Role of templating agents on the growth morphology of AIPO4

Abstract

Large numbers of techniques are known to yield advanced materials, particularly ceramics, and currently the templating techniques, where the templating agents are used to control the nucleation of inorganic clusters from the aqueous or nonaqueous solution are gaining importance [1, 2]. Preorganized architectures consisting of functionalized surfaces act as templates for the nucleation and growth of inorganic materials [3]. The templates are frequently used to promote the formation of the desired structure during synthesis of inorganic materials and it is understood that the templating agents, normally organic nitrogen-containing bases, may serve as structure directing agents, as buffers or as void fillers [4]. The templating is a well-known step for the nucleation and growth of inorganic compounds in the biomineralization process, where the inorganic– organic interaction leads to preorganization, nucleation, and growth of biomaterials [5]. Several groups have investigated the preparation of aluminum phosphate using a templating agent in a nonaqueous medium [6–8]. In the last few years, the research on the molecular sieves particularly, Al-phosphate, has increased due to its importance as catalyst carrier for the oxidation of linear alkanes using molecular oxygen [9] and its possible use in nano-laser tubes [10]. In this letter, the effect of templating agents on the synthesis of microporous AlPO4 is discussed. We used aluminum-isopropoxide to prepare boehmite sol, which was reacted with orthophosphoric acid to yield AlPO4 in ethylene glycol medium. Al-isopropoxide with purity >99.96% was prepared by reacting aluminum metal with isopropyl alcohol followed by vacuum distillation. In the present investigation, 100 g of Al-isopropoxide were hydrolyzed in 1000 cm3 distilled water. Subsequently, 50 cm3 of the Al-sol was dissolved in 100 cm3 ethylene glycol and reacted with H3PO4 acid at 373 K for 3 h to yield AlPO4 by the following reaction.