Mixed oxides acidity generation theories

The mechanism of formation of strong Brpnsted acidity on silica-alumina and protonic zeolites will be discussed later. It results from the association of covalent silica based structures with aluminum in different ways. In any case, in spite of the so-called acidity generation theories in the case of mixed oxides [33,129,130], it seems clear today [131] that these effects are not general phenomena. 

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