Clathrate formation in binary aqueous systems with CH2Cl2, CHCl3 and CCl4 at high pressures

Double Gas Hydrates at High Pressures: The Highest Decomposition Temperatures

“…The next hydrate belongs to CS‐I in the case of THF 2,8. The same situation, most probably, takes place in the water‐CHCl 3 , CCl 4 , and SF 6 systems 2,7. The nature of the high‐pressure hydrates is unknown at present.…”

“…The data on the double SF 6 ‐H 2 O system are presented for the first time and will be the subject of a special publication. In the double systems under consideration (water‐CHCl 3 , CCl 4 , THF, and SF 6 ) three hydrates are formed in the pressure interval 1 bar‐15 kbar (see References 2 and 7, also Fig. 3).…”

“…2,8 The same situation, most probably, takes place in the water-CHCl 3 , CCl 4 , and SF 6 systems. 2,7 The nature of the high-pressure hydrates is unknown at present. Our data show, that CS-II double clathrate hydrates are the only stable clathrate phases in the 1 bar-15 kbar pressure interval (and the decomposition temperature of these hydrates significantly increase) if D -cavities in the CS-II clathrate frameworks of CHCl 3 , CCl 4 , THF, and SF 6 hydrates are filled by the xenon molecules.…”

“…The starting aqueous THF solution, with the 1:17 (THF: H 2 O) molar ratio of components, was prepared using distilled water and tetrahydrofuran (purified from peroxides, dried, and then distilled) by weighing. Aqueous emulsions of CHCl 3 and CCl 4 were prepared as indicated in Reference 7. A known volume of these solutions (about 0.03 ml) was transferred by a micropipette into a plastic ampoule for DTA (the ampoule was filled with SiC powder with grain size about 0.01 mm 5 ).…”

Experimental Determination of CCl4 Hydrate Phase Equilibria up to High Pressures

“…If chlorinated hydrocarbons are to be used as hydrate formers in industrial purposes, such as the two above-mentioned applications, experimental information on the hydrate phase behavior of such systems is necessary. Dyadin et al investigated the hydrate phase behavior of the three chlorinated methane derivatives of CH 2 Cl 2 , trichloromethane (CHCl 3 ), and CCl 4 . They observed that at very high pressures, up to 5000 bar, the clathrate hydrates of structure II can be transformed to another structure, which they believed to be structure I.…”