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Morphology Controlled Coating Of Catalytically Active Gold Structures Within Flow-Focused Millifluidic Reactor, Chelliah V. Navin
Morphology Controlled Coating Of Catalytically Active Gold Structures Within Flow-Focused Millifluidic Reactor, Chelliah V. Navin
LSU Master's Theses
Synthesis of micro/nanomaterials within confined flow-based systems such as microfluidics has always been a promising research. However, the inability to scale up reagent volumes due to geometric constraints and pressure development within the channels at higher flow rates has limited their usage. In recent times, millifluidics has emerged as a useful technique where, apart from the synthesis, the in situ characterization of materials becomes easier. In this study, formation of morphology-controlled gold structures at different time intervals (viz. 1, 5, and 9 h) within a millifluidic chip reactor was investigated using gold chloride and dimercaptosuccinic acid (DMSA) as precursor reagents …
Synthesis, Characterization, And Testing Of Atomically-Precise Au Clusters Supported On Tio₂ For Co Oxidation, Sarthak Gaur
Synthesis, Characterization, And Testing Of Atomically-Precise Au Clusters Supported On Tio₂ For Co Oxidation, Sarthak Gaur
LSU Doctoral Dissertations
Supported Au catalysts have been studied extensively for CO oxidation. These catalysts are known to catalyze this reaction even at sub-ambient temperatures. While recent literature demonstrates catalytic activity of gold nanoparticles <2 nm, the next stage in fine tuning this catalysis process is to develop gold clusters prepared with atomic precision. Such atomically precise gold catalysts supported on TiO2 hitherto have not been investigated for CO oxidation. The main objective of this work is to synthesize atomically-precise Au38 clusters in a flask-based method using principles of wet chemistry, to characterize these clusters using various advanced spectroscopic techniques, and to test these clusters as potential catalytic materials for CO oxidation. Furthermore, we have tested TiO2-supported Au38 clusters and a commercially purchased Au/TiO2 catalyst for CO oxidation at 30 °C and 60 °C, and used DRIFTS as a probe spectroscopic technique to correlate kinetics with the mechanism occurring on the surface of both catalysts in order to device the mechanistic pathways for CO oxidation. The work reported in this dissertation is the first spectroscopic observation of the phenomena where sulfur may have beneficial effect on the catalytic activity of Au/TiO2 catalysts. Such an interesting observation where sulfur has beneficial effect on catalytic activity of Au/TiO2 catalysts has never been observed in the past. We have also synthesized and tested Fe3O4@Au core-shell nanoparticles supported on TiO2 for CO oxidation. We show for the first time that, core-shell type nanogold catalysts are better suited compared to pure gold nanoparticles for heterogeneous gas phase catalysis of CO oxidation. By conducting comprehensive experiments towards understanding CO oxidation catalysis using X-ray photoelectron spectroscopy, infrared spectroscopy, and temperature programmed reduction, we show that the enhanced catalytic activity is due to a combination of factors ranging from synergistic interaction between Au and Fe, complete removal of organic capping ligands and the presence of metallic gold (Au0) in the active catalyst.
Insights Into The Catalytic Mechanisms Of The Protein Enzymes, Pfkfb3 And Vlde, Using X-Ray Crystallography, Michael Christopher Cavalier
Insights Into The Catalytic Mechanisms Of The Protein Enzymes, Pfkfb3 And Vlde, Using X-Ray Crystallography, Michael Christopher Cavalier
LSU Doctoral Dissertations
This work describes the crystallographic studies of two enzymes and provides mechanistic insights into their respective catalytic processes. The first study investigates the molecular basis of the fructose-2,6-bisphosphatase reaction of the inducible isoform of the bifunctional enzyme, 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFKFB3). The bifunctional enzyme is solely responsible for the cellular concentration of a regulator of glucose metabolism, fructose-2,6-bisphosphate. PFKB3 was investigated using the crystal structures of the enzyme in a phospho-enzyme intermediate state (PFKFB3-P•F-6-P), in a transition state-analogous complex (PFKFB3•AlF4), and in a complex with pyrophosphate (PFKFB3•PPi). With these structures, the structures of the Michaelis complex and the transition state were extrapolated. …
Studies Of A Dirhodium Tetraphosphine Catalyst For Hydroformylation And Aldehyde-Water Shift Catalysis, Aaron Rider Barnum
Studies Of A Dirhodium Tetraphosphine Catalyst For Hydroformylation And Aldehyde-Water Shift Catalysis, Aaron Rider Barnum
LSU Doctoral Dissertations
Research into the dirhodium tetraphosphine catalyst precursor [rac-Rh2(nbd)2(et,ph-P4)](BF4)2 shows it is capable of forming a highly active and regioselective hydroformylation catalyst in situ when using an acetone or acetone/water solvent. Hydroformylation experiments (using 1-hexene), FT-IR studies, and acid-base studies were performed to better understand the various complexes of the dirhodium catalyst cycle. These studies lead to the newly proposed catalyst mechanism when performed in an acetone/water solution, using the monocationic [rac-Rh2(H)(µ-CO)2(CO) (et,ph-P4)]+ as the proposed active catalyst complex for hydroformylation. For the conversion of 1-hexene to heptanal, it is capable of performing an initial rate of 30 turnovers per min, …