Application of thermogravimetry and differential scanning calorimetry for the evaluation of CO2 adsorption on chemically modified adsorbents

• The CO2 adsorption capacities and adsorption heats were studied using TG/DSC.
• The order of CO2 adsorption capacity of original adsorbents was zeolite > ACF > AC.
• The CO2 adsorption capacity of zeolite-K2CO3 was the highest.
• The alkaline modified zeolite could reduce the CO2 adsorption heat.
• Zeolite modified with alkaline agents provided weak adsorption sites for CO2.

Commercial adsorbents – zeolite, granular activated carbon (GAC), and activated carbon fiber (ACF) – were modified with various alkaline agents – NaOH, K2CO3, diethanolamine (DEA), 2-amino-2methyl-1-propanol (AMP), and monoethanolamine + AMP (MEA + AMP) – to improve CO2 adsorption. The CO2 adsorption capacities and heat of adsorption of various adsorbents were studied using thermogravimetry/differential scanning calorimetry (TG/DSC). The CO2 adsorption capacity of the original adsorbents was in the order zeolite > ACF > AC. The CO2 adsorption capacities of AC, ACF, and zeolite modified with NaOH and K2CO3 were higher than capacities of those modified with the other compounds. The CO2 adsorption capacity of zeolite–K2CO3 was the highest. Zeolite modified with alkaline agents provided weak adsorption sites for CO2 because of the decrease in the adsorption heat. Therefore, zeolite has a suitable pore volume and mesoporous structure for use as a support for loading inorganic alkaline agents for CO2 capture.