Modeling of Carbon Capture Process

An adsorbent’s desorption kinetics and adsorption capacity are key parameters in planning, modeling and designing direct air capture (DAC) systems. Determining these parameters reveals the thermodynamics requirements as well as the properties that favor the CO₂ adsorption process. This research work presents a review of prior research along with new experimental data on the desorption kinetics and adsorption capacity of activated carbon and zeolite for CO₂ capture. Commercial grade activated carbon and zeolite were studied by thermogravimetric analysis (TGA). Each adsorbent was subjected to four cycles with each cycle consisting of equilibration, adsorption and desorption. The adsorbents were studied at 0.04, 1, 3, and 5% of CO₂ concentration to evaluate the adsorption behavior with variable amount of CO₂ that are representative of DAC processes. At 0.04% of CO₂ concentration, activated carbon and zeolite were observed to have a desorption activation energy of 141.14 and 28.11 kJ/mol, respectively. Activated carbon and zeolite at a partial pressure of 0.04% CO₂ resulted in an adsorption capacity of 5.79 and 2.9 mg CO₂ /g, respectively. The TGA results from this study support efficient CO₂ adsorption processes are attained when employing higher partial pressure of CO₂.