Effect of maize starch on methane hydrate formation/dissociation rates and stability

• Effect of different concentrations of maize starch as a promoter on methane hydrate formation/dissociation was studied.
• At 800 ppm of starch concentration, an increase in hydrate formation rate up to 2.5 times was observed.
• Hydrate formed at 800 ppm of starch showed the most stability; however, the stability at −4 °C was less than that at −1 °C.

The effects of maize starch on the methane hydrate formation/dissociation rates and stability were investigated in the present work. Maize starch at 5 concentrations of 200, 400, 600, 800 and 1000 ppm was tested. The results showed that maize starch at low concentrations had no significant effect on hydrate formation; however, at the concentrations higher than 400 ppm, maize starch increased the hydrate formation rates. The most effective concentration of maize starch was 800 ppm. At this concentration, methane can be stored in hydrate 2.5 times more than in the case of pure water when no maize was used. Hydrate stability was studied at ambient pressure and two temperatures below the ice point (272.2 K and 269.2 K). The results showed that for all samples the maximum dissociation rate occurred at the beginning of the process and then the rate decreased. At all concentrations, mole percentage dissociated at 272.2 K was lower than at 269.2 K and the hydrate formed at 800 ppm maize starch had the maximum stability.