The microcatalytic technique applied to a zero order reaction: The dehydration of 2-butanol over hydroxyapatite catalysts

Abstract

A comparison has been made between microcatalytic and steady state flow reactor data for the dehydration of 2-butanol over a series of hydroxyapatite catalysts. The conventional steady state flow experiments revealed that the reaction was zero order in 2-butanol, but weakly inhibited by the product water. Unlike first order reactions, where identical results are derived from the two techniques, the microcatalytic results were not identical with those from the steady state experiments. Instead, they indicated that the surface-adsorbed species were not in equilibrium with the gas phase, and that products continued to desorb long after the gas pulse had passed. Thus, plots of conversion vs. reciprocal flow rate did not extrapolate to zero at infinite flow rate. Instead, the finite conversion intercept was a measure of the “site monolayer” from which products decsorbed very slowly. This fact was used to count the active sites for dehydration. Together, the two methods yield complementary information, not obtainable from one method alone. The design of a versatile, high-temperature, microcatalytic reactor is given.