Synthesis of aluminosilicate and gallosilicate zeolites via a charge density mismatch approach and their characterization

J Am Chem Soc. 2011 Feb 16;133(6):1917-34. doi: 10.1021/ja1095057. Epub 2011 Jan 19.

Abstract

Aluminosilicate and gallosilicate zeolite syntheses via a charge density mismatch (CDM) approach are compared at intermediate-silica compositions (Si/Me = 5-16, where Me is Al or Ga). With a variation of the crystallization temperature and of the type and/or concentration of alkali metal ions added as a crystallization structure-directing agent (SDA) to tetraethylammonium-tetramethylammonium, tetraethylammonium-hexamethonium, and strontium-choline mixed-SDA systems, we were able to obtain 11 different zeolite structures. However, only 5 out of a total 40 pairs of aluminosilicate and gallosilicate synthesis runs at otherwise identical chemical compositions were found to give the same zeolite product with no detectable impurities, suggesting that the structure-directing ability of Ga is quite different from that of Al even in intermediate-silica synthesis conditions. The CDM approach to offretite synthesis led to hexagonal plate-like crystals with aspect ratios lower than 0.3, and UZM-22 exhibited no significant preference of Al substitution for particular tetrahedral sites, especially for site T1, unlike its framework type material ZSM-18. More interestingly, the EU-1 zeolite obtained from an aluminosilicate synthesis mixture containing Li(+) as an inorganic crystallization SDA in the tetraethylammonium-hexamethonium double-organic additive system has been characterized to locate about half of its Li(+) ions in the framework, while the Li distribution over the 10 topologically different tetrahedral sites is nonrandom in nature.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aluminum Silicates / chemical synthesis*
  • Chemistry Techniques, Synthetic / methods*
  • Electrons*
  • Magnetic Resonance Spectroscopy
  • Models, Molecular
  • Molecular Conformation
  • Thermodynamics
  • Zeolites / chemical synthesis*
  • Zeolites / chemistry*

Substances

  • Aluminum Silicates
  • Zeolites
  • aluminosilicate