Synthetic analogues of the microporous minerals umbite (AM-2) and penk
vilksite, polytype 20 (AM-3), have been prepared. The facile syntheses
of two other titanosilicates, AM-1 and AM-4, have also been reported.
AM-1 and the previously reported, layered titanosilicate known as JDF
-L1 have been shown to have the same structure. AM-4 is a new micropor
ous titanosilicate with a unique and unknown structure, containing eig
ht different Na sites. All AM-n materials have been characterized by s
everal techniques, viz. SEM, powder XRD, single-and triple-quantum Na-
23 and Si-29 MAS NMR, water adsorption measurements, and TGA/DSC. AM-n
materials are thermally stable up to ca. 600 degrees C. The dehydrati
on-hydration processes seem to be reversible (or quasi reversible) for
AM-1, -2, and -3 but not so for AM-4.