Catalysts containing Au deposited on Fe3O4 (commercial Cerac) and on Fe2O3 were synthesized, characterized by XPS, XRD, Mössbauer spectroscopy, H2TPR, isopropanol decomposition – a probe reaction of acid-base properties, and tested in oxidation of CO and C3H8. Au//Fe3O4 cat a lyst, containing a mixture of magnetite and maghemite (gamma-Fe2O3) phases, was found to be more acidic containing more surface OH groups and less reducible than Au/alfa-Fe2O3 (hematite). The activity in oxidation of CO and propane was higher for Au/alfa-Fe2O3 catalyst as compared with Au/Fe3O4.
Vanadyl diphosphate (Identical to vanadyl pyrophosphate) promoted with Bi, Cs, Co and Te was studied as catalyst in the oxidation of propane, n-butane and n-pentane. The additives modified the surface P/V ratio as determined by XPS, and Br?nsted and Lewis acidity, determined by TPD of ammonia and transformation of 2-methyl-3-butyn-2-ol. The specific rate of the oxidation of hydrocarbons correlated with the nucleophilicity of surface oxygenions. With in crease of Lewis acid ity the se lec tiv ity to maleic an hydride in oxidation of n-bu tane increased, whereas in oxidation of n-pentane the selectivity to phthalic an hydride increased and that to maleic an hydride decreased. The mechanism is discussed.
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