A Short Review of Aerobic Oxidative Desulfurization of Liquid Fuels over Porous Materials

Oxidative desulfurization (ODS) has attracted much attention owing to the mild working conditions and effective removal of the aromatic sulfur-containing compounds which are difficult to desulfurize using the industrial hydrodesulfurization (HDS) technique. Molecular oxygen in ambient air have been recognized as an ideal oxidant in ODS due to its easy availability, non-toxicity and low cost in recent years. However, molecular oxygen activation under mild operating conditions is still a challenge. Porous materials and their composites have drawn increasing attention due to their advantages, such as high surface area and confined pore space, along with their stability. These merits contribute to the fast diffusion of oxygen molecules and the formation of more exposed active sites, which make them ideal catalysts for aerobic oxidation reactions. The confined space pore size offers a means of catalytic activity and durability improvement. This gives rise to copious attention toward the porous catalysts in AODS. In this review, the progress in the characteristics and AODS catalytic activities of porous catalysts is summarized. Then, emphasis on the molecular oxygen activation mechanism is traced. Finally, the breakthroughs and challenges of various categories of porous catalysts are concluded.