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A Mn/Ti–Si catalyst was synthesized and investigated using the NH3selective catalytic reduction (NH3-SCR) of NO in a dry flow and in the presence of H2O or SO2. In particular, the effect of H2O and SO2was studied in several model reactions to obtain a deeper insight into the impact of poisoning compounds on N2O formation. The adsorption behavior of NO and NH3indicated that H2O and SO2decreased the adsorption capacity for NO and increased the adsorption capacity for NH3. The formation of N2O from the disproportionation of NO was negligible. The increase in the adsorption capacity for NH3caused by H2O and SO2did not result in an increase in N2O formation. The formation of N2O from the reaction of NO with NH3was significantly inhibited by H2O and SO2, which could be attributed to the inhibition of the pathway viathe Langmuir–Hinshelwood mechanism. The SCR measurements indicated that the formation of N2O primarily originated from the oxidation of NH3and was suppressed in the presence of H2O or SO2, with a stronger observable effect in the presence of H2O. The formation of N2O is influenced by both the acid–base properties and the redox properties. A mechanism for N2O formation and the suppression effect of H2O and SO2over the Mn/Ti–Si catalyst was proposed, which suggested that the NH3adsorbed on the Brønsted acid sites could inhibit the formation of N2O.

Fe- and Cu-oxides supported on γ-alumina (γ-Al2O3; metal loading of 3 mass %) were investigated as alternative catalysts to the conventional Ag-based system in the selective catalytic reduction of NO with ethanol (EtOH-SCR). The catalysts were characterized by elemental analysis, N2sorption, X-ray diffraction, temperature-prgrammed desorption of NH3, temperature-programmed reduction with H2, diffuse reflectance UV-VIS (DR-UV-VIS) spectroscopy, and compared with 3 mass % Ag/γ-Al2O3as a reference catalyst. Catalytic experiments were carried out between 423 K and 773 K in the steady state and by temperature-programmed surface reaction (TPSR) experiments. For all catalysts, the highest NO conversion (900 ppm (ppm = parts of the mixture component per million parts of all mixture components) NO, 900 ppm EtOH, 0.5 vol. % H2O, 4 vol. % O2in He) was found at 573 K. While 84 % of NO were converted over the Ag-based catalysts, only 20–60 % NO conversion was observed for the Fe- and Cu-containing catalysts. Total oxidation of ethanol as an unwanted side reaction occurs over 3 mass % Cu on γ-Al2O3already at 573 K, whereas the highest activity of 3 mass % Fe on γ-Al2O3for this conversion was reached at 743 K. For lower temperatures, partial oxidation of ethanol leads to organic by-products which can act as active intermediates in EtOH-SCR. TPSR experiments show that ethanol reacts over both the Fe- and the Cu-based catalysts to organic by-products, such as ethene or acetaldehyde, which affect the EtOH-SCR reaction.

Various pseudohomogeneous models for the selective catalytic reduction of NOxby methane were developed by considering reaction schemes and kinetic mechanism. The models were applied to predict the performance of Ce/In-promoted sulfated zirconia catalysts in a wide temperature range from 300 to 700 °C in a fixed bed reactor assuming plug-flow. A nonlinear kinetic model fits the experimental data better than a simple linear model. The mass balance differential equations were solved numerically. The model parameters were estimated by the Simplex-method of Nelder–Mead with a fourth order Runge–Kutta–Merson-method. The finally chosen model is better suited for the prediction of the In-free catalysts than for the mixed oxide catalysts or the Ce-free catalysts. The model suggests that CO formed in the process plays no role in the reduction of NO by CH4. This was confirmed by experimental evidence. The investigated Ce/In zirconia system was better suited for NO reduction by CH4than those published previously.

The oxidative scission of methyl ethyl ketone and 2-butanol on a VOx-TiO2and a VOx/SbOy-TiO2catalyst was studied in the temperature range of 120 to 280°C in the presence of water vapour. The catalytic performance of the two catalysts was investigated by variation of reaction temperature and contact time, and the catalysts were characterized by BET, XRD, XPS, TPR-H2, TPD-NH3, and temperature programmed desorption of lattice oxygen (TPD-O2). The investigations indicate that the addition of Sb2O3to VOx-TiO2favours the selective formation of acetic acid and depresses total oxidation to COxin the catalytic oxidation of methyl ethyl ketone and 2-butanol due to changes in the redox properties of the VOx-TiO2system. Moreover, the higher acidity of the VOx-TiO2catalyst favours the dehydration of 2-butanol to n-butenes.