Advanced preparation by sol-gel method of the encapsulated Pd/Al2O3 catalysts for methane combustion

In this work, the influence of the preparation method and the thermal treatment on the textural, structural and catalytic activity of Pd/Al2O3 catalyst is investigated. The palladium occluded into the alumina support appears on the surface when the encapsulated catalyst is calcined at 700degreesC. Compared to the catalysts prepared by impregnation method, higher resistance to sintering during calcination up to 800degreesC and during ageing under reaction mixture at 500degreesC for 72h is observed on the encapsulated catalyst. The nature of the metal-support interaction seems to be the reason. Furthermore, the catalytic activity in methane combustion is observed to be dependent both on palladium particle size and metallic surface area. Moreover, during the catalyst ageing under reaction mixture at 500degreesC, less reactive catalytic sites are obtained. The large palladium particles are more inhibited than the small ones.