Synthesis of mesostructured lamellar aluminophosphates in the presence of alkylpyridinium cationic surfactant

Abstract

A series of mesostructured lamellar aluminophosphates and silicoaluminophosphates have been synthesized hydrothermally using alkylpyridinium bromide surfactant templating or mixed surfactants of alkylpyridinium and cetyltrimethylammonium bromide. The synthesis of present aluminophosphate-based mesostructured materials can be performed within the following molar gel composition: Al2O3:(0 8-1.9) P2O5:(0.3-1.0) CPBr:(0.8-4.2) TMAOH:(100-350) H2O:(0-1.0) SiO2 at various temperatures in the range of 80-150 degreesC for 0.5-4 days. The effect of various synthetic factors, such as P/Al ratio, TMAOH/Al ratio, water content, surfactant concentration, synthesis temperature, and reaction time, has been discussed. The addition of Si in the mixture gel requires more base content. The interlayer distance of materials decreases with either increasing water content in the reaction mixture or decreasing alkyl chain length of the templating surfactant alkylpyridinium cation. The mesostructured aluminophosphate-based materials were also prepared with templates mixtures of cetylpyridinium bromide and cetyltrimethylammonium bromide. and their interlayer distance of materials can be finely controlled by changing the CPBr/CTABr molar ratio. Al-27 and P-31 nuclear magnetic resonance spectra have been carried out to understand the local atomic arrangements and coordination environments of these solid products. (C) 2001 Elsevier Science B.V. All rights reserved.