New Phase Equilibria Data for Clathrate Hydrates of Tetrahydrofuran + Carbon Dioxide and Tetrahydrofuran + Nitrogen: Experimental Study of Reliability of Literature Data

Tetrahydrofuran (THF) is an organic water soluble hydrate former, which is used in gas separation, storage and transportation processes using gas hydrate technology. Gas hydrates or clathrate hydrates are solid crystalline compounds, which are formed from combination of water and small guest molecules. Clathrate hydrates can form crystalline structures I (sI), II (sII) and H (sH), where each structure is composed of a certain number of cavities formed by water molecules. The cooperation of two large and small guest molecules are normally required for the formation of structure II with heavy molecules or structure H. Heavy molecules occupy large cavities while small molecule(s) (called help gas) fill the remaining cavities. Tetrahydrofuran can form structure II with or without the presence of a help gas. Most of phase equilibrium data for tetrahydrofuran clathrate hydrates have been reported for the tetrahydrofuran + methane, tetrahydrofuran + carbon dioxide, tetrahydrofuran + nitrogen and tetrahydrofuran + hydrogen systems. A preliminary study shows that some of experimental data reported in the literature are not in good agreement, which require studying their reliability. In this work, we report new phase equilibrium data for clathrate hydrates of tetrahydrofuran + carbon dioxide and tetrahydrofuran + nitrogen. The experimental data were generated using an isochoric pressure-search method. The new equilibrium data are compared with the corresponding experimental data reported in the literature to study the reliability of the literature data.