Structural comparison of partially dehydrated partially Co super(2+)-exchanged zeolites X (FAU, Si/Al = 1.40) and Y (FAU, Si/Al = 1.70)

(ProQuest: ... denotes formulae and/or non-USASCII text omitted; see image).The structures of partially dehydrated and partially Co super(2+)-exchanged zeolites X (Si/Al = 1.40) and Y (Si/Al = 1.70) were determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group Fd ... m and were refined to the final error indices R sub(1)/wR sub(2) = 0.0773/0.2152 and 0.0683/0.2184, respectively. Their unit-cell formulas are |Co sub(26.1)Na sub(21)(H sub(3)O) sub(7.1)(H sub(2)O) sub(14.2)|[Si sub(112)Ald80 sub(384)]-FAU (a = 24.7892(2) ) and |Co sub(29.3)Na sub(6.2)(H sub(3)O) sub(5.9)(H sub(2)O) sub(5.9)|[Si sub(121)Ald71 sub(384)]-FAU (a = 24.7346(2) ), respectively. In the structure of Co super(2+)-X, Co super(2+) ions occupy sites I', II', II, and III'; the Na super(+) ions are at sites I' and II. In the structure of Co super(2+)-Y, Co super(2+) ions occupy sites I', II', II, and III'; the Na super(+) ions are at site I'. Because of the low pH of the Co super(2+) exchange solution, some H sub(3)O super(+) ions are observed in both structures. The number of Co super(2+) ions in zeolite was increased slightly as Si/Al ratio increased, and Na super(+) content and the unit cell constant of the framework were decreased.