Structure-H hydrate of mixed gases: Phase equilibrium modeling and experimental validation

• Published in: Journal of molecular liquids 2021-12, Vol.343, p.117605, Article 117605
• Main Authors: Dhamu, Vikas, Thakre, Niraj, Jana, Amiya K.
• Format: Article
• Language: English
• Subjects: Clathrate hydrate; Experimental validation; Mixing rule; Patel-Teja; Phase equilibrium; Wong-Sandler
• ISSN: 0167-7322; 1873-3166
• DOI: 10.1016/j.molliq.2021.117605

•Phase equilibrium model is developed for sH-type hydrates of mixed gases.•Wong-Sandler mixing rule for Patel-Teja equation of state is implemented.•Solubility of the vapor phase components is considered using Henry’s law.•Proposed model is validated for hydrates of both liquid and gaseous heavy formers.•The proposed Wong-Sandler mixing rule outperforms the conventional models. Clathrate hydrates are solid ice-like compounds that entrap the gas or liquid molecules into their cavities of hydrogen-bonded water molecules. As compared to commonly available sI and sII structures of clathrate hydrate, the sH-type is reported to possess more stability and gas uptake capacity. Despite copious implications of the sH-type hydrates of mixed gases in gas storage and separation, the phase equilibrium modeling to predict their formation condition is rarely available in the literature due to inaccurate estimation of the interactions between the guest components. In this view, we develop a novel methodology using the Wong-Sandler mixing rule extended for the three-parameter Patel-Teja equation of state, in association with the statistical thermodynamics based van der Waals and Platteeuw model to define the hydrate phase. This apart, the solubility of the help gases in water is estimated using the Patel-Teja model instead of the empirical correlations. It is observed that the proposed formulation is capable of predicting the experimental phase equilibrium data with a range of 1.389–2.812 %AARD for a variety of sH hydrates (i.e., neohexane, methylcyclopentane, isopentane, 2,2-dimethylpentane and a recently discovered first vapor phase heavy former tetrafluorocyclobutane) having methane, nitrogen or carbon dioxide as their co-guest.