ISSN:
0001-1541
Schlagwort(e):
Chemistry
;
Chemical Engineering
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Chemie und Pharmazie
,
Werkstoffwissenschaften, Fertigungsverfahren, Fertigung
Notizen:
Rate studies are reported of the effect of rehydration-dehydration cycling on the vapor hydration behavior of solid K2CO3. 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 K2CO3·3/2H2O were found to depend on the conditions of the prior dehydration. Rehydration is comparatively very slow at relative pressures below P/Peq ≃ 1.5; rates increase linearly with pressure above P/Peq ≃ 3. Hydration rates of K2CO3 particles obtained as anhydrous are substantially slower than those of identically-sized crystals produced by prior dehydration of K2CO3·3/2H2O; 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.
Zusätzliches Material:
10 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/aic.690300110
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