Comparing physisorption and chemisorption solid sorbents for use separating CO2 from flue gas using temperature swing adsorption

Abstract

We have examined the capture of carbon dioxide from flue gas by adsorption on solid sorbents using an equilibrium model for a packed bed temperature swing adsorption (TSA) process for a wide range of sorbents. This model determines the working capacity of the sorbent by looking at the difference between the equilibrium adsorbed concentrations at the adsorption and desorption conditions, and uses the sensible and latent heating requirements to determine the minimum energy usage. Using the results of this model, a class of sorbents can be constructed that have nearly identical physical properties but variable heats of adsorption for carbon dioxide to mimic different adsorption mechanisms. Parametric studies are run to determine the calculated minimum energy requirements per ton of carbon dioxide captured for this class of sorbents and a global minimum is found. This paper also discusses the effect of heat of adsorption on adsorption isotherms and what isotherm shapes are most beneficial for minimizing energy usage in carbon capture.