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Sorption and diffusion of gaseous hydrocarbons in synthetic mordenite
Author(s) -
Satterfield Charles N.,
Frabetti Alton J.
Publication year - 1967
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.690130426
Subject(s) - sorption , diffusion , desorption , chemistry , mordenite , analytical chemistry (journal) , methane , propane , hydrocarbon , zeolite , molecular sieve , atmospheric temperature range , thermodynamics , chromatography , adsorption , organic chemistry , catalysis , physics
Diffusion coefficients for the C 1 to C 4 paraffin hydrocarbon gases in single crystals of the synthetic zeolite (molecular sieve) sodium mordenite were determined from transient sorption rate and desorption rate measurements over the temperature range 25° to 140°C. and pressure range 0 to 20 cm. Hg, and found to be of the order of 10 −9 to 10 −10 sq. cm./sec. Diffusion coefficients for desorption were from three to sixty times smaller than those for sorption. Activation energies for methane and ethane were 1.7 and 1.9 kcal./mole, respectively. Equilibrium sorption capacity and diffusion coefficients are markedly affected by the conditions of synthesis and by mechanical treatments such as grinding. For propane at 29°C. and at 2.0 cm. Hg pressure, the sorption capacity in 2.5 μ crystals was only 50% of that in 21 by 21 by 33 μ crystals and the diffusion coefficient was only 1/50 of that in the larger crystals. Light mechanical grinding of the larger crystals lowered the sorption capacity 30% and the diffusion coefficient by a factor of 35.