Methane hydrate formation enhanced by thermally expanded graphite with multi-sized pores

Abstract

Methane hydrate has been endowed with great potential in energy storage and transportation, but the sluggish formation kinetics restrict its industrial application. Herein the thermally expanded graphite (EG), with multi-sized pore structure that can be effectively controlled by expanding and grinding processes, is used to promote the nucleation and growth of methane hydrates. The results demonstrate that the EG exhibits a remarkable promotion in the formation of methane hydrate from water, with high gas storage capacity of 143 V/V, short induction time of 10 min, and rapid gas storage rate of 1 V·V·min−1, which are attributed to its well-designed multi-sized pore structure. Thereinto, the nano-sized pores can effectively adsorb guest molecules, increasing the guest–host contact area; meanwhile, the micron-sized pores with moderate scale not only provide abundant channels for mass transfer of reactants but also enable good thermal conductivity for heat transfer to soundings. This work provides an insight into the promotion effect of multi-sized porous medium in hydrate formation, and offers an effective strategy for fabricating high-performance promotors through pore designing.