Li+-exchanged Zeolites X and Y (FAU) from Undried Formamide Solution

Two single-crystals of fully dehydrated, partially Li+-exchanged zeolites X (Si/Al = 1.09, crystal 1) and Y (Si/Al = 1.56, crystal 2), were prepared by flow method using 0.1 M LiNO3 at 393 K for 48 h, respectively,followed by vacuum dehydration at 673 K and 1 × 10-6 Torr. Their structures were determined by single-crystal X-ray diffraction techniques in the cubic space group Fd and Fd m at 100(1) K for crystals 1and 2, respectively. They were refined to the final error indices R1/wR2 = 0.065/0.211 and 0.043/0.169 for crystals 1 and 2, respectively. In crystal 1, about 53 Li+ ions per unit cell are found at three distinct positions;9 at site I’, 19 at another site I’, and the remaining 25 at site II. The residual 25 Na+ ions occupy three equipoints; 2 are at site I, 7 at site II, and 16 at site III’. In crystal 2, about 31 Li+ ions per unit cell occupy sites I’ and II with occupancies at 22 and 9, respectively; 3, 4, 23, and 3 Na+ ions are found at sites I, I’, II, and III’,respectively. The extent of Li+ ion exchange into zeolite X (crystal 1) is higher than that of zeolite Y (crystal 2), ca. 73% and 56% in crystals 1 and 2, respectively. KCI Citation Count: 1