Vehicular pollution control- removal of carbon monoxide through catalytic converters

Abstract

In an attempt to find a substitute to noble-metal based catalysts in the catalytic converters for the removal of CO from automotive exhaust, non-noble metal based catalysts of perovskite based oxides were tested. Perovskites of the structure ABO₃, where A cation had La, Ba or Ca and B cation had Co or Fe were used for the reaction. Substituted perovskite of the form A_1-xA'_xBO₃, where A' was Ce metal, was also used. The perovskite catalyst were tested in unsupported as well as supported forms. The supports used were zirconia, ceria or a mixture of the two in different proportions. The results indicate that among the unsupported catalysts, LaCoO₃ is the best. Among the substituted catalysts, La_0.3Ce_0.7CoO₃ gave the best performance showing 100% CO conversion at 200°C. The support, zirconia (20%) and ceria (80%) mixture was found to be the best combination. The durability runs up to 6 h show the activity pattern in the order: La_0.3Ce_0.7CoO₃ > La_0.6Ce_0.4CoO₃ >LaCoO₃.