Effects of different surface species on the infrared spectrum of CO adsorbed on Rh/Al2O3
Abstract
The effects of surface species (formed in the hydrogenation of CO and CO2 on supported Rh catalysts) on the bonding of chemisorbed CO on Rh have been investigated by infrared spectroscopy. It appeared that neither the intensities nor the locations of the bands of adsorbed CO and formate were influenced by each other, indicating that the adsorption sites for CO and formate species at 300 K on Rh/Al2O3 are basically different. The adsorption of ethylene (or its fragments) lowered the amount of CO adsorbed on Rh. It left the position of the Rh(CO)2 bands unaltered, but it caused a red shift in the band of Rh—CO species. The deposition of carbon on the surface also changed the structure and adsorptive properties of Rh, and shifted the Rh—CO bond to lower frequency.