A Stable Extra‐Large‐Pore Zeolite with Intersecting 14‐ and 10‐Membered‐Ring Channels

Abstract

The development of inorganic frameworks with extra-large pores (larger than 12-membered rings) has attracted considerable attention because of their potential applications in catalysis, the separation of large molecules, and so forth. We herein report the synthesis of the new extra-large-pore zeolite NUD-2 by using the supramolecular self-assembly of simple aromatic organic cations as structure-directing agents (SDAs). NUD-2 is a high-silicon-content germanosilicate with interconnecting 14×10-membered-ring channels. The SDAs in NUD-2 can be removed by calcination in air at 550 °C to yield permanent pores with a BET surface area of 500 m(2) g(-1) . Both germanium and organic cations in NUD-2 can also be removed by treatment with acid at lower temperature, thus not only affording recycling of germanium and SDAs, but also providing a highly stable siliceous zeolite. In addition, aluminum ions can be incorporated into the framework of NUD-2. The NUD-2 structure is yet another extra-large-pore zeolite synthesized by using the supramolecular self-assembling templating approach, thus demonstrating that this approach is a general and applicable strategy for synthesis of new large- and extra-large-pore zeolites.

Assembly–Disassembly–Organization–Reassembly Synthesis of Zeolites Based on cfi-Type Layers

“…), which were published after we began this project. 18,19 From SEM/EDX analysis we confirmed the presence of germanium and the rectangular thin-plate morphology of the sample ( Figure S3). These results also indicated that the size of the single crystals was suitable for single crystal X-ray diffraction experiments.…”

Co‐Structure‐Directing Effect in Ionothermal Synthesis of Extra‐Large‐Pore Aluminophosphate Zeotype with −CLO Topology

“…For all three samples of DNL-1 obtained with different co-SDAs, the solid-state 1 H! [32] The intactness of the [EMIM] + cation in the structure was confirmed by solution 13 CNMR spectroscopy of these solids amples dissolved in concentrated HCl, for which all resonances of [EMIM] + can be well resolved without splitting.T hese results prove that, for all three samples, the IL cation was occluded in the ÀCLO structure. [21,32] Moreover,distinct splitting of the resonances was observed, especially at d = 13.7 and 11.2 ppm;t his was due to different crystallographic positions of [EMIM] + in different cages of the ÀCLO structure.…”

“…[11][12][13] Successful examples are still limited and the feasibility seems to depend on the zeolite structures. Postsynthesis refers to the isomorphous substitution of aluminum or silicon for germanium in germanosilicate zeolites under acidic conditions.…”

Topotactic Conversion of Alkali‐Treated Intergrown Germanosilicate CIT‐13 into Single‐Crystalline ECNU‐21 Zeolite as Shape‐Selective Catalyst for Ethylene Oxide Hydration

“…Recently, a novel intergrowth germanium zeolite CIT‐13 (*CTH topology) was reported consisting of cfi layers interconnected by D4R units and intersecting 14‐ and 10‐R channels . Subsequently, two germanosilicates, NUD‐2 and SAZ‐1, were announced to possess structures analogous to CIT‐13. The 14‐R channels running parallel to the crystallographic c axis bear a striking resemblance to the UTL topology, whereas the arrangement of 10‐R channels along the b axis is ill defined, giving rise to two or more possible framework structures (the sequences AAAA and ABAB and others), which was revealed by the serious mosaicity along the b axis in the TEM images .…”

“…Recently,anovel intergrowth germaniumz eolite CIT-13 (*CTH topology) was reportedc onsisting of cfi layersi nterconnectedb yD 4R units and intersecting 14-and 10-R channels. [12] Subsequently,t wo germanosilicates,N UD-2 [13] and SAZ-1, [14] [a] X.…”