An improved model for graphitized thermal carbon black: crystallite stacking model

Abstract

Adsorption of argon on graphite at 77K and 87K is commonly used as a reference for characterization of carbon materials and is typically studied in most molecular simulations with the solid-fluid potential energy 10-4-3 equation whose molecular parameters are suggested by Crowell and Steele. The Steele 10-4-3 potential model assumes graphite as a homogeneous flat surface[1], and therefore the simulated adsorption of argon on graphite is a progressive molecular layering process with an open space of infinite extent above the graphite surface. In reality, graphite is composed of nano-crystallites with narrow interstices between these crystallites [2] which enhances the solid-fluid potential field at the junction of these crystallites to induce the formation of condensate at pressures approaching the saturation vapour pressure. In this work, we propose a more realistic model of graphite as a crystallite stacking model to account for the contacts between nano-crystallites and we show that the simulation results of this new model can describe well the experimental data for argon adsorption on graphite at 77 K and 87 K. This is the first time in the literature that we are able to describe the formation of condensate in adsorption of gases on graphite at high loadings.