Measurements for the Dissociation Condition of Carbon Dioxide Hydrate with each Additive of Cyclopentanol, Cyclohexanol, Cycloheptanol, Cyclohexanone, or Cycloheptanone

In this study, the equilibrium conditionsfor the dissociationof carbon dioxide hydrate in the presence of various additives wereexamined. To provide new experimental data and discuss the additiveeffect of cyclic ketones and cyclic alcohols, the equilibrium dissociationtemperatures and pressures for carbon dioxide hydrates with the additiveof cyclopentanol, cyclohexnol, cycloheptanol, cyclohexanone, or cycloheptanonewere measured by an isochoric method. The experimental data were takenat a pressure range of 1.7 to 3.5 MPa and a concentration of 5 wt%. The Clausius-Clapeyron equation was used to speculate thestructure of carbon dioxide hydrate with these additives. It was foundthat the additives of cyclohexanone and cycloheptanone had an inhibitoryeffect on the formation of carbon dioxide hydrates with the sI structure.Cycloheptanol had a slight inhibitory effect on the formation of carbondioxide hydrates at lower temperatures, but this effect disappearedat higher temperatures, and this additive also belongs to the sI structure.The addition of cyclopentanol and cyclohexnol additives showed a promotioneffect in a low-pressure region on the formation of carbon dioxidehydrates, and the sII hydrate can be produced when adding these twoadditives.