A TiO2 and apatite coated fibrous ceramics photocatalyst filter has been developed. This filter has a function to absorb and decompose bacteria and various other materials. TiO2 was coated on the surface of the fibrous ceramics by a sol-gel method, then the filter was soaked in a pseudo-body solution containing excessive phosphate ion for 1 day at 37°C. In this research, it is recognized that this filter has absorbed and decomposed colon bacillus, methylene blue and acetaldehyde effectively.

Simulation in catalyst and sorbent research spans a wide range of techniques and applications complementing and enhancing experimental approaches. This includes (i) model construction and visualization, (ii) materials characterization through simulation of experiments such as x-ray diffraction, (iii) atomistic simulations of dynamic processes such as docking and diffusion using empirical potentials, and (iv) quantum mechanical methods predicting chemical bonding and reactivity. Thorough technical validation, algorithmic and accessibility enhancements, and a strong industrial focus continue to drive key developments. The focus on practical catalyst and sorbent problems is illustrated here by (i) a simulation of the energetic diffusion barrier experienced by a toluene molecule in the microporous material boggsite and (ii) the structure, energetics and bond strengths of acidic protons in faujasite using a localized-orbital density functional approach.

The structure of a-alumina (α-A12O3) is well known to be hexagonal close packed. In contrast, the structures of the so-called transition aluminas (-γ-alumina, η-alumina,…) are the subject of controversy. We report theoretical calculations which show that -γ-alumina is actually a sequence of compounds with the general formula H3mAl2−mO3. (0 ≤ m ≤ ⅓). m = ⅛ is a unique form, HAl5O8, with a perfect spinel structure. For m > 8, there are interstitial H atoms whereas for m < ⅛. there are vacancies. This picture is supported m > ⅛ by calculations of material density and proton vibrational frequencies. The results are in excellent agreement with measured values. The present new systematic approach accounts for a wide range of seemingly contradictory data and leads to the conclusion that γ-alumina behaves as a “reactive sponge” by storing and releasing water in a novel reactive way.

This paper describes experimental studies of the growth morphology of Au/SiO2 nanocomposites consisting of nanometer-sized metal particles imbedded in a metal oxide, formed by the sequential deposition of metal and metal-oxide layers by RF sputtering. The materials work is aimed at the development of novel resistive-type exhaust gas constituent sensors. Using digitized images from a transmission electron microscope and an automated particle counting routine, we have measured the particle size distributions for films with varying layer thicknesses and deposition conditions. We find strong dependence of the particle size and overall composite structure on the Au and SiO2 layer thicknesses, in agreement with previous work.[1] We also identified four microstructure classes which can occur.

Silica-copper molybdates prepared by sol-gel and impregnation methods were tested as catalysts in the oxidation of propene at 400°C, both in a pulse and in a flow reactor. Their catalytic activity is connected to their structural features, as revealed by electron paramagnetic resonance (EPR) and X-ray diffraction (XRD) characterization.

We studied the structure of coarse and nano-scale powders of CeO2 using pulsed neutron scattering. The diffraction data were analyzed using Rietveld refinement, and were also Fourier-transformed to obtain the pair-distribution function (PDF). The Frenkel type oxygen defects consisting of vacancies in the oxygen sublattice and oxygen ions in the octahedral interstitial sites of the fluorite structure were observed in cerium oxide for the first time. The interstitial oxygen ions were found to recombine with vacancies when the sample underwent thermal treatment at 1073 K. We suggest that these defects are directly involved in the oxygen storage mechanism of ceria used in automotive catalytic converters.

Very high angle (∼ 100mrad) annular dark-field (HAADF) images in a dedicated scanning transmission electron microscope (STEM) can be used to quantitatively measure the number of atoms in a cluster on a support material. We have developed a computer program which will automatically find the location of the particles and then integrate the intensity to find the number of atoms per cluster. We have examined ultra-small Pt clusters on a C substrate by this novel mass-spectroscopic technique. We discovered that the Pt clusters maintain their three-dimensional shape, and are probably spherical in shape.

Chemical etching method has been frequently used in defect investigation for crystalline materials in solid-state chemistry / physics and fundamental materials research. Recently, we apply this technique into catalytic materials fabrication. In this work, crystalline catalysts of orthorhombic MoO 3 have been prepared via a vapor phase deposition method and their crystallographic structure has been affirmed by XRD and FTIR investigations. A chemical etching method has been developed for restructuring these thermally processed catalysts. Using a 0.1 M NaOH etchant, {001} and {100} plane areas of the catalysts can be significantly increased while surface steps, ledges, and terraces are created upon this etching. Moreover, alternate crystal plane combinations of either {100} and {010}, or the {001} and {010} are observed on crystal edges and rectangular etch pits in the basal planes {010}. Technological merits and the processing parameters of this new method have also been identified. Following the findings of the current work, it is believed that the chemically carved surface structures may be crucial for certain MoO 3-involving catalytic reactions.

A catalytic study has been performed in WS2 irradiated with electrons at 1000 kGy. The purpose is to compare irradiated WS2 with WS2 crystalline in terms of DBT conversion, selectivity and surface area analysis. Also, Scanning Electron Microscope (SEM), X-raydiffraction were performed to show microstructural changes induced by irradiation. We found that DBT conversion increased by 55 % if compared with WS2 crystalline. The surface area decreased and the initial rate constants increased by a factor of four times. The selectivity for DCH after irradiation has decreased, while the selectivity for DIF and PCH has increased substantially. The DYH/DHS ratio has decreased in 42 %. The SEM micrographs showed that irradiation, at this level, produced certain damage in the crystallinity. The X-ray analysis showed different distribution in the intensity of the principal peaks after irradiation was achieved. This behavior could be correlated to the surface area decrement and the enhancing of the catalytic activity in WS2.

NOx reduction efficiency under simulated lean burn conditions is examined for a nonthermal plasma in combination with borosilicate glass, alumina, Cu-ZSM-5 and Na-ZSM-5. The non-thermal plasma alone or with a packed bed of borosilicate glass beads converts NO to NO2 and partially oxidizes hydrocarbons. Alumina and Na-ZSM-5 reduce a maximum of 40% and 50% of NOx respectively; however, the energy cost is high for Na-ZSM-5. Cu-ZSM-5 converts less than 20% with a very high energy consumption.

A series of aluminas modified with 3-15 wt% S102 (AMASAs) and 2-9 wt% TiO2 (AMATAs) were prepared by a deposition and/or coprecipitation methods. The pore size distribution was varied by means of a pH-swing procedure where alternating pH acid-alkaline values generated 100-200 Å pores, particularly in the AMASAs case. However, the incorporation of TiO 2 in the AMATAs even after the pH-swing procedure results in a pore size and volume decrease- The degree of TiO 2 reduction is much higher in AMATAs obtained by deposition than those obtained by coprecipitation. The use of AMASAs as catalyst supports of 2.4 wt% Ni and 8.8 wt% Mo in the hydroconversion of a vacuum distillation residue brings about 1.5 times higher conversion to lighter fractions in comparison with a commercial alumina-based catalyst. AMATA-based catalyst shows similar activity and selectivity to the commercial catalyst. However, the presence of TiO2 (6 wt%) considerably increases the N and V removal, and decreases the formation of sediments.

Ni/(P)Ti-HMS catalysts were prepared and characterized by several physicochernical techniques. The addition of phosphorous to the original mesoporous materials modified the acid-base surface properties. The activity in cyclohexane dehydrogenation is higher than on conventional catalysts.

Progress in several important electrochemical technologies, including batteries, fuel cells, sensors, and electrosynthesis, is currently materials-limited. A common feature of all electrode reactions is the imbalance (i.e., loss or generation) of ions at the electrode surface. We describe in this paper a method by which excess ions in the electrode diffusion layer can be imaged, and used to identify the best electrode materials from a combinatorial array of compositions.

Although in principle this method can be applied to many electrochemical problems, we have focused on finding better electrocatalysts for direct methanol fuel cells (DMFCs). The DMFC performs two half-cell reactions: oxidation of methanol, and reduction of oxygen. Two of the most important problems in DMFCs are the poor performance of the electrocatalysts, and the crossover of methanol from the anode to the cathode side of the cell. An ideal situation would be the simultaneous development of two new catalysts: an anode that oxidizes methanol at low overpotential, and a “methanol-tolerant” cathode that reduces oxygen without oxidizing methanol.

Based on previously developed rules for predicting the activity of ternary alloy catalysts (Ley, et al., J. Electrochem. Soc. 1997, 144, 1543), we began searching quaternary combinations of noble metals for the anode, and ruthenium selenide-type materials for the cathode reaction. The anode and cathode reactions generate and consume protons, respectively, creating a substantial pH gradient at the electrode surface. Changes in local pH are imaged by means of an appropriate fluorescent indicator: Ni-PTP for the anode and Eosin Y for the cathode. DMFC testing confirms the utility of the screening method, in that a Pt/Ru/Os/Ir quaternary catalyst was substantially superior to the best binary and ternary catalysts prepared under similar conditions.

Conventional MOCVD method has been explored to prepare Pd supported catalysts. Pd and PdO phases were found on the surface of the support. Small Pd particles about 1 to 3 nm and dispersions up to 19%were obtained by MOCVD. TPR results indicated that several surface Pd compounds are reduced. At temperatures below 25°C, PdO, the main compound, is completely converted to metallic Pd which forms hydrides. At higher temperatures, between 500 to 800°C, the reduction peaks could be attributed to Pd-support interactions and a strong support dehydroxylation. All catalysts were inactive in benzene hydrogenation and a significant conversion was only detected a temperatures above 100 °C. This was explained by the reduced accessibility of Pd sites imposed by the carbon contamination and by the Pd-Al2O3 interactions.

The investigation of surface Pt/alumina, Pt/ carbon (Sibunit) and Pt/SiO2 species prepared by anchoring of Pt carbonyl clusters of various nuclearity as precursors for high dispersive and thermostable platinum supported catalysts for hydrocarbons conversion, using RDF (radial distribution functions) and chemisorption methods, has shown strong metal-support interaction with formation of Pt/alumina phase with highly dispersed (practically monoatomic) and homogeneously distributed Pt atoms onto alumina surface. The catalytic properties were studied in methane oxidation and cyclohexane dehydrogenation reactions.

Heteropoly acids (HPA) are well known solid acids as well as oxidation catalysts. They find application in both homogeneous and heterogeneous reactions. As catalysts, problems associated with surface area and instability are diminished by supporting the HPA. It has been reported that supporting these materials on oxide substrates or porous carbon materials has resulted in some degree of instability. It has also been shown that encapsulating HPA in sol-gel silica matrices has produced an increase in catalytic performance without compromising the catalytic activity of the HPA. In this work, we analyzed the activity of a silica sol-gel supported HPA catalyst. The reaction which was chosen to illustrate such issues was the oxidation/dehydration of 1-butanol. In addition, the specific role of the support in the catalytic process is described. In this work, we characterized the silica-sol gel supported HPA catalyst to try to understand the effect of preparation in the overall catalytic selectivity and activity.

Mechanochemical activation of solid inorganic precursors and sol-gel routes followed by hydrothermal treatment in the presence of surfactants were used to synthesize highly dispersed NZP-type complex zirconium phosphates. Genesis of samples real structure and its impact on the surface properties and catalytic performance in the reactions of hexane isomerization and dehydroaromatization have been studied.

Highly ordered self-assembly organized silica meso-structured architectures have attracted increasing attention because these materials provide a rich source for scientific research and technological applications. This approach to meso-structured materials has been extended to non-silica oxides, especially transition-metal-oxides which might promise applications involving electron transfer or magnetic interactions. We report the syntheses of transition-metal-oxides meso-structured thin films (MSTF), such as TiO2, V2O5, Fe2O3 and Nb2O5, using a surfactant templating processing with spin coating method. X-ray diffraction patterns of the films showed that the films generally oriented in a lamellar structure. The phase transferring in V205 MSTF was also investigated.