Development of base metal oxide catalyst for automotive emission control

Abstract

Activity of alumina was tested for CO and hydrocarbon oxidation using the flow reactor system. The mechanism of the CO oxidation was elucidated by isotopic tracer technique using a closed circulation system. CO oxidation was found to proceed via the formation of a carbonate type of intermediate species. Water enhances the CO oxidation and CO2 retards alumina activity. Carbon deposition was also investigated during CO oxidation on alumina. Carbon formed was found to act as an in-situ active site that promoted CO oxidation. Results obtained showed alumina to be promising for CO oxidation. Pb showed opposite effects on CO and hydrocarbon reactions. Hydrocarbon reactivity test conducted showed that methanol is the most reactive on alumina giving 100% conversion at 500 °C. However, carbon deposited affected the formation of several products at this temperature. Further study on methanol oxidation using alkaline treated alumina showed better performance for auto emission control. CeO2, known to have an oxygen storage capacity, was tested as an additive to alumina for methanol oxidation and propylene oxidation. Results proved that CeO2-AL2O3 gave much higher activity for CO oxidation, methanol oxidation, and propylene oxidation than alumina.