The SiMCM-41 mesoporous molecular sieve was synthesised by the hydrothermal method. The physicochemical characterisation by
infrared spectroscopy, X-ray diffraction and thermogravimetry, showed that the material presents a well-defined structure.
In this study, the determination of the total acidity and relative strength of the acid sites of the SiMCM-41,was performed
by desorption of adsorbed n-butylamine combined with thermogravimetric measurements. The total acidity, determined by means of the amount of amine desorbed
normalised by mass of solid, was equivalent to 0.927 mmol g–1, in the temperature range from 96 to 235°C. By using the Flynn and Wall integral kinetic model, at 5, 10 and 20°C min–1 heating rates, it was determined that the activation energy to desorb n-butylamine was 90.7 kJ mol–1, in the same temperature range, evidencing that SiMCM-41 presents only weak acid sites on its surface.