Sorption properties of graphene airgel in relation to methane

Abstract

A new nanostructured carbon material is synthesized, which represents aerogel based on reduced graphene oxide. Aerogel obtained by using supercritical methods for processing a hydrogel in isopropyl alcohol. Resulting material has sufficiently high specific surface in terms of BET — 657 m2/g with high specific pore volume DFT — 0.766 cm3/g, which creates good prospects for its use for the adsorption of energetically important gases, in particular methane. A favorable factor for increasing the rate of adsorption-desorption in such systems is the large volume of mesopores with diameters of about 4.5 – 6.5 nm. Adsorption of methane at temperatures of 298.15, 303.15, 313.15 K and pressures up to 100 bar was studied on the synthesized graphene aerogel. The maximum value of methane adsorption under temperature 298.15 K and pressure of 100 bar reaches 7.31 mmol/g. The characteristic parameters of the adsorption process were analyzed using the empirical models of the Langmuir and Freundlich isotherms. The adsorption process was investigated at the level of evaluating thermodynamic parameters, which indicate its change from a random state to an ordered one, and its exothermic and physical nature. The obtained results can be used in the design of storage systems for adsorbed natural gas.