Polyoxometalates Pillared Hydrotalcite: Synthesis and Catalysis in Transesterification of Dimethyl Carbonate and Phenol

The salts of para-tungstic and para-molybdic were heterogenized for their effective use as solid catalysts in the transesterification reaction of dimethyl carbonate and phenol by inserting them between the layers of Mg₂Al-hydrotalcite. These catalysts were characterized by FT-IR spectra and X-ray powder diffraction. Polyoxometalates (POMs) clusters were intercalated into the interlayer of layered double hydroxide (LDH) via anion exchange with organic acid precursor in Mg₂Al-LDH, and the integrity of the clusters ^6- and ^6- was maintained. The intercalated para-molybdic cluster showed high catalytic activity and reusability in the transesterification under mild reaction conditions. When the reaction was carried out at 180?℃, with a molar ratio of phenol to DMC of 1∶1, a reaction time 10?h, and a catalyst amount 1%(wt), the conversion of phenol was 10.0%, the selectivities of diphenyl carbonate and methyl phenyl carbonate were 10.7% and 86.1%, respectively.