文摘
Interactions between amines and carbon dioxide (CO2) are essential to amine-functionalized solid adsorbents for carbon capture, and an in-depth knowledge of these interactions is crucial to adsorbent design and fabrication as well as adsorption/desorption processes. The local structures of CO2 adsorbed on a tetraethylenepentamine-impregnated mesoporous silica SBA-15 were investigated by solid-state 13C{14N} S-RESPDOR MAS NMR technique and theoretical DFT calculations. Two types of adsorption species, namely, secondary and tertiary carbamates as well as distant ammonium groups were identified together with their relative concentrations and relevant 14N quadrupolar parameters. Moreover, a dipolar coupling of 716 Hz was derived, corresponding to a 13C鈥?sup>14N internuclear distance of 1.45 脜. These experimental data are in excellent agreement with results obtained from DFT calculations, revealing that the distribution of surface primary and secondary amines readily dictates the CO2 adsorption/desorption properties of the adsorbent.
Keywords:
carbon dioxide capture; adsorption; amine-impregnated mesoporous silica; solid-state NMR; DFT calculation; amine鈭扖O2 interaction