Photocatalytic Reactions of Hydrocarbons and Fossil Fuels with Water. Hydrogen Production and Oxidation

Article abstract of DOI:10.1021/j150662a046

Photocatalytic H2 production from several aliphatic and aromatic compounds with water was investigated with powdered Pt/TiO2 catalyst suspended in solution.Various fossil fuels such as coal, tar sand, and pitch also reacted with water, producing both H2 and CO2 from an early stage of irradiation.The photocatalytic oxidations of their model compounds, especially a linear hydrocarbon and benzene, were studied in the presence of silver ion as an electron acceptor.For aliphatic hydrocarbons, they are oxidized to alcohols, aldehydes, and carboxylic acids, successively.CO2 was found to be formed through the photo-Kolbe type of reaction of carboxylic acids produced, which explained well the result of the complete decomposition of n-hexadecane.For benzene, we could detect phenol, catechol, hydroquinone, and muconic acid.On the basis of these results, the possibility of the direct oxidation of benzene by photogenerated holes and its ring-opening process peculiar to the photocatalytic reaction are discussed.The main reaction path for CO2 production was suggested in which the benzene ring opens not by way of phenol and catechol, but by way of the intermediates whose reactivities are much larger than that of benzene.