Comparison of effect of La-modification on the thermostabilities of alumina and alumina-supported Pd catalysts prepared from different alumina sources

The thermostability of La-free and La-modified aluminas derived from different alumina sources including pseudo-boehmite. aluminum sulfate, aluminum nitrate, and aluminum chloride have been studied by characterizations of BET specific surface area (BET) and X-ray powder diffraction (XRD). Further, the activity and thermal durability of monolith-supported Pd catalysts using above different alumina as washcoats for silnultaneously catalytic oxidation of C3H8, C3H6 and CO have been investigated using continuous flowing reaction. The experimental results show that the oxidation activity uc er the alumina-supported Pd catalysts does not keep in agreement with the surface area of aluminas derived from four aluminum sources. Lanthanum modification improves the activity of all catalysts: calcined over 1000 degreesC for simultaneously catalytic oxidation of C3H8,C3H6 and CO. Alumina source plays a role on the activity and thermostability of alumina and alumina-supported Pd catalysts. The experimental results show that pseudo boehmite is the best alumina source used for catalytic oxidation at high temperature over 1000 degreesC. (C) 2001 Elsevier Science B.V. All rights reserved.