CRYSTAL STRUCTURE OF ZEOLITE Y AS A FUNCTION OF ION EXCHANGE

The crystal structures of a series of hydrated Na-, NH4-, Caand La-exchanged zeolite Y have been de-termined as a function of exchange conditions using synchrotron powder diffraction data. Four sieves were also studied in the dehydrated state in situ at 300°C. Only small differences in the framework structures were observed; the largest differences involve 02 and 03, to which the cations are coordinated. In hydrated NaY (LZ-Y52), sites I', II, and II ' are occupied. In ammonium-exchanged sieves, the Na at sites I ' and II are re-placed by NH4 ions, with the residual sodium displaced to sites 11'. In uncalcined Ca-FAU, the Ca are dis