Intergrown New Zeolite Beta Polymorphs with Interconnected 12-Ring Channels Solved by Combining Electron Crystallography and Single-Crystal X-ray Diffraction

Abstract

Two new polymorphs of zeolite beta, denoted as SU-78A and SU-78B, were synthesized by employing dicyclohexylammonium hydroxides as organic structuredirecting agents. The structure was solved by combining transmission electron microscopy and single-crystal X-ray diffraction. SU-78 is an intergrowth of SU-78A and SU-78B and contains interconnected 12-ring channels in three directions. The two polymorphs are built from the same building layer, similar to that for the zeolite beta family. The layer stacking in SU-78, however, is different from those in zeolite beta polymorph A, B, and C, showing new zeolite framework topologies. SU-78 is thermally stable up to 600 °C.

Synthesis of chiral polymorph A-enriched zeolite Beta with an extremely concentrated fluoride route

“…To date, pure polymorph C22, nearly pure polymorph B23, and the intergrowth zeolite Beta of polymorph B and C H 21 have been synthesized. Intergrown zeolite Beta of D and E has been recently reported, which gave two intense X-ray diffraction peaks at 2θ = 7.0 and 9.7° 24. However, chiral polymorph A has not been synthesized yet.…”

Structure Determination of Zeolites by Electron Crystallography

“…Several most complex zeolite structures were solved by combining HRTEM and PXRD, such as TNU-9 (TNU) [34], IM-5 (IMF) [35], and SSZ-74 (−SVR) [36]. HRTEM was also combined with single-crystal X-ray diffraction to solve the structure of a disordered germanosilicate SU-78 [49]. IM-5 is also a high-silica zeolite with 2D 10-ring channels.…”

“…SU-78 is a germanosilicate with crystals large enough (10 μm × 10 μm × 30 μm) for single-crystal X-ray diffraction at a synchrotron facility [49]. The SXRD data however showed streaks for reflections with indices hkl (h = 3n ± 1) and sharp spots for the 0kl reflections.…”

“…The parts with SU-78A and SU-78B are marked (Reprinted with the permission from Ref. [49]. Copyright 2012 American Chemical Society) examining the plane group symmetry of the HRTEM image.…”

“…Since 2006, 16 novel zeolite structures have been solved by electron crystallography alone or in combination with other techniques. These are TNU-9 (TUN) [34], IM-5 (IMF) [35], SSZ-74 (−SVR) [36], ITQ-26 (IWS) [37], ITQ-37 (−ITV) [38], ITQ-38 (ITG) [39], ITQ-39 (*-ITN) [40], ITQ-40 (−IRY) [41], ITQ-43 [42], ITQ-51 (IFO) [43], ITQ-53 [44], ITQ-54 [45], PKU-14 [46], PKU-16 (POS) [47], EMM-23 (*-EWT) [48], and SU-78 [49]. The power of electron microscopy for structural analysis of zeolites and other porous materials has been reviewed in several articles [50][51][52][53][54][55].…”