Owing
to the unique properties of aluminum nanoparticles, these
nanoadditives show promise in improving the combustion performance
of traditional hydrocarbon fuels. Here, the ignition and combustion
processes of the simplest hydrocarbon, methane, with the addition
of aluminum nanoparticles, were investigated using ReaxFF molecular
dynamics simulations. The oxidation of the initially unoxidized aluminum
nanoparticles is a microexplosive violent combustion process. The
simulation results revealed that the presence of such aluminum nanoparticles
reduces the ignition delay of methane and improves its combustion
efficiency. The activation energy of methane dissociation is significantly
reduced by ∼47% in the presence of aluminum nanoparticles compared
to the pure methane system. It is found that the mechanism of this
combustion enhancement is from the significant increase in the number
of atomic oxygen with the addition of aluminum nanoparticles, which
accounts for the decomposition of methane by more than 60%. Moreover,
the formation of atomic oxygen is mainly caused by the instability
of low-coordination atoms on the surface of the Al
x
O
y
cluster. Further simulations
of aluminum particles with oxide shells show that such particles can
also promote the production of atomic oxygen to a small extent. It
is believed that the findings presented here provide an important
perspective on understanding the influence of aluminum nanoparticles
on the combustion of hydrocarbon fuels at an atomic scale, and have
an instructive significance in improving combustion efficiency.