Highly efficient and stable PbO-ZrO2 catalyst for the disproportionation of methyl phenyl carbonate to synthesize diphenyl carbonate

Heterogeneous PbO-ZrO2 catalysts (PbZr) were first prepared by coprecipitation method, and used to catalyze the liquid-phase disproportionation reaction of methyl phenyl carbonate (MPC) to synthesize diphenyl carbonate (DPC). PbZr with PbO loading of 15.2 wt% (15.2PbZr) exhibited the best catalytic performance. Under the optimal conditions (200 degrees C, 2.5 h, and 1.2 g catalyst), the conversion of MPC reached 76.6% and the selectivity of DPC was 99.3%, respectively, which were significantly higher than those of heterogeneous catalysts reported before. The characterization results of XPS, H-2-TPR, XRD and BET analyses showed that 15.2PbZr gave the strongest interaction between Pb and Zr, the highest dispersion of PbO as well as the largest surface area and pore volume. Moreover, for 15.2PbZr, though reused for five recycles, the conversion of MPC still reached 75% and the selectivity of DPC was kept at 99.0%, implying that 15.2PbZr represented superior reusability. Besides, the structure of the 15.2PbZr after five times reaction was almost identical to that of the fresh, and Pb was almost not leached out of the catalyst, indicating that the stability of Pb species was improved, due to the existence of favorable interaction between Pb and Zr as well as part of the Pb entering into ZrO2 structure. Thus, 15.2PbZr may serve as a promising catalyst for MPC disproportionation. (C) 2016 Published by Elsevier B.V.