Synthesis of hydrophobic bifunctional mesoporous solid acid catalysts and their performance evalution in the esterification reaction of acetic acid with ethanol
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摘要: 通过水热合成法一步合成了具有不同疏水基团－CH3 、－(CH3)2 和－(CH3)3的双功能介孔固体酸SBA-15-SO3H－(CH3)x催化剂。通过X射线粉末衍射(XRD)、N2吸脱附、元素分析等方法对催化剂进行了表征，并在乙酸乙酯酯化反应中进行催化性能评价。结果表明，随着疏水前驱体中甲基数的增加，样品的疏水性增强。SBA-15-SO3H-(CH3)x催化剂的催化活性随着疏水性的增强而提高，而具有较强疏水性的材料SBA-15-SO3H-(CH3)3在反应中具有较高的催化性能。以SBA-15-SO3H-(CH3)3为催化剂，酯化反应的最优条件为：温度为120℃，乙酸与乙醇摩尔比为4∶1，催化剂质量分数为1 %，反应时间为1h。在此条件下，乙醇的转化率和乙酸乙酯的选择性分别为93%和100%。Abstract: Single-step synthesis of bifunctional mesoporous solid acid materials SBA-15-SO3H－(CH3)x containing different hydrophobic alkyl (methyl, dimethyl or trimethyl) was carried out by hydrothermal treatment of gels. The catalysts were characterized by XRD, N2 adsorption, elementary analysis, and were tested in the esterification reaction of acetic acid with ethanol. The results revealed that the hydrophobicity of the as-prepared materials increased with the increase of methyl number of hydrophobic precursors, and the catalytic activity increased with the hydrophobicity of the materials. Among these materials, SBA-15-SO3H－(CH3)3 showed good performance toward the esterification reaction. Effects of reaction temperature, catalyst amounts, reaction time and the molar ratios of acetic acid/ ethanol over the catalyst SBA-15-SO3H－(CH3)3 were also studied. Under the optimal reaction conditions of temperature 120℃, n(acetic acid)∶ n(ethanol) = 4∶1, catalyst 1%, time 1h, the conversion of ethanol and the selectivity of ethyl acetate were 93% and 100%, respectively.
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Key words:
- solid acid catalysts /
- mesoporous /
- hydrophobicity /
- esterification
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