A novel gravimetric method for characterization of nanoporous materials using CO₂

Abstract

Nanoporous materials are widely used in applications such as gas storage, catalysis, and separation processes, where accurate characterization of pore structure is essential. This study presents a novel gravimetric method that utilizes carbon dioxide (CO₂) as a probe gas for determining surface area, pore volume, and pore size distribution. Unlike traditional nitrogen (N₂) adsorption techniques, which rely on volumetric measurements at cryogenic temperatures and are limited by low saturation pressure and larger molecular size, this method operates at near-ambient temperatures and elevated pressures, leveraging CO₂'s smaller kinetic diameter and higher adsorption energy to achieve improved pore accessibility. The adsorption data, obtained using both gravimetric and volumetric methods, were analyzed and used to calculate the characterization parameters for six samples of MCM-41 and SBA-16. These measurements were further validated through complementary characterization techniques, including high-resolution transmission electron microscopy (HRTEM) and X-ray diffraction (XRD). The results demonstrate the superior precision of the gravimetric method in capturing fine structural details and show encouraging agreement with vendor-supplied specifications. This highlights the potential of the proposed method for use in broad applications such as gas storage, energy, and environmental technologies.