Nakagawa Takashi, Nitani Hiroaki, Tanabe Shuji, Okitsu Kenji, Seino Satoshi, Mizukoshi Yoshiteru, Yamamoto Takao A
Department of Nuclear Engineering, Graduate School of Engineering, Osaka University, Yamadaoka 2-1, Suita, Osaka 565-0871, Japan.
Ultrason Sonochem. 2005 Mar;12(4):249-54. doi: 10.1016/j.ultsonch.2004.02.002.
Bimetallic Au/Pd nanoparticles supported on a silica matrix were prepared by an ultrasonic technique. The samples heat-treated at 100, 200, 300 and 400 degrees C were examined with techniques of XRD (X-ray diffraction), TEM and XAS (X-ray absorption spectrometry) for studying correlation between their structure and the catalytic activity of hydrogenation of cyclohexene. Even after the heat treatment at 400 degrees C, the particles were smaller than 20 nm and well dispersed in the matrix without agglomeration nor sintering. Results of the XRD, TEM and XAS indicated that the as-prepared particles have a core/shell structure of Au/Pd and transform into a random alloy at 300 degrees C. The catalysis seemed to be deactivated by alloying.
采用超声技术制备了负载在二氧化硅基质上的双金属金/钯纳米颗粒。利用X射线衍射（XRD）、透射电子显微镜（TEM）和X射线吸收光谱（XAS）技术对在100、200、300和400摄氏度下热处理的样品进行了检测，以研究其结构与环己烯氢化催化活性之间的相关性。即使在400摄氏度下热处理后，颗粒仍小于20纳米，且在基质中分散良好，没有团聚或烧结现象。XRD、TEM和XAS的结果表明，所制备的颗粒具有金/钯核壳结构，并在300摄氏度时转变为无序合金。催化作用似乎因合金化而失活。
