Equilibrium data of CO₂-based semi-clathrates from quaternary ammonium solutions

Amina Bouchemoua (1, 2, 3) , Pedro Brantuas (1, 2, 3) , Jean-Michel Herri (1, 2, 3)

1 SPIN-ENSMSE - Centre Sciences des Processus Industriels et Naturels
2 LPMG-EMSE - Laboratoire des Procédés en Milieux Granulaires
3 GENERIC-ENSMSE - Département Géochimie, environnement, écoulement, réacteurs industriels et cristallisation

CO₂ mitigation represents a major industrial and scientific challenge of this century, therefore CO₂ capture and sequestration is a route to solve a part of the problem, especially for the industries in which the gases to be treated are well localized. CO₂ capture by using hydrate formation has revealed to present an energetic interest because it is less intensive than other methods. In this process the cost of the separation is due to compression of gases to reach the gas hydrate formation conditions at which water and gas forms a solid that encapsulates preferentially CO₂. In fact, the hydrate formation requires high pressures and low temperatures, which explains the use of thermodynamic promoters to decrease the operative pressure. Quaternary ammoniums salts represent an interesting family of components because of their thermodynamic effect, but also because they can generate crystals that are easily handable. In this work, we have made experiments concerning the equilibrium of pure gas hydrates (CO₂, N₂ and CH₄) in presence of the tetra-n-butyl ammonium bromide (TBAB) and compared these data to literature. We have applied the Clausius-Clapeyron equation, to the results obtained and the literature data, thus observing that the hydrates have a pure component behavior. In the specific case of N₂-TBAB semi-clathrates, observations showed that the pressure is first order depending on the temperature only and independent from the TBAB concentration. For the CO₂-TBAB and CH₄-TBAB semiclathrates the results are different. In fact, the equilibrium pressure is clearly dependent on both the temperature and TBAB concentration, for that reason the constant B from the Clausius-Clapeyron equation becomes a function of the TBAB concentration. Another point of our investigation is the effect of other types of quaternary ammoniums to find an additive that allows the formation of hydrates close to room temperature and atmospheric pressure.

Mots clés: gas hydrates; quaternary ammoniums salts; CO2; CH4; N2; phase equilibrium

Domaines: Génie des procédés

Amina Bouchemoua, Pedro Brantuas, Jean-Michel Herri. Equilibrium data of CO₂-based semi-clathrates from quaternary ammonium solutions. 7th International Conference on Gas Hydrates (ICGH 2011), Jul 2011, Edimbourg, United Kingdom. pp.439. ⟨hal-00617481⟩