Estudo teórico da energia de combustão de moléculas potencialmente energéticas

Abstract

The growing demand for aviation fuels and the progressive depletion of petroleum resources pose challenges related to transport logistics, pollution, and technological development, making the advancement of Sustainable Aviation Fuels (SAFs) essential. In this context, research emerges as a fundamental tool for optimizing production methodologies and evaluating compounds with physicochemical properties similar to those of conventional kerosene. This study assesses the use of the B3LYP, M06-2X, M08-HX, G4, and G4-MP2 methods to determine energy-related properties, such as the enthalpy of combustion, of different organic molecules with high potential for SAF applications. Initially, the structures of organic molecules composed of carbon, hydrogen, and oxygen with known experimental enthalpy of combustion values were analyzed. The results are complemented by cycloparaffins synthesized from plant sources, which are promising candidates for SAF components due to their high energy content and suitable flash and freezing points. The results demonstrate that Percentage Relative Errors (PRE) tend to stabilize for molecules that release greater amounts of energy during combustion, and that the application of empirical corrections based on experimental data leads to a reduction in the Average Percentage Relative Error (APRE) across all tested theoretical methods. Additionally, the combustion enthalpy calculated using the M08-HX method shows an APRE comparable to that obtained with the G4-MP2 method, and when empirical corrections derived from experimental data of similar molecules are applied, the APRE approaches that of the composite G4 method. The B3LYP and M06-2X methods also show improved performance when empirical corrections are employed, indicating the viability of Density Functional Theory (DFT) methods for analyzing complex molecular structures at a significantly lower computational cost than that required by composite methods. Therefore, an in-depth investigation of these theoretical approaches applied to SAF molecules and aviation kerosene enables a more accurate determination of physicochemical properties, leading to more reliable analyses for the formulation of new fuels.