(A) study on the aluminophospate materials with a layer type structure

Abstract

Aluminophosphate materials with a layer type structure were synthesized hydrothermally from reactive aluminophosphate gels and amines. In the aluminophosphate molecular sieves the organic additives become entrapped or clathrated within the crystalline products. Many of the aluminophosphate molecular sieves exhibit excellant thermal stability. In contrast, in the layer type aluminophosphates the organic additives are intercalated between aluminophosphate layers. The layer structures undergo crystallographic collapse when the interlayer organic species is removed. Hetroatom-incorporated aluminophosphate molecular sieves, CoAPO-44 and MAPO-5 were synthesized using Co(II) and Mg(II), and cyclohexylamine as a templating agent. However, layer type aluminophosphate materials were obtained when Co(II) and Mg(II) were not present or cyclohexylamine was present in excess. Primary amines with a bulky alkyl group can produce both layer type materials and molecular sieves depending on the reaction conditions. It seemed that in the case of the presence of the metal ion, metal-amine species having the proper arrangement for the formation of molecular sieves may be formed.