Cation-directed syntheses of novel zeolite-like metalloaluminophosphates STA-6 and STA-7 in the presence of azamacrocycle templates

Abstract

Hydrothermal syntheses of divalent metal cation-containing aluminophosphates, or MAPOs (M = Mg, Mn, Fe, Co or Zn), have been performed using the azamacrocycle 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane as a structure directing agent. Whereas STA-6 (St. Andrews-6), a small pore zeotype with a one-dimensional channel system, is prepared when magnesium, manganese or iron is included in the synthesis gel, a new solid, STA-7, is prepared in the presence of cobalt or zinc. The structure of STA-7 has been solved and found to possess a tetrahedrally connected framework with a fully three-dimensional interconnected small pore channel system. The organic template molecules included during synthesis can completely be removed without loss of framework integrity from the cobalt form. Syntheses using the hexaazamacrocycle 1,4,7,10,13,16-hexamethyl-1,4,7,10,13,16-hexaazacyclooctadecane have also been successful in preparing STA-7 in the presence of divalent metal cations. Both STA-6 and STA-7 structure types can be considered to be built up of cages and chemical analysis and computer simulation suggest strongly that the macrocycles act to template these cages.