Improved Combustion Enthalpy Predictions Obtained by DFT-Based Methods through Empirical Correction: A Study of Cycloparaffins for Sustainable Aviation Fuel

The growing demand for aviation fuels and the progressive depletion of petroleum resources pose challenges related to transportation logistics, pollution, and technological development, making the advancement of sustainable aviation fuels (SAFs) imperative. In this context, computational research plays a critical role in optimizing production methodologies and predicting compounds with physicochemical properties comparable to those of conventional kerosenes. In this context, this study evaluated the performance of different DFT approximations (B3LYP, M06-2X, and M08-HX) and composite methodologies (G4 and G4-MP2) in predicting combustion enthalpies of organic molecules with high potential as SAF candidates. Initially, the experimental enthalpies of combustion were analyzed to assess the accuracy of each theoretical approach. The analysis was extended to cycloparaffins synthesized, which are promising SAF candidates due to their high energy content and suitable flash and freezing points. The results showed that the relative error tended to stabilize for molecules with higher combustion energies. The enthalpy of combustion calculated by the M08-HX method presented errors comparable to those of G4-MP2. The DFT methods demonstrated greater accuracy when employing the combustion energy correction proposed in this study, highlighting the viability of density functional theory (DFT) approximations. The analysis of complex structures at a significantly lower computational cost than composite methodological approaches indicates that the careful selection and empirical refinement of theoretical methods allow for a more accurate prediction of the combustion enthalpies.