Tuning Behavior of (Cyclic Amines

- In this study, the tuning phenomena, gas storage capacity, and thermal expansion behaviors of binary (cyclopentylamine + CH4) and (cyclopropylamine + CH4) clathrate hydrates were investigated for the potential applications of clathrate hydrates to gas storage. To understand the tuning behaviors of binary (cyclopentylamine + CH4) and (cyclopropylamine + CH4) clathrate hydrates, 13C solid-state NMR spectroscopy was used, and the results confirmed that maximum tuning factors for the binary (cyclopentylamine + CH4) and (cyclopropylamine + CH4) clathrate hydrates were achieved at 0.5 mol% and 1.0 mol% of guest concentration, respectively. The gas storage capacity of binary (cyclopentylamine + CH4) and (cyclopropylamine + CH4) clathrate hydrates were also checked, and the results showed the CH4 capacity of our hydrate systems was superior to that of binary (tetrahydrofuran + CH4) and (cyclopentane + CH4) clathrate hydrates. The synchrotron diffraction patterns of these hydrates collected at 100, 150, 200, and 250 K confirmed the formation of a cubic Fd-3m hydrate. In addition, the lattice constant of clathrate hydrates with cyclopentylamine and methane were larger than that with cyclopropylamine and methane due to the effects of molecular size and shape.