Spectroscopic identifications of structure II hydrate with new large alcohol guest molecule (Cyclopentanemethanol)

Highlights: • Cyclopentanemethanol (CPeM) was discovered as new structure II hydrate agent. • Guest inclusion and interaction behaviors of CPeM are revealed by spectroscopic identifications. • Thermodynamic conditions of CPeM + CH₄ hydrate were compared with those of pure CH₄ hydrate. Herein the guest inclusions and interactions in a binary (cyclopentanemethanol + CH₄) hydrate were explored via ¹³C NMR spectroscopy and XRD analysis. The ¹³C NMR spectra of the binary (cyclopentanemethanol + CH₄) hydrate confirmed the formation of structure II hydrate with the inclusion of cyclopentanemethanol and CH₄ in the structure II hydrate cages. Rietveld analysis on XRD profiles of the binary (cyclopentanemethanol + CH₄) hydrate confirmed the formation of a cubic Fd3m hydrate and the possible host–guest interactions. Finally, the thermodynamic stability of the binary (cyclopentanemethanol + CH₄) hydrate was relatively stable than that of the pure methane hydrate.