Modification of low-grade ceria by high-energy mechanical milling: changesin phase composition, reducibility, and oxygen storage capacity

Cerium concentrate, a mixture of ceria (about 60 wt.%) and other rare-earth (mostly lanthanum) oxides, partially transforms into a solid solution upon high-energy mechanical milling. Temperature-pro rammed reduction of the mi lled material resembles that of the high-oxygen-storage material, ceria-zir conia, but the kinetics of oxygen removal, observed in pulse experiments wi th either CO or H-2, are much slower. The oxygen storage capacity of a Pd c atalyst made with the milled material is found to be less than that of one made with unmilled material when measured on a short (<1 min) time scale. ( C) 2001 Elsevier Science B.V. All rights reserved.