The Use of Triquaternary Alkylammonium Ions in the Synthesis of STA-5, a Magnesioaluminophosphate with the BPH Framework Topology

Abstract

The triquaternary organic cations 1,3,5-Tris(triethylammoniomethyl)benzene ( 1 ) and 1,3,5-Tris(quinuclidiniomethyl)benzene ( 2 ) were synthesized and used as structure-directing agents in the synthesis of magnesioaluminophosphates (MAPOs). 2 Results in the preparation of STA-1, a known structure composed of intersecting large pore channels, whereas 1 results in the synthesis of STA-5, a MAPO with the BPH topology. The structure of STA-5, which contains a one-dimensional cage and channel structure limited by 12-membered rings, was solved using powder X-ray data and confirmed by microcrystal diffraction at a synchrotron source. STA-5 has trigonal symmetry, space group P 321, a = 13.221(1) Å, c = 13.339(1) Å. The template was found to be incorporated intact, and by a combination of computation and diffraction, was found to fill space effectively in the channel, with nearly every supercage being occupied by a template molecule. Upon calcination in oxygen at 550 °C, the template is removed, leaving the framework of STA-5 intact.