Abstract:

A series of Zr-based metal-organic frameworks (Zr-MOFs) were prepared by using a solvothermal method and by compounding ZrOCl₂ and different organic ligands, such as terephthalic acid, 1,3,5-benzenetricarboxylic acid, 1,2,4-benzenetricarboxylic acid and 1,2,4,5-benzenetetracarboxylic acid. The physical and chemical properties of the obtained Zr-MOFs were characterized by XRD, N₂ adsorption-desorption isotherms, FTIR, TGA and SEM. The catalytic performance of the Zr-MOFs was studied by reacting ethyl acetate N-acylation with benzylamine to produce N-acetylbenzylamine.We proved that the catalytic activity of the Zr-MOFs can be easily tuned by changing the number and position of the —COOH group in the organic ligands. The number of —COOH in organic linkers has influences on the crystal structure, Lewis and Br?nsted acidity in the MOFs and hence is the major determinants for their catalytic behavior. The results showed that MOF-808 had the highest activity and the yield of N-acetylbenzylamine was up to 95% at 80℃ for 12h. In addition, the MOF-808 catalyst still maintained a yield of 90% for N-acetylbenzylamine after reused for five times，confirming its remarkable recycling stability.

Key words: metal-organic frameworks (MOFs), catalysis, catalyst

摘要：

以二氯氧锆（ZrOCl₂）和不同的有机配体，如对苯二甲酸、均苯三甲酸、1,2,4-苯三甲酸和1,2,4,5-苯四甲酸为原料，采用溶剂热法合成了一系列Zr基金属-有机框架（Zr-MOFs）材料。利用X射线粉末衍射（XRD）、氮吸附脱附等温线、傅里叶变换红外光谱（FTIR）、热重分析（TGA）和扫描电子显微镜（SEM）对材料进行一系列表征。以乙酸乙酯与苯甲胺反应转化为N-乙酰苄胺为模型反应，研究所得Zr-MOFs材料的催化性能。结果表明，Zr-MOFs材料的催化活性可以通过改变有机配体中羧酸基团的数目和位置来调控，有机配体中羧基数目主要影响Zr-MOFs材料的晶体结构以及Lewis酸性和Br?nsted酸性，从而影响催化活性。相同条件下，具有MOF-808晶体结构的Zr-MOF材料催化活性最高，80℃反应12h，N-乙酰苄胺的产率高达95%。此外，该催化剂具有良好的循环使用稳定性，重复使用5次后，N-乙酰苄胺的产率仍保持90%。

关键词: 金属-有机框架材料, 催化, 催化剂