Journal
MICROPOROUS AND MESOPOROUS MATERIALS
Volume 142, Issue 1, Pages 168-177Publisher
ELSEVIER SCIENCE BV
DOI: 10.1016/j.micromeso.2010.10.052
Keywords
MCM-22 family; EMM-10; Layered zeolite precursor; Disordered zeolite; Electron diffraction
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We the report discovery of zeolite EMM-10, a new member of the MWW family, and its layered zeolite precursor, EMM-10P. The latter is closely related to the layered precursor MCM-22P but its layers are stacked without vertical alignment. The layers are believed to be twisted off-register or otherwise disordered in-plane but still hydrogen bonded through silanols. The proposed structural disorder is concluded from the X-ray powder diffraction pattern, which is very similar to that of MCM-22P but lacks the discrete interlayer reflections, especially (1 0 1) and (1 02). EMM-10P complements the series of three distinct, as-synthesized MWW materials, viz: MCM-22P, MCM-49 and MCM-56, all differing in packing of the MCM-22 monolayers. The EMM-10P precursor was synthesized using a diquaternary ammonium template while the preceding three materials were obtained with hexamethyleneimine as the structure directing agent. Upon calcination EMM-10P partially converts to an ordered MWW structure but, to a large extent, the stacking disorder persists while the layers fuse together. Basic characterization including sorption, electron diffraction, electron microscopy, NMR, and swellability with surfactants, reveals properties similar to MCM-22. EMM-10, therefore, represents a further extension of the already uniquely diverse MCM-22 zeolite family, and corresponds to an anticipated structure variation. It has also broader fundamental implications, illustrating the growing contribution of disordered structures among zeolites and the need for better characterization tools and methods. (C) 2010 Elsevier Inc. All rights reserved.
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