| 摘要 |
An ammonia oxidation catalyst cartridge unit comprises a pair of retaining meshes spaced apart by less than 50 mm defining an enclosure filled with a random packed mass of particles of a composition comprising oxides of at least one metal selected from manganese, iron, nickel and cobalt, especially cobalt and at least one element A selected from rare earths and yttrium in such proportions that the element A to cobalt atomic ratio is in the range of 0.8 to 1.2. The catalyst particles have a minimum dimension of at least 0.5 mm and a maximum dimension of not more than 5 mm, and the spacing between the meshes is at least 4 times, but not more than 50 times, the maximum dimension of the particles. The unit may extend across the ammonia oxidation reactor cross section or a catalyst cartridge may comprise a grid or apertured plate, extending across the cross section of the reactor, with a unit as aforesaid in each aperture.
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