Influence of synthesis route on the catalytic properties of La 1− xSr xMnO 3

Abstract

Lanthanum Strontium Manganate (LSM) powders were synthesised by six different routes, namely solid state reaction, drip pyrolysis, citrate, sol–gel, carbonate and oxalate co-precipitation. The LSM samples, produced by firing to 1000°C for 5 h were then characterised by way of XRD, TPD’s of oxygen, TPR and catalytic activity for a simple oxidation reaction, that of carbon monoxide to carbon dioxide. It was found that although the six samples had similar compositions and surface areas they performed quite differently during catalytic characterisation. These observed differences correlated more closely to the mode of synthesis, than to the physical properties of the powders, or their impurity levels, indicating that the surface structures created by the different syntheses perform very differently under catalysis conditions. Co-precipitation and drip pyrolysis produced structures that were most efficient at facilitating oxidation type reactions.