The synthesis of Mg2+ doped β-MnOOH which is known as feitknechtite is reported. Feitknechtite is a layered material having the Cd12 structure. The characterization of Mg2+ doped feitknechtite was done with X-ray powder diffraction, elemental analysis, energy dispersive X-ray analysis, scanning electron microscopy, alternating current (AC) impedance, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential scanning calorimetry, average oxidation state titrations of manganese, and acidity measurements. The formation of feitknechtite is related to the MnO4−/Mn2+ ratio used in the synthesis. Feitknechtite can be converted to synthetic birnessite or octahedral layer birnessite (OL-1) which is a precursor to the 6.9 Å tunnel structure material todorokite.

The microstructure of nanoporous, carbogenic molecular sieves (CMS) was studied using high resolution electron microscopy and neutron diffraction. The narrow range of pore sizes observed in these complex materials suggests that although these materials are globally amorphous, the local microstructural features are more organized. Our work, focused on poly(furfuryl alcohol)-derived CMS, is aimed at characterizing the evolution of this microstructure. Microscopy results show that materials synthesized at low temperature have some degree of organization but that the microstructure is featureless and symmetric at longer length scales. This symmetry is broken at higher synthesis temperatures as thermodynamic driving forces lead to further organization of the carbon atoms into more ordered structures but the length scales remain short. Micrographs of high temperature CMS show a high degree of curvature and features reminiscent of fullerene. The connectivity of the carbon atoms in the CMS has been probed using powder neutron diffraction. This data suggests that the atoms in the CMS form ordered structures on the length scale of 15Å which are distinctly different from the structure of graphite. These observed changes in the microstructure directly impact the adsorptive and molecular sieving characteristics of the CMS as illustrated by the marked differences between the diffusivities of oxygen and nitrogen. This property is crucial for the very demanding separation of nitrogen from oxygen in air.

Al-, Ti- and Zr-pilared clays were characterized and NiMo/Pilc's were tested in HDS reactions. The combination of activity measurements with Mossbauer Spectroscopy and x-ray microanalysis at microscopical scale give insight in the metal phases migration during pillaring, reaction and regeneration steps. α-Fe phase in free Fe2O3 islands predominate together with structural Fe3+ phase, but during the catalytic reaction Fe2+ forms. Delamination of the Ti- and Zr-Clay supports, together with high Lewis acidity might enhance their catalytic properties.

The synthesis and crystal structure determination of d,l-Co(en)3.Ga3P4O16, xH2O (Pnna, a = 8.6502(9), b = 21.528(3), c = 13.717(2) Å) is described. This novel layered material contains Ga3P4O163- macroanions. The preparation and preliminary catalytic testing of a vanadium doped aluminophosphate that is isostructural with the gallophosphate is also discussed.

The synthesis and characterization of ULM-16, a new fluorinated gallophosphate Ga4(PO4)F2 • 1.5 NC6H14 • 0.5 H2O • 0.5 H3O, is described. This material is hydrothermally prepared at 180°C using cyclohexylamine as the structuring agent. It cristallizes in the orthorhombic space group Pbcn (n° 60) with a = 27.329(4) Å, b = 17.377(2) Å, c = 10.2124(5) Å, V = 4849.6 (9) Å3 and Z = 8. The structure is built up from vertex-linked GaO4 and PO4 tetrahedra, GaO4F trigonal bipyramids and GaO4F2 octahedra forming hexameric units and infinite double crankshaft chains (called cc or UUDD). The hexameric unit is similar to that found in ULM-3, ULM-4, ULM-5 and ULM-8. The two types of building units are fully connected by vertex-sharing with respect to a strict Ga-P alternation. The 3-D framework consists of cylindrical tunnels delimited by sixteen and six polyhedra running along [001]. The cyclohexylamine molecules are trapped in the wider pores and interact with the bridging fluorine atoms and hydration water through hydrogen bonds. The ULM-16 topology is closely related to that of ULM-5 where, in ULM-16, the infinite crankshaft chains replace the isolated D4R cages of ULM-5. TGA curve (under argon) indicates that the ULM-16 structure is intact up to 800°C. Structural relationships will be stated explicitly for the different structures of the ULM-n series containing the hexameric units.

This work describes the designed synthesis and physical characterization of carbons containing predictable microporosity. The approach is to pyrolyze aromatic hydrocarbons such as pyrene within a pillared clay. The pillared clay serves two functions. It performs as the inorganic template around which the designer carbon can be formed, and it acts as an acid catalyst to promote condensation of the aromatics similar to the Schöll reaction. These precursors then undergo thermal polymerization and carbonization at 700 °C. Removal of the pillared clay template is accomplished by standard acid demineralization techniques, leaving behind carbons with 15 to 50 Å holes.

The vanadium containing molecular sieve VAPO-5 was characterized by using cyclic voltammetry. The as-synthesized and calcined samples contain loosely bound VO2+ species that can be removed by immersion in the aqueous electrolyte solution. The steady-state cyclic voltammograms of VAPO-5 reveal two distinct reversible V(5+)/V(4+) processes centered at Eeq(I) = 0.11 V/SCE and Eeq(II) = −0.07 V/SCE. These processes have been proposed to arise from framework vanadium located at structurally distinct sites V-O-T (T = Al or P).

La3+ −Al3+ and Ce3+ −A13+ pillar precursors were synthesized and intercalated in swelling montmorillonite type clays. 27Al-NMR and 139La-NMR spectra do not confirm chemical interaction between Al and La ions in solution, but after pillaring and calcination (400°C) d-spacings in the range 18.5 Å−20.5 Å indicate indeed a strong interaction between the Al-La species. Also, Ce4+ (Sulfate) cations do interact with Al3+ in the pillar-precursor-solution, into the pH interval 2.78≤p.H ≤3.99.

ULM-19 or [Fe4(PO4)4F2], [C6H14N2], was obtained in a monocrystalline form from the dehydration of single crystals of ULM-12, or [Fe4(PO4)4F2(H2O)3], [C6H14N2] at 260°C. It is monoclinic (S.G. P21/n) with a = 10.009(7), b = 12.235(8), c = 17.28(2) Å, β = 106.04(5)°, V = 2034(3) Å3, Z = 4. Its structure, which can be described from the corner sharing of hexameric Fe3P3 and dimeric FeP units, directly derives from that of ULM- 12 by the loss, on three of the four Fe(III) polyhedral sites of the structure of ULM-12, of the terminal water molecules. This induces drastic changes in the coordination polyhedra of Fe(III): three octahedra and one square pyramid in ULM-12, and one octahedron, one square pyramid, one trigonal bipyramid and one tetrahedron in ULM-19. These evolutions were confirmed and characterized by in situ Mössbauer spectrometry measurements using a cryofurnace. The loss of water opens 6-ring channels beside the 12-ring tunnels already existing in ULM-12.

NMD samples from Brazil have been submitted to magnetic and particle size separations and characterized by X-ray diffraction and fluorescence and thermogravimetric analyses. Results showed that simple physical treatments can lead to more than 60% enriched MnO2 materials which could satistify some electrochemical applications. The electrical properties of the samples conditionated as pressed pellets have been investigated by four-points direct current probe and impedance spectroscopy, varying the conditions of preparation and measurement. It is proposed that the higher frequency impedance is equivalent to the intrinsic electronic resistance of the MnO2 phases while at lower frequencies occurs an interphase charge separation coupled with a possible ionic transport. The corresponding contact resistance depends on the article size distribution of the material, the compactation pressure of pellets and the iron content of the materials. The interphase dielectric relaxation does not behave ideally; the depression of the impedance semicircles as shown in the Nyquist plane is assumed to be related to the roughness of the bulk interfaces.

Large quantity of fly ash is generated every year from the electric power plants. Due to the shortage of disposal sites and tighter regulations, new viable ways of utilizing fly ash are needed. The formation of a porous material comprising fly ash was investigated. It was found that a porous material can be made by mixing fly ash with phosphoric acid, followed by heat treatment. The porous material is light-weight (bulk density ˜1 g/cm3), machinable, and with reasonable strength. Due to the high percentage of close porosity, the porous material has a great potential for thermal insulation applications.

Organically-functionalized mesoporous silicas have been prepared at room temperature, in a base-catalysed reaction, by the co-condensation of tetraethoxysilane and organosiloxanes ((C2H5O)3Si-R; R = C6H5 or n-C8H17) in the presence of surfactant (C16H33N(CH3)3Br) templates. The resulting materials are covalently linked, hexagonally ordered, hybrid inorganicorganic networks.

A simple and versatile synthetic route, whereby primary amine surfactants are the template in the assembly of aluminosilicate inorganic species, is used to prepare aluminosilicate mesoporous molecular sieves in which Brønsted acidity is generated by simply calcining the as-synthesised material. Al incorporation is accompanied by charge-balancing protonated amine molecules. Si and Al are incorporated into the mesoporous framework to yield materials with textural properties similar to those of MCM-41 but with substantially higher Brønsted acidity.

The pore surface of mesoporous MCM-41 type materials have been functionalized with silanes to yield surface bound chelate ligands that include ethylenediamine (ED), diethylenetriamine (DET) and ethylenediaminetriacetic acid salt (EDT). Additionally, The grafted DET ligand was reacted with salicylaldehyde to generate the supported tetradentate Schiff base ligand designated as DES. The MCM-41 bound ligands were used to prepare a series of covalently attached cobalt(II) complexes that potential as oxygen carriers and catalysts. These materials were characterized by FTIR and cyclic voltammetry as well as elemental analysis.

We have synthesized monolithic particulate gels of periodic mesoporous silica by adding tetramethoxysilane to a homogeneous alkaline micellar precursor solution. The gels exhibit 5 characteristic length scales over 4 orders of magnitude: fractal domains larger than the particle size (>500 nm), particles that are ˜150 to 500 nm in diameter, interparticle pores that are on the order of the particle size, a feature in the gas adsorption measurements that indicates pores ˜10–50 nm, and periodic hexagonal arrays of ˜3 nm channels within each particle. The wet gel monoliths exhibit calculated densities as low as ˜0.02 g/cc; the dried and calcined gels have bulk densities that range from ˜0.3–0.5 g/cc. The materials possess large interparticle (˜1.0–2.3 cc/g) and intraparticle (˜0.6 cc/g) porosities.

The supramolecular templating technique was used to synthesize both hexagonal (Hx- ZrO2) and lamellar (L-ZrO2) phases of zirconium oxide. Under the conditions used in this work, the use of long chain primary amines and quaternary ammonium surfactants resulted in the exclusive formation of lamellar and hexagonal phases, respectively. The use of long chain cetyldimethylamine afforded a mixture of a hexagonal and a lamellar phases. Effects of synthesis parameters such as the ZrO2/surfactant ratio, ZrO2/water ratio, the nature of surfactant, the crystallization temperature and time on the formation of mesostructured ZrO2 were also studied. Addition of 1,3,5-trimethylbenzene (TMB) as a swelling agent led, in the presence of cetyltrimethylammonium bromide, to the formation of a lamellar phase rather than to pore enlargement. These materials were characterized by XRD, FTIR, XPS and EDX techniques. Regardless of their structure, the as-synthesized materials collapsed upon calcination. Treatment with monobasic potassium phosphate followed by calcination at 350 °C led to the formation of a stable porous Zr–P oxide with a surface area as high as 540 m2/g.

MCM-41 mesoporous materials were synthesized under different hydrothermal conditions using organic templates, i.e. CTMA-Br, DTMA-Br. Reaction temperature (120 to 195 °C) and reaction time (24 to 120 hr) varied and their influence on the structure properties of MCM-41 was sought i.e. d = 36 to 41.6 Å for distinct micelles diameters. Also, insertion of polyaromatics into the surfactant micelles was determinant in the final pore diameter, i.e d = 35.4 to 48.6 Å.

A lean NOx catalyst is needed to control NOx emissions generated by oxygen-rich combustion processes to obtain higher fuel economy. We have developed such a catalyst using modified mesoporous molecular sieves (MCM-41). An iron(II)-complex impregnated MCM-41 has been synthesized which has been further treated with [Pd(NH3)4]Cl2. This treatment resulted in further exchange of Na+ ions of the molecular sieves with Pd(NH3)42+ thus forming Catalyst A. The catalytic activity towards NOx, CO and HC was studied using simulated exhaust gas, as well as engine exhaust gas.

Several organic reactions that proceed through a sol-gel transition have been identified at LLNL. The most-studied reaction involves the aqueous polycondensation of resorcinol (1,3- dihydroxybenzene) with formaldehyde. Recently, we have shown that phenol can be added to this polymerization as a comonomer. The resultant crosslinked gels are supercritically dried from carbon dioxide (Tc=31°C, Pc = 7.4 MPa) to give resorcinol-phenol-formaldehyde (RPF) aerogels. Because RPF aerogels are composed of a highly crosslinked aromatic polymer, they can be pyrolyzed in an inert atmosphere to form vitreous carbon monoliths (CRPF). The resultant aerogels are black in color and no longer transparent, yet they retain the high porosity (40–98 %), ultrafine cell/pore size (< 50 nm), high surface area (600–800 m2/g), and interconnected particle (˜10 nm) morphology of their organic precursors. In this study, we examine the acoustic and mechanical properties of these materials as a function of precursor material and pyrolysis temperature. It is shown that the elastic moduli of RPF and CRPF is higher than that of pure RF / CRF aerogels at a given density. Upon pyrolysis RPF aerogels tend to shrink to a larger extent.

During the past five years, we have developed in our laboratory a new type of solar cell based on a photo-electrochemical process. A respectable photovoltaic efficiency (i.e. 10%) is obtained by the use of mesoporous, nanostructured films of anatase particles. We will show how the TiO2 electrode microstructure influences the photovoltaic response of the cell. More specifically, we will focus on how processing parameters such as hydrothermal growth temperature, binder addition and sintering conditions influence the film porosity, pore size distribution, and consequently affect the solar cell efficiency.