Abstract: In order to improve catalytic activity and thermal resistance of close-coupled catalysts, Ba-modified alumina (Ba-Al₂O₃) with different BaO contents was prepared by peptization method. All samples were characterized by low temperature N₂ adsorption-desorption, X-ray diffraction, and NH₃ temperature-programmed desorption. The results showed that the Ba-Al₂O₃ sample with 8% BaO exhibited the best textural properties, the largest acidic amount, and the strongest surface acidity. Its specific surface area and pore volume were 142 m²/g and 0.45 ml/g after calcination at 1273 K for 5 h and 114 m²/g and 0.37 ml/g after calcination at 1373 K for 5 h, respectively. Pt-Rh close-coupled catalysts supported on Ba-Al₂O₃ were prepared by impregnation method with Pt-Rh content of 1.5 g/L. The catalytic activity results showed that adding BaO into the support can effectively improve the catalytst activity in propane conversion. When the BaO content was 8%, the catalyst exhibited the best catalytic performance. The light-off temperatures for propane over fresh and aged catalysts were 513 and 557 K, respectively.

Key words: alumina, barium oxide, platinum, rhodium, close-coupled catalyst, thermal stability, propane