In this work, density
functional theory calculations were performed
to study the reactions originating from char(N). This study first
provides a clear indication of the radical preference order for char(N).
The approaching oxygen inhibits the formation of the N–N bond
by attracting electron density from the surface nitrogen. On the contrary,
CO is beneficial considering its large partial of the electronic distribution.
The structure sensitive energies resulting from the electron difference
and steric hindrance give us the indication that NCH3,
HNC, NH, and NCO are very important in the reduction of char(N) to
N2. Furthermore, our calculations suggest that the exothermic
surface desorption by about −233.9 kJ/mol is the dominant reaction
for N2 formation. It is expected to be competitive with
surface migration. The results will provide reliable data required
to predict NO
x
destruction, which will
help in design of the low NO
x
burner to
enable the expanded use of coal in China.