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Ceramic Hot tubes are developed as a cost effective substrates for 2 and 3 wheelers Catalytic Converter. These are used instead of ceramic honeycomb substrates for the applications where, lower conversion is enough to meet the emission norms. Ceramic hot tubes are more appropriate for 4-stroke two wheelers which are marginally failing to meet Indian emission norms for year 2000. The low thermal expansion cordierite based ceramic hot tubes offer very high thermal shock resistance, high temperature strength, very low back pressure and adequate geometrical surface area. The unique design of this product can withstand severe thermal stresses up to 1200°C. This is required for long durability against mechanical vibrations and extraordinary temperature rise expected in Indian two and three wheelers. Hence ceramic hot tubes have advantage over metallic hot tubes. Under the present work, two different configurations of ceramic hot tubes have been developed.

The reduction of cold start emission is widely recognized method to meet the stringent automotive emission norms using catalytic converters. One of the effective ways is to use HC traps before the main converters. This system mainly consist of ceramic honeycomb coated with the zeolite molecular sieves which can adsorb HC during the transient cold start period and release to the main converters when it has reached light-off. High catalytic surface area, good HC trapping efficiency, high thermal durability and good mechanical strength are the important properties of zeolite coated honeycombs. They are prepared either by washcoating the zeolite on the substrate or by in-situ crystallization by wet hydrothermal method. The adhesion of the coating is better in the wet hydrothermal process but the honeycombs become mechanically weaker. To overcome this, a new method of forming the zeolite film on the ceramic honeycombs by solid state in situ crystallization has been developed.