Two Zeolite Structures Solved

By applying advanced crystal analysis methods, two research groups have revealed the structures of two distinctive zeolites. Zeolites are porous crystalline aluminosilicates that are widely used as catalysts in oil refining and petrochemical synthesis. Knowledge of the structures indicates the types of applications for which the materials may be best suited. In one study, Jiuxing Jiang and Avelino Corma of Polytechnic University of Valencia, in Spain, and coworkers synthesized a novel silicogermanate, ITQ-43 (Science, DOI: 10.1126/science.1208652). On the basis of electron tomography and other methods, the group determined that the zeolite contains interconnecting pores in two size ranges: 2-nm-diameter cloverleaf-shaped channels defined by 28-membered rings, and 0.6-nm-diameter 12-membered-ring cylindrical channels. In a second study, Lynne B. McCusker of ETH Zurich and coworkers solved the structure of zeolite SSZ-57, which had puzzled researchers for about a decade (Science, DOI: 10.1126/science.1207466). That zeolite is built from a 1:15 ratio of 12-membered rings and 10-membered rings, the researchers report.