Abstract

Perovskite-type compounds La 1-xAg xMn 0.9Co 0.1O 3(xAg=0.0, 0.1, 0.2, 0.3) were prepared by the amorphous citrate method, characterized by nitrogen adsorption, XRD, FTIR, SEM-EDAX, TPR, O 2-TPD and XPS techniques, and tested in the catalytic removal of n-hexane in a flow reactor under an excess of oxygen. Partial substitution of La 3+ by Ag + was found to produce a large increase in the catalytic activity. Since all the samples exhibit almost the same specific area, the catalyst activity was found to depend mainly on the crystalline structure and on a new source of surface oxygen that comes from the interaction between O- and the low coordinated metal site. For the studied composition, characterization data revealed that the degree of substitution of x Ag=0.1 shows the cleanest surface composition, i.e. almost total insertion of silver in the LaMn 0.9Co 0.1O 3.5. The highest reaction rate found for x Ag= 0.3 is explained considering that almost the same Ag insertion is obtained, but the larger surface of segregated Ag particles contributes to enhancement in activity. © 2009 Elsevier B.V. All rights reserved.