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Angew Chem Int Ed Engl. 2017 Oct 16;56(43):13475-13478. doi: 10.1002/anie.201707452. Epub 2017 Sep 21.

CIT-9: A Fault-Free Gmelinite Zeolite.

Author information

1
Chemical Engineering, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA, 91125, USA.
2
Center for Surface Chemistry and Catalysis, KU Leuven, Celestijnenlaan 200F, Heverlee, 3010, Belgium.
3
Chevron Energy Technology Company, 100 Chevron Way, Richmond, CA, 94802, USA.

Abstract

A synthetic, fault-free gmelinite (GME) zeolite is prepared using a specific organic structure-directing agent (OSDA), cis-3,5-dimethylpiperidinium. The cis-isomers align in the main 12-membered ring (MR) channel of GME. Trans-isomer OSDA leads to the small-pore zeolite SSZ-39 with the OSDA in its cages. Data from N2 -physisorption and rotation electron diffraction provide evidence for the openness of the 12 MR channel in the GME 12×8×8 pore architecture and the absence of stacking faults, respectively. CIT-9 is hydrothermally stable when K+ -exchanged, while in the absence of exchange, the material transforms into an aluminous AFI-zeolite. The process of this phase-change was followed by in situ variable temperature powder X-ray diffraction. CIT-9 has the highest Si/Al ratio reported for GME, and along with its good porosity, opens the possibility of using GME in a variety of applications including catalysis.

KEYWORDS:

AFI zeolite; gmelinite; organic structure-directing agents; rotation electron diffraction; zeolites

PMID:
28857426
DOI:
10.1002/anie.201707452

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