Solubility of CO₂ in Aqueous Formic Acid Solutions and the Effect of NaCl Addition: A Molecular Simulation Study

Abstract

There is a growing interest in the development of routes to produce formic acid from CO2, such as the electrochemical reduction of CO2 to formic acid. The solubility of CO2 in the electrolyte influences the production rate of formic acid. Here, the dependence of the CO2 solubility in aqueous HCOOH solutions with electrolytes on the composition and the NaCl concentration was studied by Continuous Fractional Component Monte Carlo simulations at 298.15 K and 1 bar. The chemical potentials of CO2, H2O, and HCOOH were obtained directly from single simulations, enabling the calculation of Henry coefficients and subsequently considering salting in or salting out effects. As the force fields for HCOOH and H2O may not be compatible due to the presence of strong hydrogen bonds, the Gibbs–Duhem integration test was used to test this compatibility. The combination of the OPLS/AA force field with a new set of parameters, in combination with the SPC/E force field for water, was selected. It was found that the solubility of CO2 decreases with increasing NaCl concentration in the solution and increases with the increase of HCOOH concentration. This continues up to a certain concentration of HCOOH in the solution, after which the CO2 solubility is high and the NaCl concentration has no significant effect.

Carbonation in Low-Temperature CO2 Electrolyzers: Causes, Consequences, and Solutions

“…Creative GDE designs will be of paramount importance to overcome the flooding problem. , Multiscale/multiphysics modeling: CO2R at the electrode is a complex phenomenon that involves multiple phases (gas/liquid/solid) and reactions (homogeneous and heterogeneous), which are affected by the presence of electrolytes and electric field. Advanced modeling of the near-electrode and membrane environment will provide useful insights into the carbonation phenomena that is affected by mass transport, electrochemical and homogeneous reactions, and thermal effects. − Moreover, advanced thermodynamic modeling using electrolyte equations of state and molecular simulation are essential for predicting the key thermodynamic, transport, and structural properties of the relevant liquid systems. − Such properties are the mutual solubilities (e.g., gases in the aqueous electrolyte phase), transport coefficients (i.e., Maxwell-Stefan and self-diffusivities, ionic conductivities, viscosity), and partial molar properties. − Electrolyte-free electrolysis: The presence of electrolytes in CO 2 electrolyzers has several disadvantages. First, liquid products are contaminated with the electrolytes, which complicate the downstream process.…”

The Impact of Metal Centers in the M-Mof-74 Series on Carbon Dioxide and Hydrogen Separation

“…This approach is elaborated and results in many fitting parameters of the force field, possibly leading to lower transferability. An attempt to reproduce experimental data on adsorption of H 2 in M-MOF-74 [51] was made in the study of Pham et al [23], where the Buch model [69], Belof Stern Space model [70], Darkrim-Levesque model [71] [74] validated in our previous studies [60,75] remains a separated subject of our future research.…”

A Strategy for Enhanced Carbon Storage: A Hybrid CO2 and Aqueous Formate Solution Injection to Control Buoyancy and Reduce Risk

“…Where the caprock cannot be effective, additional control over the CO2 buoyancy is desired to support the discontinuous geologic barriers. Some authors have worked with aqueous solutions based on formic acid [17] to enhance the CO2 solubility in brine or on formate ions [18,19] to enhance the pore-space utilization in carbon storage while avoiding various issues with CO2 storage. Additional benefits of the formate solution have been found for carbonate rocks concerning the wettability alteration to enhance oil recovery [18,[20][21][22].…”