Robert M Weimer

US Patent:

53822803, Jan 17, 1995

Filed:

Nov 16, 1993

Appl. No.:

8/153387

Inventors:

Jung S. Choe - Harleysville PA
Lyndon J. Kellogg - Salington PA
Robert F. Weimer - Allentown PA

Assignee:

Air Products and Chemicals, Inc. - Allentown PA

International Classification:

B01D 5304

US Classification:

95 98

Abstract:

A two stage pressure swing adsorption process is set forth for producing the less strongly adsorbed component of a feed gas mixture wherein the first stage utilizes a first adsorbent for bulk removal of the more strongly adsorbed component and wherein the second stage utilizes a second adsorbent for trace removal of the more strongly adsorbed component. A further feature of the present invention is that the desorbed gas from the second stage's depressurization step (consisting primarily of the desired less strongly adsorbed component) is recycled to the first stage in order to improve its performance. In a preferred embodiment of the present invention, high purity nitrogen (less than 1000 ppm oxygen, preferably less than 100 ppm oxygen) is produced from an air feed using a kinetically controlled carbon molecular sieve adsorbent in the first stage and an equilibrium controlled metal complex-based adsorbent in the second stage.