Investigation of thermodynamic and kinetic effects of cyclopentane derivatives on CO2 hydrates for potential application to seawater desalination

Abstract

In recent decades, gas hydrates have received significant attention due to their potential roles in energy and environmental applications. The formation of gas hydrates involves a process to assemble variously shaped frameworks made of hydrogen bonded networks of H2O molecules, and thus ionic species, such as Na+, K+, Mg2+, Ca2+, Cl-, SO42-, etc., can be excluded from the solid gas hydrate phase. Therefore, gas hydrates can potentially be utilized in desalination technology. For potential application to a hydrate-based desalination (HBD) process, three cyclic compounds, cyclopentane (CP), cyclopentanone (CP-one), and cyclopentanol (CP-ol), were selected, focusing on a comparison of thermodynamic and kinetic effects. From the thermodynamic view, the study confirmed that the hydrate formation was favorable in the order of CP, CP-one, and CP-ol in the presence of CH4 or CO2. For the kinetic comparison, however, CP-ol and CP-one showed a relatively shorter induction time than CP. The conversion yield of CO2 hydrate of CP-one was more than double those of CP and CP-ol hydrates, which is ascribed to the unique hydration of the ketone during the hydrate formation. The findings suggest that CP-one could be a promising candidate for the HBD process.