| 摘要 |
PURPOSE:To permit the stable combustion of methane, the most hardly burnt, within a wide temperature range from a low temperature to a high temperature by arranging specified catalysts at a fore stage and an after stage respectively. CONSTITUTION:A catalyst, constituted of a bearer containing a composite oxide consisting of a single compound or two kinds or of oxides selected from alumina, silica, titania or zirconia and an activating constituent of palladium oxide born by said bearer, is arranged at a fore stage (inlet side of gas) while another catalyst, consisting of a bearer containing the oxide of rare earth elements and palladium oxide as well as the oxide of rare earth elements, which are born by said bearer is arranged at an after stage. When most hardly combustible methane, for example, is burnt, the oxidation of methane is started in the fore stage catalyst at 350 deg.C or lower while the temperature of the fore stage catalyst layer is controlled so as to be lower than 700 deg.C and the temperature of the after stage catalyst is controlled so as to be within the temperature range of 700-1000 deg.C through the catalyst at the after stage. By this method, a low temperature igniting property is improved and most hardly combustible methane can be burnt stably within the temperature range from a low temperature to a high temperature. |
