Acid-base interactions measurement pyridine adsorption

The overall acidic nature of Al-substituted MTS, expected on simple chemical grounds, may be proved by non-spectroscopic measurements, e.g., immersion calorimetry [31], or determination of the adsorption capacity for a base molecule (volumetric or gravimetric, e.g., [32]). Other overall methods employed to define acidity are also based on the interaction with strong bases, usually ammonia or pyridine. The interaction may be followed either by calorimetry (in the adsorption run) or through temperature-programmed desorption (TPD). Both techniques reveal the presence of sites, differing in one case by the differential heat of adsorption and in the second case by the temperature of the desorption peak. 

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