ISSN:
0001-1541
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Process Engineering, Biotechnology, Nutrition Technology
Notes:
The isotope exchange technique (IET) can be used to simultaneously measure multicomponent gas adsorption equilibria and self-diffusivities of the components in a single isothermal experiment without disturbing the overall adsorbed phase. An experimental protocol for the IET and corresponding data analysis procedures is described. Isotherms and self-diffusivities for adsorption of N2 as a pure gas were measured on commercial samples of a carbon molecular sieve and a 4-Å zeolite using IET, as well as those of O2 and N2 from their binary mixtures. The carbon molecular sieve did not exhibit thermo-dynamic selectivity for air separation, but had a kinetic selectivity of O2 over N2 Mass-transfer resistances for self-diffusion of N2 and O2 on the carbon molecular sieve were controlled by pore mouth restrictions in the carbon, but those for adsorption of N2 into the 4-Å zeolite by Fickian diffusion inside the adsorbent. A linear driving force model described the uptakes of N2 and O2 in the carbon molecular sieve. The Fickian diffusion model described the N2 uptake in the 4-Å zeolite. Mass-transfer coefficients for both O2 and N2 on the carbon molecular sieve increased linearly with increasing gas-phase partial pressure of these gases, and the pressure of O2 did not affect mass-transfer coefficients for N2. The self-diffusivity of N2 in the 4-Å zeolite decreased with increasing adsorbate loading.
Additional Material:
13 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/aic.690431009
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