Photocatalytic Upcycling of Polystyrene

Polystyrene as a hard, transparent and stable synthetic resin, has been widely used as the disposable containers. The slow polystyrene degradation under natural conditions and lack of direct recovery result in the white pollution and waste of resources. The structure characteristics such as aromatic units and single linkage make polystyrene a potential feedstock to produce aromatic compounds. Photocatalysis has been widely used to degrade and upcycle plastic. Early researches on photocatalytic transformations of polystyrene focus on the degradation into small molecules and CO2, targeting at decreasing the plastic accumulation in the environment. The emerging photocatalytic selective polystyrene conversion into value-added aromatics can motivate the sorting and recovery of polystyrene. This chapter summarizes the developments in photocatalytic selective oxidation of polystyrene into benzoic acid and acetophenone, which includes homogeneous catalytic systems, heterogeneous catalytic systems, and self-catalysis systems. The composites in catalytic systems, reaction conditions, catalytic performance and mechanism studies are discussed. At last, the perspective on future real-life polystyrene upgrading into diverse products under green conditions is proposed.