Kinetics of methane hydrate formation in the presence of activated carbon and nano-silica suspensions in pure water

• Methane hydrate kinetics studied in suspension of activated carbon and nano-silica.
• Activated carbon observed to be an efficient kinetic promoter for hydrate formation.
• Activated carbon showed improved performance over nano-silica.
• The induction time of hydrate formation was reduced in the presence of suspensions.
• Deactivated carbon shown to be an inhibitor and reduced gas carrying capacity.

New kinetic promoters must be researched for hydrate formation suitable for natural gas storage and transportation to push this technology towards economic feasibility. In this study, the kinetics of the methane hydrate formation have been investigated in the presence of activated carbon and nano-silica (0.5, 1.0 and 2.0 wt%) suspensions in an aqueous solution. Experiments were conducted at 8 MPa and 275.15 K using methane gas as the hydrate former. Particles (activated carbon and nano-silica) were analyzed using scanning electron microscope (SEM) and X-ray diffraction before use. Information on the number of moles of gas consumed during hydrate formation, induction time, rate of hydrate formation, water-to-hydrate and gas-to-hydrate conversion were investigated. It was seen that the kinetics of hydrate formation were more favorable at higher concentrations of particles of activated carbon and nano-silica in the suspension. The effect of the deactivation of activated carbon was also studied and has shown a reversed trend when compared to other particles, behaving as an inhibitor for methane hydrate formation. The rate of hydrate formation was enhanced in the presence of activated carbon and was on the higher side when compared to suspensions of nano-silica. The water-to-hydrate and gas-hydrate conversions observed were in-line with the trends seen in the moles of gas consumed, with activated carbon being more effective than the rest of the particles. The induction time was observed to be reduced in the presence of suspensions of activated carbon when compared to the other hydrate forming systems studied in this work. In general, the results show that both activated carbon and nano-silica have promoting effects on methane hydrate formation kinetics, however, the effect of activated carbon is significantly more pronounced. This study provides a precursor for an improved understanding on the role of particle suspensions for methane hydrate formation suitable for gas storage applications.

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