Premium
Rate processes in cycling a reversible gas‐solid reaction
Author(s) -
Stanish M. A.,
Perlmutter D. D.
Publication year - 1984
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.690300110
Subject(s) - dehydration , chemistry , anhydrous , isothermal process , water vapor , cycling , vapor pressure , particle (ecology) , thermodynamics , dissolution , dehydration reaction , particle size , analytical chemistry (journal) , chromatography , organic chemistry , history , biochemistry , physics , oceanography , archaeology , geology
Rate studies are reported of the effect of rehydration‐dehydration cycling on the vapor hydration behavior of solid K 2 CO 3 . Isothermal rate data were obtained at different temperatures and water vapor pressures for the reaction of narrowlysized anhydrous particles. Effects of different particle preparation histories on the rehydration rate were investigated and correlations of rate with particle pore structure explored. Rehydration rates of dehydrated K 2 CO 3 ·3/2H 2 O were found to depend on the conditions of the prior dehydration. Rehydration is comparatively very slow at relative pressures below P / P eq ≃ 1.5; rates increase linearly with pressure above P / P eq ≃ 3. Hydration rates of K 2 CO 3 particles obtained as anhydrous are substantially slower than those of identically‐sized crystals produced by prior dehydration of K 2 CO 3 ·3/2H 2 O; after one rehydration‐dehydration cycle, rehydration rates are increased by as much as two orders of magnitude and this distinction between sources virtually disappears. Diffusional resistances based on calculated water vapor diffusivities are qualitatively consistent with the observed effects of cycling but do not by themselves account fully for the observations.