Measurements of number and strength distribution of Brønsted and Lewis acid sites on sulfated zirconia by ammonia IRMS–TPD method

The ammonia IRMS–TPD (infrared-mass spectroscopy/temperature-programmed desorption) method was applied to sulfated zirconia in order to measure the acidic properties [number, strength and type (Brønsted or Lewis) of acid site]. Because the TPD profile was broad, the acid strength distribution was calculated by means of a simulation method on the basis of theoretical equations. The Brønsted acid strength distribution changed according to the calcination temperature of zirconia support. The presence of strong Brønsted acid site on samples prepared by an equilibrium adsorption of H2SO4 was in agreement with the high catalytic activity of these samples for reaction (mainly cracking) of heptane.

Number and strength distributions of Brønsted and Lewis acid sites were completely analyzed by the ammonia IRMS–TPD method. The detected presence of strong Brønsted acid sites on samples prepared by impregnation of H2SO4 on low temperature-calcined zirconia was in agreement with the high catalytic activity.Figure optionsDownload as PowerPoint slide