MgO–SBA-15 Supported Pd–Pb Catalysts for Oxidative Esterification of Methacrolein with Methanol to Methyl Methacrylate

Novel MgO–SBA-15 supported catalysts were prepared for oxidative esterification of methacrolein (MAL) with methanol to methyl methacrylate (MMA). The MgO–SBA-15 supports were synthesized with different magnesia loadings from different magnesium precursors and hydrochloric acid molar concentrations. The MgO–SBA-15 supports and Pd–Pb/MgO–SBA-15 catalysts were characterized by several analysis methods. The results revealed that the addition of MgO improved the ordered structure of SBA-15 supports and provided surface alkalinity of SBA-15 supports. The average size of the Pd3Pb particles on magnesia-modified Pd–Pb/MgO–SBA-15 catalysts was smaller than that on the pure silica-based Pd–Pb/SBA-15 catalysts. The experiments on catalyst performance showed that the magnesia-modified Pd–Pb/MgO–SBA-15 catalysts had higher activity than pure silica-based Pd–Pb/SBA-15 catalysts, showing the strong dependence of catalytic activity on the average size of active particles. The difference of activity between Pd–Pb/SBA-15 catalysts and Pd–Pb/MgO–SBA-15 catalysts was due to the discrepant structural properties and surface alkalinity provided by MgO, which led to the different Pd3Pb particle sizes and then resulted in the different number of active sites. Besides magnesia loadings, other factors, such as hydrochloric acid molar concentration and magnesium precursors, had considerable influences on the catalytic activity.

Novel MgO–SBA-15 supported Pd–Pb catalysts were prepared for oxidative esterification of methacrolein (MAL) with methanol to methyl methacrylate (MMA). The synthesis conditions were investigated including magnesium precursors, magnesia loadings and hydrochloric acid molar concentration. The results show that the addition of MgO improves the ordered structure and provides surface alkalinity of SBA-15 supports, which decreases the Pd3Pb particle size and improves the catalytic activity. Under the optimal preparation conditions, 78.5% conversion of MAL together with 72.5% MMA selectivity was obtained. This new catalyst shows promising industrial application feasibility due to the high reaction efficiency and the ease of catalyst separation and recycling.Figure optionsDownload as PowerPoint slide