Continuous\nFlow Hydroxylation of Benzene to Phenol\nin a Photocatalytic Millistructured Flat-Plate Reactor

Phenol can be produced from benzene via photocatalytic\nhydroxylation.\nA continuous flow flat-plate reactor emerges as a promising option,\nas it allows for a large irradiation window and a short photon penetration\ndepth. In this work, TiO<sub>2</sub> (Degussa P25) was applied as\na photocatalyst. The use of smectite clays and a 3D-printed casting\ntemplate was the key to the uniform immobilization of photocatalysts\nover the glass window surface. Acetonitrile was selected as a carrier\nsolvent for benzene since the fluid dynamics exhibited an efficient\nmixing with the aqueous H<sub>2</sub>O<sub>2</sub> flow solution.\nFurthermore, the response surface methodology was employed to examine\nthe effects of residence time, temperature, and light power. Our flat-plate\nreactor produced a high photocatalytic space-time yield of 1.2 ×\n10<sup>–11</sup> mol/W s, which is about 1–2 orders\nof magnitude higher than the reported batch setups. The transport\nphenomena equation was also formulated to elucidate the kinetics of\nthe photocatalytic reaction, giving the adsorption constant and the\nintrinsic kinetic constant to be 0.0535 m<sup>3</sup>/mol and 8.21\n× 10<sup>–6</sup> mol/(m<sup>2</sup>·s), respectively.