Morphologically disordered pore model for characterization of micro-mesoporous carbons

Abstract

We present a new morphologically disordered slit-shaped pore (MDSP) model for simulating gas adsorption in micro-mesoporous carbonaceous materials. The MDSP model qualitatively accounts for the inherent roughness of carbon pore walls in accord with the atomistic structural model of LMA10 reference carbon material. The MDSP model is applied to pore size distribution (PSD) calculations from nitrogen adsorption isotherms measured at 77.4 K in the range of pore widths from 0.72 to 40 nm. The MDSP model improves significantly the nitrogen adsorption porosimetry and, being fully atomistic, it is transferable to study various adsorbate-adsorbent systems. Computations of PSD functions for a series of carbonaceous materials, including activated carbon fiber, granular activated carbons, synthetic activated carbons showed that MDSP generates smooth Gaussian-type PSD functions with a well-defined average pore size. Furthermore, PSD functions computed from the MDSP model are free from the artificial gaps in the region of narrow micropores (∼1 nm and ∼2 nm) predicted from the standard slit-shaped pore models with ideal graphite-like walls. MDSP is not only a complementary model to existing approaches, such as quench-solid density functional theory method, but it paves the way to efficient atomistic simulations of various compounds within morphologically disordered carbon nanopores.