CRYSTAL STRUCTURE OF ZEOLITE NICKEL FAUJASITE

The crystal structure of vacuum-dehydrated, nickel-exchanged natural faujasite has been determined using single-crystal X-ray techniques. The nickel exchange and subsequent dehydration have considerably modified the zeolite framework. Nickel(II) occupies two-thirds of the SI sites and in these sites attains near-perfect octahedral coordination with framework oxygens (Ni-O, 2.29 Å). The remaining nickel ions are distributed in four additional unique positions. Two of these positions are in the region of the SI' site and the other two are in SII and SII' sites. A trace of residual water may play a major role in determining the nickel ion distribution.