| 摘要 |
PROBLEM TO BE SOLVED: To maintain a high methane oxidizing capacity stably over a long period by using a catalyst in which palladium is supported on zirconium oxide in order to purify hydrocarbons in an exhaust gas containing oxygen at least in an amount necessary for the complete oxidation of reducible substances besides methane. SOLUTION: In a catalyst for purifying hydrocarbons in an exhaust gas containing an excess amount of oxygen necessary for the complete oxidation of reducible substances besides methane such as the combustion exhaust gas of natural gas, palladium and as required platinum are supported on zirconium oxide. A zirconium oxide carrier is impregnated with a solution containing palladium ions or containing palladium ions and platinum ions, dried, and burned in order to prepare the catalyst. In this process, the amount of supported palladium is 2-20% in weight ratio to zirconium oxide. In the purification of hydrocarbons in exhaust gas, the temperature difference of the exhaust gas before and behind a catalyst layer is regulated not to exceed 150 deg.C. |
