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Water-soluble polymers have shown dual characteristics either as hydrate promoters (enhanced the rate of gas hydrate formation) or inhibitors (retarded the hydrate formation kinetics). Therefore, in this study, we evaluate the promotional/inhibition effect of the environmentally friendly biodegradable, water-soluble polymers for methane hydrate formation. An unstirred high-pressure reactor was used to synthesize methane hydrates of frozen biopolymers. A comparative analysis of the hydrate formation growth for concentrations ranging from 0.1 to 4.0 wt % of the frozen crushed bipolymer was performed. Further, to probe the impact of melting rates of the frozen powder on methane hydrate growth, frozen powdered biopolymers were characterized using the nuclear magnetic relaxation (NMR) spectroscopy method at a temperature of 272.2 K. From the kinetic and NMR experiments, a direct correlation between the transition rate of water to hydrate and the melting rate of frozen powdered biopolymers was established. Furthermore, this study allows us to classify the best biopolymers to enhance the kinetics of hydrate formation. Our findings highlight the promise of engaging biopolymers for solidified natural gas technology to store and transport natural gas.

The results on a dissociation behavior of propane hydrates prepared from “dry water” and contained unreacted residual water in the form of ice inclusions or supercooled liquid water (water solution of gas) were presented for temperatures below 273 K. The temperature ramping or pressure release method was used for the dissociation of propane hydrate samples. It was found that the mechanism of gas hydrate dissociation at temperatures below 273 K depended on the phase state of unreacted water in the hydrate sample. Gas hydrates dissociated into ice and gas if the ice inclusions were in the hydrate sample. The samples of propane hydrates with inclusions of unreacted supercooled water only (without ice inclusions) dissociated into supercooled water and gas below the pressure of the supercooled water-hydrate-gas metastable equilibrium.