Direct synthesis of diphenyl carbonate over heterogeneous catalyst: effects of structure of substituted perovskite carrier on the catalyst activities

The perovskite-type compound LaMnO_(3) was substituted for the part of La in position A and for the part of Mn in position B by citrate method.The phases were detected by X-ray diffraction.Powder morphologies were scanned by scanning electron microscopy.The valence of atoms was determined by X-ray photoelectron spectroscopy.It was found that the perovskite can form crystal defect and increase the proportion of high valence B element by doping.Active component Pd was loaded on various perovskite supports for synthesis of diphenyl carbonate.The results showed that the activities of catalysts in which supports have crystal defect by substitution were higher.It can be concluded that perovskite with defect structure by doping could lead to the formation of oxygen vacancy where the lattice oxygen became exchangeable with the oxygen gas.Also,this improved the redox process of the carrier by transferring electrons and activities of catalysts.