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AssigneeEngelhard Corporation
InventorsPascaline H. Tran, Xinsheng Liu, James M. Chen, Gerard D. Lapadula, Howard Furbeck
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The present invention is directed to a metal-promoted zeolite beta catalyst useful in the selective catalytic reduction of nitrogen oxides with ammonia in which the zeolite beta is pre-treated so as to provide the zeolite with improved hydrothermal stability. The stabilized beta zeolite is provided by incorporating into the zeolite structure non-framework aluminum oxide chains. The aluminum oxide chains can be incorporated into the zeolite structure by a unique steaming regimen or by treatment with rare earth metals, such as cerium. The treatment process is unlike well-known methods of dealuminizing zeolites for the purpose of increasing the silica to alumina ratio. In the present invention, the non-framework aluminum oxide is characterized by FT-IR by a peak at 3781±2 cm−1, which when present, stabilizes the zeolite against further dealumination such as under oxidizing and harsh hydrothermal conditions.
A stabilized iron-promoted aluminosilicate zeolite beta having a silica to alumina mol ratio of at least 8 and an FT-IR absorption peak at 3781±2 cm−1, said stabilized zeolite beta further including cerium.
A stabilized iron-promoted aluminosilicate zeolite having a pore structure which is interconnected in all three crystallographic dimensions by pores having an average kinetic pore diameter of at least about 7 angstroms, and having an FT-IR absorption peak at 3781±2 cm−1, said stabilized zeolite further including cerium.
Dependencies are inferred from the claim text.