Influence of the Pre-treatment Parameters

However, the formation of Lewis acid sites cannot be revealed only from this shifting of the band in the acidity spectrum, since as already mentioned, calorimetry alone is not able to provide a simple procedure for identification of the nature of sites, and needs to be associated with another technique like infrared spectfoscopy. 

It is important to notice that the dehydroxylation at high temperatures produces an irreversible transformation a sample outgased at 1073 K, rehydrated at room temperature and outgased again at 673 K, does not exhibit the initial acidity spectrum [46]. 

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