Thermophysical Analysis and Molecular Modeling of 2-Propanol–Glycol Ether Mixtures Between 293.15 K and 323.15 K: Implications for Renewable Fuel Formulations

Abstract

Abstract Short-chain alcohols and glycol ethers are increasingly being considered as promising additives or components in biofuels due to their favorable physicochemical properties and alignment with the growing demand for sustainable and low-emission energy sources in the transportation sector. This study presents experimental data for five binary mixtures of 2-propanol with glycol ethers: 2-(2-methoxyethoxy)ethanol, 2-(2-ethoxyethoxy)ethanol, 2-methoxyethanol, 2-phenoxyethanol, and 2-butoxyethanol. Measurements of excess molar enthalpy ( $${H}_{m}^{E}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>H</mml:mi> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> <mml:mi>E</mml:mi> </mml:msubsup> </mml:math> ), density ( ρ ), speed of sound ( u ), and refractive index ( n D ) were performed over the temperature range 293.15 K–323.15 K at 0.1 MPa. Derivative thermodynamic properties, excess molar volume ( $${V}^{E}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow> <mml:mi>V</mml:mi> </mml:mrow> <mml:mi>E</mml:mi> </mml:msup> </mml:math> ), isentropic compressibility ( k s ), and refractive index deviation (Δ n D ), were calculated from the experimental data. Density data were correlated using PC-SAFT and Peng–Robinson equations of state, while polynomial equations were employed to fit ρ , u , n D , and k s as functions of composition. The Redlich–Kister equation was used to fit $${V}^{E}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msup> <mml:mrow> <mml:mi>V</mml:mi> </mml:mrow> <mml:mi>E</mml:mi> </mml:msup> </mml:math> and Δ n D . Excess molar enthalpy ( $${H}_{m}^{E}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msubsup> <mml:mi>H</mml:mi> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> <mml:mi>E</mml:mi> </mml:msubsup> </mml:math> ) was modeled using both the Redlich–Kister correlation and thermodynamic activity coefficient models, UNIQUAC, NRTL, and Modified UNIFAC, to interpret molecular interactions. All the studied mixtures exhibit endothermic behavior. The results contribute to a deeper understanding of the behavior of alcohol/glycol ether mixtures and their potential application in fuel formulations.