Sustainable Methane Hydrate Formation Via Superabsorbent Polymers (SAPs) and Tetrahydrofuran (THF)

For developing sustainable hydrate-based gas storage system (HBGS), superabsorbent polymers (SAPs) and tetrahydrofuran (THF) were introduced for the methane hydrate formation. With THF-absorbed SAPs, methane hydrate was formed immediately without induction time. These nucleation behaviors were maintained over 20 cycles of formation-dissociation, indicating that THF-absorbed SAPs could be utilized for the sustainable hydrate formation in a non-stirred system. Also, from simulating real enclathration/regeneration process by adding ventilation/recharging step of methane gas during formation-dissociation cycles,¹ the storage capacity of methane hydrates was slightly declined from the loss of volatile THF during ventilation step. However, due to ‘tuning phenomena’ of THF, the capacity of methane hydrates eventually reached a constant value. From Raman and power X-ray diffraction (PXRD) spectroscopy, it was revealed that methane molecules were partially occupied 5¹²6⁴ cages, resulting in a constant storage capacity. This work can provide insights into designing a sustainable hydrate-based gas storage system without energy-intensive mechanical agitation.

1. D.W. Kang, W. Lee, Y.H. Ahn, J.W. Lee, Confined tetrahydrofuran in a superabsorbent polymer for sustainable methane storage in clathrate hydrates, Chem. Eng. J. 411 (2021), 128512