The effect of iron on the adsorption properties of CuMnZrO2 catalysts studied by temperature-programmed desorption and FTIR spectroscopy

The adsorption of CO on the precipitated Fe-CuMnZrO2 catalysts for mixture alcohols synthesis were investigated using temperature programmed desorption and FTIR spectra recorded at adsorption temperature in the range 298-673 K, in order to detect any synergy in the adsorption of CO on CuMnZrO2 as a result of iron addition. In the case of CuMnZrO2 catalyst, only one kind of CO adsorbed or desorbed, which was ascribed to weakly adsorbed CO species on copper sites, was detected in FTIR and TPD study. Moreover, for CuMnZrO2 catalyst the formation of bidentate carbonate species was favored at 298 K, and bicarbonate species formed at higher temperature. When iron was introduced in CuMnZrO2 catalyst, it was found that the adsorption features of catalysts changed significantly. The presence of iron improved the copper dispersion, which resulted in increasing of the total adsorption of CO, and intensified the reaction between CO and catalyst surface. Several kinds of CO adsorbed or desorbed were detected on Fe-CuMnZrO2. The formation of bicarbonate species took place at 298 K, and formate species was detected at higher temperature, suggesting that the presence of iron greatly influenced the process of methanol synthesis. (C) 2004 Elsevier B.V. All rights reserved.