GAS-ABSORPTION IN SLURRIES OF FINITE-CAPACITY MICROPHASES

Absorption of a gas into slurries constituted by "fine" particles microdispersed in a liquid phase, which remove the diffusing solute gas dissolved in the liquid phase, from near the gas-liquid interface by reaction, complexation, solubilization (including surface adsorption) or catalytic action, is a relatively novel means for intensifying the specific rates of gas absorption and even manipulating selectivity in the case of multiple gaseous solutes. It has been shown in this paper that it is possible to develop analytical models for describing the absorption behaviour in the presence of microphase constituents which have a finite, exhaustible capacity to "store" the diffusing solute and/or the concentration of the solute within the microphase vs that in its vicinity in the original liquid phase shows a non-linear equilibrium relationship. The non-linearities may be approximated by segmental (piecewise) linearization. Mass transfer models of this type are conceptualized in terms of different zones of "varying" capacity within a liquid surface element. A theory has been developed for such exhaustible microphases including the conditions of validity for the various rate expressions and structured classifying regimes. Data on the absorption of hydrogen into slurries of lanthanum-nickel alloys in oil, reported in the literature, have been analyzed. The predicted values of the specific rate are found to be in reasonable agreement with the experimentally observed values. © 1990.