La(OH))_3和La_2O_2CO_3纳米棒的合成及其催化Claisen-Schmidt缩合反应性能(英文)  

La(OH)_3 and La_2O_2CO_3 nanorod catalysts for Claisen-Schmidt condensation

作　　者：王非[1] 塔娜[1] 李勇[1] 申文杰[1] 

机构地区：[1]中国科学院大连化学物理研究所催化基础国家重点实验室,辽宁大连116023

出　　处：《催化学报》2014年第3期437-443,共7页

基　　金：supported by the National Natural Science Foundation of China (20923001,21025312);the National Basic Research Program of China (973 Program,2013CB933100)~~

摘　　要：通过调节溶液的pH值,在水热条件下合成出长径比为2-45的La(OH)3纳米棒.对水热合成过程中间体的结构演变分析,发现高碱度有利于小尺寸晶核的形成,La(OH)3晶体结构的各向异性导致这些晶种沿着C轴方向生长,进而形成纳米棒结构.将La(OH)3纳米棒前驱体于773 K焙烧可以得到长径比为2-20的La2O2CO3纳米棒.随着长径比的增加,La2O2CO3纳米棒暴露的(110)晶面逐渐增加,La3+-O2-碱性位的数目也从0.08增加到0.24 mmol/g.因此,在Claisen-Schmidt缩合反应中,La2O2CO3纳米棒催化剂上的反应速率随着长径比的增加而逐渐增大.La（OH）3 nanorods of 15 nm diameter and up to 700 nm long were synthesized using different pH values of the solution used in the hydrothermal synthesis. A more alkaline solution favored the formation of tiny La（OH）3 nuclei, which grew along the c-axis due to their anisotropic nature and led to the formation of rod-shaped crystals. Calcination of the La（OH）3 nanorods at 773 K gave La2O2C03 nanorods. Their basic properties were correlated with their size. As the aspect ratio increased from 2 to 20, the basic sites increased from 0.08 to 0.24 mmol/g; which was due to a higher exposure of （110） planes. In the catalysis of the condensation reaction of benzaldehyde with acetophenone, the reaction rate was correlated with the number of La^3＋-O^2- pairs on the exposed （110） facets of the La2O2C03 nanorods.

关 键 词：氢氧化镧 碳酸氧镧 纳米棒 晶面 碱性 Claisen—Schmidt缩合反应 

分 类 号：O621.251[理学—有机化学]