Photoreactive polymer composite for selective oxidation of benzene to phenol

Abstract

In this work, the photocatalytic hydroxylation of benzene to phenol in presence of H2O2 is studied using, for the first time, a photoreactive polymer composite based on N-doped TiO2 (N-TiO2) embedded into a monolithic syndiotactic polystyrene aerogel (N-TiO2/sPS, 10/90 w/w). N-TiO2/sPS is able to enhance the phenol selectivity and yield compared to bare N-TiO2. The best results in terms of selectivity (98%) and phenol yield (57%) are achieved under visible light in acidic conditions (pH=2), preserving a high benzene conversion (58%). In addition, N-TiO2/sPS is recovered from the aqueous solution containing the reaction products and reused several times without significant loss of photoreactivity and reduction of phenol yield. The described photoreactive solid phase represents a "proof of concept" that could allow a significant leap forward in the development of innovative green processes for the selective oxidation of aromatic hydrocarbons under mild conditions.