Cobalt mixed oxides deposited on the SiC open-cell foams for nitrous oxide decomposition

Abstract Supported Co 3 O 4 and Co 4 MnAlO x mixed oxides were prepared by deposition on the SiC open-cell foams by wet impregnation and suspension methods and characterized by AAS, BET, XRD, SEM, TEM, TPR-H 2 , XPS and nitrogen adsorption methods. Prepared supported catalysts as well as active phase Co 3 O 4 and Co 4 MnAlO x in grain form prepared from parent solutions were tested for nitrous oxide decomposition. Catalytic activity of grain active phase was governed by methods of preparation; Co 3 O 4 and Co 4 MnAlO x prepared by suspension method were significantly more active than those from solutions for impregnation method. Suspension method provided active phase with higher surface areas and sites with better reducibility, both of these factors contributed to higher N 2 O conversions. In contrast to this, N 2 O conversions over supported catalysts were dependent more on chemical composition of active phase than on method of preparation. Both catalysts containing Co 4 MnAlO x mixed oxide revealed higher conversion of N 2 O than catalysts containing Co 3 O 4 . STEM analysis of the most active Co 4 MnAlO x prepared by suspension method showed (i) segregation of Co 3 O 4 nanocrystals of cuboctahedral shape containing (100) and (111) facets (this segregation was confirmed also by XPS and TPR-H 2 ) and (ii) Co-Mn-Al oxide nanoparticles with very small un-faceted grains assembled into elongated fiber-like agglomerates were observed by STEM.