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In the present study the catalytic activities of several TiO2-supported metal and metal oxide catalysts have been tested simultaneously for the selective catalytic reduction of nitrogen oxides with ammonia (NH3-SCR) using high-throughput-screening equipment. Two different series of various catalyst samples were evaluated for different feed gas compositions, both with and without water, and before and after SO2 exposure. The first series of samples consisted of catalysts containing a single metal or metal oxide (Mg, V, Cr, Mn, Fe, Co, Ni, Cu, Mo, Rh, Ag, W, Ir, or Pt), including a commercial SCR catalyst sample for comparison. Of the metals investigated in the first series, Cr, Mn, Fe, and Rh were found to have the most interesting catalytic properties, regarding activity and selectivity at high or low temperatures. A second series of samples were prepared containing combinations of the selected metals, and the results from the catalytic tests show a general trend of increased SCR activity at lower temperatures when Rh is added to the multiple-metal samples. The results further indicate that it is possible to widen the active temperature window by combining different metals in the catalyst formulation.

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Vibrational properties of surface species formed upon H2 and D2 exposure of silica supported platinum particles have been investigated with in situ diffuse reflection infrared Fourier transform spectroscopy. Experiments have been performed at 50-250 degrees C, using different platinum loading of the samples in the absence and presence of oxygen. In addition, electronic structure calculations and vibrational analysis have been performed within the density functional theory for H adsorption on a silica cluster, (HO)3SiOSi(OH)3. The spectroscopy experiments showed reversible formation of isolated OH and OD groups on the silica surface when the samples were exposed to H2 and D2, respectively. In addition to the absorption peak corresponding to isolated OH and OD groups, an intense broad band was observed around 3270 cm(-1) (2500 cm(-1)) during H2 (D2) exposure. Supported by the calculations, this band was assigned to perturbed OH groups on the silica surface. The surface coverage of new OH groups was found to correlate to the platinum loading in the samples, indicating that the new silanol groups were formed in the vicinity of the Pt particles. In the investigated temperature interval, the formation rate of OH groups was not found to be temperature dependent.

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The sensing mechanism of metal insulator silicon-based field effect transistor devices (MISFET) for H 2 and NH 3 detection has been studied for Pt/SiO 2 and Ir/SiO 2 model sensors with in situ infrared spectroscopy and density functional theory calculations (DFT). The spectroscopy experiments showed reversible formation of isolated OH groups on the silica surface upon H 2 or NH 3 exposure. In addition, an intense broad band was observed around 3270 cm -1 . Supported by the calculations, this band was assigned to perturbed OH groups on the silica surface. These results strongly indicate that dissociation and spill-over of hydrogen occurs during exposure of Pt/SiO 2 and Ir/SiO 2 to H 2 or NH 3 . These results indicate a common sensing mechanism for hydrogen and ammonia.

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