An ab initio free energy study of the reaction mechanism and rate-limiting steps of CO2 capture by aqueous glycine

Xinyou Ma; Vyacheslav S. Bryantsev; Santanu Roy

doi:10.1016/j.xcrp.2023.101642

An ab initio free energy study of the reaction mechanism and rate-limiting steps of CO₂ capture by aqueous glycine

Xinyou Ma, Vyacheslav S. Bryantsev, Santanu Roy

Research output: Contribution to journal › Article › peer-review

5 Scopus citations

Abstract

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.

Original language	English
Article number	101642
Journal	Cell Reports Physical Science
Volume	4
Issue number	11
DOIs	https://doi.org/10.1016/j.xcrp.2023.101642
State	Published - Nov 15 2023

Funding

All authors were supported by the US Department of Energy , Office of Science , Office of Basic Energy Sciences , Chemical Sciences , Geosciences , and Biosciences Division , Separation Sciences . This work was produced by UT-Battelle LLC under contract no. DE-AC05-00OR22725 with the US Department of Energy. This research used resources of the Compute and Data Environment for Science ( CADES ) at the Oak Ridge National Laboratory , which is supported by the Office of Science of the US Department of Energy under contract no. DE-AC05-00OR22725 . Additionally, this research used resources of the National Energy Research Scientific Computing Center ( NERSC ), a US Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory , operated under contract no. DE-AC02-05CH11231 . All authors were supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division, Separation Sciences. This work was produced by UT-Battelle LLC under contract no. DE-AC05-00OR22725 with the US Department of Energy. This research used resources of the Compute and Data Environment for Science (CADES) at the Oak Ridge National Laboratory, which is supported by the Office of Science of the US Department of Energy under contract no. DE-AC05-00OR22725. Additionally, this research used resources of the National Energy Research Scientific Computing Center (NERSC), a US Department of Energy Office of Science User Facility located at Lawrence Berkeley National Laboratory, operated under contract no. DE-AC02-05CH11231. The authors thank Ms. Diāna Stamberga (ORNL) for her help with preparing Scheme 1 and Dr. Dengpan Dong (ORNL) for pre-equilibrating the initial snapshots for AIMD using classical molecular dynamics simulations. This manuscript has been authored in part by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the US Department of Energy (DOE). DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan (http://energy.gov/downloads/doepublic-access-plan). S.R. and V.S.B. designed the project. X.M. performed AIMD simulations and trajectory analysis. All authors contributed to writing and proofreading the manuscript. All authors declare no financial or non-financial competing interests.

Keywords

AIMD
CO
direct air capture
enhanced sampling
reaction kinetics
transition state theory

UN SDGs

This output contributes to the following UN Sustainable Development Goals (SDGs)

Access to Document

10.1016/j.xcrp.2023.101642

Cite this

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title = "An ab initio free energy study of the reaction mechanism and rate-limiting steps of CO2 capture by aqueous glycine",

abstract = "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.",

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