9 research outputs found
DFT Study on the Methane Synthesis from Syngas on a Cerium-Doped Ni(111) Surface
The methanation of syngas (CO and
H<sub>2</sub>) on the Ce-doped
Ni(111) surface (Ce–Ni(111)) has been investigated by using
the density functional method. The doped Ce enhances the adsorption
energy of the intermediates on the catalytic surface, except for H<sub>2</sub>, particularly for O-containing species. On the Ce–Ni(111)
surface, the reaction pathway CO + 3H<sub>2</sub> → CHO + 5H
→ CH + O + 5H → CH<sub>4</sub> + H<sub>2</sub>O is the
most favorite, in which the energy barrier is 1.18 eV for the rate-determining
step. Compared with the pure Ni(111) surface, the doping of Ce improves
the catalytic activity both thermodynamically and kinetically. The
microkinetic analysis also supports that the methanation of syngas
has high reaction rate on the Ce–Ni(111) compared with the
pure Ni(111). The temperature has great influence on the reaction
rate, while H<sub>2</sub>/CO ratio shows only slightly impact. Our
study also explains the experimental observation that the doped Ce
can reduce the reaction temperature from ∼500 °C on the
pure Ni(111) to ∼340 °C on the Ce–Ni(111) surface.
The coverage of CHO is the largest on the Ce–Ni(111) surface.
We expect that the obtained results could be useful for the future
experimental study in searching the high efficient catalysts