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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.
By adjusting the pH value of the solution, La (OH) 3 nanorods with length-diameter ratio of 2-45 were synthesized under hydrothermal conditions.Analysis of the structural evolution of the intermediate during the hydrothermal synthesis showed that the high alkalinity was conducive to small size The formation of nuclei and the anisotropy of the La (OH) 3 crystal structure lead to the growth of these seed crystals along the C axis, which leads to the formation of nanorod structures. La (OH) 3 nanorod precursors can be calcined at 773 K La 2 O 2 CO 3 nanorods with diameters ranging from 2 to 20. As the aspect ratio increases, the exposed (110) crystal plane of La 2 O 2 CO 3 nanorods increases gradually and the number of La 3+ -O2-basic sites increases from 0.08 to 0.24 mmol / g In the Claisen-Schmidt condensation reaction, the reaction rate on La2O2CO3 nanorod catalyst gradually increases with the increase of the aspect ratio.