Investigation of [BMIM]FeCl4 ionic liquid as an additive for carbon capture using gas hydrates with seawater

Abstract

Carbon capture through gas hydrate formation represents a highly promising avenue for mitigating greenhouse gas emissions. The unique structure of gas hydrates allows for the efficient trapping of gases like CO₂, potentially offering a robust solution for carbon sequestration. However, the practical implementation of this technology faces several challenges, primarily related to the kinetics of hydrate formation and the stability of hydrates under varying conditions. The use of promoters has shown potential in overcoming some of these kinetic barriers. A few years ago, iron-based ionic liquids were studied as kinetic promoters for gas hydrates. Since hydrate formation kinetics pose a well-known challenge for developing hydrate-based technologies, this study aims to evaluate the effectiveness of [BMIM]FeCl₄ ionic liquid for carbon capture from seawater. The research is divided into three stages: analyzing the influence of NaCl concentration on the liquid–liquid equilibrium of brine and ionic liquids; examining the thermodynamic equilibrium of CO₂ hydrates in the presence of seawater and ionic liquids; and investigating the kinetics of hydrate formation. The first stage produced a two-phase ternary diagram relevant to expected industrial conditions, and the kinetic constants for gas-to-liquid and liquid-to-hydrate mass transfer were estimated. The results demonstrated a thermodynamic inhibition effect for CO₂ hydrates. However, from a kinetic perspective, no significant improvement was observed. Consequently, [BMIM]FeCl₄ did not prove to be an effective overall promoter.