were prepared by phase transfer with cationic surfactant (7, Surface-covered nanometer-sized CuO/Al 2 O 3 , CuO-ZnO/ 8) and metal surfactant (such as carboxylate) (9, 10). The Al 2 O 3 , and CuO/ZnO catalysts were prepared by phase transfer basic principle of the phase transfer technique is to transfer with carboxylate. The surface-covered structure was studied using sol particles which are modified with surfactant molecules XPS, XRD, TEM, and high-resolution electron microscope. The from an aqueous medium into an organic solvent. By this results indicated that amorphous CuO and ZnO were dispersed means, the aggregation between particles in further treaton the surface of nanometer-sized Al 2 O 3 particles in catalysts ment, such as drying, can be avoided to a great extent. The CuO-ZnO/Al 2 O 3 and CuO/Al 2 O 3 , respectively. The thickness of preparation included preparation of aqua sol particles, adits surface layer is about several angstroms. No spinel structure sorption of surfactant on the sol particles and the transfer of was found in the catalyst. The particle size of the surface-covered
CuO/Al 2 O 3 catalyst was about 2-3 nm. Al 2 O 3 in the catalyst was the particles from aqueous solution to organic solvent, reamorphous. Surface-covered material CuO in the catalyst with moval of aqueous solution and wash of organic phase, relow CuO content was also armophous. A large amount of copper moval of organic solvent, drying, and calcination. carboxylate resulted in crystalline CuO and Cu 2 O. The protective The metal element in the nanometer-sized particles preability of carboxylate to sol particles differs from the metal element pared by carboxylate phase transfer come from both the sol of carboxylate. แญง 1997 Academic Press particles and the surfactant. Therefore it is possible that a