Evidence for Multiple CO Hydrogenation Pathways on Pt/Al2O3

Article abstract of DOI:10.1021/j100345a008

The reactivity of CO toward hydrogen over 12percent Pt/Al2O3 is examined by temperature-programmed reduction of adsorbed CO(CO TPR) and infrared spectroscopy.The CO TPR spectra show two methane formation rate maxima near 490 and 613 K.The relative intensities of these peaks depend on sample pretreatment temperature with the 490 K peak dominating with higher reduction temperatures.Infrared spectra show the CO chemisorbs molecularly on Pt at 300 K, but some bound CO is converted to alumina-bound methoxy species as the sample is heated to 400 K in H2.IR spectra recorded during CO TPR show the 490 K peak reflects hydrogenation of the surface methoxy to methane.The second CO TPR peak is due to methanation of the remaining CO on Pt.