Metal-oxide catalysis hydrocarbon activation over

It is also shown that carbonaceous deposits built upon oxides via spill-over from metal sites is active in ethene hydrogenation in its own right. Thus during catalysis of hydrocarbon reactions some sites (metallic and acidic) are lost or made unavailable while simultaneously others are generated. This complex yet intriguing situation emphasises the need for in-situ characterisation of catalytic surfaces. 

A third topic, not specific to the use of dioxygen as oxidizing agent, concerns selectivity and, in particular, the closely related aspect of over-oxidation. This problem is most severe in the partial oxidation of saturated hydrocarbons, because activation of alkanes is usually more difficult than that of any of the oxygenated products (e.g., alcohols and aldehydes), which are easily oxidized further. The reason is simply that C-H bonds of functionalized alkanes are generally weaker than those of the parent hydrocarbons. Moreover, as far as metal catalysis is concerned, the polar oxidation products can... 

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