Evaluation of Methods for Determining the Pore Size Distribution and Pore-Network Connectivity of Porous Carbons

Abstract

The pore size distribution (PSD) and the pore-network connectivity of a porous material determine its properties in applications such as gas storage, adsorptive separations, and catalysis. Methods for the characterization of the pore structure of porous carbons are widely used, but the relationship between the structural parameters measured and the real structure of the material is not yet clear. We have evaluated two widely used and powerful characterization methods based on adsorption measurements by applying the methods to a model carbon which captures the essential characteristics of real carbons but (unlike a real material) has a structure that is completely known. We used three species (CH4, CF4, and SF6) as adsorptives and analyzed the results using an intersecting capillaries model (ICM) which was modeled using a combination of Monte Carlo simulation and percolation theory to obtain the PSD and the pore-network connectivity. There was broad agreement between the PSDs measured using the ICM and the geometric PSD of the model carbon, as well as some systematic differences which are interpreted in terms of the pore structure of the carbon. The measured PSD and connectivity are shown to be able to predict adsorption in the model carbon, supporting the use of the ICM to characterize real porous carbons.

Structural prediction of graphitization and porosity in carbide-derived carbons

“…Improvements to the slit-pore model introduce defects [19] and/or three-dimensional networks. [20,21] More complex geometric methods employ fullerenic [22] or polymeric [23] fragments to create a three-dimensional structure.…”

Physicochemical Properties of Carbon Materials: A Brief Overview

“…The extent to which shielding occurs in a real pore network depends on the connectivity of the network, with the shielding effect being more pronounced for less well connected networks." This is an increasingly popular subject of computational simulations of varying degree of sophistication [175][176][177][178][179]. Often painstaking evaluation of the degree of pore accessibility using molecular probes of judiciously selected sizes has been useful both at a fundamental level [162,[180][181][182][183][184][185][186][187][188][189][190][191][192][193] and for the potential commercialization of carbon molecular sieves [194][195][196][197][198][199][200][201][202][203][204][205][206][207][208][209][210].…”

Pore wall thickness and interpore influence on adsorption of alkanes in carbons using explicit pore models

“…virtual porous carbons-VPC Biggs and Buts 2000 and reverse Monte Carlo models (Thomson and Gubbins 2000). Explicit model also are more general and have the advantage of giving a direct link between carbon structure and adsorption phenomena (Cai et al 2007;Do and Do 2006;Lucena et al 2010a). These are desirable attributes that can help molecular simulation techniques to become a practical and accessible tool for the experimental community (Maginn 2009).…”