The Center for Microfibrous Materials Manufacturing at Auburn University has developed a new class of composite materials consisting of adsorbent/reactant particles embedded in a matrix of sinter-bonded micro-fibers with diameters of order 100 and 10 µm, respectively. These materials have demonstrated remarkable chemical reactivity properties, enhancing net reaction rates by up to a factor of five. Classical chemical engineering approaches do not accurately predict the reactive flow characteristics. Computational Fluid Dynamics (CFD) is being used to analyze the flow through these materials and to investigate the underlying mechanisms behind the enhancement in chemical reactivity. One of the effects of the microfibrous matrix is to physically separate the particles, thus allowing much smaller particles to be used compared to a standard packed bed. In order to study the effect of particle separation on chemical conversion rates, packed beds are diluted with void, diluted with inert particles, and diluted with inert fibers. The effects of different types of dilution on chemical conversion are studied by varying the dimensionless numbers which characterize different gas-phase reactions: viscosity, diffusivity, and reaction rates. The dimensionless numbers that are varied in this study are Reynolds number, Peclet number, and Damkohler number.