Deactivation Mechanism Of Ceo2-Based Mixed Oxide Catalysts Supported On Sio2

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), H-2 temperature-programmed reduction (H-2-TPR), N-2 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.