Effect of mass transfer on the reaction rate in a monolithic catalyst with porous walls

The influence of reacting gas flow on the heterogeneous reaction in catalyst volume of honeycomb porous monolith with triangular channels was studied. The spatial distributions of the reacting gas flow, the rates of local mass transfer between channel walls and gas flow, as well as the interaction of transfer processes and a catalytic reaction were determined on the basis of the computational fluid dynamics. The reactions of deep oxidation and steam reforming of methane were considered as model reactions. It was shown that there is no stabilization of the reacting flow over the whole channel length under studied conditions. The most intensive changing of the gas streams appears near the channel inlet, which causes the highest local rates of interphase exchange processes, the rate difference is up to two orders of magnitude. A higher reaction rate exists in the initial part due to penetration of feed components into the catalyst volume through the frontal surface. This leads to increasing the effectiveness factor whose value is above unity near the channel inlet. The reaction rate limitation by the transport of reagents inside porous wall was observed along the monolith length.