title: CO2 Absorption in an Alcoholic Solution of Heavily Hindered Alkanolamine: Reaction Mechanism of 2-(tert-Butylamino)ethanol with CO2 Revisited.
abstract: To advance the optimal design of amines for postcombustion CO2 capture, a sound mechanistic understanding of the chemical process of amines with good CO2 capture performance is advantageous. A sterically hindered alkanolamine, 2-(tert-butylamino)ethanol (TBAE), in ethylene glycol (EG) solution was recently reported to have better CO2 capture performance and unusual reactivity toward CO2, in comparison with those of the prototypical alkanolamines. However, the reaction mechanism of TBAE with CO2 in EG solution is unclear. Here, various quantum chemistry methods were employed to probe the reaction mechanism of TBAE with CO2 in EG and aqueous solution. Six reaction pathways involving three kinds of possible reactive centers of TBAE solution were considered. The results indicated that the formation of anionic hydroxyethyl carbonate by the attack of -OH of EG on CO2 is the most favorable, which is confirmed by complementary high-resolution mass spectrum experiments. This clarified that the speculated zwitterionic carbonate species is not the main product in EG solution. The reaction process of TBAE in aqueous solution is similar to that in EG solution, leading to bicarbonate, which agrees with experimental observations. On the basis of the unveiled reaction mechanisms of TBAE + CO2, the role of the key tert-butyl functional group of TBAE was revealed.
authors.affiliation: †Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology and ‡State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, People's Republic of China.
authors.forename: Hong-Bin
authors.initials: HB
authors.lastname: Xie
authors.affiliation: †Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology and ‡State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, People's Republic of China.
authors.forename: Xiaoxuan
authors.initials: X
authors.lastname: Wei
authors.affiliation: †Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology and ‡State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, People's Republic of China.
authors.forename: Pan
authors.initials: P
authors.lastname: Wang
authors.affiliation: †Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology and ‡State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, People's Republic of China.
authors.forename: Ning
authors.initials: N
authors.lastname: He
authors.affiliation: †Key Laboratory of Industrial Ecology and Environmental Engineering (MOE), School of Environmental Science and Technology and ‡State Key Laboratory of Fine Chemicals, Dalian University of Technology, Dalian 116024, People's Republic of China.
authors.forename: Jingwen
authors.initials: J
authors.lastname: Chen