Title: EU-12: A Small-Pore, High-Silica Zeolite Containing Sinusoidal Eight-Ring Channels
Authors: Juna Bae, Jung Cho, Jeong Hwan Lee, Sung Man Seo, and Suk Bong Hong
Journal: Angewandte Chemie
Abstract: Zeolite EU-12, the framework structure of which has remained unsolved during the past 30 years, is synthesized at a specific SiO2/Al2O3 ratio using choline as an organic structure-directing agent, with both Na+ and Rb+ ions present. Synchrotron powder X-ray diffraction and Rietveld analyses reveal that the EU-12 structure has a two-dimensional 8-ring channel system. Among the two distinct 8-ring (4.6 ⅹ 2.8 and 5.0 ⅹ 2.7 Å) channels along c axis, the smaller one interconnects with the sinusoidal 8-ring (4.8 ⅹ 3.3 Å) channel along a axis. The other large one is simply linked up with the sinusoidal channel by sharing 8-rings (4.8 ⅹ 2.6 Å) in the ac plane. The proton form of EU-12 was found to show a considerably higher ethene selectivity in the low-temperature dehydration of ethanol than H-mordenite, the best catalyst for this reaction.
The EU-12 framework structure: the projection down the c axis, showing the arrangement of the two types of 8-ring channels, labeled A and B, respectively. Note that while the Type A channels intersect with the sinusoidal channels, the Type B channels link to the sinusoidal ones via their 8-rings.