Adsorption studies of Câ†3 hydrocarbons on single crystal, thin film and supported metal substrates using FTIR spectroscopy
This study involved the investigation of C3-hydrocarbon adsorption on a range of metal and supported metal surfaces using FTIR spectroscopy. The initial aim was to use 'model' metal surfaces i.e. single crystal and polycrystalline metals, to determine fingerprint spectra for various adsorption complexes of propene and propyne. These fingerprint spectra were then to be used to help determine the nature of surface species formed on 'real' industrial catalysts. The single crystal study involved adsorption of both propene and propyne on Pt(111) at temperatures of 90 K and >300K. Adsorption of propene on Pt(111) at 90 K yielded the first infrared spectrum of the di-σ propene surface complex. Spectra obtained at higher temperatures for this system provided the signature of the propylidyne species. Upon adsorption of propyne on Pt(111) at 90 K the fingerprint spectrum of a 'Type A' propyne surface complex was recorded. Adsorption of propene on thin polycrystalline films of copper and palladium, at low temperature was investigated using transmission infrared spectroscopy. In this study the first infrared spectra of the π-adsorbed propene complex were recorded. The second half of the study involved investigation of the surface species formed on 'real' industrial catalysts, i.e. Al2O3 and Pt/Al2O3. Infrared spectra were recorded for a wide range of surface species such as propene complexes, acrolein, acrylate, carboxylates, hydrogencarbonate, and carbonates. These results showed that the main surface chemistry involved on these catalysts was that of the oxide support and not that of the platinum metal.