Spectroscopic identification and conversion rate of gaseous guest-loaded hydroquinone clathrates

The formation of hydroquinone clathrates with CO2, CH4, N2, and H2 was investigated using X-ray diffraction, Raman spectroscopy, and solid-state 13C NMR spectroscopy. Of the hydroquinones prepared at 5.0 MPa, the CH4- and CO2-loaded hydroquinones show complete conversion to β-form hydroquinone clathrates while the N2-loaded hydroquinone shows only partial conversion; there is no indication of the formation of hydroquinone clathrate with H2. The CO2-loaded hydroquinone is fully converted to the β-form hydroquinone clathrate even at 1.0 MPa. Solid-state 13C NMR measurements of the hydroquinone clathrate samples prepared at different pressures reveal that the conversion rate for the formation of clathrate compounds from CH4 and N2 decreases with decreasing pressure.