High silica crystalline zeolites and process for their preparation.

摘要

Crystalline aluminosilicate zeolites having increased silica to alumina mole ratios are prepared by a process wherein a conventional crystalline aluminosilicate zeolite is treated to remove alumina from the crystal lattice. By-product non-framework amorphous alumina is then selectively removed from the zeolite either by using a blocking agent, to prevent removal of framework aluminum during a subsequent acid treatment, or by using a selective organic acid extracting agent. The invention is also directed to high silica crystalline zeolites prepared by the present process.