TITLE:
Operating Patterns and Reaction Mechanism of Propane Pyrolysis Pathway
AUTHORS:
Zheng Wu, Hui Fang, Rui-Shen Xie, Mei-Feng Chen, Qian-Feng Zhang
KEYWORDS:
Propane, Pyrolysis, Reaction Pathway, Reaction Mechanism, Transition State, Energy, Calculational Chemistry
JOURNAL NAME:
Open Journal of Modelling and Simulation,
Vol.14 No.2,
February
14,
2026
ABSTRACT: In the context of the accelerated transition of the global energy structure to decarbonization, propane is not only rich in reserves but also has a low carbon-to-hydrogen ratio, which is a natural advantage for the production of high-value-added chemicals (e.g., ethylene and propylene) through efficient conversion. This study employs the M06-2X/6-31++G(d,p) density functional theory method combined with transition state theory to calculate the energy barriers for each radical reaction involved in propane pyrolysis. The results indicate that in the initial reaction, the dissociation energy of the propane C-C bond is lower than that of the C-H bond, confirming that symmetrical cleavage of the C-C bond is the dominant initiation pathway in the early stages of pyrolysis. Based on the principles of radical chain reactions, four core pyrolysis reaction pathways were designed, with a focus on comparing the energy characteristics of propylene and ethylene formation: Path 1 and 2 utilize primary propyl radicals (n-C3H7•/i-C3H7•) as active centers, with ethylene formation energy barriers of 136.83 kcal/mol and propylene formation energy barriers of 145.98 kcal/mol; Path 3 and 4 introduce secondary radicals (C2H5•) to participate in chain transfer, the formation energy barrier of ethylene is 120.87 - 174.8 kcal/mol, and that of propylene is 124.79 - 174.8 kcal/mol; This study reveals the core mechanism for selectively controlling propylene and ethylene production by comparing bond dissociation energy patterns with pathway energies. It provides critical theoretical foundations for optimizing cracking process parameters and catalyst design, thereby supporting the chemical industry’s transition toward low-carbon and high-efficiency operations.