Liquid Densities of Xylene Isomers and 2-Methylnaphthalene at Temperatures to 523 K and Pressures to 265 MPa: Experimental Determination and Equation of State Modeling

Abstract

Experimental density data for o-xylene, m-xylene, p-xylene, and 2-methylnaphthalene, are reported at pressures (P) to 265 MPa and temperatures (T) to 525 K using a variable-volume, high-pressure cell. The reported data agree to within ±0.4% of available literature data. o-Xylene has the largest densities and p-xylene has the smallest densities in the P–T range investigated in this study although the 525 K isotherms for all three aromatics virtually superpose at high pressures. The aromatic densities are modeled using the Peng–Robinson (PR), high-temperature, high-pressure, volume-translated Peng–Robinson (HTHP VT-PR), and perturbed chain statistical associating fluid theory (PC-SAFT) equations of state (EoS). Generally, the PC-SAFT EoS gives the best predictions of the HTHP density data with mean absolute percent deviations (δ) within 1.0%, even though the pure-component parameters are fitted to low-pressure vapor pressure and saturated liquid density data. δ decreases to 0.4% for calculations with a new set of PC-SAFT parameters obtained from a fit of the HTHP experimental density data obtained in this study.