Influence of organic templates on the structure and on the concentration of framework metal ions in microporous aluminophosphate catalysts

Energy minimization methods are used to investigate the packing energies of triethylamine and triethylammonium templates in two distinct aluminosilicate structures, AIPO(4)-5 (AFI code) and the chabazitic AIPO(4)-34 polymorph (CHA), both of which may be synthesized as Co-AIPOs from the same gel, depending on the concentration of Co2+ and template. We show that higher (cationic) concentrations of template, induced by higher (negatively charged) Co2+ substitution levels in the framework, favor the formation of a chabazitic structure. The AIPO(4)-5 polymorph is, however, marginally more stable in the untemplated state, a result which is consistent with the reversion of the chabazitic phase to the AIPO(4)-5 polymorph at higher temperatures or increased reaction time.