Toward the understanding of chemical absorption processes for post-combustion capture of carbon dioxide: electronic and steric considerations from the kinetics of reactions of CO₂(aq) with sterically hindered amines

Conway, William; Wang, Xiaoguang; Fernandes, Debra; Burns, Robert; Lawrance, Geoffrey; Puxty, Graeme; Maeder, Marcel

Title: Toward the understanding of chemical absorption processes for post-combustion capture of carbon dioxide: electronic and steric considerations from the kinetics of reactions of CO₂(aq) with sterically hindered amines
Creator: Conway, William; Wang, Xiaoguang; Fernandes, Debra; Burns, Robert; Lawrance, Geoffrey; Puxty, Graeme; Maeder, Marcel
Relation: Environmental Science & Technology Vol. 47, Issue 2, p. 1163-1169
Publisher Link: http://dx.doi.org/10.1021/es3025885
Publisher: American Chemical Society
Resource Type: journal article
Date: 2013
Description: The present study reports (a) the determination of both the kinetic rate constants and equilibrium constants for the reaction of CO₂(aq) with sterically hindered amines and (b) an attempt to elucidate a fundamental chemical understanding of the relationship between the amine structure and chemical properties of the amine that are relevant for postcombustion capture of CO₂ (PCC) applications. The reactions of CO₂(aq) with a series of linear and methyl substituted primary amines and alkanolamines have been investigated using stopped-flow spectrophotometry and ¹H NMR measurements at 25.0 °C. The specific mechanism of absorption for each of the amines, that is CO₂ hydration and/or carbamate formation, is examined and, based on the mechanism, the kinetic and equilibrium constants for the formation of carbamic acid/carbamates, including protonation constants of the carbamate, are reported for amines that follow this pathway. A Brønsted correlation relating the kinetic rate constants and equilibrium constants for the formation of carbamic acid/carbamates with the protonation constant of the amine is reported. Such a relationship facilitates an understanding of the effects of steric and electronic properties of the amine toward its reactivity with CO₂. Further, such relationships can be used to guide the design of new amines with improved properties relevant to PCC applications.
Subject: chemical absorption processes; post-combustion; carbon dioxide; amines
Identifier: http://hdl.handle.net/1959.13/1298777
Identifier: uon:19716
Identifier: ISSN:0013-936X
Language: eng
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