Knowledge Bank

The infrared spectra of ethylene and propylene chemisorbed on silica-supported nickel (9.2 wt. %) have been obtained. Interpretation of the spectra is based on analogy with the spectra of hydrocarbons of known structure neglecting any possible effects of strain on the spectra of of the adsorbed hydrocarbons. In the case of chemisorbed ethylene the position of the absorption due to C-H stretching was essentially in the region characteristic of saturated hydrocarbons. In addition a band attributed to $CH2$ deformation was observed at 6.91 microns. On the basis of these data it was concluded that the chemisorbed species consists mainly of $H2C\ast -C\ast H2$ (asterisk indicates bonding to the nickel surface). Evidence was obtained for the existence of a half-hydrogenated state, $C\ast H2CH3$, by exposing the chemisorbed ethylene to hydrogen. Infrared spectra of chemisorbed propylene and hydrogen exposed chemisorbed propylene were also obtained.