Novel Mg O–SBA-15 supported catalysts were prepared for oxidative esterification of methacrolein(MAL) with methanol to methyl methacrylate(MMA). The Mg O–SBA-15 supports were synthesized with different magnesia load...Novel Mg O–SBA-15 supported catalysts were prepared for oxidative esterification of methacrolein(MAL) with methanol to methyl methacrylate(MMA). The Mg O–SBA-15 supports were synthesized with different magnesia loadings from different magnesium precursors and hydrochloric acid molar concentrations. The Mg O–SBA-15 supports and Pd–Pb/Mg O–SBA-15 catalysts were characterized by several analysis methods. The results revealed that the addition of Mg O improved the ordered structure of SBA-15 supports and provided surface alkalinity of SBA-15 supports. The average size of the Pd3 Pb particles on magnesia-modified Pd–Pb/Mg O–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/Mg O–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/Mg O–SBA-15 catalysts was due to the discrepant structural properties and surface alkalinity provided by Mg O, which led to the different Pd3 Pb 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.展开更多
基金Supported by the Key Program of the National Natural Science Foundation of China(21036007)the National High-Tech Project of China(2012AA062903)
文摘Novel Mg O–SBA-15 supported catalysts were prepared for oxidative esterification of methacrolein(MAL) with methanol to methyl methacrylate(MMA). The Mg O–SBA-15 supports were synthesized with different magnesia loadings from different magnesium precursors and hydrochloric acid molar concentrations. The Mg O–SBA-15 supports and Pd–Pb/Mg O–SBA-15 catalysts were characterized by several analysis methods. The results revealed that the addition of Mg O improved the ordered structure of SBA-15 supports and provided surface alkalinity of SBA-15 supports. The average size of the Pd3 Pb particles on magnesia-modified Pd–Pb/Mg O–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/Mg O–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/Mg O–SBA-15 catalysts was due to the discrepant structural properties and surface alkalinity provided by Mg O, which led to the different Pd3 Pb 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.
