Infrared studies of the adsorption of alkenes on non-stoichiometric boron phosphate

Abstract

The infrared spectra of a number of alkenes chemisorbed on non-stoichiometric boron phosphate of P/B < 1 and P/B > 1, where P/B is the molar ratio of phosphorus to boron, show similar absorption bands characteristic of saturated species. Spectra were obtained on adsorption of an alkene on a sample previously exposed to a poison, or vice versa. These spectra and results from measurements of the amount of alkene adsorbed on bare surfaces, and on those containing various amounts of preadsorbed pyridine, provide evidence that the adsorbed species is common to all the alkenes. These adsorbed species can be interpreted as carbonium ions of various kinds, which rapidly convert to tertiary carbonium ions, and subsequently to oligomeric forms of the hydrocarbons.