We investigate the influence of structural heterogeneity around the transport properties of simple gases in a Hybrid Reverse Monte Carlo (HRMC) constructed model of silicon carbide-derived carbon (SiC-DC). carbon dioxide using molecular dynamics simulation, based on a maximum in the variation of self-diffusivity with loading. A comparison of the MD simulation results with self-diffusivities from quasi-elastic neutron scattering (QENS) measurements and, with macroscopic uptake-based low-density transport coefficients, discloses the presence of internal barriers not captured in MD simulation and QENS experiments. Nevertheless, the simulation and macroscopic uptake-based diffusion coefficients agree within a factor of 2C3, indicating that our HRMC model structure captures most of the important energy barriers affecting the transport of CH4 in the nanostructure of SiC-DC. Introduction Understanding transport properties of fluid molecules in microporous materials is usually of great importance due to intriguing features SB 252218 of fluidic phenomena at the nanoscale.1?3 Many industrial and scientific applications such as gas storage and separation, petroleum refining, electrochemical energy storage, nanofluidics and materials testing require fundamental understanding of fluid properties in SB 252218 confined spaces. In recent years, there has been quick development of a variety of new microporous materials such as carbide derived carbons (CDC),4?7 carbon nanotubes,8,9 and metalCorganic frameworks (MOF),10?13 and enhanced desire for the complexity of the fluid transport in such nanostructures.1?3,14?17 Nevertheless, the transport properties of fluid molecules in such tight confinements are not very well understood. Established methods such as the dusty gas model (DGM)18 or Knudsen model have limited applications in nanoscale confinements,19,20 while Maxwell-Stefan type models21,22 disregard the effect of fluid inhomogeneities in combination adsorption,23 and more rigorous models based on the Boltzman equation rely on approximations24 that may not be accurate in thin nanopores.15 On the other hand, molecular dynamics simulation can in theory provide exact results for prediction of fluid properties in confined spaces based on appropriate potential models. Nevertheless, this type of simulation can potentially suffer from inadequacy of the pressure field used, lack of a realistic adsorbent model and requirement of large computational resources for capturing slow diffusion processes. This is particularly true in the case of disordered microporous materials, where diffusion of gas molecules takes place at considerably slow rates. The use of realistic structures is, however, now within reach, with the development of the hybrid reverse Monte Carlo (HRMC) simulation method.25?31 You will find relatively few diffusion studies based on realistic disordered adsorbent models in the literature. Notable among these is the work of Moore et al. who analyzed diffusion of argon in a disordered BPL carbon model,26 and those reported earlier by Gubbins and co-workers27,28,30,32 on diffusion of argon and nitrogen SB 252218 in structural model of saccharose based porous carbons, as well as a more recent study conducted by Nguyen and Bhatia on anomalies of water self-diffusion in the disordered structure of activated carbon.33 TSPAN11 A key advance achieved by using realistically constructed models of disordered materials, as opposed to SB 252218 idealized slit pore or crystalline models for diffusion studies of fluid molecules, is to address the significant influence of surface and structural heterogeneity on transport properties of adsorbed molecules. The effect of energy distribution arising from the micropore size distribution is already shown to be the source of system heterogeneity in activated carbon materials.34,35 Moreover, the surface roughness of the adsorbent is known to have influence on surface diffusion of microporous solids.36 Both of these features, that is, surface roughness and micropore size distribution, have been found to exist in the amorphous structure of silicon carbide derived carbon (SiC-DC),25 and may be expected to be inherent to carbide derived carbons in general. It is therefore important that effects of structural.