Polyhedron lead hydroxide carbonate （2PbCO3·Pb（OH）2 ） microcrystals have been prepared in solution phase via a facile method in the presence of surfactant cetyltrimethylammonium bromide （CTAB）. All the samples were characterized by powder X-ray diffraction ,pattern （XRD）, field-emission scanning electron mi- croscopy （FE-SEM）, high-resolution transmission electron microscopy （HRTEM）, and selected area electron diffraction （SAED）. The possible growth mechanism was discussed. 2PbCO3·Pb（OH）2 microcrystals were found to be a novel and efficient catalyst for the synthesis of diphenyl carbonate （DPC） by transesterification of dimethyl carbonate （DMC） with phenol. Compared with some other catalysts, such as AlCl3, ZnCl2, and Mg5（CO3）4（OH）2, 2PbCO3·Pb（OH）2 microcrystals are stable and show relatively high activity at low catalyst amount. When the reaction was carried out at 180 12, with a molar ratio of phenol to DMC of 2：1, a reaction time 14 h, and a catalyst amount 0.2% （molar ratio to phenol）, the selectivity of DPC and methyl phenyl carbonate （MPC） was 14.7% and 78.8%, respectively.
β-Co（OH）2 and Mg（OH）2 nanoplates were synthesized via a facile template-free hydrothermal approach.The different conditions of preparation and catalytic properties of the products were studied and discussed.The products were characterized by X-ray diffraction,transmission electron microscopy,scanning electron microscopy,selected area electron diffraction（SAED）,and gas chromatograph.
SUN Ling-naWANG Ke-liLUO Sheng-junGUO Qing-rongHU Chang-wen
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 [W7O24 ]^6- and [Mo7O24 ]^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.
