Percolation of gases into (K, Ca)–A zeolites and their cation distribution
- 1 January 1978
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases
- Vol. 74, 613-621
- https://doi.org/10.1039/f19787400613
Abstract
The sorption capacity of (K12–2xCax)–A zeolite was measured as a function of its composition, for O2, N2 and Ar at 77 and 90 K, and for n-butane at 298 and 323 K. The molecular sieving character of the zeolite changed gradually from 3A to 5A in a range of 4 ⩽x⩽ 6, in contrast to the case of the (Na, Ca)–A system. Using the percolation process theory, the concentration of windows permeable to these gases is deduced as a function of x. Results show that there are three kinds of window, i.e., an open window unblocked by any cation, a window blocked by K+ and that blocked by Ca2+. O2, N2 and Ar cannot pass through the windows blocked by either K+ or Ca2+ at 90 K, while n-butane can pass through that blocked by Ca2+ but only few of those blocked by K+ at 298 K. The site selectivity of Ca2+ is discussed and the diagram of cation distribution in (K, Ca)–A, which had been provisionally proposed previously, is refined.Keywords
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