Correlations between the optical basicity of catalysts and their selectivity in oxidation of alcohols, ammoxidation and combustion of hydrocarbons

The optical basicity Lambda of metallic oxides is obtained by a linear comb ination of the optical basicity of cations and depends on their valence, co ordination and spin state. Lambda quantifies the electron donor/acceptor po wer of the solid, which may be correlated with its redox properties. During catalysis, it is expected that the electron donor/acceptor property of the selective catalyst matches the acceptor/donor property of the reactant to be selectively transformed into the product. The selectivity is accounted f or by Delta I which is the difference between the ionization energies of re actant and product. Each selective catalyst/reactant-product couple is char acterized by (Lambda, Delta I) value. Linear relationships between the (Del ta I, Lambda) obtained for various catalyst/reaction couples are drawn for several types of selective oxidation reactions: mild oxidation of alkanes, of olefins and of alcohols, ammoxidation of hydrocarbons. total oxidation o f alkanes and of olefins. (C) 2000 Published by Elsevier Science B.V.