RESUMEN
The pathways for the CO2 absorption and desorption in an aqueous solution of a heavily hindered alkanolamine, 2-(t-butylamino)ethanol (TBAE) were elucidated by X-ray crystallographic and (13)C NMR spectroscopic analysis. In the early stage of the CO2 absorption, the formation of carbonate species ([TBAEH]2CO3) was predominant, along with the generation of small amounts of zwitterionic species. With the progress of the absorption, the carbonate species was rapidly transformed into bicarbonate species ([TBAEH]HCO3), and the amounts of the zwitterionic species increased gradually. During desorption at elevated temperature in the absence of CO2, [TBAEH]HCO3 was found to transform into [TBAEH]2CO3, where CO3(2-) strongly interacts with two [TBAEH](+) via hydrogen bondings.
Asunto(s)
Aminas/química , Dióxido de Carbono/química , Agua/química , Absorción , Cristalografía por Rayos X , Etanol/química , Iones , Espectroscopía de Resonancia Magnética , Conformación Molecular , SolucionesRESUMEN
Despite the academic and industrial importance of the chemical reaction between carbon dioxide (CO(2)) and alkanolamine, the delicate and precise monitoring of the reaction dynamics by conventional one-dimensional (1D) spectroscopy is still challenging, due to the overlapped bands and the restricted static information. Herein, we report two-dimensional infrared correlation spectroscopy (2D IR COS) and principal component analysis (PCA) on the reaction dynamics of a sterically hindered amine, 2-[(1,1-dimethylethyl)amino]ethanol (TBAE) and CO(2). The formation of carbonate rather than carbamate species, which contribute to the unusual high working capacity of â¼1 mole CO(2) per mole of TBAE at 40 °C, occurs through deprotonation of the hydroxyl group, protonation on the nitrogen atom of the amino group, and formation of a carbonate species due to the steric hindrance of the tert-butyl group. In particular, PCA captures the chemical transition into a carbonate species and the main contributions of ν(CO(2)), ν(OH), ν(C - N), and ν(C=O) bands to the carbonation, while 2D IR COS verifies the interrelation of four bands and their changes. Therefore, these results provide a powerful analytic method to understand the complex and abnormal reaction dynamics as well as the rational design strategy for the CO(2) absorbents.
Asunto(s)
Alcoholes/química , Aminas/química , Dióxido de Carbono/química , Análisis de Componente Principal , Solubilidad , Espectroscopía Infrarroja por Transformada de FourierRESUMEN
Anomalous thermal transition and crystallization behaviors of three room temperature ionic liquids (RTILs) in graphene multilayers (GMLs), in a different manner to bulk RTILs, occurred due to the molecular orientation of the confined system triggered by the complex π-π stacking and hydrogen bonding interactions.