Infrared and carbon dioxide chemisorption study of Mo/ZrO2 catalysts

The interaction of Mo with zirconia has been investigated by infrared spectroscopy (IR) and carbon dioxide chemisorption. Quantitative analysis of the IR results indicated that Mo interacts preferentially with the most basic hydroxyl group (high frequency band at 3775 cm−1). An approximately 79% decrease in the 3775 cm−1 band is observed vs. 21% for the low frequency band at 3673 cm−1, with increasing the Mo loading up to 1 wt%. The relative decrease of the IR band at 3775 cm−1 was identical to that measured for the CO2 uptake. The Mo cross-sections estimated from CO2 chemisorption results were much higher than those typically reported for the Mo system. It was concluded that, as previously reported for the Mo/Al2o3 system, CO2 chemisorption overestimates the surface coverage of Mo/ZrO2 catalysts.