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Park M.B.,Center for Ordered Nanoporous Materials Synthesis | Park M.B.,ETH Zurich | Ahn N.H.,Center for Ordered Nanoporous Materials Synthesis | Broach R.W.,UOP LLC | And 3 more authors.
Chemistry of Materials | Year: 2015

A reliable formation pathway for UZM-5 zeolite crystals in the presence of tetraethylammonium, tetramethylammonium, and Na+ ions at 150 °C has been proposed based on the 13C MAS NMR and IR spectra of a series of solid products recovered as a function of time during the crystallization process, as well as on the crystal structure of as-made UZM-5 determined using synchrotron powder X-ray diffraction and Rietveld analyses. The nucleation of this cage-based small-pore zeolite begins with the construction of the largest 26-hedral lta-cages among its four different structural units. The next step is the attachment of 14-hedral wbc-cages to the preorganized lta-cage at shared 6-rings in an appropriate orientation that will allow the growth of two wbc-cage layers linked by 8-hedral rth-cage formation along both a and b axes. The resulting interlayer space is readily converted to a layer of lta-cages by interconnecting two opposing wbc-cages, with the concomitant formation of interlayer d4r-cages and 8-rings. Over the outer surface of the resulting UZM-5 nuclei, which resembles one-half of an lta-cage, the crystal growth may take place in a self-assembled manner as described above. © 2015 American Chemical Society.


Park M.B.,Center for Ordered Nanoporous Materials Synthesis | Park M.B.,ETH Zurich | Ahn S.H.,Center for Ordered Nanoporous Materials Synthesis | Ahn N.H.,Center for Ordered Nanoporous Materials Synthesis | Hong S.B.,Center for Ordered Nanoporous Materials Synthesis
Chemical Communications | Year: 2015

Nanocrystalline MEI- and BPH-type zeolites, denoted as PST-11 and PST-12, respectively, have been synthesized using both tetraethylammonium and tetramethylammonium ions, the two simplest alkylammonium species, in the presence of Li+ and Sr2+. PST-12 formation is the first example of a combination of forced and multiple cooperative structure-directions in the charge density mismatch synthesis of zeolites. This journal is © 2015 The Royal Society of Chemistry.


Shin J.,Center for Ordered Nanoporous Materials Synthesis | Ahn N.H.,Center for Ordered Nanoporous Materials Synthesis | Camblor M.A.,CSIC - Institute of Materials Science | Zicovich-Wilson C.M.,Autonomous University of the State of Morelos | Hong S.B.,Center for Ordered Nanoporous Materials Synthesis
Chemistry of Materials | Year: 2014

A study was conducted to demonstrate the synthesis of aluminosilicate natrolites and control of their tetrahedral atom ordering. A robust method was developed to synthesize the aluminosilicate version (Al-NAT) of this natural mineral using a small amount of the mineral natrolite, scolecite or previously prepared Al-NAT zeolites as seed crystals. The synthesis of Al-NAT materials with nonfibrous morphologies was valuable for providing opportunities for industrial and environmental applications. The situ disorder-order transformation allowed controlling the degree of T-atom ordering in the zeolite framework and the corresponding chemical and physicochemical properties. The characterization results showed a smooth and continuous transformation in Al-NAT zeolites under the crystallization conditions investigated under the study.


Jo D.,Center for Ordered Nanoporous Materials Synthesis | Lim J.B.,Center for Ordered Nanoporous Materials Synthesis | Ryu T.,Center for Ordered Nanoporous Materials Synthesis | Nam I.-S.,Center for Ordered Nanoporous Materials Synthesis | And 2 more authors.
Journal of Materials Chemistry A | Year: 2015

We have synthesized an aluminosilicate RTH-type zeolite with Si/Al = 10 using 1,2,3-trimethylimidazolium (123TMI+) as an organic structure-directing agent (OSDA) together with Na+ or K+ in hydroxide media and without the use of seed crystals. The zeolite obtained is characterized by a cuboid morphology made of very small ill-defined crystallites, largely different from the plank-like morphology typically observed for RTH-type zeolite crystals thus far. More interestingly, we show experimental evidence demonstrating that two 123TMI+ ions are located within each [46586484] cavity of the RTH framework, forming antiparallel dimers, as found by Rietveld refinement. When hydrothermally aged at 1023 K, Cu-RTH is much less active for NO reduction with NH3 than Cu-SSZ-13, the best catalyst known for this reaction to date. However, while the CO2 uptake (3.2 mmol g-1) on Na-RTH at 298 K and 1.0 bar is lower than that (4.5 mmol g-1) on zeolite Na-Rho, a well-studied small-pore zeolite that selectively adsorbs CO2, it exhibits much faster CO2 sorption kinetics. This renders our RTH zeolite potentially useful as a selective CO2 adsorbent. © The Royal Society of Chemistry 2015.


Shin J.,Center for Ordered Nanoporous Materials Synthesis | Ahn N.H.,Center for Ordered Nanoporous Materials Synthesis | Camblor M.A.,CSIC - Institute of Materials Science | Cho S.J.,Chonnam National University | Hong S.B.,Center for Ordered Nanoporous Materials Synthesis
Angewandte Chemie - International Edition | Year: 2014

The transformation from a disordered into an ordered version of the zeolite natrolite occurs on prolonged heating of this material in the crystallizing medium, but not if the mother liquor is replaced by water or an alkaline solution. This process occurs for both aluminosilicate and gallosilicate analogues of natrolite. In cross experiments, the disordered Al-containing (or Ga-containing) analogue is heated while in contact with the mother liquor of the opposite analogue, that is, the Ga-containing (or Al-containing) liquor. Therefore, strong evidence for the mechanism of the ordering process was obtained, which was thus proposed to proceed by intraframework migration of tetrahedral atoms without diffusion along the pores. Migration is first triggered, then fuelled by surface rearrangement through reactions with the mother liquor, and stops when an almost fully ordered state is attained. Classical dissolution-recrystallization and Ostwald ripening processes do not appear to be relevant for this phase transformation. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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