NEW INSIGHTS INTO THE MODE OF FORMATION OF ALPO4-N MOLECULAR-SIEVES

Here we report the synthesis of several aluminophosphates including the polymeric [AlP2O8H2](-)[Et(3)NH](+), the 20-membered ring JDF-20 framework, the porous macroanionic [Al3P4O16](3-) AlPO4-5-1ike sheet structure, AlPO4-5, tinsleyite and AlPO4-cristobalite, all from a tetraethylene glycol - water solvent system and a 2:1 P:Al gel. The cocrystallization as well as the structural similarities between the [AlP2O8H2](-)[Et(3)NH](+) chain and the JDF-20 phase together provide new insight into the made of formation of aluminophosphate molecular sieves and allows one to postulate reaction pathways for the transformation between the two phases. ?The water content of the reaction mixture appears to play a crucial role in determining the nature of the final products. The hydrolysis of polymeric [AlP2O8H2](-) to various related chain structures followed by their ordered condensation, permits the formation of the ''building blocks'' of a wide range of AlPO4-n structures, such as VPI-5, AlPO4-5, AlPO4-11, tinsleyite and many others, as well as dense aluminophosphate phases, such as, AlPO4-cristobalite.