c to 572 u00b0 f 300 u00b0 c this is followed by flowing uhp nitrogen without addition of hydrogen through the catalytic adsorbent bed while maintaining a temperature in the bed of at least 300 u00b0 f 149 u00b0 c and preferably within the range of 300 u00b0 f 149 u00b0 c to 572 u00b0 f 300 u00b0 c for a period of time to desorb or remove the unwanted species from the catalytic adsorbent bed thereafter the bed is cooled to a temperature of no greater than 120 u00b0 f 49 u00b0 c and at that time is ready to be placed in service normally two or more beds would be available to permit the continuous purification of the cryogenically produced nitrogen by having one bed on stream effecting removal of unwanted species from the cryogenically produced nitrogen while the other bed or beds are being regenerated or have been regenerated and are idled waiting for reengagement in the process after a conventional regeneration with hydrogen a purifier packed with 3 66 lbs of a commercial nickel alumina ni al 2 o 3 catalyst catalyst a was challenged with 2 4 ppm co and 3 6 ppm o 2 in a nitrogen gas flow of 3 5 scfm the purifier was operated at 80 u00b0 f and 80 psig inlet pressure the packed bed height was 48 inches since co 2 a product from the chemical reaction between co and o 2 is the first impurity to break out of the catalytic adsorber the purifier has to be regenerated once co 2 breaks through the packed bed a 24 hour regeneration procedure without hydrogen according to the following scheme was tested ______________________________________ time duration hrs ______________________________________1 heat up to 204 4 u00b0 c 400.