Necessary conditions for the existence of asymmetric composition and temperature profiles in catalyst pellets

Abstract

For a single irreversible chemical reaction in an infinite catalyst slab with a uniform environment, it is shown that temperature and composition profiles unsymmetric about the center plane of the slab may occur only when there are concentrated heat and mass transfer coefficients, the effective thermal conductivity and diffusion coefficient in the slab, and the heat of reaction. In particular, for a conventional irreversible reaction, it is found that asymmetric profiles may exist only if the reaction is exothermic and Sh′ > Nu′ where Sh′ and Nu′ are the modified Sherwood and Nusselt numbers.