Enhancing Hydroxylation of Benzene to Phenol over Vanadium-Modified Hollow TS-1 Catalysts

Direct hydroxylation of benzene to phenol is a more environmentally friendly way to generate phenol compared with the traditional method. This study developed vanadium-modified hollow-structured titanium silicate-1 (TS-1) as a catalyst for the effective hydroxylation of benzene to phenol under moderate conditions using hydrogen peroxide as an oxidant. The synthesis of TS-1 zeolites has been improved using traditional hydrothermal, crystal seed, and dissolution–recrystallization techniques. Compared with conventional TS-1, hollow-structured TS-1 exhibited a higher mesopore volume and surface area. Later, vanadium doping increased the charge density associated with the framework Ti centers and acid site content. In the radical reaction process, the adsorption and activation of benzene on highly reactive Ti–OOH intermediates, as well as the improvement of performances toward benzene hydroxylation to phenol, were facilitated by the increase in the concentration of open active centers and acid and electron characteristics.