Preparationg And Research Of CeO₂-ZrO₂-Al₂O₃ Oxygen Storage Materials

Using catalysts to purify automotive exhaust gas has more and more been regarded by human society. It is generally accepted that the most important factor in this catalyst is the oxygen storage materials, which have a direct relation to the puring performance. The influence on the preformance of oxygen storage materials prepared by different additives or by different condition of the CeO₂-ZrO₂ and CeO₂-ZrO₂-Al₂O₃ samples preparation was studied in detail. Oxygen pulse technique, XRD, H₂-TPR and BET surface area analysis methods were used to characterize the oxygen storage capacity ( OSC), textual property, reduction bahavior and surface area of the materials above respectively.The results suggest that the OSC, texture property and reduction capacity of the aged CeO₂-ZrO₂ solid solution are improved by adding different additives. Moreover, OSC and BET of the fresh and aged samples can been improved by enhancing the solution pH and adding polymers, H₂O₂, alkaline earth oxide to the oxygen storage materials respectively. When 50wt% PEG, H₂O₂/Ce=1 and 2-6wt% alkaline earth oxide was added, the oxygen storage materials can get the most ideal synthesis properties. The materials prepared by various precipitator showed different properties. The studies imply that the samples prepared by salvolatile have the lowest BET, after calcinated at 600℃ and 1000℃ for 5h respectively.The samples prepared by ammonia or urea-ammonia have the higher BET and OSC, but after aged at 1000℃ for 5h, BET and OSC decreased sharply, meaning a bad thermal stability. The samples prepared by salvolatile have the smaller BET and OSC before the aged, after aged at 1000℃ for 5h, the BET decreased sharply, but the OSC keep well. The BETand OSC of the samples prepared by ammonia-salvolatile keep well after aged, exhibiting a promising thermal resistance.When 10-75wt% AI2O3 was added, the oxygen storage materials can secure large BET and OSC even after exposed to high temperatures for a long time.Since the samples formed a single cube phase, sintering is suppressed. While 90wt% AI2O3 was added, the BET of the samples decreased and the phase of the samples break up .