The Effect of Catalyst Layer Thermal Gradients On Catalyst Efficiency in Wall-Coated Microreactors

Microreactors can be used to reform hydrocarbons to produce hydrogen for use in a fuel cell for portable power via heat-exchanger reactor configurations. In such a design, the reactor consists of endothermic reaction channels coupled in parallel with combustion channels to supply heat. This heat-exchanger reactor configuration can result in significant thermal gradients between reactor channels which are expected to be focused primarily within the catalyst coating itself. An accurate catalyst model must therefore be developed which determines the dependence of catalyst efficiency on not only the classical considerations of transport limitations within the catalyst but also on the presence of an externally-forced thermal gradient across the catalyst layer.

The governing differential equations have been developed to numerically model the effect of thermal gradients across the catalyst layer on catalyst performance in wall-coated microreactors. The equations have been rendered dimensionless in order to allow for applicability to any reaction conditions. Modeling results show that catalyst layer thermal gradients have a significant impact on catalyst efficiency and selectivity. The proper implementation of accurate modeling results will allow for enhanced thermal management and an increase in overall reactor performance.