Methane hydrate formation in dispersed polyvinyl alcohol cryogel

Abstract

Kinetics of methane hydrate formation in frozen water solutions (FWS) and polyvinyl alcohol (PVA) cryogel stabilized with hydrophobic silica nanoparticles was first studied. PVA cryogel is a macroporous heterogeneous gel formed at the special conditions of the freezing and subsequent melting processes of the PVA water solution. Such parameters as a rate and a conversion of water to hydrate were investigated for dispersed FWS, PVA cryogel, and dispersed ice at the same thermodynamics conditions using the same equipment. It was found out that the transformation the main part of water contained in FWT and PVA cryogel into hydrate was more than ten times faster than that for dispersed ice. The resistance to hydrate formation/dissociation processes was studied for dispersions of PVA cryogel. Gas hydrate formation and dissociation were carried out at isochoric conditions using temperature cycling. It was shown that cryogels of PVA water solution stabilized with hydrophobic silica nanoparticles were resistant to gas hydrate formation/dissociation processes prompting suggestions that cryogels of PVA water solution might be reused for gas hydrate formation/dissociation multiple times without significantly decrease in the conversion water to hydrate.