PLASMA ASSISTING CATALYTIC APPARATUS FOR REMOVING NOx AND EXHAUST GAS CLEANING METHOD

摘要

PPROBLEM TO BE SOLVED: To restrain the discharge of NOx drastically even when exhaust gas is heated or the speed of a car is accelerated or decelerated after an internal-combustion engine is started. PSOLUTION: The plasma assisting catalytic apparatus consists of a plasma generating unit 1, an NOx adsorbing unit 2 and an NOx removing unit 3 obtained by depositing an element of group IIIb on a porous body. The unit 2 and the unit 3 are arranged in this order from the upstream side of exhaust gas to the downstream. NO in the exhaust gas is oxidized into NOx by the discharge plasma from the unit 1. NOx is adsorbed in the unit 2 when the temperature of the exhaust gas is low, for example, when the engine is started. When the temperature of the exhaust gas becomes high, NOx is released from the unit 2 and the released NOx is reduced and removed in the unit 3. In other words, NOx can be removed efficiently by the synergistic action of the units 2 and 3 under the temperature-transitional condition that the temperature rises or falls. PCOPYRIGHT: (C)2004,JPO&NCIPI