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.