Characterization of the PSD of activated carbons by a heterogeneity model: Surface Defects in form of Geometric Rugosity

J.C.A DE OLIVEIRA; D.A. SOARES MAIA; K. SAPAG; R.H. LOPEZ; C.L. CAVALVANTE JR; D.C.S. AZEVEDO; G. ZGRABLICH

Delray Beach

Workshop; 6th International Workshop-Characterization of Porous Materials (CPM-6); 2012

Quantachrome Instrument

The separation of gas mixtures by adsorption is an important process in many industrial and environmental applications. The selective adsorption of CO2 from combustion gas mixtures on activated carbons depends strongly from the Pore Size Distribution (PSD). The PSD also determines properties like the specific surface and the micropore volume. The proposed model calculates the PSD taking into account the defects in form of geometrical rugosity in the inner surface of each graphitic slit pore. It was found, by mixing a complete series of heterogeneous pores with 25% of repulsive sites, a noticeable improvement in the fitting between the theoretical and the experimental N2 isotherms for carbon molecular sieves samples. In this study, it was particularly examined the effects of surface rugosity in the determination of the PSD for a controlled series of microporous carbons from peach stones as the precursor material. It was used to obtain the PSDs of the samples, on the basis of Grand Canonical Monte Carlo (GCMC) simulated isotherms, from adsorption of N2 at 77 K and of CO2 at 273 K. These results were also compared with different models of heterogeneity, like the Quenched Solid Density Functional Theory (QSDFT) and the Mixed Geometry Model (MGM) in order to test the self-consistency and robustness of the proposed model.