Study on the pulse reaction technique: IV. Pulse reaction kinetics coupled with a strongly adsorbed reactant

Abstract

Sometimes, a catalyst surface is covered by the reactant and the reaction rate appears to be of the zeroth-order with respect to the gas-phase concentration. A theoretical analysis of the pulse reaction kinetics of such a reaction has been made on the basis of a hypothetical isotherm consisting of two straight lines. The conversion in the pulse technique is always larger than that in the flow technique. The deviation from the flow technique decreases with a decrease in the catalyst volume, and the conversion becomes identical to that in the flow technique at a sufficiently small catalyst volume. The effect of the reciprocal flow rate is different from that of the catalyst volume, that is, the conversion at a sufficiently large flow rate is entirely different from that in the flow technique. The conversion significantly depends on the pulse width. It increases with a decrease in the pulse width, and becomes identical to that in the first-order reaction at a sufficiently small pulse width. It is noteworthy that the conversion is essentially independent of the initial concentration at a sufficiently small pulse width, because, sometimes, the conversion independent of the pulse size is regarded as an evidence of the first-order reaction.