| 摘要 |
<p>PROBLEM TO BE SOLVED: To obtain an NOx absorbent capable of efficiently absorbing/removing a low concentration of NOx contained in a combustion exhaust gas by adding the oxide of one type of element selected from among iron, nickel, manganese, copper, cobalt, chromium and zinc to a porous alumina as a main component. SOLUTION: A lowly concentrated NOx absorbent is formed of a porous alumina as a main component and the oxide of element selected from iron, nickel, manganese and cobalt borne by the porous alumina. In this case, the average pore diameter or/and the peak pore diameter of the porous alumina are 0.2-10nm and the pore volume is 0.03cc/g. Further, this lowly concentrated NOx absorbent is caused to release the once absorbed NOx by heating the absorbent at 300-600 deg.C. Besides, the NOx absorbent is capable of maintaining the NOx removing rate at 80% or more in the air at a space velocity of 10.324h<-1> and a linear velocity of 39cm/s and under other atmospheric conditions such as NOx concentration of 3.0ppm, moisture concentration of 1.5% and temperature of 25 deg.C. This NOx removing rate should persist for 10 hours or more.</p> |
