Effects of CeO₂ on the XPS valence band spectra of coal under the combustion initialization stage at 400℃

In order to get the catalytic mechanism of CeO₂ on graphite and coal at 400℃, the morphologies of coal, graphite, and CeO₂ before and after combustion were analyzed through X-ray photoelectron spectroscopy (XPS). It is found that the particle size of coal is mostly between 11.727 and 64.79 μm, while the particle size of CeO₂ is between 1.937 and 11.79 μm. The agglomeration of coal and CeO₂ can be seen by scanning electron microscopy (SEM) after reaction. XPS results show that with the addition of CeO₂, the intensity of binding energy gets stronger, but there is no energy peak transition. Comparing the character of coal with and without the addition of CeO₂, it can be seen that the C-C bond fractures first at 400℃, while the C-H energy-band takes electrons at the same time to be far away from the Fermi level, and the O 2s, O 2p, and C sp hybrid orbitals are all excited. Adding CeO₂ can enhance the activity of the whole coal. In addition, through XPS analysis, combined with the oxygen transfer theory and the electron transfer theory, the catalytic mechanism of CeO₂ for pulverized coal combustion could be obtained.