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Published March 10, 2020 | Supplemental Material
Journal Article Open

Fluoride-free Synthesis of Germanosilicate CIT-13 and Its Inverse Sigma Transformation To Form CIT-14

Abstract

Germanium-containing, extra-large pore molecular sieve CIT-13 is synthesized without the use of fluoride. After the removal of occluded organics, CIT-13 obtained from fluoride-free preparation shows significant differences from CIT-13 samples prepared in the presence of fluoride. CIT-13 prepared using a fluoride-free method is able to undergo inverse sigma transformation to yield CIT-14 and transforms into a CIT-5-type germanosilicate much faster than Ge-CIT-13 of similar Si/Ge ratios from a fluoride-containing synthesis. A Rietveld-refined structure solution for CIT-14 reveals that this new molecular sieve possesses 12- and 8-membered ring channels. Results from ¹⁹F magic-angle spinning (MAS) and ¹H–²⁹Si cross-polarized MAS nuclear magnetic resonance spectroscopy reveal that CIT-13 crystallized without fluoride has germanium siting which is different from CIT-13 synthesized in the presence of fluoride.

Additional Information

© 2020 American Chemical Society. Received: December 9, 2019; Revised: February 3, 2020; Published: February 5, 2020. The Chevron Energy and Technology Company provided financial support for this research. We thank Dr. Kevin Stone at the 2-1 Powder Diffraction Beamline at Stanford Synchrotron Radiation Lightsource at SLAC National Accelerator Laboratory for his assistance with the acquisition of PXRD data. J.H.K. would like to thank the Samsung Scholarship for financial support for his graduate studies. Author Contributions: The manuscript was written through the contributions of all authors. All authors have given approval to the final manuscript. The authors declare no competing financial interest.

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Supplemental Material - cm9b05072_si_003.cif

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August 19, 2023
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October 19, 2023