GRAND CANONICAL MONTE CARLO SIMULATION-ASSITED PORE-WIDTH DETERMINATION OF MOLECULAR SIEVE CARBON BY USE OF AMBIENT TEMPERATURE N_2 ADSORPTION

摘要

Molecular sieve carbons (MSCs) are valuable materials for separation of gas mixtures or purification of gases. There are several trials to develop better MSC adsorbents by several methods such as chemical vapor deposition (CVD) or high temperature treatment. Therefore, characterization of the modified MSC has gathered a keen interest. The most reliable and well established method to determine the pore size distribution of microporous carbons stems from the analysis of N2 adsorption isotherm at 77K. However, the MSCs have ultramicropores of which width is presumed to be close to N_2 molecular diameter and the adsorbed molecules at the entrance of micropores hardly diffuse into the inside of ultramicropores at 77K, leading to a so called blocking effect at the pore entrance. In this work we propose a new approach to determine the width of ultramicropores using an experimental adsorption isotherm of N_2 at 303K with combination of grand canonical Monte Carlo (GCMC) simulation.