archives@tulane.edu / Porous materials possess voids of varying size of and uniformity and are of great significance in many areas such as adsorption, separations, sensors, gas storage, and catalysts. Organic-inorganic hybrid materials, as one type of porous materials, combines hard and soft matter synergistically, and have attracted considerable attention. As the scientific community pushes the boundaries of hybrid materials, more complicated architecture have been developed to achieve the desired functionality. Multifunctional materials with elaborate designs of architecture, especially actives sites for certain applications are needed. Dendrimer-encapsulated nanoparticles (DENs) have attracted interest since they were first introduced. This synthetic approach leads to well-defined sizes, compositions and structures of nanoparticles controlled by the dendrimer template. Melamine-based dendrimers were successfully grafted to OMS supports through an aminosilane handle. More recently the supported dendrimers were used as templates to form Palladium nanoparticles, resulting in encapsulated palladium/dendron-OMS materials. Multiple characterizations were used to validate both the structural integrity of the dendrimers and the nature of the metal nanoparticles formed. Probe reactions have shown the accessibility of both metal sites and amine sites from dendron. In this work, we used the organic architecture tethered to the support to not only make the metal nanoparticles while attached to the solid surface, but also utilize the metal and ligand functionalities of the resulting material. Multiple active sites indicate the dendron encapsulated palladium nanoparticles can be further used as multifunctional catalysts. Support topology and dendron structure of the encapsulated palladium/dendron-OMS play important roles in the catalysis and capture performance. We studied how the pore structures influence the loading of dendron, further influence carbon dioxide capture properties. We also studied how the different types of amines in the dendron unit participate in binding multiple types of small molecules by designing similar dendrons with different peripheral nitrogen. Carbon dioxide uptake is controlled by the peripheral amines with little interior contribution. However, interior nitrogen atoms participate in metal binding and catalysis, though involved with different kinds of nitrogen types. Sustainably meeting the growing energy needs of the planet is one of the 21st century’s grand challenges. Many pathways to meeting our energy needs while reducing fossil-fuel consumption have been posited, all with challenges. One possible route is to convert biomass into fuels. We utilized encapsulated palladium/dendron-OMS as multifunctional catalyst, they are used for multistep reaction. We designed a three-step process that includes hydrogenation of phenol, aldol condensation, and hydrogenation of aldol reaction product to produce fuels from oxygenates using palladium containing dendrons supported on OMS. The operating conditions of low temperature and low pressure hydrogen in aqueous media is consistent with green chemistry goals. / 1 / Yueyun Lou

Bibliography: leaves [89-92]

<p>The objectives of this project was to ameroliate two waste materials, namely Acid Mine Drainage and Fly Ash and recover the solid residues for conversion into an adsorbent to treat brine. The solid residues were then converted into zeolite P through low temperature hydrothermal treatment. The adsorption capacity of the solid residues, zeolite P derived from the solid residues was compared to the commercial zeolite Y and fresh Arnot fly ash. The quality of the resulting water was assessed using different analytical methods before the reaction with adsorbents and after the reaction and a comparison was done based on the removal efficiency of elements Zeolite P from solid residues was successfully synthesized as confirmed by XRD, BET and FTIR. Brine treatment with fly ash, solid residues, zeolite P and commercial zeolite Y adsorbents was done concentration on the following major elements Na, K, Mg, Ca and Si. Zeolite P had higher or similar removal efficiency that the commercial zeolite Y for the following elements K, Ca and Mg. Fly ash is the only adsorbent that managed to reduce the concentration of Na in brine and also had a good removal efficiency of Mg. Si leached out of all the adsorbents which could be ascribed to Si being the major component of these adsorbents which could indicate some dissolution of these adsorbents under the conditions tested. Overall, zeolite P did not completely remove the major elements, especially for Na, but did result in a cleaner waste stream which would improve brine processing.</p>

Biofuels like ethanol are gaining serious momentum because of concerns over climate change and the rising cost of fossil fuels. Saskatchewan is the first province in Canada to pass a law requiring ethanol blended into its gasoline. A blend rate of 7.5% is mandated as of January 2007. This legislation is not yet fully enforced as ethanol production cannot currently meet demand, but local production is increasing. The traditional method of production is via grain fermentation; however the food versus fuel debate indicates this is unethical when food shortages and prices are already on the rise. Gasification is a robust technology for processing raw, non-food grade biomass into syngas (H2 and CO) which can then be further converted to ethanol via gas-to-liquid conversion technology. Condensable materials called tars form during gasification and must be further converted to gaseous products to avoid problems downstream. This can be achieved via optimization of process conditions and catalysis. The research for this thesis was carried out in two phases. Phase 1 examined the effects of process conditions on the noncatalytic temperature-programmed gasification of wood (Jack Pine) biomass. Temperature was varied from 700 to 825oC, water flow rate was varied from 2 to 5 cm3/h, and N2 flow rate from 16 to 32 cm3/min. When varying biomass gasification conditions, overall % carbon conversion to gaseous products reached a maximum of 70% at 825oC, 5.0 cm3/h H2O, and 32 cm3/min N2. 670 cm3 product gas per g biomass was produced, with 35.8 mol% H2 and H2:CO of 1.56. In Phase 2, catalytic gasification of wood biomass was carried out using a double bed micro reactor in a two-stage process. Temperature programmed steam gasification of biomass was performed in the first bed at 200-850oC. Following in the second bed was isothermal catalytic decomposition gasification of volatile compounds (including tars). Dolomites from Canada, Australia and Japan were examined for their effects on tar abatement and the overall gaseous product. The gasification of pine sawdust resulted in 74% of carbon emitted as volatile matter during tar gasification (200-500oC biomass bed temperature). High temperature, high H2O flow rate and low carrier gas flow rate are recommended for improving biomass conversion to gaseous products. Dolomites improved tar decomposition by an average 21% at 750oC isothermal catalyst bed temperature. For Canadian dolomites, iron content was found to promote tar conversion and the water-gas shift reaction, but the effectiveness reached a plateau at 1.0 wt% Fe present in dolomite. The best dolomite was Canada # 1, from an area west of Flin Flon, Manitoba. This dolomite yielded 66% tar conversion (25% above noncatalytic results) at 750oC using 1.6 cm3 catalyst/g biomass. Carbon conversion increased to 97% using 3.2 cm3 catalyst/g biomass at the same temperature. The dolomite seemed stable after 15 hours of cyclic use at 800oC.

The development of reactive organometallics has become a vital part synthetic chemistry. Organosilanes potentially represent a cheap, robust, and environmentally benign precursor to reactive organometallics, but the nature of the very stable C−Si bond has generally prevented their use as precursors to more reactive organometallics. We present investigations into copper fluoride complexes which activate organosilanes in anhydrous media under mild conditions, effecting transmetalation to produce stable and in some cases isolable organocopper species containing sensitive functional groups including carbonyl groups, aryl bromides, benzylic chlorides, and alkyl ketones. This discovery allows us to better understand the fundamental reactivity of presumed intermediates in copper-catalyzed reactions and to develop new catalytic bond-forming processes including allylations of aldehydes, 1,4-addition of vinyl epoxides, and intramolecular ring closures.

Biofuels like ethanol are gaining serious momentum because of concerns over climate change and the rising cost of fossil fuels. Saskatchewan is the first province in Canada to pass a law requiring ethanol blended into its gasoline. A blend rate of 7.5% is mandated as of January 2007. This legislation is not yet fully enforced as ethanol production cannot currently meet demand, but local production is increasing. The traditional method of production is via grain fermentation; however the food versus fuel debate indicates this is unethical when food shortages and prices are already on the rise. Gasification is a robust technology for processing raw, non-food grade biomass into syngas (H2 and CO) which can then be further converted to ethanol via gas-to-liquid conversion technology. Condensable materials called tars form during gasification and must be further converted to gaseous products to avoid problems downstream. This can be achieved via optimization of process conditions and catalysis. The research for this thesis was carried out in two phases. Phase 1 examined the effects of process conditions on the noncatalytic temperature-programmed gasification of wood (Jack Pine) biomass. Temperature was varied from 700 to 825oC, water flow rate was varied from 2 to 5 cm3/h, and N2 flow rate from 16 to 32 cm3/min. When varying biomass gasification conditions, overall % carbon conversion to gaseous products reached a maximum of 70% at 825oC, 5.0 cm3/h H2O, and 32 cm3/min N2. 670 cm3 product gas per g biomass was produced, with 35.8 mol% H2 and H2:CO of 1.56. In Phase 2, catalytic gasification of wood biomass was carried out using a double bed micro reactor in a two-stage process. Temperature programmed steam gasification of biomass was performed in the first bed at 200-850oC. Following in the second bed was isothermal catalytic decomposition gasification of volatile compounds (including tars). Dolomites from Canada, Australia and Japan were examined for their effects on tar abatement and the overall gaseous product. The gasification of pine sawdust resulted in 74% of carbon emitted as volatile matter during tar gasification (200-500oC biomass bed temperature). High temperature, high H2O flow rate and low carrier gas flow rate are recommended for improving biomass conversion to gaseous products. Dolomites improved tar decomposition by an average 21% at 750oC isothermal catalyst bed temperature. For Canadian dolomites, iron content was found to promote tar conversion and the water-gas shift reaction, but the effectiveness reached a plateau at 1.0 wt% Fe present in dolomite. The best dolomite was Canada # 1, from an area west of Flin Flon, Manitoba. This dolomite yielded 66% tar conversion (25% above noncatalytic results) at 750oC using 1.6 cm3 catalyst/g biomass. Carbon conversion increased to 97% using 3.2 cm3 catalyst/g biomass at the same temperature. The dolomite seemed stable after 15 hours of cyclic use at 800oC.

Soluble polymers that have phase selective solubility are useful in synthesis because they simplify purification and separation. Such selectively soluble polymers simplify catalyst, reagent, and product recovery and enable the use of Green chemistry principles in homogeneous catalysis. However, while homopolymers have been reported that have excellent thermal and phase-dependent solubility, less is known about copolymers. Also, less is known about the phase selective solubility of polar aprotic N,N-dialkyl polyacrylamides. This work describes a library synthesis of dye-labeled poly(N-n-octadecylacrylamide-co-N-n-butylacrylamide) copolymers and study of the effects of polymer composition in phase selective solubility of these copolymers. To study the relative importance of n-octadecyl versus n-butyl groups, copolymers with different ratios of n-octadecylacrylamide and n-butylacrylamide but with similar degrees of polymerization and polydispersity were prepared by a split-pool synthesis using a highly soluble poly(N-acryloxy-2-dodecylsuccinimide) as the precursor. Polymer sequestrants were used to remove excess amines and the byproduct N-hydroxyl-2- dodecylsuccinimide without fractionation of the polyacrylamides. Results demonstrated that poly(N-n-octadecylacrylamide-co-N-n-butylacrylamide) copolymers’ phase selective solubility is equally dependant of the polar n-butyl and nonpolar n-octadecyl groups on the copolymers. Dye-labeled poly(N,N-dialkylacrylamide)s prepared by the polymerization of N,N-dialkylacrylamides monomers with methyl, ethyl, propyl, butyl, hexyl, and dodecyl N-alkyl groups in a variety of thermomorphic or latent biphasic polar/nonpolar solvent mixtures were also prepared. Studies showed that poly(N,N-dialkylacrylamide)s have phase selective solubility that is highly dependent of the size of the N-alkyl group. Soluble polymers are known to be useful supports for catalysts. This thesis also describes approaches to immobilization of a variety of catalysts on polyisobutylene (PIB). The most effective of these catalysts were analogs of pyridyl N-oxides that have been used as organocatalysts for the catalytic allylation of a variety of aromatic aldehydes. PIB-supported N-oxide promoted the allylation of aldehydes in up to 99% isolated yield. The products were isolated in the polar phase of a thermomorphic system and the catalyst was recycled through five cycles.

The synthesis, characterization and structure-function relationships of mono- and bimetallic dendrimerencapsulated nanoparticles (DENs) are described. Control over the factors influencing the structure of bimetallic DENs has been attained for PdAu and AuAg systems. The bimetallic DENs are characterized by UV-vis, HRTEM, and single-particle energy dispersive x-ray spectroscopy (EDS). In addition, we use catalysis and selective extraction to chemically probe the surface structure. The fabrication of TiO2-supported Pd, Au and PdAu nanocomposites from DEN precursors is shown to be a viable route for the synthesis of catalytically active, reasonably monodisperse heterogeneous catalysts. Using the dendrimer-templating synthesis, tight control over the size of 1- 2 nm Pd DEN catalysts has led to the observation of a particle-size effect for the hydrogenation of allyl alcohol. We have proposed that for particles with diameters between 1.5“ 1.9 nm the reaction occurs preferentially on the exposed face atoms.

Thesis(M.S.)--Case Western Reserve University, 2009 / Title from PDF (viewed on 2009-11-23) Department of EMC - Aerospace Engineering Includes abstract Includes bibliographical references and appendices Available online via the OhioLINK ETD Center

Thesis (M. Phil.)--University of Hong Kong, 2001. / Includes bibliographical references.