Capture of carbon dioxide from flue gases by amine-functionalized TiO2 nanotubes

The novel carbon dioxide (CO2) adsorbents with high capture efficiency were prepared through impregnating TiO2 nanotubes (TiNT) with four kinds of amines, namely monoethanolamine (MEA), ethylenediamine (EDA), triethylenetetramine (TETA) and tetraethylenepentamine (TEPA), respectively. The samples were characterized by thermogravimetric analysis, low temperature N2 adsorption and transmission electron microscopy. CO2 capture was investigated in a dynamic packed column. The TEPA-loaded sample showed a better adsorption capacity due to its higher amino-groups content. In condition, TiNT-TEPA-69 shows the highest CO2 adsorption capacity among the four TEPA-loaded samples, approximately 4.37 mmol/g at 60 °C. The adsorption capacity was enhanced to 5.24 mmol/g under moisture conditions. TiNT-TEPA-69 was selected as adsorbent to study the adsorption/desorption behavior in the absence of moisture and in the presence of moisture. While the former is fairly stable after 5 adsorption/desorption cycles, the latter decreases dramatically.