三苯胺酸为稳定剂的Pt金属簇的合成及其催化加氢性能

在乙醇水溶液中合成了以三苯胺酸为稳定剂的Pt金属簇。采用透射电子显微镜、傅里叶变换红外光谱、X射线粉末衍射方法对Pt金属簇进行了表征。实验结果表明,以三苯胺酸为稳定剂可以在较宽的金属与稳定剂配比范围内制备出Pt溶胶;当Pt与三苯胺酸的摩尔比为5时,所得Pt金属簇平均粒径约为2 nm,大约有56个三苯胺酸分子与一个Pt金属簇表面原子相结合,每个Pt金属簇粒子具有约50%的空表面,因而可有效地催化间苯氧基苯甲醛的加氢反应。在氢压0.1MPa、反应温度30℃的条件下,三苯胺酸稳定的Pt金属簇催化间苯氧基苯甲醛加氢反应11 h后,间苯氧基苯甲醛的转化率大于99%;3次重复实验结果表明,三苯胺酸稳定的Pt金属簇的催化加氢活性没有明显降低。

Synthesis of Platinum Metal Cluster Stabilized by 4 -Diphenylamino -Benzoic Acid and Its Catalytic Performances in Hydrogenation

Platinum metal cluster,used in catalytic hydrogenation of m-phenoxy benzaldehyde,was prepared in aqueous ethanol solution by using 4-diphenylamino-benzoic acid(DPABA)as stabilizer.The platinum metal cluster was characterized by means of TEM,FTIR,and XRD.Stable colloidal suspension of platinum metal cluster could be obtained in relative wide range(1~10)of n(Pt) ∶n(DPABA).When n(Pt) ∶n(DPABA)=5,average diameter of platinum metal cluster was 2nm.Each Pt atom on cluster surface was bonded with about 56 DPABA molecules.About 50% of platinum metal cluster surface was not passivated and available for catalytic hydrogenation of m-phenoxy benzaldehyde.Conversion of m-phenoxy benzaldehyde was more than 99% at(30℃) for 11h by using the platinum metal cluster as catalyst.The catalyst could be reused at least three times without obvious loss of catalytic activity.