Abstract:

Here we reported the effect of the Cu-Mn-Ce-SiO₂ (CMC-SiO₂) interaction on the physical and chemical aspects of the catalytic combustion of toluene by adjusting the loading amount of the CMC mixed oxide on SiO₂. Notably, the CMC/KIT-6 catalyst with low CMC loading performed poorly with an obvious deactivation, owing to the inhibition of the metal oxides active sites, while the activity recovered after washing away some SiO₂. The catalysts were characterized by X-ray diffraction (XRD), H₂ temperature-programmed reduction (H₂-TPR), N₂ adsorption, and high-resolution transmission electron microscopy (HRTEM). Although there is no change in crystal structure after loading on SiO₂, active oxygen species immigrate from lattice to surface for SiO₂ surface rich in hydroxyl groups and having high dispersion of CMC, leading to deactivation of the CMC catalyst. However, it is worth mentioning that the lattice oxygen played a key role in catalytic combustion. The activity of the CMC catalyst recovered when the quantity of lattice oxygen increased upon removing surface -OH groups by calcination or removing some SiO₂ by alkali washing.

Key words: SiO₂, Cu-Mn-Ce mixed oxide, Deactivation, Supporting effect, Catalytic combustion