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Single‐step thermal method to measure intracrystalline mass diffusion in adsorbents
Author(s) -
Grenier Ph.,
Bourdin V.,
Sun L. M.,
Meunier F.
Publication year - 1995
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.690410905
Subject(s) - sorption , thermal diffusivity , diffusion , methanol , analytical chemistry (journal) , desorption , adsorption , chemistry , zeolite , volume (thermodynamics) , pellets , mass transfer , materials science , chromatography , thermodynamics , organic chemistry , composite material , physics , catalysis
A single‐step thermal method is used to measure intracrystalline mass diffusion. Sorption/desorption rates is zeolite samples (large crystals, monolayers of pellets, or even a single pellet) after a pressure of volume step are followed by monitoring the sample surface temperature by infrared detection. For a volume step, the pressure is also measured yielding the adsorbed mass. Sorption rates of water vapor in NaX are measured both on large 100 ‐ μm crystals and pellets. This fast system correcsponds to the limit of the pressure‐step termal method (using 100 ‐μm crystals). Sorption rates of methanol in the same large NaX crystals show good precision by the pressure‐step method. The methanol results show that a surface barrier may occur after thermal regeneration of the sample in the presence of methanol traces. A major advantage of this method is that the shape of response curves can provide useful information on the nature of the masstransfer resistance despite its limits. Sorption rates of methanol vapor on mordenite H (zeolon) pellets prove that the intracrystalline diffusivity may be extracted from pellet measurements for a slow diffusing species.