Separation of Methane from Natural Gas by New Method of MWNT in Hydrates Process

In this study, multi-walled carbon nanotube (MWNT) was synthesized by catalytic process of chemical vapor deposition (CVD) at 700 C and the crystal and physical structures of synthesized MWNT were confirmed by XRD analysis and SEM image respectively. Thereafter, the nanofluid was prepared by adding 1wt% of MWNT in distilled water and 1.5 g surfactant of SDS was added to the solution in order to achieve maximum stability of MWNT in water. The prepared nanofluid was used in the process of gas hydrate formation. After the formation of hydrate, with gradual increasing temperature of the reactor, the hydrate slowly became unstable and its gas was released. Through analysis of 95% of the hydrate formed, samples were taken from the released gas. Thereafter, the compositions were determined by GC analysis and were compared with the feed gas and also to MWNT non-existence. Generally, the process of gas hydrate formation causes enrichment of gas by methane and the hydrate holds within itself impurities and undesirable non-carbon compounds. The results showed a 2.79% increase in methane compared to the feed gas and reduction of corrosive compounds such as carbon dioxide and decrease of undesirable compounds such as nitrogen and oxygen. Moreover, there is no requirement for purification processes and during storage, gas is purified in the form of hydrate in a parallel manner and without any additional costs. In addition, it was observed that MWNT increased initial solubility of gas in water by 2.7 times and the volume of gas storage in hydrate by 12.5% and caused more rapid stability of hydrate for an hour.