Carbon oxidation with Ag/ceria prepared by self-dispersion of Ag powder into nano-particles

• Published in: Catalysis today 2011-10, Vol.175 (1), p.93-99
• Main Authors: Shimizu, Ken-ichi, Kawachi, Hiroshi, Komai, Shin-ichi, Yoshida, Kaname, Sasaki, Yukichi, Satsuma, Atsushi
• Format: Article
• Language: English
• Subjects: carbon; Carbon oxidation; Catalysis; catalytic activity; Ceria; Chemistry; Colloidal state and disperse state; DPF; Exact sciences and technology; General and physical chemistry; new methods; oxidation; oxygen; particle size; Powders; Self-dispersion; Silver; temperature; Theory of reactions, general kinetics. Catalysis. Nomenclature, chemical documentation, computer chemistry
• ISSN: 0920-5861; 1873-4308
• DOI: 10.1016/j.cattod.2011.03.053

[Display omitted] ► A calcination of physical mixture of Ag metal powder and CeO 2 at 500 °C results in self-dispersion of Ag into nano-particles. ► The obtained catalyst showed high activity for soot oxidation comparable to Ag/CeO 2 prepared by impregnation method. ► A key role of oxygen vacancy of CeO 2 surface on the self-dispersion was suggested. This study reports a unique and novel method of preparation of Ag/CeO 2 catalyst for carbon oxidation. A calcination of physical mixture of Ag metal powder and CeO 2 at 500 °C results in self-dispersion of Ag into nano-particles on CeO 2. From TEM images, the average diameter of Ag particles in Ag power before calcination was around 66 nm, while the particle size of Ag became smaller around 8 nm with very narrow distribution. Oxygen vacancy on CeO 2 surface is suggested to play an important role in the self-dispersion of Ag. The obtained catalyst showed high activity for soot oxidation comparable to Ag/CeO 2 prepared by impregnation method. The promotion effect of CeO 2 was not observed in physical mixtures with Cu, Au and Pt. Mechanical mixtures of Ag and various metal oxide supports were also examined. The addition of Ag to CeO 2, SnO 2, ZrO 2, ZnO, TiO 2, and Nb 2O 5 significantly lowered the temperature of carbon oxidation than those of supports, while that to Co 3O 4, CaO, La 2O 3, NiO, SiO 2, Al 2O 3 and MgO did not.