Heterogeneous Photocatalytic Oxidative Cleavage of Polystyrene to Aromatics at Room Temperature

Heterogeneousphotocatalytic aerobic oxidation systems have beendeveloped for selective degradation of polystyrene (PS) to aromaticmonomers at room temperature and ambient pressure. The TiO2 particles modified with potassium stearate or N,N-diethyl-3-(trimethoxysilyl)propan-1-amine photocatalyzedthe oxidative cleavage of commercial PS to benzoic acid with up to43.5 mol % yield. Mechanistic studies revealed that the initial alkylC-H oxidation and C-C cleavage were greatly improvedby these alkaline modifiers. The superoxide anion radical and singletoxygen acted as the key oxidative species during the degradation process.Common PS waste from daily life also underwent efficient degradationwith 18-44.2 mol % yields of benzoic acid on the developedcatalysts. This study reports on the reusableheterogeneous photocatalystfor upgrading of polystyrene to benzoic acid at room temperature.

Automated summary

Heterogeneous photocatalytic systems have been developed to selectively degrade polystyrene (PS) to aromatic monomers at room temperature and ambient pressure. By modifying TiO2 particles with potassium stearate or N,N-diethyl-3-(trimethoxysilyl)propan-1-amine, the oxidative cleavage of commercial PS to benzoic acid can achieve up to 43.5 mol % yield. The use of alkaline modifiers greatly improves the C-H oxidation and C-C cleavage reactions, and the key oxidative species in the degradation process are found to be the superoxide anion radical and single oxygen. Furthermore, this study demonstrates the efficient degradation of common PS waste to benzoic acid on the developed photocatalysts with yields ranging from 18 to 44.2 mol %.