Angewandte Chemie International Edition · 2020 · 27 citations · 52 references
A quasi-pure C<sub>H</sub> polymorph of microporous zeolite beta, named ECNU-36, was obtained as a highly crystalline silicate using 1,5-bis(tetramethylimidazolium) hydroxide as organic structure-directing agent (OSDA) in fluoride media. An appropriate concentration of free fluoride in the synthetic mother liquor was crucial to purify the C<sub>H</sub> -phase. The framework structure of ECNU-36 consists of polymorph C<sub>H</sub> (>95 %) and polymorph B, elucidated by a combination of PXRD data, DIFFaX simulation, EDT, and HRTEM techniques. For the first time, the framework structure of beta C<sub>H</sub> polymorph was directly confirmed and solved using electron diffraction data. The pure-silica ECNU-36 showed an unusual crystal morphology, composed of stacked nanosheets, with typical 17 nm thickness and exposed {100} facets, which exhibited attractive adsorption performance for hydrocarbons and aromatics.
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Stable single-unit-cell nanosheets of zeolite MFI as active and long-lived catalysts
Minkee Choi, Kyungsu Na, Jeongnam Kim et al. · Nature · 2009 · 2.2K citations
Materials Science, Molecular Sieve, Chemical Engineering +11