Latest results on the catalytic oxidation of light alkanes, as probe VOC molecules, over Ru-based catalysts: Effects of physicochemical properties on the catalytic performances

Volatile organic compounds (VOCs) are recognized as having a major responsibility for the increase in global air pollution due to their contribution to ozone and photochemical smog. Currently, the most active catalysts for VOCs oxidation are based on noble and transition metals. Among noble metals, platinum, palladium and rhodium exhibit high activity and selectivity at low temperature, but they are unstable in the presence of chloride compounds. Systems based on transition metal oxides (such as V₂O₅, MnO₂, Co₃O₄-based oxides) are generally less active than noble metals, some formulations are stable to chlorines and their cost is significantly lower. Supported ruthenium catalysts have received much attention over the past years, because of their high activity in oxidation as well as reduction reactions. Such catalysts have proved to be among the best catalytic systems for oxidation of various substrates, such as carbon monoxide, ammonia, hydrogen, alcohols, diesel soot, and even in low temperature oxidation of HCl. However, few studies on VOCs oxidation over supported Ru have been conducted so far, especially in light alkane combustion. The physicochemical properties of Ru catalysts have been found to strongly influence activity and stability. Therefore, the comparison between catalysts prepared by different methods and pretreated in different conditions is difficult. In order to give a general overview on the state of art, the present chapter focuses on the latest results on the catalytic performance of Ru catalysts for light alkanes oxidation with special attention to the structureactivity relationship.