2024 AIChE Annual Meeting

(346e) Choice of Reference State for Adsorption Thermodynamics

Authors

Sasidhar Gumma - Presenter, Indian Institute of Technology Tirupati
Orhan Talu, Cleveland State University
The choice of a reference state for reporting adsorption equilibrium data in porous solids has been an ongoing debate in the adsorption community for a long time. Prof Myers has authored several manuscripts on this topic that identify the challenges and summarize the benefits of using various frameworks for measurement and reporting of equilibrium capacity and adsorption enthalpies.

In this paper, we will revisit some of the ideas from Myers’ earlier works on the choice of reference state for Gibbs’ dividing surface and its implications on reporting of adsorption equilibrium. We will summarize the advantages and benefits of each one of these reference states. In particular, we concentrate on two important quantities (a) differential enthalpy of adsorption (isosteric heat) that can be derived from modelling of experimental measurements via the Clapeyron equation and (b) adsorption selectivity which may vary widely based on the choice of reference state. We would also demonstrate that a suitably chosen reference state allows one to readily relate the thermodynamic quantities in the framework to the experimental measurements and/or molecular simulation results.