Greenhouse gas emissions are the major cause of climate change, and tremendous efforts have been put in carbon capture and storage development to reduce emissions or atmospheric concentrations of CO2 that is the primary greenhouse gas. Monoethanolamine (MEA) is a commercially available and most frequently used CO2 solvent in post-combustion capture, however it suffers from thermal and chemical degradation and high energy production cost. Phosphoenolpyruvate (PEP) found in C4 plants could be a novel green absorbent in biomimetic carbon capture through its Crassulacean Acid Metabolism (CAM) mechanism, and could potentially substitute the most commonly used absorbent MEA in future post-combustion capture systems. In this study, a new ReaxFF model has been developed to describe the CAM reactions involving PEP and the atomic interactions in the P/C/O/H system. 2nd generation water parameters were combined with P/C parameters for more accurate water description and P’s electrostatic parameters were specially treated to correct P/O interactions. The developed P/C/O/H ReaxFF model was able to predict partial charges, molecular structures, bond dissociation energies, reaction energies and activation energies of the molecules and reactions involved in the CAM process, and accurately describe the aqueous bicarbonate and PEP systems. Molecular dynamics simulation using this ReaxFF model depicts how bicarbonate reacts with PEP in solution and determines the impact of local structure on reactions necessary to perform carbon capture using PEP, which enables the potential design of PEP variant as the optimal carbon capture absorbent.

Aqueous Phosphoenolpyruvate as a Novel Biomimetic Carbon Capture Absorbent and its ReaxFF Model Development

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