Beyond conventional activation barriers: synergistic QM-MD/DFT exploration of fluorinated oxidizer-enhanced hydrocarbon decomposition

Abstract

Hydrocarbon fuels are a major focus of fuel application and research due to the high volumetric calorific value. The addition of ClF₃O with strong oxidizability as an initiator in fuels is considered to be an effective method to improve the overall thermal decomposition rate. This study employs the quantum mechanics molecular dynamics (QM-MD) and density functional theory (DFT) to investigate the thermal decomposition reaction of C₇H₁₆ initiated by ClF₃O, focusing on reaction mechanism, decomposition temperature, and product distribution. The decomposition reactions channels of ClF₃O/C₇H₁₆ mainly occur through two types of reactions: initiating decomposition by ClF₃O and decomposition of fuel itself. From the QM-MD simulations, we find ClF₃O can accelerate C₇H₁₆ decompositions, since the H-abstraction on C1 site of C₇H₁₆ can be initiated by ClF₃O and other small molecular radical at relatively lower temperatures, which is more likely to occur due to its low activation energy compared to the C-C bond cleavage. The H· and CH₃· radicals generated by dehydrogenation and C-C bond cleavage in the self-decomposition stage further promoted the decomposition of C₇H₁₆ and produced a variety of alkane radicals. Meanwhile, the product HF could promote the self-decomposition of C₇H₁₆ because of its acid properties. This work might provide important theoretical insights for fluorine-containing compounds as initiators to induce thermal decomposition reactions of hydrocarbon fuels.