Carbon dioxide transport in molten calcium carbonate occurs through an oxo-Grotthuss mechanism via a pyrocarbonate anion.
The reactivity, speciation and solvation structure of CO2 in carbonate melts are relevant for both the fate of carbon in deep geological formations and for its electroreduction to CO (to be used as fuel) when solvated in a molten carbonate electrolyte. In particular, the high solubility of CO2 in carbonate melts has been tentatively attributed to the formation of the pyrocarbonate anion, C2O5(2-). Here we study, by first-principles molecular dynamics simulations, the behaviour of CO2 in molten calcium carbonate. We find that pyrocarbonate forms spontaneously and the identity of the CO2 molecule is quickly lost through O(2-) exchange. The transport of CO2 in this molten carbonate thus occurs in a fashion similar to the Grotthuss mechanism in water, and is three times faster than molecular diffusion. This shows that Grotthuss-like transport is more general than previously thought.
Department of Chemistry, École Normale Supérieure - PSL Research University, 24 rue Lhomond, 75005 Paris, France.|Sorbonne Universités, UPMC Univ. Paris 06, PASTEUR, 75005 Paris, France.|CNRS, UMR 8640 PASTEUR, 75005 Paris, France.
Dario
D
Corradini
PSL Research University, Chimie ParisTech - CNRS, Institut de Recherche de Chimie Paris, 75005 Paris, France.
François-Xavier
0000-0001-5318-3910
FX
Coudert
Department of Chemistry, École Normale Supérieure - PSL Research University, 24 rue Lhomond, 75005 Paris, France.|Sorbonne Universités, UPMC Univ. Paris 06, PASTEUR, 75005 Paris, France.|CNRS, UMR 8640 PASTEUR, 75005 Paris, France.
Rodolphe
R
Vuilleumier