Optimal solutions and control strategies for photocatalytic conversion of toluene

Toluene is widely used as a raw material for many chemical products/pharmaceutical intermediates and as a solvent in many chemical and manufacturing industries. The conversion of toluene into higher value chemicals (benzyl alcohol, benzaldehyde, and benzoic acid, etc.) using sunlight is a very promising means. To achieve the full conversion and utilization of toluene, it is necessary to construct photocatalysts with high conversion and selectivity while synergistically optimizing the optimal reaction environment to significantly affect the photoconversion of toluene. High-performance photocatalysts not only widely absorb sunlight, but also have abundant active sites and generation of free radicals, which can promote the chemical bonds cleavage of toluene, thus greatly increasing the yield of higher-valued products. In addition, the type of photocatalyst and the modification strategy would influence the selectivity of toluene photo-conversion. Therefore, it makes sense that this review presents the reaction mechanism and the influence of reaction factors for the (mainly) photo-oxidation of toluene, a thorough analysis and prediction of the reaction mechanism by theoretical calculations, and the toluene oxidation by different photocatalysts (in particular halogen-containing perovskite materials) to yield specific products, as well as photocatalysts' modifications. Finally, the challenges and prospects for designing efficient photocatalysts and optimizing the toluene oxidation reaction process are summarized.