Several aspects of the application of monolithic catalysts in multiphase reactions are highlighted: why, hydrodynamics and preparation. A bright future for monolithic systems in this area is predicted for application in chemical industry.

A new process, GPM, has been developed to produce low density ceramic articles in any ceramic composition. This new process can produce articles with densities as low as 5% of the theoretical density (95% void fraction). The modulus of rupture values for the GPM material are in general 3-4 times as strong as the same density and composition ceramic foam. Products made with this new process are finding wide applicability in the catalyst and catalyst support media, low mass kiln furniture, ceramic pre-forms for metal/polymer infiltration and insulation markets. The microstructure, pore size and interconnectivity, and the fluid absorption properties of the GPM material are discussed.

The physical surface characteristics of three reticulated ceramic materials with and without wash coating are presented. The effect of an addition of 30 volume percent, 15-micron fugitive material on these characteristics is also reported. The fugitive increased pore volume but had little impact on surface area and strength.

In this paper a novel processing technique has been used to produce a range of low overpotential nickel based electrocatalytic coatings for use in the Chlor-alkali industry. These coatings include pure nickel as well as Raney nickel alloys, with particular focus upon the beneficial effects of molybdenum additions to Raney nickel.

Structural characterisation of all coatings has been carried out using X-ray diffraction for quantitative phase identification, backed up by optical and electron microscopy for analysis of phase distribution. Measurement of the coatings' electrochemical properties has been performed in fully functioning micro-pilot scale electrolysis cells.

High surface area, microporous, amorphous silicon imidonitride, characterized by infrared spectroscopy, MAS 29Si NMR and surface area and porosity measurements has been prepared by the treatment of co-oligomers of methylsilazane and dimethyl silazanes with gaseous ammonia at temperatures up to 700°C. The material has a narrow pore-size distribution showing a maximum in the range associated with wide- pore zeolites (ca. 0.72 nm mean). Variation of the organic content of the silazane is a means of controlling the surface area of the resulting solid. The Knoevenagel condensation reaction of benzaldehyde with a series of active methylene compounds has been used to probe the basicity and size-selectivity of these microporous solid base catalysts.

Group V and VI nitrides and carbides were synthesized by the temperature programmed reaction of metal oxides with ammonia or an equimolar mixture of methane/hydrogen. The synthesis protocols were developed using thermogravimetric techniques. The resulting nitrides and carbides were primarily mesoporous and possessed surface areas in the range of 11 – 81 m2/g. Their alkane activation rates were comparable to a Pt-Sn/AL20 3 dehydrogenation catalyst and the surface area normalized reaction rates decreased in the following order: Mo2N > W2C > WC > W2N > WC1−x > VCoa0.05N > MO2C > VN = VC > NbMo0.01 N > NbMo0.05 > NbN = NbC. The activities measured at 450°C ranged between 1011 – 1013 molecules/cm2/s for n-butane and 1012 – 1013 molecules/cm2/s for n-hexane. The Group VI nitrides and carbides were far more active than the Group V materials. The Group VI materials catalyzed the hydrogenolysis and dehydrogenation reactions with similar activities whereas the Group V materials were more than 98% selective to dehydrogenation. While the metal atom type had the most significant effect on the catalytic properties, the lattice structure of the material also played a role. In particular, we observed that WC (hex) was almost twice as active as WC1-x (fcc). Nitrides and carbides of the same metal and lattice structure possessed similar catalytic properties, implying that the effect of the non-metal atom type was minimal. The W2N catalyst was found to be highly selective towards n-butane isomerization. The multimetallic nitrides each demonstrated some form of synergy.

Mo2N powder, macrocrystals and nanoparticles and porous Mo metal were synthesized using temperature programmed reduction of MoO3 powder and crystals with reactant feed gases consisting of NH3 N2/H2 mixtures and pure H2. The Mo-based catalysts were characterized using BET, XRD, TGA, SEM, and STM. The Mo-based catalysts were also analyzed for the hydrodesulfurization (HDS) of thiophene. The relatively lower surface area Mo2N macrocrystalline catalysts (SSA = 44 m2/g) have a greater area specific activity than that of the higher surface area Mo2N powder catalysts (SSA = 150 m2/g) for the HDS of thiophene. Mo metal catalysts have significantly lower activity for thiophene HDS than Mo 2N catalysts and the HDS selectivities of non-sulfided Mo metal catalysts are significantly different from those of Mo 2N catalysts.

The facile synthesis of three-dimensional macroporous arrays of titania, zirconia and alumina was recently reported [1]. The synthesis of these materials has now been extended to the oxides of iron, tungsten, and antimony, as well as a mixed yttrium-zirconium system and organically modi- fied silicates. These materials were characterized by Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), X-ray energy dispersive spectrometry (EDS), and powder X-ray diffraction (XRD). Ordered structures of iron, tungsten, and antimony were formed from alkoxide precursors as in the originally reported synthesis, but the template was removed at a lower temperature. Samples of vinyl- and 2-cyanoethyl-modified silicates were formed from a mixture of organotrialkoxysilane and tetraalkoxysilane precursors; the polystyrene template was removed by extraction with a THF/acetone mixture. These results show the ease of extending the original syn- thesis to a wide range of systems. Also, the ability to form homogenous mixed-metal oxides will be important for tailoring the dielectric and photonic properties of these materials.

Nano-crystalline, zirconium oxide/oxyhydroxide particulates were produced using a novel, continuous, flow-through hydrothermal technology developed at the Pacific Northwest National Laboratory. Homogeneous aqueous solutions containing ZrO(NO 3)2 and urea were pumped at pressures of 6000-8000 psi through a heated stainless steel reaction tube at 340-350°C. Flow at pressure was maintained using a nozzle at the down-stream end of the reaction tube. In this process, termed Rapid Thermal Decomposition of precursors in Solution (RTDS), the formation of zirconium oxide/oxyhydroxide nano-crystals (diameters of generally less than 15-nm) occurred during the solution's brief residence time (<15 seconds) in the reaction tube, yielding aqueous slurries of agglomerated particulates. Powders were separated from these slurries, washed, then dried. RTDS powder prepared from 0.3M ZrO(NO3)2 and 0.6M urea were mixed with binder and formed into pellets using a commercial screw extruder. These extrudates were subsequently sintered at 500°C, yielding zirconia catalyst support pellets with a measured surface area of 113 m2/g. After application of 3% ruthenium metal to the sintered RTDS zirconia extrudates, the resulting catalyst was evaluated for catalytic activity using the hydrothermal hydrogenation of the sugar xylose to xylitol as a model reaction. After 3 hours at 140°C, the RTDS catalyst exhibited useful activity with 92% conversion and 66% selectivity to xylitol formation.

A family of microporous zirconium-silicate framework materials designated as UZSi (UOP zirconium silicates) has been synthesized and structurally characterized. A general hydrothermal synthesis approach yielded a variety of known and novel zirconium-silicate topologies consisting of ZrOa23(oct) and SiO20(tet) units. A novel microporous framework (UZSi-9, Na2ZrSi3O9·x H2O) has been synthesized and structurally characterized. This framework contains A- and A-propeller units, which can also be found in the framework of the compositionally similar UZSi-1 1 (Na2ZrSi3O9·x H2O). Both UZSi-9 and UZSi-II adsorb and desorb water with a Type I microporous isotherm.

A layered titanate with a lepidocrocite-type structure has been pillared with Al13 Keggin ions to prepare a porous and high-surface-area material. Pillaring was achieved by ion exchange of hexylammonium (HA-Ti) or tetrabuthylammonium (TBA-Ti) intercalated titanates with Keggin Al13 complex. The thermal stability of the Al13 intercalates depended on the amount of aluminum incorporated. The surface area and porosity can be tailored by controlling the amount of aluminum uptake and by the nature of base used to prepare the aluminium pillaring solution. In addition, the material derived from HA-Ti exhibited a sharp pore size distribution with an average diameter of 2 nm, while the pillared product obtained from TBA-Ti showed mostly a broad mesoporous distribution with an average pore diameter of 4 nm.

Precursor compounds of MgCo(11)Co(111)-HTlcs for Mg-Co oxide catalysts have been synthesized by coprecipitation in an ammoniacal solution and hydrothermal treatments under various O2/N2 atmospheres. Using elemental analysis (EA) and redox titration, it is found that about 23% of original Co2+ are oxidized to Co+3, resulting in formation of hydrotalcite-like (HTI) structure. The anion (NO3) intercalation increases with the rise in O2 partial pressure. X-ray diffraction pattern shows a conversion from brucite-like to HTl structures with increase of O2 partial pressure. It is found that thermal stability of the HTl-compounds is proportional to the Mg content. Higher specific surface areas are observed for decomposed products with low Co/Mg ratio. A trace amount of CO3O4 is also detected by FTIR for samples synthesized under high O2 partial pressures, which can be attributed to a deeper oxidation of Co2+.

Catalytic combustion is one means of meeting increasingly strict emissions requirements for ground-based gas turbine engines for power generation. In conventional homogeneous combustion, high flame temperatures and incomplete combustion lead to emissions of oxides of nitrogen (NOx) and carbon monoxide (CO), and in lean premixed systems unburned hydrocarbons (UHC). However, catalyst-assisted reaction upstream of a lean premixed homogeneous combustion zone can increase the fuel/air mixture reactivity sufficiently to provide low CO/UHC emissions. Additionally, catalytic combustion extends the lean limit of combustion, thereby minimizing NOx formation by lowering the adiabatic flame temperature. An overview of this technology is presented including discussion of the many materials science and catalyst challenges that catalytic combustion poses ranging from the need for high temperature materials to catalyst performance and endurance. Results of ongoing development efforts at Precision Combustion, Inc. (PCI) are presented including modeling studies and experimental results from both bench-scale and combustor-scale studies.

Cation-substituted hexaaluminate compounds, ABAl11O19-μ (A = La, Pr, Sm, and Nd; B = Cr, Mn, Fe, Co, Ni, and Cu) were investigated for application to high temperature catalytic combustion. Two series of modifications of the compounds was made by cation substitution; substitution of large cations in the mirror plane with lanthanides ions, and of transition metals for Al site in the spinel block. In a series of AMnAlllO19-μ, surface area and catalytic activity increased with an increase in ionic radius of lanthanides. La3+ is superior as the large cation in the mirror plane of the hexaaluminate to other tri-valent cations with small ionic radii. The catalytic activi- ties of LaBAl11O19-μ, were enhanced when Mn and Cu were employed as the B-site substituents. Although Mn and Cu were also effective substituents for enhancing catalytic activity in Ba-based hexaaluminate compounds, their activity was low as compared with the La-based catalysts. These results indicate that the redox cycle of transition metal in hexaaluminate lattice and cata- lytic activity appears to be affected sensitively with the electronic or structural effect of large cation in the mirror plane.

The catalytic activity of lantane perovskytes in the combustion of propylene was studied. The catalysts were LaFeO3, LaNiC3, LaCoO3, La2-xSrxNiO4 and La1-xSrxCoO3 where x is the amount of Sr substitution. Below 400°C the only products are CO2 and H2O, and above 400°C besides the total oxidation products, acroleine, acetaldehyde acetone and other partial oxidation products were obtained. The substitution of La by Sr improves the catalytic behaviour.

We report on experiments using nanosize MoS2 to photo-oxidize organic pollutants in water using visible light as the energy source. We have demonstrated that we can vary the redox potentials and absorbance characteristics of these small semiconductors by adjusting their size, and our studies of the photooxidation of organic molecules have revealed that the rate of oxidation increases with increasing bandgap (i.e. more positive valence band and more negative conduction band potentials). Because these photocatalysis reactions can be performed with the nanoclusters fully dispersed and stable in solution, liquid chromatography can be used to determine both the intermediate reaction products and the state of the nanoclusters during the reaction. We have demonstrated that the MoS2 nanoclusters remain unchanged during the photooxidation process by this technique. We also report on studies of MoS2 nanoclusters deposited on TiO2 powder.

Photoctalysis of a unique hollandite compound was investigated for the reductions of nitric oxide (NO) in gas phase and nitrate ion (NO3) in water with reducing agents under UV irradiation. Both NO and NO3 are hazardous chemicals to human. Recently, it was reported that titanium oxide (TiO2) photocatalyst perfomaed the oxidative decomposition of NO to NO3. However, an ideal photocatalytic removal of NO would be the reductive decomposition of NO to N2 and O2 without by-products. In this study, the surface activity of the unloaded hollandite, prepared by sol-gel method, was applied to the photocatalytic reaction. The present photocatalysis was quantitatively examined by using on-line mass spectrometry and ion chromatography, and the adsorption species on the hollandite surface was analyzed by in-situ IR spectroscopy. UV-ixradiated hollandite extu'bited high selectivity for the formation of N2 in the reductive decomposition of NO. Moreover, this catalyst also showed the reductive decomposition of NO3 to NO2 and N2 in water. In particular, the photocatalytic decomposition of NO3 would be a new pathway that has not been reported for popular photo-catalysts such as unloaded TiO2. Probably, this type compound is expected to have potentialities as a new type photocatalyst.

Self-assembled functional dye molecules in mesoporous transition metal oxides have been synthesized directly by Pc (phthalocyanine) molecules doped within hexadecyltrimethylammonium bromide (C16 TMA) micelles assembled with oxide frameworks such as Vanadia (VOX), FeOx, MoO3 and WO3 to produce Pc-doped mesostructured materials. The Pc molecules were heavily doped inside the mesoporous channels and dye's optical absorption were measured. Pc molecules in contact with mesoporous transition metal oxides interfaces are optically excited and provide reductive electrons to water molecules to decompose into hydrogen by visible light exposures.

K4Nb6O173H2O has a cation exchange ability in K+ ion existing in the interlayer and a property of photocatalyst host. As a preliminary step in the preparation of this catalyst, the cation exchange plays an important role. In this study, we prepared potassium niobate intercalated with Wn2+ and Mn(III)TMPyP7+ (Mn(III)5,10,15,20-tetra(4-pyridyl)-porphyrin) ions and observed the evidence of cation exchange in the interlayer by means of atomic force microscopy. AFM images showed that the Mn2+ ion and MnTMPy7+ cations regularly occupied the potassium sites. This indicates that the metallic oxide reduction center was formed in the interlayer by the cation exchanged species prior to redox treatment and not on the surface of the potassium niobate.

Continuous titania fibers were prepared by a polytitanoxane precursor method. Polytitanoxane was synthesized through hydrolysis and polymerization reaction between partially chelated titanium isopropoxide and water without acid catalyst. Polytitanoxane, which was precipitated from an isopropanol solution by adding adequate amount of water to titanium isopropoxide, was then dried and dissolved in tetrahydrofuran. The concentrated viscous solution of polytitanoxane was considerably stable to further self-condensation and had good spinnability. The precursor fiber which was obtained by spinning the solution was calcined to form titania fibers.

Two types of titania fibers were obtained under different calcination conditions from the same precursor fiber; Dense fiber with high tensile strength of higher than 1 GPa, and porous fiber with high surface area of more than 10 m2/g.

Photocatalytic activity of those fibers was studied using the phenol mineralization reaction in water. The phenol degradation ability of high-surface-area titania fiber was almost the same as that of commercial titania powder for photocatalyst.