Heterogeneous Photocatalytic Oxidative Cleavage of Polystyrene to Aromatics at Room Temperature

Heterogeneous photocatalytic aerobic oxidation systems have been developed for selective degradation of polystyrene (PS) to aromatic monomers at room temperature and ambient pressure. The TiO2 particles modified with potassium stearate or N,N-diethyl-3-(trimethoxysilyl)propan-1-amine photocatalyzed the oxidative cleavage of commercial PS to benzoic acid with up to 43.5 mol % yield. Mechanistic studies revealed that the initial alkyl C–H oxidation and C–C cleavage were greatly improved by these alkaline modifiers. The superoxide anion radical and singlet oxygen acted as the key oxidative species during the degradation process. Common PS waste from daily life also underwent efficient degradation with 18–44.2 mol % yields of benzoic acid on the developed catalysts.