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The valence states of molybdenum in molybdenum oxide catalysts supported on γ-Al2O3 have been studied by the ESCA technique. Molybdenum oxide was found to interact with aluminium oxide in the course of catalyst preparation at 1000°C. In a freshly prepared catalyst molybdenum is present primarily in the hexavalent state. In the reduced catalyst Mo6+, Mo5+ and Mo4+ are present.

Kinetic studies of hydrogen and carbon monoxide adsorption on reduced Re2O7/Al2O3 catalysts have revealed that its activation energy decreases with increasing reduction degree of rhenium oxide. Adsorption of gases is suggested to take place on metallic rhenium atoms.

The well known phenomenon of heterogeneous-homogeneous catalysis is believed to involve surface formation of free radicals, their escape to the gas phase, and subsequent radical, possibly chain reactions [i]. However, the chain and chain radical reactions are most frequent also in strictly heterogeneous catalytic reactions [2]. It is widely accepted that radical oxygen forms Oand 02 are involved in the catalytic oxidation of hydrocarbons (see review [3]). Large amounts of radical sites can be obtained on the catalyst surface by mechanical treatment.

Diffuse reflectance spectra have been recorded for WO3/SiO2 and WO3/γ-Al2O3 catalysts after various steps of treatment of these samples, in particular, after treatment of WO3/SiO2 by HCl. It is shown that for WO3/γ-Al2O3 the temperatures of the onset of reaction and WO3 reduction coincide.

Thermodesorption studies on the interaction of propylene and oxygen over solid CoO−MgO solutions have been carried out. The activation energy of desorption, Ed, for 12% CoO−MgO, 1, 5% CoO−MgO and MgO samples was found to be 10.5, 6.5 and 8.8 kcal/mol, respectively. Pre-adsorption of oxygen or simultaneous adsorption of propylene and oxygen were shown to lead to irreversible adsorption of propylene on the solid solutions.

The interaction between γ-Al2O3 and ethylene, propylene, α-butene, carbon monoxide and dioxide, formic acid, acetone and methane has been studied by diffuse reflectance spectroscopy and adsorption measurements. After the reaction between γ-Al2O3 and olefins at 300 °C two UV absorption bands appear at 325 and 345 nm. The conclusion has been reached that the 345 nm band can be ascribed to the alkenylcarbonium ion (primary product)_formed in the reaction of an olefin molecule with an active surface center. The absorption band at 325 nm is attributed to another alkenylcarbonium ion formed in the reaction of an olefin molecule with the primary product. The bands at 345 and 415 nm appearing after interaction of γ-Al2O3 with acetone at 200 °C have been ascribed to carbonium and oxonium structures.

Diffuse reflectance spectra of 10 wt.% MoO3 supported on γ-Al2O3 and SiO2 have been measured after various steps of treatment. γ-Al2O3 was pretreated by 0.05 and 1.0 wt.% KOH. The comparison of spectral data and catalytic properties allows to predict the optimal oxidation state of molybdenum ions in surface clusters (approximately Mo5+), necessary to obtain supported MoO3 catalysts for propene metathesis with high activity and selectivity.

From the analysis of kinetic behaviour in carbohydrate synthesis from formaldehyde and spectral data on the structure of catalytically active Ca(OH)2 complexes with carbohydrates a step-wise mechanism of autocatalysis of formaldehyde condensation to carbohydrates in the presence of Ca(OH)2 is proposed. A kinetic equation to describe the initial step of autocatalysis is given.