PILLARING STUDIES ON SOME LAYERED OXIDES WITH RUDDLESDEN-POPPER RELATED STRUCTURES

Pillaring studies on four layered oxides, KCa2Nb3O10, KCa3Nb3 TiO13, K Ca4Nb3Ti2O16, and KCa2Sr0.5Nb3Ti0.5O11.5, possessing Ruddlesden-Popper related structures have been carried out. The aluminum keggin ion, [A l13O4(OH)24(H2O)12]7+, Was used as the polymeric cation for the pillar . These samples were characterized by X-ray diffraction, thermogravime tric analysis, infrared spectroscopy, neutron activation analysis, and sorption studies. X-ray diffraction and other structural studies sugg est that the polymeric cations were incorporated into the interlayer a nd upon calcination the layer thicknesses observed correspond to that expected for the formation of the dehydrated polymers in between the l ayers as a composite. BET surface area measurements and sorption exper iments indicate that these products are nonporous oxides suggesting th at the interlayer regions are stuffed rather than pillared. (C) 1994 A cademic Press, Inc.