Amine-modified MCM-41 mesoporous silica for carbon dioxide capture

This paper presents an easy way to obtain a material with CO2 sorption properties by using commercially available MCM-41. In order to increase MCM-41 CO2 sorption capacity, 2.48 mmol g(-1), of amine groups were anchored onto silica surface. A few carefully chosen spectroscopic techniques - namely infrared diffuse reflectance spectroscopy and solid-state C-13 and Si-29 nuclear magnetic resonance - demonstrated that amino groups are covalently bounded to mesoporous silica and not just adsorbed on it. CO2 uptake by the samples was investigated by microcalorimetry experiments performed at 30 degrees C. The amine functionalized material, MCM-41-NH2, exhibited a higher uptake of CO2 at very low pressures compared with the nongrafted material. The modified material presented heat of adsorption of -98 versus -32 kJ mol(-1) for MCM-41 at low pressures. The mode of CO2 uptake in MCM-41-NH2 was both chemisorption at low pressures and physisorption at high pressures. Solid-state C-13 nuclear magnetic resonance performed on amine-functionalized MCM-41 after CO2 adsorption experiments, showed a signal attributed to carbamate that was formed as a product of the reaction between CO2 and amine groups. This material has potential for CO2 recovery at low pressures/concentrations. (C) 2011 Elsevier Inc. All rights reserved.