Synthesis and characterization of an unusual lamellar aluminophosphate synthesized from an alcohol system

Abstract

An unusual lamellar aluminophosphate [Al₄P₂O₁₁·2C₆H₁₃NH₂·4H₂O]·3H₂O was synthesized from a mixture of H₃PO₄, Al(OPrⁱ)₃, ethylene glycol and an unbranched primary alcohol. It was characterized by X-ray powder diffraction, scanning electron microscopy, infrared, magic angle spinning NMR spectroscopy, differential thermal and thermogravimetric analysis. It is composed of PO₄, AlO₄ and AlO₆ structural units, and the ratio of octahedral to tetrahedral Al in the as-synthesized compound is about 1:1. This material exhibits a very large weight loss at elevated temperatures. Upon dehydration it possesses a considerable water adsorption capacity. The water adsorption isotherm is linear. Of the seven water molecules in the empirical formula, four are co-ordinated to the Al atoms and the other three are located between adjacent layers.