Calorimetric Study of Amine Adsorption on α- and γ-Titanium Phosphate

Abstract

Using a microcalorimetric technique, we have determined the differential heat of adsorption of ethyl- and n-butylamine over α- and γ-titanium phosphate phases. The recorded data were compared with those obtained by using N2/77 K adsorption−desorption isotherms, X-ray diffraction peak broadening studies, and scanning electron microscopy. At low coverage, the measured heat of adsorption decreases with increasing coverage, which means the solids have superficial heterogeneity. The γ-phase external surface is more energetic than the α-one. The average heats of adsorption in the interlamellar region of the α-titanium phosphate at 298 K (ethylamine, 95 kJ mol-1; n-butylamine, 110 kJ mol-1) are in good agreement with gas-phase proton affinities data.