| 摘要 |
Catalysts and catalytic structures are provided comprising a substrate, an intermediate oxide layer and a catalytic layer. For example, the catalyst may comprise: (a) a metal substrate made from a heat and oxidation resistant alloy of iron including chromium (3-40) wt. %, aluminum (trace - 10) wt. %, cobalt (0 - 5.0) wt. %, nickel (trace 72) wt. % and carbon (0 - 0.5) wt. %, balance essentially iron, the metal substrate being extended on an assembly of at least two juxtaposed sheets made from the alloy with at least one sheet shaped so that when contacted with an adjacent sheet channels are formed therebetween for the passage of gaseous reactants through the substrate; (b) an aluminum oxide film on the surface of the extended metal substrate, the film being formed by oxidizing the surface of the metal substrate; (c) a high surface area aluminum coating disposed over the aluminum oxide film and keyed to the substrate through the film; and (d) a catalytic layer comprising at least one metal selected from the group consisting of ruthenium, rhodium, palladium, iridium, platinum, silver, gold, and alloys of at least one of such metals with at least one additional element comprising a base metal selected from the group consisting of aluminum, magnesium, chromium, molybdenum, tungsten, manganese, iron, rhenium, cobalt, titanium, vanadium, copper, zinc, cadmium, indium, thorium, bismuth, tin, lead, antimony, a lanthanide or an actinide, the base metal being present in an amount from a trace to 25 wt. % on the high surface area alumina coating. Such catalysts have been found to be useful for a wide variety of catalytic reactions, e.g. the catalytic oxidation of ammonia in the manufacture of nitric acid and the catalytic oxidation of organic compounds. |
