A New Analytical Isotherm Equation for Adsorption on Heterogeneous Adsorbents

A new analytical isotherm equation is derived to describe the adsorption of gases on energetically heterogeneous surfaces. It is assumed that the local isotherm for a specific site is given by the Jovanovic model, and the distribution of energetically different sites is represented by a modified Morse-type energy distribution function. The model has four parameters, the saturation adsorption capacity and three energy distribution parameters. All the model parameters are related to the Henry’s law constant. The new isotherm equation was tested against published equilibrium adsorption data on several hydrocarbon-silica gel, hydro-carbon-activated carbon, and hydrocarbon-zeolite systems at different temperatures and pressures. The new model provides an accurate and simple description of adsorption of gases on heterogeneous adsorbents, and gives an excellent correlation of the experimental adsorption data for the systems tested. © 1990, Taylor & Francis Group, LLC. All rights reserved