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[Display omitted] • The pyrolysis mechanism of n -heptane are investigated using ReaxFF simulations and DFT calculations. • The initiation reactions of pyrolysis are detailed analyzed. • The cleavage of C C bonds is the easiest. • The kinetic analysis of n -heptane pyrolysis has been carried out. The pyrolysis of endothermic hydrocarbon fuel with high heat sink can reduce the surface temperature of engines and aircraft fuselage. The pyrolysis mechanism of n -heptane as a model compound for endothermic hydrocarbon fuel was investigated by using ReaxFF reactive molecular dynamic simulations and density functional theory calculations. The results showed that the breakage of C C bonds of n -heptane were easier than that of C H bonds, in which the cleavage of C2 C3 bond is the easiest to generate C 2 H 5 and C 5 H 11 radicals. Temperature has a significant effect on the pyrolysis process of n -heptane, and the increase of temperature will accelerate the pyrolysis of n -heptane and promote the formation of pyrolysis products. The pre-exponential factor and apparent activation energy of the n -heptane pyrolysis were 5.4456 × 1014 s−1 and 231.3 kJ·mol−1, respectively. [ABSTRACT FROM AUTHOR]

[Display omitted] • Development of a slab model for alumina-loaded Pt/Ba, considering the effects of both sites simultaneously. • The species exchange process of nitrogen-containing species between proximate Ba and Pt sites is different from the conventional view. • A good linear relationship between NOx adsorption energy and its migration energy barrier. • Detailed electronic structure analysis reveals the reason in essence. Based on density functional theory (DFT) calculations, NO x tends to migrate from Ba to Pt sites within the Lean NO x trap (LNT), rather than reacting at Pt sites before migrating to Ba sites for storage as traditionally believed. Compared with NO and N 2 O, NO 2 has the highest migration energy barrier, and there is a good linear relationship between the adsorption energy of NO x and its migration energy barrier. Furthermore, the essential cause of the above phenomenon is revealed. This study contributes to the exchange of NO x between noble metal catalytic sites and alkaline earth metal storage sites within the LNT. [ABSTRACT FROM AUTHOR]