Monte Carlo simulation method for calculating pore size distributions from high-pressure CO2 adsorption in Micro-Mesoporous Carbons

Abstract

An original methodology is suggested for evaluating the pore size distribution in carbons in the wide range of micro- and mesopores from 0.385 to 10 nm from a single isotherm of high-pressure adsorption of CO2 at 273 K. The proposed method is based on the reference theoretical isotherms calculated by Monte Carlo simulations in model pores of slit and cylindrical geometry. The relationship between the pore size and the pore filling pressure is established. Special attention is given to predicting of the capillary condensation transitions in mesopores by using the meso-canonical ensemble (gauge cell) Monte Carlo simulations. The proposed technique is demonstrated and verified against the conventional N2 and Ar low temperature adsorption methods drawing on the example of micro-mesoporous carbons of the CMK family. Advantages and limitations of CO2 adsorption characterization of nanoporous materials are discussed and further improvements are proposed.