Carbamate stabilities of sterically hindered amines from quantum chemical methods: Relevance for CO2 capture

Abstract

The influence of electronic and steric effects on the stabilities of carbamates formed from the reaction of CO2 with a wide range of alkanolamines was investigated by quantum chemical methods. For the calculations, B3LYP, M11-L, MP2, and spin-component-scaled MP2 (SCS-MP2) methods were used, coupled with SMD and SM8 solvation models. A reduction in carbamate stability leads to an increased CO2 absorption capacity of the amine and a reduction of the energy required for solvent regeneration. Important factors for the reduction of the carbamate stability were an increase in steric hindrance around the nitrogen atom, charge on the N atom and intramolecular hydrogen bond strength. The present study indicates that secondary ethanolamines with sterically hindering groups near the N atom show significant potential as candidates for industrial CO2-capture solvents. Get in my way! Steric hindrance around the amine group of secondary alkanolamines provides fine-tuning to optimize the carbamate stability as, for example, relevant for CO2 capture. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.