Comparison of nitrogen and carbon dioxide as molecular probes of low surface area carbonaceous materials

Abstract

We investigate the pore size distributions obtained from the inversion of the adsorption integrals of nitrogen and carbon dioxide on low surface area (-20 m 2 .g -1 ) and medium surface area (∼70 m 2 .g -1 ) carbonaceous materials. Simple single-site (SS) Lennard-Jones models and multiple-site (MS) models incorporating partial charges have been compared for each probe gas. The multiple-site model produced an improved fit for the nitrogen isotherm compared to the single-site model, while the carbon dioxide isotherm was equally well matched by both models. The pore size distribution obtained from the carbon dioxide isotherm was able to successfully predict the nitrogen adsorption isotherm up to moderate pressures for both materials.