The Effect of Co2+-Ion Exchange Time into Zeolite Y (FAU, Si/Al = 1.56): Their Single-Crystal Structures

Three single crystals of fully dehydrated Co2+-exchanged zeolite Y (Si/Al = 1.56) were prepared by the exchange of Na75-Y (|Na75|[Si117Al75O384]-FAU) with aqueous streams 0.05 M in Co(NO3)2, pH = 5.1, at 294 K for 6 h, 12 h, and 18 h, respectively, followed by vacuum dehydration at 673 K. Their single-crystal structures were determined by synchrotron X-ray diffraction techniques in the cubic space group Fd3m at 100(1) K. They were refined to the final error indices R1/wR2 = 0.0437/0.1165, 0.0450/0.1228, and 0.0469/0.1278, respectively. Their unit-cell formulas are |Co29.1Na11.8H5.0|[Si117Al75O384]-FAU, |Co29.8Na11.0H4.4|[Si117Al75O384]-FAU, and |Co30.3Na9.5H4.9|[Si117Al75O384]-FAU, respectively. In all three crystals, Co2+ ions occupy sites I, I' and II; Na+ ions are also at site II. The tendency of Co2+ exchange slightly increases with increasing contact time as Na+ content and the unit cell constant of the zeolite framework decrease