Probing local diffusion and reaction in a porous catalyst pellet

Abstract

In the present work, we report on the direct measurement of spatially resolved concentration profiles inside a single catalyst pellet under reaction conditions using a capillary sampling method. CO oxidation on a platinum-coated, porous alumina cylinder was chosen as test reaction system. CFD simulations were conducted to probe the invasiveness of the method, which turned out to be acceptable for practical application. Spatially resolved CO2 mole fraction profiles inside the particle are presented for different reaction conditions. Phenomena that result from the interplay between diffusion and reaction such as boundary layers, bifurcation, multiple steady states and kinetic oscillations are also shown. The method might allow the knowledge-based optimization of many industrial fixed-bed processes without requiring major changes to the process layout.