Vapor-liquid equilibria and mixture densities for 2,2,4,4,6,8,8-heptamethylnonane + N2 and n-hexadecane + N2 binary mixtures up to 535 K and 135 MPa

Abstract

In this work, we report high-pressure, high-temperature (HPHT) mixture density and T-p isopleth (bubble (BP) and dew (DP) point) data for hexadecane (HXD) + N2 and heptamethylnonane (HMN) + N2 mixtures from ~323 to 523 K and pressures to ~100 MPa. Isothermal, mixture density data for both mixtures are measured in the single–phase region from the BP pressure to ~135 MPa and with ~14–90 mol% N2. A HPHT variable-volume, windowed view cell is used for both density and phase behavior measurements using the synthetic method. Mixture densities are correlated with the modified Tait equation and isothermal BP/DP data are correlated with an Antoine-type equation to allow for reliable interpolation of the data sets. Mixture densities and BP/DP pressures are modeled with the PC-SAFT equation coupled with pure component parameters calculated with two different group contribution methods. Although fairly reasonable predictions of liquid mixture densities are obtained when the binary interaction parameter, kij, is set to zero for both HXD + N2 and HMN + N2 mixtures, a value of kij equal to at least 0.119 is needed for both systems to obtain reasonable predictions of isothermal p-x behavior.