Direct hydroxylation of benzene to phenol by supported vanadium substitution polyoxometalates using H2O2 as oxidant

A practical method for the direct hydroxylation of benzene to phenol catalyzed by supported vanadium-substituted polyoxometalates using H 2 O 2 as an oxidant is described. Three vanadium-doped polyoxometalate Na 2 H 3 PMo 10 V 2 O 40 · x H 2 O catalysts were designed and prepared through support on graphitic carbon nitride (g-C 3 N 4 ), montmorillonite, and activated carbon and named as CN-PMoV 2 , M-PMoV 2 , and C-PMoV 2 , respectively. Their characterization was elucidated through the Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), inductively coupled plasma-atomic emission spectrometry (ICP-AES) and scanning electron microscopy (SEM). This heterogeneous catalyst demonstrated promising activity in the hydroxylation of benzene to phenol with H 2 O 2 . Especially, CN-PMoV 2 catalyst was highly active and selective even under mild conditions. Moreover, CN-PMoV 2 catalyst still has a certain catalytic effect even after three instances of repeated use.