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 energi es of triethylamine and triethylammonium templates in two distinct alu minosilicate structures, AIPO(4)-5 (AFI code) and the chabazitic AIPO( 4)-34 polymorph (CHA), both of which may be synthesized as Co-AIPOs fr om 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 polymorp h is, however, marginally more stable in the untemplated state, a resu lt which is consistent with the reversion of the chabazitic phase to t he AIPO(4)-5 polymorph at higher temperatures or increased reaction ti me.