Incorporation of germanium and boron in zeolite chabazite

Part of the framework silicon (ca. 8%, Si/Ge + B ≈ 12) in the zeolite chabazite (IZA code CHA) was isomorphously replaced by germanium and boron. [B–Si–Ge–O]-CHA was synthesized using 6-azonia-spiro-[5,5]-undecane hydroxide as the structure directing agent and characterized by XRD, NMR, EDS, TG and chemical analyses. GeO2 and H3BO3 were the germanium and boron sources, which play a pivotal role in the zeolite synthesis. The introduction of these elements into the zeolite framework was verified by EDS, 11B and 29Si MAS NMR methods. In particular, the appearance of low-field resonance peaks in the 29Si MAS NMR spectrum revealed new environments for silicon compared to purely siliceous chabazite. Germanium and boron atoms are randomly distributed, in fact no symmetry reduction from the topological one was detected by the high resolution synchrotron data.

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► Synthesis of [B–Si–Ge–O]-CHA zeolite using azonia-spiro compounds as organic additive.
► GeO2 and H3BO4 are required for the zeolite crystallization.
► Proof of germanium incorporation in the CHA framework.