(Solid + liquid) equilibrium of binary mixtures containing ethyl esters and p-xylene by differential scanning calorimetry

Current concerns regarding the environmental and economic sustainability of petroleum-based transportation fuels, including jet fuel, are driving interest into alternative fuels. To study the feasibility of using biodiesel in aviation engines, a deeper knowledge on solid–liquid equilibrium (SLE) of biodiesel/jet fuel blends is required. This work presents SLE data of binary mixtures containing p-xylene, a representative compound of aviation fuel, and fatty esters present in ethylic biodiesel. Experimental data were obtained through differential scanning calorimetry. A simple eutectic behavior was observed for all binary systems, although small regions of partial miscibility are also present. Observed eutectic temperature and composition (ethyl ester mole fraction) are 259.0 K and 0.45, 269.0 K and 0.32, 275.5 K and 0.22, 280.0 K and 0.15, and 247.7 K and 0.58 for systems containing ethyl laurate, ethyl myristate, ethyl palmitate, ethyl stearate and ethyl oleate, respectively. Good agreement was obtained between experimental and calculated data when using UNIFAC (Dortmund) model or Flory–Huggins equation, with root-mean-square deviations ranging from 0.47 to 1.90 K. The systems exhibit significant deviations from ideality, which cannot be neglected in model calculations.