Excess molar enthalpies of (carbon dioxide+ethylene glycol dimethyl ether or 2-methoxyethyl ether) 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: 1996
• Tongue: English
• Weight: 403 KB
• Volume: 28
• Category: Article
• ISSN: 0021-9614
• DOI: 10.1006/jcht.1996.0054

✦ Synopsis

The excess molar enthalpies H E m of {xCO2+(1-x)CH3(OCH2CH2)n OCH3}, where n=1 (ethylene glycol dimethyl ether) and n=2 (2-methoxyethyl ether) were measured at the temperatures 298.15 K and 308.15 K and pressures (7.5, 10.0, and 12.5) MPa. No (vapour+liquid) phase boundaries were observed from the H E m behaviour. The values of H E m of all the mixtures are negative over the entire composition, temperature, and pressure range.

An analysis using the Peng-Robinson equation with a composition-dependent interaction parameter confirms that the large negative values of H E m observed at T=308.15 K and p=7.5 MPa are due to the proximity to the critical point of CO2. In contrast to the behaviour of ethylene glycol dimethyl ether mixtures, for which (1H E m /1p)T,x is positive, the pressure dependence of H E m for the 2-methoxyethyl ether mixtures became negative in the solvent-rich region at T=298.15 K. The Peng-Robinson equation reproduces the main features observed, but fails to predict the reversal in (1H E m /1p)T,x .