카드늄으로 이온교환된 제올라이트 X의 질소 흡착 결정구조

Crystal Structure of Nitrogen Adsorption of Cd^2+ ion Exchanged Zeolite-X

The structure of nitrogen adsorption complex of fully dehydrated Cd^{2+} ion exchanged zeolite-X, |Cd{46}(N){18}|[Si{100}Al{92}O{384}], was determined in the cubic space group Fdoverline{3} at 21(1) ^{circ}C [a = 24.863(4) ] by single crystal X-ray diffraction analysis. The crystal was prepared by ion exchange in a flowing steam of 0.05 M aqueous solution Cd(NO3)2 : Cd(O2CCH3)2 = 1:1 for five days, followed by dehydration at 500^{circ}C and 2{times}10^{-6} Tor. for two days, and exposured to 100 Tor. zeolitically dry nitrogen gas at 21(1) ^{circ}C. The structure was determined in atmosphere, and was refined within F0 > 4{sigma}(F0) using reflection for which the final error can appear in indices R1 = 0.097 and wR2 = 0.150. In this structure, Cd^{2+} ions occupied four crystallographic sites. Nine Cd^{2+} ions filled the octahedral site I at the centers of hexagonal prisms (Cd-O = 2.452(16) {AA}). Eight Cd^{2+} ions filled site I (Cd-O = 2.324(19) {AA}). The remaining 29 Cd^{2+} ions are found at two nonequivalent sites II (in the supercages) with occupancy of 11 and 18 ions. Each of these Cd^{2+} ions coordinated to three framework oxygens, either at 2.159(15) or 2.147(14) {AA}, respectively. Eighteen nitrogen molecules were adsorbed per unit cell and three per supercage.