The effect of Rh addition on Pd/gamma-Al2O3 catalysts deposited on FeCrAlloy fibers for total combustion of methane

Bimetallic Pd-Rh/Al2O3 catalysts were deposited by dip coating on FeCrAlloy type fibers. The effect of different gaseous pretreatments (under O-2/H-2 or H-2 flows) on the physico-chemical properties and the catalytic activity in the total combustion of methane was investigated. The gaseous pretreatments did not seem to exert any particular influence on the catalytic activity of these systems. When palladium is partially replaced by rhodium, the catalytic performances of the so-obtained bimetallic catalysts are lower than those of the monometallic Pd-based one. However it should be remarked that bimetallic catalysts with a Pd loading of 1% at least, show better methane conversion than the monometallic Rh-based samples. The long duration tests demonstrated that a bimetallic Pd-Rh catalyst has a better catalytic behaviour than a Pd-only catalyst. Such a behaviour could be due to the presence of Rh2O3, in the bimetallic catalyst, which avoids PdO reduction to Pd-0 and consequent sintering. It is worth noticing that no direct interaction between I'd and Rh was observed. A cooperation between PdO and Rh2O3 seems to explain the higher catalytic performances of bimetallic Pd-Rh catalysts. (c) 2007 Elsevier B.V. All rights reserved.