Photocatalytic selective oxidation of the terminal methyl group of dodecane with molecular oxygen over atomically dispersed Ti in a mesoporous SiO2 matrix

Abstract

Extraordinarily high selectivity (80–93%) for the oxyfunctionalization of the terminal methyl group was discovered in the photocatalytic selective oxidation of dodecane with molecular oxygen in a continuous flow system under mild gas phase reaction conditions over mesoporous TiO₂–SiO₂ mixed oxide photocatalysts. The oxygenated hydrocarbon products were mainly aldehydes with carboxylic acids and ketones as minor products. By dispersing most of the Ti atomically in a tetrahedral coordination in a SiO₂ matrix, the oxygenated products were stabilized by diluting contiguous Ti sites present on the surface of TiO₂ particles. The preferential oxidation of the terminal methyl group was ascribed to the extensive C–C bond breaking by photogenerated holes prior to oxyfunctionalization.