| 摘要 |
<p>PURPOSE: To obtain the adsorbent on which NOx in an exhaust gas can be adsorbed even at a comparatively high temp. and with which the amount of NOx discharged into the atmosphere is reduced even when the oxygen concentration in the exhaust gas is high by preparing the adsorbent through depositing rhodium on cerium oxide. CONSTITUTION: This adsorbent is prepared by depositing rhodium on cerium oxide, namely, by mixing a rhodium solution such as rhodium nitrate aq. solution, etc., with powdery cerium oxide and drying the resulting mixture with an evaporation drying-up method, i.e., evaporation to dryness, spray drying method, etc. At this time, the amount of rhodium used is preferably 0.32 to 1.43 pts.wt. based on 100 pts.wt. of the amount of cerium oxide and this adsorbent is deposited on a monolith carrier so that the amount of rhodium is 0.1 to 2.0g, preferably 0.45 to 2.0g per 1L of the monolith carrier. This adsorbent is particularly effective when it is placed in the exhaust gas passage of an engine operated at a lean fuel-air ratio.</p> |
