Effect of MnOx modification and template type on the catalytic performance of ceriazirconia in CO and soot oxidation

The effect of the template nature and modification with MnOx on the catalytic efficiency of Ce0.8Zr0.2O2 (CZ) in oxidation of CO (2 vol% CO and 1 vol% O-2 in He, pulse feeding) and soot particles (tight contact between soot and catalyst, TGA/DSC) was analyzed. The CZ catalysts were prepared using the CTAB and sawdust (SD) templates and modified with Mn (8 wt%) by wet impregnation followed by calcination at 400 degrees C. SEM-EDS, XRD, Raman and photoelectron spectroscopy, N-2 adsorption, EPR, TPR-H-2 and catalytic tests results demonstrated better catalytic activity of CZ(SD) in CO oxidation than of CZ(CTAB) because of the biomorphic texture, higher structural defectiveness and improved oxygen mobility of the former catalyst. Low surface reducibility and low concentration of active oxygen species on the CZ(SD) surface deteriorated its catalytic efficiency in the topochemical reaction of soot oxidation. Despite the different structure and degree of interaction between MnOx and CZ, the Mn-modified catalysts showed the similar catalytic properties: much better than of both unmodified catalysts in CO oxidation and worse than of CZ(CTAB) in soot oxidation. Mn2+ ions incorporated better into the surface layer of CZ(SD) than of CZ(CTAB), for which the inhomogeneous distribution of MnOx and decreased specific surface area were observed.