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

Abstract

1-Propyl-2,3-dimethyl-1H-imidazol-3-ium ([pmIm] +), 3-(2,3-dihydroxypropyl)-1,2-dimethyl-1Himidazol-3-ium ([dhmIm] +) and 1-benzyl-2,3-dimethyl-1H-imidazol-3-ium ([bzmIm] +) cations were used as organic templates for crystallizing SAPO-5 with AFI microporous framework. The physicochemical 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 2 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 (SBET, Smic, Sext and Vtotal) as high polar/hydrophilic template exhibited stronger chemical interaction with the AFI framework during template removal process via calcination process.

Effects of Synthesis Parameters on the Crystallization Profile and Morphological Properties of SAPO-5 Templated by 1-Benzyl-2,3-Dimethylimidazolium Hydroxide

“…The hydroxide solution was then concentrated to 33.0 wt% at 50 • C before it was further used for SAPO-5 synthesis. with different morphological and physicochemical properties [9,10]. Isomorphous Si substitution, surface area, particle size and surface acidity of the SAPO-5 samples are affected when different SDAs are used in the crystallization process.…”

“…SAPO-5 can be readily crystallized under hydrothermal conditions at 180-200 • C for 1-3 days in the presence of alkylamine organic templates, such as triethylamine, tripropylamine, tetraethylammonium hydroxide, tetrabutylammonium hydroxide, and N-methyldicyclohexylamine [4][5][6][7][8]. The use of so-called structure-directing agents (SDAs) with different molecular shapes, sizes, and polarities have been found to form SAPO-5 crystals with different morphological and physicochemical properties [9,10]. Isomorphous Si substitution, surface area, particle size and surface acidity of the SAPO-5 samples are affected when different SDAs are used in the crystallization process.…”

“…Unlike aliphatic amines, the delocalized π electrons in their cyclic ring together with their bulkier molecules create a versatile platform for adding functional properties and chemical modifications, thus altering the overall crystallization process of SAPO-5 materials [13,14]. The crystallization rate, crystallinity and solid yield can be tuned by using imidazolium templates with different substituted groups [10]. Besides SDAs, the crystallization process of SAPO-5 might also be affected by the synthesis parameters such as heating time, crystallization temperature, synthesis technique, amount and source of reactants, solvent, and aging [15].…”

Direct evidence of time-dependent crystallization evolution of SAPO-34 and SAPO-20 zeolites directed by trimethylbenzylammonium hydroxide for microwave-assisted ethanolysis of furfuryl alcohol

“…28 These organic templates show different shapes, hydrophilicity and sizes, and thus demonstrate different crystallization kinetics and structure-directing ability for tailoring the pore structure of zeolites. 29 Nevertheless, crystallization of different zeolites (in pure phase) using a similar organic template requires careful optimization of the synthesis conditions ( e.g. recipe, aging, pH, temperature, etc. )…”