Author:

Keywords:

cations, crystallization, oligomers, Solids, zeolites, Science & Technology, Physical Sciences, Technology, Chemistry, Multidisciplinary, Crystallography, Materials Science, Multidisciplinary, Chemistry, Materials Science, ALUMINOSILICATE GEL PRECURSORS, CHABAZITE ZEOLITES, STRUCTURAL-PROPERTIES, ALUMINUM, FRAMEWORK, CRYSTALLIZATION, CHA, CHALLENGES, CHEMISTRY, SILICA, Z-EURECA - 948449;info:eu-repo/grantAgreement/EC/H2020/948449, KA/20/038, KA/20/038#56130165, G085220N#55518315, 12E4623N#57011837, ERC-2020-STG 948449, G0D5419N#54969415, 0302 Inorganic Chemistry, 0306 Physical Chemistry (incl. Structural), 0912 Materials Engineering, Inorganic & Nuclear Chemistry, 3402 Inorganic chemistry, 3406 Physical chemistry, 4016 Materials engineering

Abstract:

Zeolites have long been regarded as difficult to modify during synthesis, as their synthesis is governed by kinetic processes. Recent breakthroughs have made it possible to exert a certain degree of control over zeolite properties with more performant materials as a result. Here, we investigate the effects alkali cations have on high-silica FAU-to-CHA interzeolite conversion (IZC) and on the resulting aluminum distributions. In this way, by using Li-cations in conjunction with an organic structure directing agent, the first route to a “fully paired” (divalent cation capacity, Co2+/Al = 0.48) high-silica SSZ-13 zeolite is demonstrated. Lithium shows great potential in steering IZC synthesis as it speeds up crystallization, and evidence was gathered in favor of a more elaborate mechanism of IZC in which dissolved Al-rich oligomers crash out of solution first and possibly spark nucleation. These findings help in gaining insights into a more general theory on zeolite nucleation in heterogeneous environments such as IZC. Furthermore, the “fully paired” sample has great potential for ion-exchanged zeolite catalysis or in adsorbents