Chiang Mai Journal of Science

In this work, the activities of platinum over alumina promoted with cerium oxide and zirconium oxide were investigated.  Each support contained various weight percents of cerium oxide and zirconium oxide to alumina was prepared by sol gel method.  The weight percent of cerium oxide to zirconium oxide was kept constant at 60 to 40.  Specific surface areas of each support were measured.  It was found that the addition of 20%CeO₂ -ZrO₂ in alumina support offered the highest specific surface area of  215 m²/g.  Furthermore, crystalline phase and size of  mixed oxide were determined by XRD. XRD results also showed that Ce₂Zr₂O₇  was formed in the support.  The amount of  cerium oxide, zirconium oxide and alumina had a strong effect to their crystalline size in the final form.  Then, each support was impregnated with 1%Pt loading and tested its activity to CO oxidation reaction.  The results showed that T_1/2  of each catalyst was 210^oC, 139^oC, 145^oC, 150^oC and 261oC for a 1%Pt/ Al₂O₃ , a 1%Pt/20%CeO₂-ZrO₂ /Al₂O₃ , a 1%Pt/40%CeO₂-ZrO₂ /Al₂O₃  a 1%Pt/60%CeO₂-ZrO₂ /Al₂O₃ and a 1%Pt/CeO₂-ZrO₂ , respectively.  The enhancement of  activity of  platinum over alumina catalyst resulted from an oxygen storage property of cerium oxide together with zirconium oxide.  Finally, the 1%Pt/40%CeO₂-ZrO₂ /Al₂O₃ has showed the best activity to CO oxidation.