On the synthesis of nitrate enclathrated sodalite in organic solvents

Abstract

Hydrothermal synthesis of sodalite has been investigated in the system NaOCH₃-2SiO₃-Al₂O₃-NaNO₃-(CH₃OH, C₅H₁₁OH) at temperatures of 423 K and 473 K. For the first time the organic solvents methanol or pentanol together with sodium methylate as base were used besides common inorganic educts as Si/Al source and sodium nitrate salt. The sodalites have been characterized by X-ray powder diffraction, as well as by ²⁹Si, ²³Na MAS NMR, and ²³Na DOR NMR measurements. IR-FT spectroscopy shows the successful enclathration of nitrate anions in the β-cages of sodalite. Reaction products of the solvent/base have been identified by ¹H ¹³C CPMAS NMR and ¹H MAS NMR. Scanning-electron micrographs show crystals larger than 15 μm grown at 473 K in pentanol.