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Published December 10, 2019 | Supplemental Material
Journal Article Open

Transformation of Extra-Large Pore Germanosilicate CIT-13 Molecular Sieve into Extra-Large Pore CIT-5 Molecular Sieve

Abstract

The 14- and 10-membered ring germanosilicate Ge-CIT-13 (*CTH) is transformed into the 14-membered ring germanosilicate Ge-CIT-5 (CFI). The transformation can occur at room temperature but requires the presence of adsorbed water. The *CTH-to-CFI transformation involves rearrangement of germanium-rich double-4-ring units in *CTH to form double-zigzag chains in CFI. The rate of transformation is dependent on the germanium content of the starting Ge-CIT-13 and the humidity of the transforming atmosphere. Other germanosilicates—UTL, IWW, and ITH—do not show this type of transformation because of arrangements of Ge-sites within their d4r units and/or to spatial restrictions regarding the d4r unit arrangement within their interlayer regions. Ge-CIT-5 can be further transformed into 10-membered-ring CIT-15 using ammonium hydroxide solution as the delaminating agent. Postsynthetic alumination of Ge-CIT-5 yielded high-silica CFI-type aluminogermanosilicates having molar Si/Al ratios in the range of 14–230, primarily depending on the acidity of the solution phase.

Additional Information

© 2019 American Chemical Society. Received: September 7, 2019; Revised: November 6, 2019; Published: November 6, 2019. The Chevron Energy and Technology Company provided financial support for this research. J.H.K. would like to thank the Samsung Scholarship for financial support for his graduate studies. J.H.K. is also grateful to Dr. Sonjong Hwang from Caltech Chemical Engineering for providing experimental support in solid-state NMR. Author Contributions: The manuscript was written through contributions of all authors. All authors have given approval to the final manuscript. The authors declare no competing financial interest.

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August 19, 2023
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