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.