Preservation of methane gas in the form of hydrates: Use of mixed hydrates

The release of methane gas was compared in pure CH4 (sI) and mixed (sII) hydrates (with C4H8O - tetrahydrofuran and C3H8 - propane) having methane as dominant constituent. We report absence of the self preservation effect in mixed hydrates, having stiochiometric composition (sII) of larger guest molecules, and they populate the 5(12)6(4) cages. Their dissociation behaviour is in accordance with the respective phase boundary curve. While a partial methane gas release was observed at 270 K, particularly, in dilute systems. Further, excess as release was at T > 270 K and complete methane release is governed by the thermodynamic stability of mixed hydrates. (C) 2015 Elsevier B.V. All rights reserved.