Patent ID: 6080226
Filing Date: 2000-06-27
Classification: B01D,C01B,Y02C,Y02P

Abstract:
A pressure swing adsorption process for the separation of nitrous oxide from a waste stream comprising nitrous oxide, nitrogen, and oxygen, said process comprising the following steps:a) passing the waste stream at effective conditions including an adsorption pressure and an adsorption temperature to a first adsorbent bed of at least two adsorbent beds in a pressure swing adsorption zone, each of said adsorbent beds containing an adsorbent selective for the adsorption of nitrous oxide relative to nitrogen and oxygen to provide a first adsorption effluent stream comprising oxygen and nitrogen;b) terminating the passing of said waste stream to the first adsorbent bed prior to the breakthrough of nitrous oxide from said first adsorbent bed;c) cocurrently depressurizing the first adsorbent bed to a first reduced pressure that is lower than the adsorption pressure and to provide a first vent stream comprising oxygen and nitrogen;d) further cocurrently depressurizing said first adsorbent bed to an equalization pressure that is lower than the first reduced pressure and passing an equalization effluent to a second adsorbent bed being repressurized;e) countercurrently depressurizing the first adsorbent bed to a desorption pressure that is lower than the equalization pressure and effective to desorb nitrous oxide and withdrawing a first desorption effluent stream comprising nitrous oxide;f) countercurrently purging the first adsorbent bed with an oxygen-lean stream to provide a second desorption effluent stream comprising nitrous oxide;g) combining the first desorption effluent stream and the second desorption effluent stream to provide a nitrous oxide stream and repressurizing the first adsorbent bed to the adsorption pressure and,h) repeating steps (a)-(g) to provide a continuous process.