Combined TPD and FTIR studies of Co/ZrO2catalysts: determination of the cobalt dispersion

Adsorption of NO on cobalt catalysts supported on zirconia and sulphated zirconia results in the formation of three main types of species: Zr4+(SO42−)‐NO and Zr4+(NO3−)‐NO nitrosyls (infrared band at 1940‐1906 cm−1), which are of low stability (temperature‐programmed desorption maximum at 55–80°C); Co2+(NO)2geminal nitrosyls (set of bands at 1903‐1868 and 1814‐1777 cm−1) characterized by temperature‐programmed desorption maxima at 90–100°C; and linear Con+‐NO species (1942‐1858 cm−1) desorbing at 120–140°C. On the basis of the results obtained, a simple temperature‐programmed desorption technique for determination of the cobalt dispersion is developed. Copyright © 2002 John Wiley & Sons, Ltd.