title: Comparison of Solvation Effects on CO2Capture with Aqueous Amine Solutions and Amine-Functionalized Ionic Liquids.
abstract: Amines are the most widely utilized chemicals for postcombustion CO2capture, because the reversible reactions between amines and CO2through their moderate interaction allow effective "catch and release". Usually, CO2is dissolved in the form of an anion such as carbamate or bicarbonate. Therefore, the reaction energy diagram is potentially governed to a large extent by the polarity of the surrounding solvent. Herein, we compared aqueous amine solutions and amine-functionalized ionic liquids by investigating their dielectric constants and performing an intrinsic reaction coordinate analysis of the CO2absorption process. Quantum mechanical calculations at the CCSD(T)/6-311++G(d,p)//B3LYP/6-311++G(d,p) level within the continuum solvation model (SMD/IEF-PCM) revealed contrasting dependencies of C-N bond formation on the dielectric constant in those solutions. Amines react with CO2on an energy surface that is significantly affected by the dielectric constant in conventional aqueous amine solutions, whereas amine-functionalized anions and CO2form stable C-N bonds with a comparatively lower activation energy regardless of the dielectric constant.
authors.affiliation: Research Institute of Innovative Technology for the Earth (RITE) , 9-2 Kizugawadai, Kizugawa, Kyoto 619-0292, Japan.
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Yamada