Abstract:

The simplest zeolite, sodalite(SOD), was synthesized iononic liquidthermally from aqueous basic aluminosilicate precursor gels in an imidazoliumbased ionic liquid, with 1-ethyl-3-methylimidazolium bromide as solvent. The synthesis was carried out at a temperature between 50 and 150 ℃ at an ambient pressure. The effects of mass ratios of aqueous gel to ionic liquid, molar ratios of n(Si)/n(Al) in gel and crystallization temperature and time on the crystallization were investigated. The morphology and structure of the as-prepared products were characterized by X-ray diffraction and scanning electron microscopy. The results show that a mixture of sodalite and zeolite X was initially precipitated in ionic liquid at a ratio 1∶3 of aqueous gel to ionic liquid, and finally transformed in to pure sodalite as the crystallisation time is prolonged, and the crystallinity of sodalite increased with the increase of n(Si)/n(Al) from 1.1 to 10. Increasing the ratio of aqueous gel to ionic liquid, zeolite X was favorable to crystallize, and it became the only product under the hydrothermal condition.

Key words: Ionothermal synthesis; Zeolite; Sodalite; Ionic liquids