The effects of reactant starvation and mass transfer in the rate measurement of fluid-solid reactions with small equilibrium constants

The purpose of this article is to analyze critically and quantitatively the effect of fluid reactant supply rates and mass transfer on the measurement of the rates of fluid-solid reactions, particularly those with small equilibrium constants. It is shown through a mathematical analysis that the measurement of the intrinsic kinetics of a reaction with a small equilibrium constant (a positive standard free energy of reaction) requires much larger rates of fluid reactant supply and mass transfer rates than that of a reaction with a large equilibrium constant. The overall reaction rate of the former also tends to be slow. Furthermore, the apparent activation energy of such a reaction approaches the standard enthalpy of reaction (DeltaH(0)), rather than the true activation energy of the chemical reaction. (C) 2004 Elsevier Ltd. All rights reserved.