsorbs NF3 over CF4, whereby the adsorbent material adsorbs a portion of the feed gas having a greater concentration of NF3 than an unadsorbed portion; removing a first product gas having a greater concentration of CF4 than the feed gas from the adsorption column; and, after removing the first product gas, removing a second product gas having a lesser concentration of CF4 than the feed gas from the adsorption column, wherein the column has a second pressure less than the first pressure after removing the second product gas.