title: Catalytic conversion reactions mediated by single-file diffusion in linear nanopores: hydrodynamic versus stochastic behavior.
abstract: We analyze the spatiotemporal behavior of species concentrations in a diffusion-mediated conversion reaction which occurs at catalytic sites within linear pores of nanometer diameter. Diffusion within the pores is subject to a strict single-file (no passing) constraint. Both transient and steady-state behavior is precisely characterized by kinetic Monte Carlo simulations of a spatially discrete lattice-gas model for this reaction-diffusion process considering various distributions of catalytic sites. Exact hierarchical master equations can also be developed for this model. Their analysis, after application of mean-field type truncation approximations, produces discrete reaction-diffusion type equations (mf-RDE). For slowly varying concentrations, we further develop coarse-grained continuum hydrodynamic reaction-diffusion equations (h-RDE) incorporating a precise treatment of single-file diffusion in this multispecies system. The h-RDE successfully describe nontrivial aspects of transient behavior, in contrast to the mf-RDE, and also correctly capture unreactive steady-state behavior in the pore interior. However, steady-state reactivity, which is localized near the pore ends when those regions are catalytic, is controlled by fluctuations not incorporated into the hydrodynamic treatment. The mf-RDE partly capture these fluctuation effects, but cannot describe scaling behavior of the reactivity.
authors.affiliation: Ames Laboratory-USDOE, Iowa State University, Ames, Iowa 50011, USA.
authors.forename: David M
authors.initials: DM
authors.lastname: Ackerman
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Wendel
authors.forename: Da-Jiang
authors.initials: DJ
authors.lastname: Liu
authors.forename: Marek
authors.initials: M
authors.lastname: Pruski
authors.forename: James W
authors.initials: JW
authors.lastname: Evans