Silica microspheres functionalized with porphyrin as a reusable and efficient catalyst for the photooxidation of 1,5-dihydroxynaphthalene in aerated aqueous solution

Silica microspheres functionalized with 5-(4-allyloxy)phenyl-10,15,20-tri(2,6-dichlorophenyl)porphyrin (APTDCPP), SiO2-MPS–APTDCPP, have been synthesized by sol–gel process and characterized using SEM, FT-IR, UV–vis and TG. The SEM images show that the morphology of the silica microspheres is spheriform and uniform with size of 2–4 μm. Their photocatalysis activity to oxidize 1,5-dihydroxynaphthalene under visible light irradiation in aerated aqueous solution has been studied and the main product has also been identified by 1H NMR and MS techniques. The factors affecting photocatalytic oxidation, such as oxygen concentration, initial concentration of substrate, amount of catalyst and the addition of NaN3, have been studied in detail. The experimental results confirmed that the hybrid material is a mild, reusable and efficient heterogeneous catalyst for the photooxidation of 1,5-dihydroxynaphthalene in aerated aqueous solution.