Alumina supported, perovskite oxide based catalytic materials and their auto-exhaust application

Substituted lanthanum manganate type perovskites have been synthesized following co-precipitation and a modified in situ method. These perovskites have been supported on cordierite honeycomb with and without alumina washcoat. Alumina washcoated supports with lanthana pre-coat, have been found suitable for the in situ synthesis of perovskites to avoid reactivity of perovskite precursors with alumina (in absence of lanthana pre-coat). This modified synthesis has resulted in remarkable improvement in surface area while, excellent catalyst adhesion has also been observed. The catalyst composition has also been promoted by a small amount of platinum, which has resulted in improved catalytic activity. These catalysts have been first evaluated using a pure gas laboratory evaluation assembly. Catalysts prepared on alumina washcoated honeycomb having lanthana pre-coat, shows better activity than the samples prepared by co-precipitation method. Catalytic converter prototypes have been prepared using the selected catalyst and evaluated on engine and chassis dynamometers. The converter shows good conversion activity for all the three pollutants, viz. CO, HC and NOx. These results substantiate the possibility of using supported perovskites for automobile applications. The detailed characterization of supported perovskites, however, could not be done conclusively and demand for further investigations, to properly understand the interaction of pre-coat, alumina washcoat and catalyst.