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Alternative TitleStudies on catalysts and supports for the direct oxidative esterification of methacrolein to methyl
Thesis Advisor张香平 ; 刁琰琰
Degree Grantor中国科学院研究生院
Degree Discipline化学工程
Keyword甲基丙烯醛   甲基丙烯酸甲酯   氧化酯化反应   载体
Abstract甲基丙烯酸甲酯(methyl methacrylate, MMA)作为重要的聚合单体,通过均聚或共聚生成聚甲基丙烯酸甲酯或甲基丙烯酸甲酯的二元、三元或四元共聚物,用于有机玻璃,涂料,医用功能材料等的生产。 本文针对甲基丙烯醛(MAL)和甲醇在氧气气氛下一步氧化酯化生成甲基丙烯酸甲酯(MMA),重点进行催化剂载体的开发及催化剂性能的研究。主要内容如下:1)制备了表面疏水型载体及其催化剂,包括SiO2-MgO-Al2O3载体和PS-Al2O3载体及其相对应的负载型Pd-Pb催化剂,考察了载体的制备条件包括正硅酸乙酯用量、聚乙二醇用量、pH值、水解温度及制备顺序,并对载体和对应的催化剂进行表征。SiO2-MgO-Al2O3载体负载的Pd-Pb催化剂,加入少量的SiO2对催化剂的转化率和选择性有一定的提高。SBA-15与Al2O3相比,易重复和大批量生产,并且具有规则的孔道、大的比表面积和可调控的孔径,有利于贵金属的分散和反应物的扩散,因此选用SBA-15为载体,SBA-15缺乏表面酸碱性,MgO的加入增强了SBA-15载体的有序性并且提供了表面碱性。2)制备了MgO-SBA-15载体及其负载型Pd-Pb催化剂。考察的载体的制备条件包括MgO用量、HCl摩尔浓度、镁前驱体、制备方法、水解时间、晶化温度及Pd和Pb的配比,并对载体和对应的催化剂进行表征。MgO-SBA-15载体负载的Pd-Pb催化剂与单独SBA-15负载的Pd-Pb催化剂相比,MAL的转化率和MMA的选择性更高。他们之间的催化活性区别主要是因为MgO提供的更好的结构和表面碱性,导致活性Pd3Pb颗粒尺寸更小,分布更均匀,相同Pd和Pb负载量时,活性位数量更多,催化活性更高。
Other AbstractIn this dissertation, SiO2-MgO-Al2O3 supported catalysts and novel MgO-SBA-15 supported catalysts were prepared for oxidative esterification of methacrolein (MAL) with methanol to methyl methacrylate (MMA). The SiO2-MgO-Al2O3 supports were synthesized with different silica loadings from different pH values and temperatures. The SiO2-MgO-Al2O3 supports and catalysts were characterized by several analysis methods. The results revealed that the small addition of silica only increased conversion of MAL, but the preparation was much complicated. Thus we changed to the novel MgO-SBA-15 supported Pd-Pb catalysts. 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 have higher activity than pure silica-based Pd-Pb/SBA-15 catalysts, which means 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 particles size 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.
Document Type学位论文
Recommended Citation
GB/T 7714
姜丽. 甲基丙烯醛一步氧化酯化反应制甲基丙烯酸甲酯的催化剂及载体的研究[D]. 中国科学院研究生院,2013.
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