Multi-component adsorption in heterogeneous carbonaceous porous media through the integration of small-scale, homogenous models

• A simplified multi-scale modeling approach to multi-component adsorption is developed.
• Extended Langmuir equation represents the adsorption isotherms in homogeneous pores.
• The methodology can estimate the transferable pore-size distributions
• Extended dual-site Langmuir equation is justified as a suitable macroscopic model

In this work, a simplified multi-scale modeling approach to multi-component adsorption is developed. A number of binary gas systems involving CO2, CH4 and N2 adsorbed on carbon pores are analyzed in three scales. Comprehensive molecular simulations at the microscopic level using the GCMC method are the basis for the validation of the simplified (mesoscopic-level) models for isotherms of homogenous adsorbent. The macroscopic models are then formulated through the integration of the smaller scale models. Three contributions are made in this work. Firstly, it is demonstrated that the form of extended Langmuir equation can represent adsorption isotherms, developed by GCMC simulation in homogeneous micro-pores under mono-layer adsorption. Secondly, the methodology for the estimation of transferable pore-size distributions using optimization algorithms is successfully provided that more than one single component adsorption isotherm is used in computations. Finally, the extended dual-site Langmuir equation is justified as a suitable macroscopic model for multi-component adsorption on heterogeneous porous media with parameters estimated from small-scale models.