| 摘要 |
PURPOSE:To obtain a catalyst showing catalytic activity in a lean region of fuel and no deterioration in the catalytic activity even for heat treatment at >600 deg.C by adding a specified amt. of at least one compd. selected from titanium oxide, zirconium oxide and aluminum oxide to zinc oxide. CONSTITUTION:The purifying catalyst for nitrogen oxide in an oxygen-rich environment is produced by adding at least one compd. selected from titanium oxide, zirconium oxide and aluminum oxide by an amt. between >=0.1mol% and <50mol% to zinc oxide. The catalyst is prepared, for example, by a coprecipitation method. In this method, the starting material selected from nitrates, acetates or chlorides of various metals is dissolved in water to prepare a mixture soln., to which an alkali soln. is added to obtain precipitate. The obtd. Precipitate is filtered, dried and calcined. By burning the precipitate at temp. higher than the temp. for use as a catalyst, decrease in activity during use is prevented. Further, the catalyst is formed into a pellet or applied on a honeycomb base body by wash coating for use. |
