| 摘要 |
Methods for preparing catalysts including a transition metal component and a zeolite component are disclosed. In some embodiments, the transition metal is deposited in a precursor solution onto a zeolite extrudate to form an intermediate integral catalyst wherein prior to the deposition, the zeolite has been subjected to an initial ion exchange with protecting cations which exchange with the protons of the zeolite. The intermediate integral catalyst is heated to decompose the transition metal, and the catalyst is subsequently subjected to a secondary ion exchange with an ionic ammonium complex which exchanges with the protecting cations. The resulting ammonium treated catalyst is heated to a temperature sufficient to decompose the ammonium complex to form ammonia and H+ ions. The transition metal in the resulting catalyst is in the form of reduced crystallites located outside the zeolite channels. No appreciable ion exchange of the transition metal occurs within the zeolite channels.
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