Transformations of the aluminum (Al13) polyoxycation intercalated in the layered lattice of molybdenum trioxide

Abstract

Moo3 partially and fully intercalated using a solution of aluminum chlorohydrate and AlC13 hydrolyzed with NaOH, both containing [A104Al,2(OH)~4(H~O)~2]7+ polyoxycations, has been studied using 27Al magic-anglespinning (MAS) NMR, 1H-27Al cross-polarization and 27Al quadrupole nutation with MAS. There are three main lines from 6-coordinated Al: a line at 14 ppm and at 0 ppm and a very broad line with a maximum close to 3u,r/2~ in the quadrupole nutation spectra. The line at 0 ppm is assigned to Al(H20)63+ ions, and the likely origin of the other two lines is discussed. The chemical shift and the quadrupole coupling constant of the line from 4-coordinated A1 at 62-65 ppm in the partially intercalated sample are different from those in the completely intercalated one. We propose that hydrolytic abstraction of the A13+ cation from the bulk of the guest species leads to the formation of an A1124+ species.

Hydrothermal Synthesis and Structure of a Potassium Tantalum Defect Pyrochlore

“…Final observed, calculated, and difference X-ray powderdiffraction patterns are plotted in Figure 4. a Rietveld refinement was used to minimize ∑wi(Io,i -Ic,i) 2 , where Io,i and Ic,i are the observed and calculated powder diffraction intensities for the ith point, respectively. Weighted and unweighted profile R-factors are defined as Rwp ) {[∑wi(Io,i -Ic,i) 2 ]/[∑wi(Io,i) 2 ]} 1/2 and Rp ) ∑|Io,i -Ic,i|/∑Io,i.…”

“…A pseudo-Voigt peak shape function was used, 24 with the half-width parameters U, V, W, and an asymmetry correction initially kept constant. For an ideal sample these parameters are instrumental characteristics, mea- a Rietveld refinement was used to minimize ∑wi(Io,i -Ic,i) 2 , where Io,i and Ic,i are the observed and calculated powder diffraction intensities for the ith point, respectively. Weighted and unweighted profile R-factors are defined as Rwp ) {[∑wi(Io,i -Ic,i) 2 ]/[∑wi(Io,i) 2 ]} 1/2 and Rp ) ∑|Io,i -Ic,i|/∑Io,i.…”

“…Instead of (Si,Al)O 4 tetrahedral structural units in zeolite molecular sieves, the OMS materials contain MO 6 (M = metal) octahedra as the basic building block in forming three-dimensional porous framework structures . Typical octahedral molecular sieves are the oxides of early transition metals, such as Mo, Ti, , and Mn, and consist of either pillared octahedral layered materials or three-dimensional octahedral tunnel structures.…”

Preparation and Properties of Fluorinated Alumina-Pillared α-Zirconium Phosphate Materials

“…The tridecamer ion [AlO 4 Al 12 (OH) 24 (H 2 O) 12 ] 7+ , referred to as Al 13 , has been widely used for pillaring layered hosts, such as swelling clays, 1 phosphates, 2 and other compounds, 3 because it has been, until recently, the only oligomeric species of Al 3+ well characterized in solution and solid state. Al 13 may be intercalated from solutions of (i) AlCl 3 ‚6H 2 O partially hydrolyzed with NaOH 4 or (ii) commercial Chlorhydrol.…”

“…The tridecamer ion [AlO 4 Al 12 (OH) 24 (H 2 O) 12 ] 7+ , referred to as Al 13 , has been widely used for pillaring layered hosts, such as swelling clays, phosphates, and other compounds, because it has been, until recently, the only oligomeric species of Al 3+ well characterized in solution and solid state. Al 13 may be intercalated from solutions of (i) AlCl 3 ·6H 2 O partially hydrolyzed with NaOH or (ii) commercial Chlorhydrol. , Upon calcination at T > 673 K, the intercalated oligomer is transformed into an aluminum oxide (pillar), which props apart the layers and generates a permanent porosity in the interlayer region of the host.…”