Phase equilibria of mixed carbon dioxide and tetrahydrofuran hydrates in sodium chloride aqueous solutions

Khalik M. Sabil, Geert-Jan Witkamp, Cor J. Peters*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

26 Scopus citations

Abstract

In this work, the competing effects of sodium chloride (NaCl) and tetrahydrofuran (THF) on carbon dioxide hydrate formation are investigated through phase equilibrium measurements. The phase behaviour in the hydrate forming region for the binary system carbon dioxide-water, the ternary systems carbon dioxide-tetrahydrofuran-water and ternary carbon dioxide-sodium chloride-water and, in addition, the quaternary system carbon dioxide-tetrahydrofuran-water-sodium chloride are determined experimentally, using a Cailletet apparatus. All measurements are made in a temperature and pressure region of 275-290 K and 0.5-7.0 MPa, respectively. In these ranges, three different hydrate equilibrium curves are measured namely: H-LW-V, H-LW-LV-V and H-LW-LV. The formation of an organic-rich liquid phase in the systems due to a liquid-liquid two-phase split between water and tetrahydrofuran when pressurized with carbon dioxide causes the occurrence of an upper quadruple point (Q2) to evolve into a four-phase H-LW-LV-V equilibrium line. The presence of sodium chloride in the quaternary system enhances the split between the two liquids due to the salting-out effect. It was found that the hydrate promoting effect of tetrahydrofuran is able to suppress the inhibiting effect of sodium chloride especially at lower concentration of sodium chloride.

Original languageEnglish (US)
Pages (from-to)38-43
Number of pages6
JournalFluid Phase Equilibria
Volume284
Issue number1
DOIs
StatePublished - Oct 15 2009

Keywords

  • Carbon dioxide hydrate
  • Phase behaviour
  • Quaternary system
  • Sodium chloride
  • Tetrahydrofuran

ASJC Scopus subject areas

  • Chemical Engineering(all)
  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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