Excess enthalpies of (carbon dioxide + propylene carbonate orN-methyl-ε-caprolactam or 1-formyl piperidine) at the temperatures 298.15 K and 308.15 K and pressures from 7.5 MPa to 12.5 MPa

✍ Scribed by Jian Ping Zhao; Peter R. Tremaine

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 592 KB
• Volume: 27
• Category: Article
• ISSN: 0021-9614
• DOI: 10.1006/jcht.1995.0122

✦ Synopsis

The excess molar enthalpies H E m of [xCO2+(1-x){C4H6O3 (propylene carbonate) or C7H13NO (N-methyl-o-caprolactam) or C6H11NO (1-formyl piperidine)}] were measured at the temperatures 298.15 K and 308.15 K and pressures (7.5, 10.0, and 12.5) MPa. (Vapour+liquid) phase boundaries were determined from the H E m s. The excess enthalpies for all of the mixtures are negative over the entire composition, temperature, and pressure range. Large changes in the values of H E m were observed near the critical temperature and pressure of carbon dioxide. The Peng-Robinson equation of state with a composition-dependent interaction parameter was used to model the behaviour of H E m . At low x the Peng-Robinson equation provided a satisfactory fit for all mixtures studied over the full range of pressures and temperatures. For {xCO2+(1-x)C4H6O3}, the predicted H E m values for xq0.5 were more negative than the experimental results. The fits to the other mixing curves were somewhat better, but show similar discrepancies at T=308.15 K and p=7.5 MPa.