[MIS16-P01] Measurement of dissociation heat of N2, O2, and Ar hydrates
Keywords:gas hydrate, dissociation heat, hydration number, calorimetry
The samples of gas hydrates were synthesized from fine ice powder and guest gases at 273.2 K and the pressure condition of 20MPa (N2) and 16MPa (O2 and Ar). The ice powder started to melt and formed these gas hydrates. Approximately 1 g of each hydrate sample was set in a pressure cell specially designed for a Tian-Calvet type heat-flow calorimeter, and its dissociation monitored. The experimental setup and technique were the same as the one that was used previously by Hachikubo et al. (2009; 2012).
Dissociation heats of N2, O2, and Ar hydrates from hydrate to gas and ice are 12.8±0.2 [kJ mol-1], 12.6±0.1[kJ mol-1], and 13.2±0.1[kJ mol-1], respectively. Yoon et al. (2003) reported that dissociation heats of N2 and O2 hydrates are 12.18 [kJ mol-1] and 11.52 [kJ mol-1], respectively, using the Clausius-Clapeyron equation. Therefore, our data are several percent smaller than the previous report.
Kang S-P, Lee H (2001) Enthalpies of dissociation of clathrate hydrates of carbon dioxide, nitrogen, (carbon dioxide + nitrogen), and (carbon dioxide + nitrogen + tetrahydrofuran). J Chem Thermodyn 33: 513-521.
Hachikubo A, Kida M, Okuda M, Sakagami H, Shoji H (2009) Dissociation heat of mixed-gas hydrate composed of methane and ethane. Seppyo 71(5): 341-351.
Hachikubo A, Khlystov O, Kida M, Sakagami H, Minami H, Yamashita S, Takahashi N, Shoji H, Kalmychkov G, Poort J (2012) Raman spectroscopic and calorimetric observations on natural gas hydrates with cubic structures I and II obtained from Lake Baikal. Geo-Mar Lett 32: 419-426.
Yoon J-H, Yamamoto Y, Komai T, Haneda H, Kawamura T (2003) Rigorous approach to the prediction of the heat of dissociation of gas hydrates. Ind Eng Chem Res 42: 1111-1114.