Reactor assembly for reducing automotive pollutant emissions

Abstract

A catalytic reactor assembly for purifying exhaust gas from internal combustion engine comprises a first bed of catalytic material which promotes reducing reactions in exhaust gas from the engine between unburned and partially burned fuel components and NO.sub.x whereby the latter is substantially converted to nitrogen and a second bed of catalytic material which promotes oxidizing reactions in the presence of added air to oxidize unburned and partially burned components of exhaust gas from the first bed. Exhaust gas is constrained to pass substantially radially outwards from the interior of the first bed to a collection space therearound and is then directed to the interior of the second bed for passage radially outwardly therethrough before discharge to atmosphere. The two catalytic beds are preferably cylindrical or annular, and located end-to-end for maximum conversions with minimum pressure drop. Baffle means are located between the catalytic beds for directing the exhaust gas from the collection space around the first bed to the interior of the second catalyst bed. Additionally, either the axis of the second bed is off-set from the axis of the first bed or the second bed has a non-uniform porosity so that there is a substantially constant pressure drop across any radial point in the second bed.