抄録
In automotive three-way catalyst, cerium dioxide and alumina are used as sub-catalyst and support, respectively. The composite particles of them are important for better catalytic performance. In the preparation of catalysts, the rheological properties of slurry are important. The dispersibility of particles is an indicator of the properties, and the surface charge of particles is an important factor for the dispersibility. In this paper, the surface charge of cerium dioxide-alumina composite particles was examined using ultrasonic vibration potential (UVP) method for the colloidal solutions. We synthesized cerium dioxide-alumina composite particles by impregnation method. We determined the UVP, zeta potential (ζ) and iep (isoelectric point) of them in water by using measured voltage value under ultrasonic irradiation. The iep depended on the composition of these particles. The iep was 7.6-7.9 for the composite particles, 8.3 for alumina and 6.8 for cerium dioxide. The surface compositions of Ce on particles were estimated by XPS. The result indicated that particle size of cerium dioxide increased with Ce-content. The surface charge of the composite particles was affected by both the surface composition and the size of cerium dioxide particles.
