Exploring the tuning patterns of cyclopentyl amine hydrate for potential application to CH4 storage

With the increasing demand on world energy consumption, natural gas has received attention as the near-term primary energy source that produces fewer CO2 emissions than other fossil fuels. Accordingly, developing ecofriendly gas storage and transport technology has remained a significant challenge. Gas hydrate is a crystalline inclusion compound formed by water molecules and has emerged as alternative option for natural gas storage. Despite the benefits of hydrates, relatively high pressure and low temperature formation conditions need to be mitigated for practical application. Here, we introduce cyclopentyl amine (CPA) as a new thermodynamic promoter for potential application for CH4 storage. We measured the synchrotron high-resolution powder diffraction and C-13 NMR spectra, and the results revealed that the CPA could form sII hydrate without help gas. We also measured the pressure - temperature phase equilibria of CPA + CH4 hydrate, and the results revealed that CPA works as a thermodynamic promoter for CH4. Further, the tuning phenomena were observed below the stoichiometric concentration of the CPA. Specifically, the tuning factor was obtained as similar to 0.34, which exhibited a critical guest concentration was 0.9 mol%. We believe that these findings provide better understanding of the tuning phenomena for potential application to CH4 storage media.