| 摘要 |
New catalyst compositions of superior hydrothermal stability, which evidence increased gasoline plus distillate yields, improved coke selectivity and reduced C4- gas yields, are based on framework dealuminated faujasitic zeolites having a framework silica to alumina molar ratio of from about 5 to 100. In a preferred embodiment, an "ultrastable Y" composited with a matrix, is subjected to a treatment with a source of aluminum and rare earth compounds followed by hydrothermal treatments to improve the hydrothermal stability and selectivity of the catalyst for catalytic cracking. This is evidenced by higher gasoline plus distillate yields and lower coke and gas production at lower catalyst useage per barrel of feed relative to commercial cracking catalysts currently being used.
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