镁铝复合介孔氧化物催化月桂酸甲酯乙氧基化反应

Performance of Mesoporous Composite Mg-Al Oxide Catalyst in Ethoxylation of Methyl Laurate with Ethylene Oxide

以十二烷基硫酸钠为模板剂、乙二胺为碱性介质,采用水热法合成了镁铝复合介孔氧化物(MMAO),采用氮吸附-脱附、X射线衍射、程序升温脱附和热重-差热分析等方法对MMAO进行了表征,并考察了MMAO在月桂酸甲酯乙氧基化反应中的催化性能。表征结果显示,合成的MMAO具有介孔结构特征,平均孔径为3.2nm,比表面积为280m2/g,孔体积为0.18cm3/g。实验结果表明,MMAO催化剂在月桂酸甲酯乙氧基化反应中具有较高的催化活性,适宜的合成条件为:反应温度180℃、初始压力0.6～0.7MPa、MMAO催化剂用量为月桂酸甲酯质量的3%。在此条件下得到的月桂酸甲酯聚氧乙烯醚的相对分子质量分布较窄,当环氧乙烷平均聚合度为5时,月桂酸甲酯聚氧乙烯醚的相对分子质量分布选择性系数为18.50。

Mesoporous composite Mg-Al oxides （MMAO） was prepared by hydrothermal method, starting from magnesium nitrate and aluminum nitrate as reactants, sodium dodecyl sulfate as template with ethylene diamine as medium. MMAO was used as catalyst in ethoxylation of methyl laurate with ethylene oxide and was characterized by means of N2 absorption-desorption,XRD,TPD and TG-DTA. The frame work structure of MMAO was hexagonal with average pore diameter of 3.2 nm, specific surface area of 280 m^2/g and pore volume of 0. 18 cm^3/g. MMAO was highly active in the ethoxylation. The reaction rate increased with rising of reaction temperature, initial pressure and MMAO dosage. Under optimal reaction conditions：reaction temperature 180 ℃, initial pressure 0.6 - 0.7 MPa, mass fraction of MMAO（ based on methyl laurate）3 %, relative molecular mass distribution selectivity coefficient of product methyl laurate polyoxyethylene ether was 18. 50 when average polymerization degree of ethylene oxide was 5.