https://doi.org/10.1007/s12034-019-1936-8
“Amines are used to enhance the CO2CO2 adsorption from a gas stream. Primary and secondary amines react with CO2CO2 to form a zwitterion species (CO2+RNH2⇄RNH+2CO−2)CO2+RNH2⇄RNH2+CO2−). In the present study, four-different amines namely, MEA, EDA, DETA and TETA were considered to find the relative performance for CO2CO2 capture under similar operating conditions. Also, to study the impact on CO2CO2 capture capacity during amine loading, the experiments were conducted at four-different amine concentrations ranging between 5 and 40 wt% at a temperature of 30∘C30∘C and the outcomes are shown in figure 8. The result shows that the CO2CO2 capture capacity of the materials increased up to around 30% amine loading. However, a decrease in CO2CO2 capture capacity was noted when the amine impregnation increased beyond 30% for the present experimental conditions.”
“An increase in CO2CO2 capture capacity with amine loading in-spite of the decreased surface area and pore volume shows that the chemisorption dominated over physisorption. The reduction in CO2CO2 capture capacity beyond 30% amine impregnation may be due to blockage of pores, which hinders CO2CO2 molecules to reach near to the active sites for adsorption. The adsorption capacity of the TETA-modified zeolite increased rapidly compared to other three-amine-impregnated sorbents. This may be due to the availability of more number of basic sites for chemisorption of CO2CO2 with increased loading. TETA has four amino groups (two primary and two secondary amino groups). The result also shows that the capture capacity of CO2CO2 with the MEA-loaded absorbent is slightly higher than that with the EDA-loaded adsorbent. This may be due to the presence of the hydroxyl group in MEA, and which have the ability to form hydrogen bonding with the adsorbate.”