(572a) Reaction-Enhanced Diffusion

A Smoluchowski level model is developed and used to predict that reaction-enhanced diffusion can result from the diffusiophoretic-like motion of a catalyst particle in response to the reaction-induced concentration gradients of reactant and/or product species. The theory predicts that the enhanced diffusivity scales with the the concentration of reactant species with a coefficient that depends subtly on the interplay between the reactant/product diffusivities, whether or not the reactants/products are attracted/repelled by the catalyst particle, and the relative importance of the rate of reaction to diffusion. The catalyst diffusion can be either be enhanced or hindered. The predictions of the theory are consistent with the available experimental data.