異なる方法で調製したルテニウム-アルミナ複合微粒子のキャラクタリゼーション

抄録

Fine particles of ruthenium-alumina composites were prepared by three different methods, i.e., direct synthesis, reduction of mixed oxide and impregnation methods. In the direct synthesis method, the sample was prepared by hydrogenolysis of a mist of a mixed solution of ruthenium chloride and aluminium nitrate. Transmission electron microscopy as well as electron and X-ray diffraction measurements showed that amorphous ruthenium clusters (<2nm) dispersed in an amorphous alumina particle were prepared by this method. Reduction of the mixed oxide prepared in the same way in a stream of air produced the particles undistinguishable from the above sample by X-ray diffraction and transmission electron microscopy, whereas the conventional impregnation method gave crystalline ruthenium clusters dispersed on the alumina surface. The infrared spectrum of adsorbed carbon monoxide showed three characteristic absorption bands at about 2000, 2070 and 2140cm^-1 in all samples, but their frequencies and relative intensities were different, depending upon the method of preparation. In the sample prepared by the direct synthesis method, the frequencies and relative intensities of these bands changed during crystallization of the ruthenium clusters by firing at high temperatures. It is concluded that the most highly dispersed metal-ceramics composite was prepared by the direct synthesis method.