| 摘要 |
1280544 Oxidation catalysts ESSO RESEARCH & ENG CO 3 Oct 1969 [23 Oct 1968] 48643/69 Heading B1E [Also in Division Fl] A catalyst for use in the purification of internal combustion engine exhaust gases comprises ruthenium and iridium in proportions such that the catalyst contains from 0.1 to 10 parts by weight of ruthenium per part by weight of iridium. The ruthenium and iridium, which may be in elemental or oxide form, may be supported on alumina, silica, zirconia or diatomaceous earth; a preferred supported catalyst contains from 0.005 to 0.5 weight per cent of ruthenium and from 0.001 to 0.05 weight per cent of iridium. The catalyst also may contain material selected from potassium hydroxide, potassium carbonate, rubidium; barium and nickel. The specification gives details of the preparation of a catalyst containing 0.01 weight per cent of each of ruthenium and iridium on alumina and of comparison catalysts containing 0.02 weight per cent of either ruthenium or iridium on alumina, the alumina in each catalyst having a surface area of 250 square metres per gram. Exhaust gas purification may be effected in two separate stages each utilising the ruthenium-iridium catalyst, the first stage employing no added (external) oxygen and the second stage being effected in the presence of added oxygen, for example air.
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