A Weakly Coordinating Anion Substantially Enhances Carbon Dioxide Fixation by Calcium and Barium Salts

TL;DR

This study demonstrates that calcium and barium salts with a weakly coordinating anion significantly improve CO2 fixation capacity, surpassing traditional carbonate methods, as shown through advanced simulations.

Contribution

It introduces a novel approach using weakly coordinating anions with alkaline earth salts to enhance CO2 capture, validated by computational methods.

Findings

Calcium salt captures 5.5 CO2 molecules per mole.

Barium salt captures 3.6 CO2 molecules per mole.

Electrostatic binding is more promising than carbonate formation.

Abstract

Carbon dioxide fixation and storage constitute a drastically important problem for the humanity nowadays. We hereby publish a new solution based on the alkaline earth salts with a weakly coordinating anion, tetrakis(pentafluorophenyl)borate. The proposed solution was validated using a robust combination of global minimum search and molecular dynamics simulations utilizing a well-tested, reliable semiempirical Hamiltonian to monitor chemical reactions. Calcium tetrakis(pentafluorophenyl)borate captures 5.5 CO2 molecules per mole, whereas barium tetrakis(pentafluorophenyl)borate captures 3.6 CO2 molecules per mole. These capacities are much higher, as compared to the established carbonate technology, which fixes only one CO2 molecule per one metal atom. The conducted simulations reveal that electrostatic binding of CO2 to alkaline earth cations is more technologically interesting than formation of carbonate salts. Our simulation results can be directly validated by sorption measurements.