Formation of aluminum diphosphonate mesostructures: The effect of aluminum source

Abstract

Mesostructured aluminum phosphonates (AOP-x) bridging with 1,1′-hydroxyl ethylidene groups, including a lamellar mesostructure (AOP-N) with crystalline framework, a well-ordered 2D-hexagonal mesophase (AOP-Cl), and a particle-packed mesostructure (AOP-S), were simply synthesized in the presence of surfactant cetyltrimethylammonium bromide in the ethanol-water system, by choosing Al(NO3)3, AlCl3 and Al2(SO4)3 as the aluminum source, respectively. The crystallinity, morphology, mesophase, and skeletal structure of the as-prepared materials were characterized by XRD, TEM, SEM, 27Al, 31P and 13C MAS NMR, and nitrogen sorption techniques. After calcination under N2 at 350 °C, the calcined AOP-x samples consist of aluminum phosphonate and phosphate, possessing desirable specific surface areas of 116–585 m2/g. The effect of the inorganic counteranions (NO3−, Cl− and SO42−) from the aluminum source on the formation of different AOP-x mesostructures was discussed in terms of their bind strength to the headgroups of the surfactant micelles, suggesting the potential for designed synthesis of non-silica-based mesostructured organic-inorganic hybrid materials.