Fourier transform infrared spectroscopic study of surface acidity by pyridine adsorption on Mo/ZrO_2-SiO_2(Al_2O_3) catalysts

摘要

Acidity of the oxidic molybdenum catalysts supported on mixed ZrO_2-SiO_2 and ZrO_2-Al_2O_3 carriers was investigated by Fourier transform infrared spectroscopy of pyridine adsorption. Deposition of molybdenum on ZrO_2-SiO_2 and ZrO_2-Al_2O_3 supports leads to formation of surface Bronsted acid sites. The number of the Bronsted and Lewis acid sites in supported-molybdenum catalysts depends on both the ZrO_2 content and the type of the support. With increasing ZrO_2 content, the Lewis acid sites increase for both series of catalysts. The Bronsted acid sites are higher for Mo/ZrO_2-SiO_2 samples compared to those for Mo/ZrO_2-Al_2O_3 and also increase with zirconia.