Magdalena Jabłońska

Advances in selective catalytic oxidation of ammonia to dinitrogen: a review

Ammonia emission to the atmosphere is an important environmental problem. A significant increase in ammonia emission is expected in automotive and energy production sectors in the near future. It is related to the spreading of technologies that use ammonia for NOx conversion in flue gases (e.g. DeNOx, DEF) and combustion of nitrogen rich fuels (e.g. biogas, biomass). Among the various methods of ammonia elimination from flue gases, its catalytic selective oxidation to dinitrogen seems to be the most promising one. Different types of catalytic systems active in selective ammonia oxidation are presented and discussed. Moreover, the possible mechanisms of ammonia oxidation and the concept of a bifunctional catalyst are discussed and analysed. Finally, future trends in these studies are suggested.

Silver–Alumina Catalysts for Low-Temperature Methanol Incineration

The use of methanol as an alternative fuel for gasoline or diesel engines increases the unregulated CH3OH emission. γ-Al2O3 modified with Cu, Mn, Ce, K, Ag, Cu–Mn, Cu–Ce, Cu–Ag or Cu–K (0.5, 1.0, 0.5:0.5, 1.0:1.0 wt% of metal) catalysed the process of methanol incineration. The highest activity reached samples containing 1.0 wt% of silver. Dispersed Ag+ species on Al2O3 served as active species for selective oxidation of CH3OH to CO2 over both Ag/Al2O3 and Cu–Ag/Al2O3. Additionally, the XPS and EPR results revealed the AgO interface between the Ag2O and CuO in the Cu–Ag system.Graphical Abstract

Selective catalytic oxidation of ammonia into nitrogen and water vapour over transition metals modified Al2O3, TiO2 and ZrO2

Copper or iron supported on commercially available oxides, such as γ-Al2O3, TiO2 (anatase) and monoclinic tetragonal ZrO2 (mt-ZrO2) were tested as catalysts for selective catalytic oxidation of ammonia into nitrogen and water vapour (NH3-SCO) in the low temperature range. Different commercial oxides were used in this study to determine the influence of the specific surface area, acidic nature of the support and crystalline phases as well as of the type of species and aggregation state of transition metals on the catalytic performance in selective ammonia oxidation. Copper modified oxide supports were found to be more active and selective to nitrogen than catalysts impregnated with iron. Activities of both transition metal modified samples decreased in the following order: mt-ZrO2, TiO2 (anatase), γ-Al2O3. Quantitative total ammonia conversion was achieved with the Cu/ZrO2 catalytic system at 400◦C. Characterisation techniques, e.g. H2-temperature programmed reduction, UV-VIS-diffuse reflectance spectroscopy, suggest that easily reducible copper oxide species are important in achieving high catalytic performances at low temperatures. c

Hydrotalcite-like materials containing manganese – a short review

Numerous hydrotalcite-like or their derivatives have been reported as catalysts for a wide variety of chemical processes including selective reduction of nitrogen oxides with ammonia (SCR, DeNOx) or NOx storage/reduction process, selective ammonia oxidation to nitrogen and water vapour (SCO), N 2 O decomposition (DeN 2 O) and total oxidation for volatile organic compounds (VOCs). Among them manganese-containing hydrotalcite-like materials and their derivatives seems to possess high activity. This paper gives an overview of Mn-containing catalysts, including the catalyst development and their possible applications. The use of mixed metal oxides obtained from synthetic hydrotalcite-like materials mainly in the role of catalysts for the total VOCs decomposition has been reviewed. Achieved results clearly show that tested materials are candidates for potential application in real catalytic processes.