Multiple methane hydrate formation in powder poly(vinyl alcohol) cryogel for natural gas storage and transportation

The aim of this work is to investigate the possibility of using a new water-containing material for multicycle gas hydrate formation with a high rate and water-to-hydrate conversion ratio in relation to natural gas storage and transportation. Recently, we developed a powdered water-containing material formed by grinding a frozen poly (vinyl alcohol) (PVA) water solution in the presence of silica nanoparticles and further thawing the prepared system. The obtained material is called powder PVA cryogel (PPVACG). In this work multiple methane hydrate formation/dissociation cycles in PPVACG were investigated for the first time. It was found that the equilibrium conditions for methane hydrate formation in PPVACG (7 wt% PVA and 5 wt% nanoparticles) were the same as those for pure bulk water. The methane hydrate formation rate as well as the water-to-hydrate conversion for PPVACGs were no less than those for the known dispersed dry water and gelatinous dry solution systems. However, PPVACGs showed a higher stability and higher methane uptake capacity in comparison with dry water and gelatinous dry solution in repeated gas hydrate formation/dissociation cycles starting from the third cycle. The results may be useful for the development of hydrate-based technologies for the storage, transportation, and utilization of natural and anthropogenic gases.

Automated summary

The study found that the new water-containing material PPVACG showed high rate and conversion ratio for gas hydrate formation, as well as increased stability and methane uptake capacity in repeated cycles compared to traditional systems.