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Hexagonal mesoporous silica (HMS) catalysts post-synthetically doped with vanadia oxo-species were characterized by means of XRD, UV-Vis spectroscopy, H 2 -TPR and studied in oxidative dehydrogenation of propane (ODH). The relationship between catalytic activity in ODH and the presence of different vanadia-oxo species (monomeric, oligomeric and oxide-like species) was suggested. Monomeric VOx species are responsible for high catalytic activity and selectivity, oligomeric species containing V-O-V bond are active but non-selective to propene and oxide-like VOx particles are significantly less active and selective.

The reduction of NO with octane under lean conditions was examined over gold supported on alumina and titania and over alumina supported bimetallic goldsilver catalysts. The silver loading was either 1.2 or 1.9 wt% whereas 0.3, 1 or 5 wt% gold was used. The catalysts were characterized by means of EDXS, N 2 -adsortion, UV-Vis and TEM to correlate recorded results with different preparation methods. UV-Vis measurements indicated that gold was present in the form of fine Au particles, single Au ions and small (Au) n d? clusters on the catalysts and silver was mainly present in the form of single Ag ions. The highest NO to N 2 reduction activity was recorded over the 0.3Au-Al 2 O 3 catalyst. The Au-TiO 2 catalysts did not result in significant NO to N 2 reduction.