(499h) Effects of Flue Gas Contaminants, Regeneration Conditions, and Amine Modification on the Adsorption of Carbon Dioxide By MIL-101(Cr)

MIL-101(Cr) has drawn much attention in recent years due to its high stability compared with other metal-organic frameworks. In this study, three trace flue gas contaminants (H₂O, NO, SO₂) were each added to a 10 vol% CO₂/N₂ feed flow and found to have a minimal impact on the adsorption capacity of CO₂. In dynamic CO₂ regeneration experiments, complete regeneration occurred in 10 min at 328 K for temperature swing adsorption-N₂-stripping under a 50 cm³/min N₂ flow and at 348 K for vacuum-temperature swing adsorption at 20 KPa. Almost 99% of the pre-regeneration adsorption capacity was preserved after 5 cycles of adsorption/desorption under a gas flow of 10 vol% CO₂, 100 ppm SO₂, 100 ppm NO, and 10% RH, respectively. Strong resistance to flue gas contaminants, mild recovery conditions, and excellent recycling efficiency make MIL-101(Cr) an attractive adsorbent support for CO₂ capture. MIL-101(Cr) was functionalized with various amine (tetraethylenepentamine, pentaethylenehexamine and polyethyleneimine) to improve the ability of CO₂ adsorption. The amine-functionalized MIL-101(Cr) was characterized with various experimental methods including N₂ adsorption/desorption isotherms, X-ray diffraction, Fourier transform infrared and thermogravimetric analysis. Both the adsorption isotherms and the isosteric heats of different adsorption capacities were obtained from experiments. Avrami's fractional order kinetic model was selected to describe the CO₂ adsorption behavior. The adsorption capacity of amine-functionalized MIL-101(Cr) increased significantly.