Infrared spectroscopic study of CO and CO2 adsorption on Rh–ZrO2, Rh–Al2O3 and Rh–MgO
Abstract
The adsorption states of CO and CO2 on Rh catalysts supported on ZrO2, Al2O3 and MgO were studied using i.r. spectroscopy. Upon adsorption of CO on reduced Rh–ZrO2, the carbonate bands due to the reaction 2CO →C + CO2, together with the bands of twin, linear and bridge CO species were observed at moderate temperatures, whereas Rh–MgO gave no appreciable formation of CO2 even at higher temperatures (> 100 °C) and Rh–Al2O3 showed intermediate behaviour. On the adsorption of CO2, the linear CO band was formed at lower frequency than that on CO adsorption. The linear CO species formed from CO2 showed higher reactivity toward hydrogen compared with that from CO adsorption.