3 research outputs found
Phase equilibrium of CP-CO<sub>2</sub> hydrate in the presence of salts: Experimental measurements and modeling
No full textWebinaire - En cette année 2020 un peu particulière, la journée scientifique s'est tenu sous la forme d’un webinaire organisé par le site clermontois représenté par l’Institut Pascal (IP).National audienceThe shortage of fresh water is one of the grand challenges that humans are facing. That requires the advent of seawater desalination and water treatment technology. As a promising novel method, the hydrate-based desalination has been developed and achieved considerable milestones in the past few years. However, the experimental data are still limited in the open literature. Therefore, in this study, thermodynamic equilibrium data of mixed CO2-Cyclopentane (CP) hydrates in the presence of salts were investigated. In particular, MgCl2 and CaCl2, which are dominant cations in water caused hard water
Investigation of [BMIM]FeCl<sub>4</sub> ionic liquid as an additive for carbon capture using gas hydrates with seawater
No full textInternational audienceCarbon 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
Phase equilibrium and dissociation enthalpies of CO<sub>2</sub>/cyclopentane hydrates in presence of salts for water treatment and CO<sub>2</sub> capture: New experimental data and modeling
No full textInternational audienceThe applications of clathrate hydrates on carbon dioxide capture and desalination is an attractive and growing subject within the hydrate community. While many promoters exists to overcome the numerous issues of hydrate-based technologies (mostly how to mild the operating conditions and improve the kinetics), there is a need to find a guest that could be recovered easily. That is why cyclopentane (CP), an organic molecule not miscible into water that can form hydrates under atmospheric pressure at 7 °C, has been studied widely in the literature. However, its behavior in forming mixed hydrates with CO2 in presence of salts is still not well understood. This work is an effort to investigate the thermodynamics of mixed CO2/CP hydrates to fulfill the gap in this field from a thermodynamic point of view. In this effort, new equilibrium data of mixed CO2/CP hydrates in the presence of salts (NaCl-KCl, MgCl2, CaCl2 which are among the main factors of hard water) have been obtained under different concentrations and pressures. Final dissociation points and as well as intermediate metastable points were obtained. Furthermore, thermodynamic consistency tests have been performed on our data and literature data to discuss their reliability. This test is important to question the idea of thermodynamic equilibrium since we suspect from a previous work the formation of several hydrate structures. Finally, three modeling approaches were considered: van der Waals and Platteeuw (vdW-P) approach, Hu-Lee-Sum (HLS) correlation, and ice melting point method derived from HLS proposition. Results showed a greater inhibition effect of cation Ca2+ compared to Mg2+ and that vdW-P method can predict equilibrium temperature within 0.2 °C uncertainty
