Catalytic total oxidation is an effective procedure to minimize emissions of volatile organic compounds (VOC) emissions in industrial gases. Catalysts in the form of meshes are remarkable as they minimize the internal diffusion of reactants during the reaction as well as the need of expensive active components. In this paper, various conditions of radio frequency magnetron sputtering of cobalt on stainless-steel meshes was applied during catalyst preparation. Properties of the supported Co₃O₄ catalysts were characterized by SEM, XRD, temperature programmed reduction (H₂-TPR), FTIR, XPS, and Raman spectroscopy. Catalytic activity was examined in deep oxidation of ethanol chosen as a model VOC. Performance of the catalysts depended on the amount of Co₃O₄ deposited on the supporting meshes. According to specific activities (the amounts of ethanol converted per unit weight of Co₃O₄), smaller Co₃O₄ particle size led to increased catalytic activity. The catalyst prepared by sputtering in an Ar+O₂ atmosphere without calcination showed the highest catalytic activity, which decreased after calcination due to enlargement of Co₃O₄ particles. However, specific activity of this catalyst was more than 20 times higher than that of pelletized commercial Co₃O₄ catalyst used for comparison.

The effect of the Co-Cu oxide catalysts composition on their physicochemical properties and performance in the deep oxidation of ethanol was studied. The catalysts with Co:Cu molar ratios of 4:1, 1:1, and 1:4 were obtained by calcination (4 h at 500 °C in air) of the coprecipitated precursors and characterized in detail using powder XRD, Raman spectroscopy, N₂ physisorption, H₂-TPR, and XPS. The powder XRD and Raman spectroscopy indicated the formation of Co₃O₄ and CuO mixtures rather than Co-Cu mixed oxides. The CuO promoted the Co₃O₄ reduction; the Co-Cu catalysts were reduced more easily than the single-component Co and Cu oxides and the main reduction maxima were shifted to lower temperatures with increasing cobalt content in the catalysts. The Co-Cu oxide catalyst with a Co:Cu molar ratio of 4:1 exhibited the best performance in ethanol gas-phase oxidation, showing the lowest T₅₀ (91 °C) and T₉₀(CO₂) (159 °C) temperatures needed for 50% ethanol conversion and 90% conversion to CO₂, respectively. The excellent catalytic properties of this Co-Cu oxide catalyst were ascribed to the synergistic effect of Co and Cu components. The high activity and selectivity of the Co-Cu catalyst was attributed to the presence of finely dispersed CuO particles on the surface of Co₃O₄.

Fundamental research on direct NO decomposition is still needed for the design of a sufficiently active, stable and selective catalyst. Co-based mixed oxides promoted by alkali metals are promising catalysts for direct NO decomposition, but which parameters play the key role in NO decomposition over mixed oxide catalysts? How do applied preparation conditions affect the obtained catalyst’s properties? Co₄MnAlO_x mixed oxides promoted by potassium calcined at various conditions were tested for direct NO decomposition with the aim to determine their activity, stability and selectivity. The catalysts were prepared by co-precipitation of the corresponding nitrates and subsequently promoted by KNO₃. The catalysts were characterized by atomic absorption spectrometry (AAS)/inductive coupled plasma (ICP), X-ray photoelectron spectrometry (XPS), XRD, N₂ physisorption, temperature programmed desorption of CO₂ (TPD-CO₂), temperature programmed reduction by hydrogen (TPR-H₂), species-resolved thermal alkali desorption (SR-TAD), work function measurement and STEM. The preparation procedure affects physico-chemical properties of the catalysts, especially those that are associated with the potassium promoter presence. The addition of K is essential for catalytic activity, as it substantially affects the catalyst reducibility and basicity—key properties of a deNO catalyst. However, SR-TAD revealed that potassium migration, redistribution and volatilization are strongly dependent on the catalyst calcination temperature—higher calcination temperature leads to potassium stabilization. It also caused the formation of new phases and thus affected the main properties—S_BET, crystallinity and residual potassium amount.