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Pillared clays as a new class of sorbents for gas separation
Author(s) -
Yang R. T.,
Baksh M. S. A.
Publication year - 1991
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.690370506
Subject(s) - oligomer , adsorption , thermal diffusivity , ion exchange , chemistry , chemical engineering , limiting , air separation , ion , materials science , chemical physics , thermodynamics , polymer chemistry , organic chemistry , oxygen , mechanical engineering , physics , engineering
Abstract High‐surface‐area, Zr‐pillared, layered clays are synthesized and characterized for their adsorption properties. Although large free interlayer spacings are claimed in the literature (as also found in this work, 14.3 Å), the limiting pore size is the narrow interpillar spacing. The distribution of interpillar spacing is determined by molecular probing and adsorption data along with a theoretical framework available from the literature. Interpillar spacing can be tailored by controlling the number density of pillars inserted during the ion exchange (oligomer inserting) step. The following variables in the ion exchange solution result in lowering the pillar density: higher pH, lower oligomer concentration, and introduction of competitive cations. By changing these variables, peak interpillar spacing is shifted by nearly 2 Å (from 5 to 7 Å). The versatility of pillared clays as sorbents for kinetic separation (i.e., separation based on diffusivity differences) has been demonstrated by the separations of air and xylene isomers.