Effects of phospholipids on pyrolysis and oxidation characteristics of Jatropha biodiesel: TG-FTIR-MS experiment and ReaxFF-MD simulation

Phospholipids, as key trace constituents of biodiesel, can have complex effects on the performance of biodiesel. Exploring the mechanism of their influence on the pyrolysis and oxidation characteristics of biodiesel is crucial for controlling the generation and emission of pollutants. To this end, this study employed TG-FTIR-MS experimental technology and the ReaxFF-MD simulation method to investigate the effects of phosphatidylethanolamine (PE) on the activation energy (Ea), gaseous product generation, and mechanism of Jatropha biodiesel pyrolysis and oxidation reactions. The results indicated that the addition of 400 ppm PE can reduce the pyrolysis Ea of Jatropha biodiesel from 87.25 kJ/mol to 80.67 kJ/mol, consistent with simulated Ea of 93.35 kJ/mol and 81.81 kJ/mol, respectively. This notably promoted the initial oxidation stage of the Jatropha biodiesel reaction, facilitating the generation of oxidation products such as CO and C2H4. In the pyrolysis reaction, PE promoted C2H4 formation, primarily through reactions involving hydrocarbon small free radicals. In the oxidation reaction, the addition of PE increased the number and variety of active free radicals in the system, with the formation reactions of H2O and CH2O involving phosphorus-containing oxygen groups. Furthermore, a small amount of nitrogenous free radicals participates in the formation reactions of C2H4 and CO.