Synthesis and characterization of a sulfur containing hydroxy sodalite without sulfur radicals

• We present a new sulfur containing hydroxysodalite (S-SOD) without any sulfur radicals.
• The S–SOD is much more stable than pure hydroxysodalite.
• Therefore S–SOD can be used for the separation of hydrogen under high pressure.
• The sulfur is most likely coordinated statistically on every possible oxygen position in the structure.

A new sulfur containing hydroxy sodalite (S–SOD) of high thermal and hydrothermal stability was synthesized and characterized. XRD measurements showed some differences to normal hydroxy sodalite (H–SOD). But the S–SOD is also quite different from natural sulfur containing sodalites like ultramarine blue. IR– and RAMAN-spectroscopy measurements detected no sulfur radicals in the structure of S–SOD, which was already assumed because of the colorless powder of S–SOD. 29Si–, 27Al– and 23Na–MAS–NMR measurements were conducted to determine the order of the structure and the type of incorporation of the sulfur into the sodalite structure. The sulfur is most likely coordinated statistically on every possible oxygen position in the structure. The pore size of the S–SOD was determined by positron annihilation measurements and is suitable for hydrogen separations.

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