Conversion of propan-2-01 in the absence of air has been used to characterize the acid-base properties of metallic oxides. Two families of solids were studied: the first, niobic acid and oxides exhibited only acidic properties, i.e. resulted only in formation of propene, the second, mixed cobalt and nickel molybdates in their a or fi forms, exhibited acidic and basic properties i.e. resulted in the formation of both propene and acetone. It was also observed that /3-phase molybdates are more active and slightly more selective for propene than the a-phase molybdates.Propan-2-01 conversion to propene (acid catalysed) and/or acetone (redox or acid-base catalysed) is widely used to characterize acid-base or redox properties of catalysts. '-"Kinetics and mechanistic studies are usually necessary to determine which types of catalytic sites are involved. For propene formation, three mechanisms are considered, namely El (Bramsted H + site), E, (acid-base pair site) and concerted ElcB (acid-base pair site).'-', For acetone formation, two mechanisms are invoked, the first with an alkoxy intermediate and the abstraction of the H on C, as the limiting step"-" and the second with the formation of an enolate intermediate and the abstraction of an H on C, as the limiting step.' Niobic acid is known to be a rather strong acid whose acidity decreases on transformation to Nb" oxide." Only propan-2-01 conversion to propene was studied in our work to characterize changes in acidic features during this transformation.CoMoO, and NiMoO, are isostructural molybdates which form solid solutions over the whole concentration range. They are known for their effect on propene oxidation (partial oxidation to acrolein and to acrylic acid, respectively). Conversion of propan-2-01 to propene and acetone was used in this work to characterize the effect of Coz+ substitution for NiZ+ on the acid-base properties (in the absence of air) and redox properties (in the presence of air).

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Copper-thorium oxide catalysts prepared with different atomic ratios Cu : Th by coprecipitation of hydroxides and calcination in dry air at 1073 K, have been characterized by electron paramagnetic resonance (EPR) and UV-VIS spectroscopies before and after being tested as catalysts for the decomposition of isopropyl alcohol. The catalysts are selective for dehydrogenation to form acetone only. The simultaneous presence of Cu2+, Cu+ and/or Cuo in the thoria with a ratio of (Cuo + Cu+)/Cu2+ z 2 is required for activity toward isopropyl alcohol dehydrogenation.

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