EXHAUST GAS PURIFICATION APPARATUS FOR INTERNAL COMBUSTION ENGINE

摘要

A fuel addition valve (14) that adds fuel into the exhaust gas passage of the engine in the form of fine fuel droplets, an upstream NOx adsorption-reduction catalyst (12), and a downstream NOx adsorption-reduction catalyst (13) are arranged in this order. Platinum Pt and palladium Pd, as noble metal, are supported on the downstream NOx adsorption-reduction NOx catalyst (13) such that the ratio of the mole number of the platinum Pt to the sum of the mole numbers of the platinum Pt and the palladium Pd is approx. 50% to approx. 80%. Only platinum Pt is supported on the upstream NOx adsorption-reduction catalyst (12). According to this structure, even when liquid fuel is supplied into exhaust gas, NOx can be effectively released from the NOx adsorption-reduction catalyst, and further the amount of NOx that the NOx adsorption-reduction catalyst can adsorb at a low temperature increases.