Pd/Pt promoted Co3O4 catalysts for VOCs combustion: Preparation of active catalyst on metallic carrier

Emission control of volatile organic compounds (VOCs) is one of the priorities for environmental catalysis. Metallic microstructural short-channel reactors of various geometries are regarded as an alternative to ceramic monoliths. The paper presents the results on the catalyst preparation and optimisation. Chromium-aluminium (CrAl) steel was surveyed in terms of its applicability for carrier manufacturing and catalyst depositing. Alumina washcoat and cobalt catalyst were deposited as organic precursors using Langmuir–Blodgett method (LB) onto precalcined CrAl sheets. Additional noble metal promoters (Pd and Pt) were deposited by chemisorption. The LB method occurred useful for the preparation of nanocomposite catalyst since it enabled controlling the quantity and even distribution of the deposited material. The catalyst surface at various stages of preparation was examined using SEM, XPS and AFM methods. Catalytic tests showed that small amount of Co₃O₄ spinel, highly dispersed on Al₂O₃ layer, is active in combustion of diluted n-hexane. The apparent activation energy for the obtained cobalt catalyst (about 52 kJ/mol) was twice as low as for a standard Pt/Al₂O₃ catalyst. The promoting effect observed for Pd-containing cobalt catalysts by the decrease in the activation energy to around 15 kJ/mol, was correlated to the high surface concentration and dispersion of the cobalt catalyst containing PdO.