Thermometric titrations for the determination of surface areas and acidities of aluminas and silica-aluminas

A thermometric titration method is developed for the determination of surface areas and acidities of solids. The surface areas and acidities of an alumina and a silica-alumina are determined using a series of alcohols and amines and compared to nitrogen BET surface areas and amine titration acidities. Two types of titrant delivery are used. The surface areas determined using incremental titrant delivery are deemed to be too small to be real and may be an artifact of the sample preparation method. The surface areas determined using continuous titrant delivery show a decrease in surface area with increasing molecular size of the titrant, which is consistent with molecular crowding limiting the extent of adsorption. The heats of adsorption are related to both the acidity of the surface and titrant.