Aqueous amino acids are promising absorbents for direct air capture (DAC) of CO2. Herein, we investigate the possibility of kinetic control of CO2 absorption with aqueous anionic glycine (GLY-) by employing extensive ab initio molecular dynamics simulations, free energy analysis, and reaction rate theory. We find that first GLY- binds to CO2 by overcoming a barrier (7.4 kcal/mol) to form a zwitterion intermediate, which then releases a proton by overcoming a similar barrier. Despite the similarity in the barrier, zwitterion formation appears to be the rate-limiting step because it is two orders of magnitude slower (microseconds) than the proton release step. This is predominantly due to stronger nonequilibrium solvent effects for the former that cause many barrier-recrossing events and effectively slow down the reaction rate. Such a detailed fundamental understanding of the amino acid-based CO2-absorption mechanism and rates is key to improving the kinetic efficiency of DAC technology.
Ma, Xinyou, et al. "An <em>ab initio</em> free energy study of the reaction mechanism and rate-limiting steps of CO<sub>2</sub> capture by aqueous glycine." Cell Reports Physical Science, vol. 4, no. 11, Oct. 2023. https://doi.org/10.1016/j.xcrp.2023.101642
Ma, Xinyou, Bryantsev, Vyacheslav S., & Roy, Santanu (2023). An <em>ab initio</em> free energy study of the reaction mechanism and rate-limiting steps of CO<sub>2</sub> capture by aqueous glycine. Cell Reports Physical Science, 4(11). https://doi.org/10.1016/j.xcrp.2023.101642
Ma, Xinyou, Bryantsev, Vyacheslav S., and Roy, Santanu, "An <em>ab initio</em> free energy study of the reaction mechanism and rate-limiting steps of CO<sub>2</sub> capture by aqueous glycine," Cell Reports Physical Science 4, no. 11 (2023), https://doi.org/10.1016/j.xcrp.2023.101642
@article{osti_2224196,
author = {Ma, Xinyou and Bryantsev, Vyacheslav S. and Roy, Santanu},
title = {An <em>ab initio</em> free energy study of the reaction mechanism and rate-limiting steps of CO<sub>2</sub> capture by aqueous glycine},
annote = {Aqueous amino acids are promising absorbents for direct air capture (DAC) of CO2. Herein, we investigate the possibility of kinetic control of CO2 absorption with aqueous anionic glycine (GLY-) by employing extensive ab initio molecular dynamics simulations, free energy analysis, and reaction rate theory. We find that first GLY- binds to CO2 by overcoming a barrier (7.4 kcal/mol) to form a zwitterion intermediate, which then releases a proton by overcoming a similar barrier. Despite the similarity in the barrier, zwitterion formation appears to be the rate-limiting step because it is two orders of magnitude slower (microseconds) than the proton release step. This is predominantly due to stronger nonequilibrium solvent effects for the former that cause many barrier-recrossing events and effectively slow down the reaction rate. Such a detailed fundamental understanding of the amino acid-based CO2-absorption mechanism and rates is key to improving the kinetic efficiency of DAC technology.},
doi = {10.1016/j.xcrp.2023.101642},
url = {https://www.osti.gov/biblio/2224196},
journal = {Cell Reports Physical Science},
issn = {ISSN 2666-3864},
number = {11},
volume = {4},
place = {United States},
publisher = {Elsevier},
year = {2023},
month = {10}}
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Compute and Data Environment for Science (CADES); Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
Sponsoring Organization:
USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division (CSGB)