New Virial-Type Model for Predicting Single- and Multicomponent Isosteric Heats of Adsorption

• Published in: Industrial & engineering chemistry research 1998-02, Vol.37 (2), p.684-696
• Main Authors: Al-Muhtaseb, Shaheen A, Ritter, James A
• Format: Article
• Language: English
• Subjects: Chemical thermodynamics; Chemistry; Exact sciences and technology; General and physical chemistry; General. Theory; Solid-gas interface; Surface physical chemistry
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie970577y

The virial isotherm for single- and multicomponent gas adsorption equilibria was used to derive a new predictive model for the isosteric heat of adsorption. The virial coefficients were considered with two different orders of temperature dependencies. The coefficients with a first-order dependence of the temperature reciprocal showed that the single-component isosteric heat of adsorption is temperature independent. However, those with second-order dependence of the temperature reciprocal showed that the single-component isosteric heat of adsorption can vary significantly with temperature. The latter form also showed when lateral or vertical interactions dominated. Both types of coefficients showed a significant temperature dependence of the multicomponent isosteric heat of adsorption. Differences between single- and multicomponent isosteric heats of adsorption, compared at the same temperature and partial loading, also increased with decreasing adsorbed phase mole fraction, decreasing temperature, higher adsorption affinity, and increasing nonideality.