Crystallization profile and morphological study of SAPO-5 templated by imidazolium cations of different functional groups

Abstract

1-Propyl-2,3-dimethyl-1H-imidazole-3-ium ([pmIm] + ), 3-(2,3-dihydroxypropyl)-1,2-dimethyl-1H-imidazole-3-ium ([dhmIm] + ) and 1-benzyl-2,3-dimethyl-1H-imidazole-3-ium ([bzmIm] + ) cations were used as organic templates for crystallizing SAPO-5 with AFI microporous framework. The physico-chemical influences of the functional groups of the templates (e.g. polarity/hydrophilicity, molecular dimension and size) on SAPO-5 formation were investigated. The results revealed that the crystallization rate, crystallinity and solid yield could be enhanced by increasing the polarity/hydrophilicity of the templates. In addition, the isomorphous Si substitution, morphology and particle size of the resulted SAPO-5 were also affected by the substituted groups of the imidazolium templates. The thermogravimetry results further supported that the selection of organic template with proper polarity/hydrophilicity could be crucial to obtain SAPO-5 with high porosity (S BET , S mic , S ext and V total ) as high polar/hydrophilic template exhibited stronger chemical interaction with the AFI framework during template removal process via calcination process. • SAPO-5 is synthesized using imidazolium-based templates. • Template's functional group affects crystallization and morphological profiles. • Proper hydrophobicity is essential to control host-guest chemical interactions. • Polar template interacts strongly with SAPO-5, hence high temperature calcination is needed.