In recent years, using natural gas hydrates (NGH) for storage and transportation of gas has been considered because gas hydrates can be stored and transported at temperatures much higher than liquefied natural gas (LNG). The major objective of this study is to investigate the effects of non-ionic surfactants polysorbate 80 (Tween-80) and polysorbate 20 (Tween-20) on the formation rate and storage capacity of methane hydrate.
Tween-20 was tested with 2 concentrations of 1000 and 2000 and Tween-80 was tested with 100 and 500 ppm and compared with the hydrate formed in pure water and aqueous sodium dodecyl sulfate (SDS) solution. The hydrate formation rate and the storage capacity were influenced by the different concentrations of surfactants and it was found that Tween-20, when prepared with 2000 ppm, speeded up the hydrate formation rate and increased its storage capacity; but when it was prepared with 1000 ppm, it inhibited the hydrate formation effectively. Tween-80 decreased the hydrate formation rate in both of the solutions. Experimental results on hydrate gas content revealed that the maximum storage capacity of 125 V/V is obtained with 2000 ppm of Tween-20 in water.