Effects of potential models on nitrogen adsorption on triangular pore: energetic characterization of activated carbon

DELGADO MONS, R.; CORNETTE, VALERIA; TOSO, JUAN PABLO; LOPEZ, RAÚL H.

Buenos Aires

Conferencia; 27th IUPAP International Conference on Statistical Physics, StatPhys27; 2019

There is an increasing interest in developing better microporous materials due to multiple industrial applications like gas separation, purification and reaction processes. Hence, an appropriate characterization of porous carbons for their structural properties, such as pore size distribution (PSD) is an important issue. Measures of nitrogen adsorption are commonly used for the determination of the PSD of porous carbons. The calculation of these textural properties and, in particular of the PSD, depend largely upon the model used to represent the geometrical and physical characteristics of the porous space. In addition, calorimetric data provide another source of potential information to characterizing on the surface properties of adsorbents, the isosteric heat of adsorption is one of the most important quantities characterizing energetic heterogeneity of the adsorbent [1?8]. Our interest is two fold, on the one hand, we investigated the influence of both the shape of the adsorbate molecule (using a pseudo-sphere and a multi-site model potential) and the geometry of the adsorbent (triangular) in the processes of nitrogen adsorption. On the other hand, we also studied the best way to characterize energetically and texturally porous carbons using mixed geometry models incorporating multi-site potentials to model the interaction of nitrogen. Using Monte Carlo simulation it is possible to obtain a collection of adsorption isotherms (the local isotherms, θL) considering different pore sizes both for the slit and triangular geometries and two adsorbate models, which we term the independent pore model.This collection of local isotherms can be combined in different ways to fit a given experimental isotherm: (i) Model PSGM-1C: Pure slit pore geometry kernel using a pseudosphere model potential. (ii) Model PSGM-3C: Pure slit pore geometry kernel using a multi-site model potential (elongated shape). (iii) Model MGM-1C: a kernel of a mixture of the slit and triangular pores geometry modeling the interaction of the adsorbate by a pseudo-sphere potential model. (iv) Model MGM-3C: a kernel of a mixture of the slit and triangular pores geometry modeling the interaction of the adsorbate by a multi-site potential model.