| 摘要 |
PURPOSE:To obtain high denitration performance and excellent durability by depositing iridium metal having a specified range of crystal size on a carrier such as crystalline silicate. CONSTITUTION:The catalyst is obtd. by depositing iridium metal having about 30Angstrom to 30mum crystal size on a carrier comprising crystalline silicate or the like expressed by the formula and having specified X-ray diffraction pattern. In the formula, R is an alkali metal ion and/or hydrogen ion, M is at least one element ion selected from among group VIII elements and rare earth elements, M' is an alkaline earth metal ion, and a>0, 20>b>=0, a+c=1, 3000>y>11. The initiating temp. of reduction by H2 in the catalyst carrying iridium is specified to <=250 deg.C. Further, in the production of the catalyst, the catalyst carrying iridium is exposed to a stoichiometric atmospheric gas or rich atmospheric gas at 150-900 deg.C, or exposed to a gas containing steam at 150-900 deg.C. Thereby, extremely efficient denitration is attained by using hydrocarbons as a reducing agent. |
