Topography and morphology of multicomponent catalytic materials based on Co, Ce and Pd oxides deposited on metallic structured carriers studied by AFM/Raman interlaced microscopes

• Published in: Catalysis today 2013-11, Vol.216, p.11-17
• Main Authors: Łojewska, J., Knapik, A., Jodłowski, P., Łojewski, T., Kołodziej, A.
• Format: Article
• Language: English
• Subjects: AFM/Raman mapping; AFM–Raman coupled system; Catalysis; catalysts; catalytic activity; Catalytic combustion of VOC; chemical composition; Chemistry; cobalt; Cobalt oxide; combustion; Exact sciences and technology; General and physical chemistry; grains; microscopes; oxides; palladium; steel; Structured reactors; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry; thermal stability; topography
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2013.05.008

•Coupled AFM/Raman microscopy grasps heterogeneity of multicomponent catalysts.•Precalcined kanthal steel (catalyst carrier) composed of α-Al2O3 and α-Fe2O3.•Washcoated precalcined steel composed of non-uniform layer of CeO2.•Depositing of cobalt the washcoated carrier gave uniform layer of Co3O4.•High activity of palladium doped Co3O4 catalyst correlated with the presence of PdO. A system of interfaced AFM and Raman microscopes was used to study heterogeneity of complex catalytic materials providing information on both the topography and the chemical composition of the surface in one measurement. The catalysts surface was examined at various stages of their preparation: precalcination of steel, washcoating, impregnation and doping. It has been shown that the surface of the precalcined steel sheets is covered mostly by α-Al2O3 although there are places where α-Fe2O3 and Fe3O4 are also present. Washcoating of the precalcined sheets gives only partly uniform grain distribution of CeO2. Impregnation with cobalt leads to formation of uniform coverage of Co3O4. Depending on the presence or absence of ceria washcoat layer, palladium doped to the cobalt catalyst may give dispersed Pd0 grains or large grains of PdO, respectively. High n-nonane combustion activity and thermal stability of cobalt palladium doped catalysts deposited directly on the precalcined steel than was correlated with the presence of PdO phase.