CHARACTERIZATION OF MICROPOROUS SOLIDS BY ADSORPTION - MEASUREMENT OFHIGH-RESOLUTION ADSORPTION-ISOTHERMS

The use of adsorption for the characterization of the micropores withi n zeolites was studied. An experimental procedure for the determinatio n of adsorption isotherms in zeolites is demonstrated. A modified stat ic technique was successfully employed for the acquisition of equilibr ium adsorption data. Adsorption isotherms were measured over a variety of zeolites. Nitrogen at 77 K and argon at 77 and 87 K were compared as adsorbates. The use of argon at 77 K is recommended, while nitrogen at 77 K can also be used and has advantages for adsorption in the sma llest pores (i.e., < 5 Angstrom) if the pressure is measured very accu rately, We did not see any particular advantages of using argon at 87 K, as was suggested by prior investigators. Current commercial equipme nt does not accurately measure high-resolution isotherms in a reasonab le time.