Browsing by Subject "Reactivity (Chemistry)"
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Item Growth, structure, and chemistry of 1B metal nanoclusters supported on TiO₂(110)(2006) Pillay, Devina; Hwang, Gyeong S.Cu, Ag, and Au nanoclusters dispersed on TiO2(110) surfaces are utilized in a wide variety of applications ranging from microelectronics to heterogeneous catalysis. The unique chemical reactivity of these clusters is largely dependent on their size, shape, spatial distribution, and interfacial interaction with the oxide support. This implies that atomic level control of these properties can offer great opportunities in the development of novel devices based on supported metal nanoclusters. It is therefore necessary to understand how formation and restructuring of these clusters alter their geometric and electronic characteristics. This thesis involves the development of a theoretical foundation for studying the growth, structure, and chemistry of Cu, Ag, and Au on TiO2(110) surfaces. Using density functional theory calculations, we have identified factors that control the chemical reactivity of these supported metal nanoclusters. First we investigated the electronic and geometric structures of the stoichiometric and reduced rutile TiO2(110) surfaces. Then we examined the surface chemistry of TiO2 towards gaseous CO and O2, as well as the structure and growth of 1B metal nanoclusters on TiO2(110). We also examined how the electronic and geometric properties of mixed metal nanoclusters, CuAun(n≤ 3), differ versus their single metal counterparts, Cum and Aum (m ≤ 4). Finally, we considered CO oxidation reactions on TiO2(110)-supported small Au clusters. While current experimental techniques are limited to providing complementary atomic-level real space information, first principles-based atomic level simulations greatly contribute to elucidating the fundamental behavior and properties of Cu, Ag, and Au nanoclusters on TiO2(110). First principles modeling has paved the way for new catalyst development by investigating how the geometric, electronic, and chemical properties of TiO2-supported 1B metal nanoclusters vary with surface defects, adsorbates, and metal dopants before valuable time and manpower is invested in experimental synthesis and characterization.Item Ligand exchange reactions of some cobalt (III) complexes.(Texas Tech University, 1974-12) Vickrey, Thomas MadisonNot availableItem Nonlinear model predictive control of a reactive distillation column(Texas Tech University, 2004-05) Kawathekar, RohitModel Predictive Control (MPC) is an optimal-control based method to select control inputs by minimizing the predicted error from setpoint for the future. Industrially popular MPC algorithms use linear convolution models for predicting controlled variable response in future. For highly nonlinear processes, the linear MPC might not provide satisfactory performance. Nonlinear Model Predictive Control (NLMPC) employs nonlinear models of the process in the control algorithm for controlled variable response in future. Reactive distillation modeling and control poses a challenging problem because the simultaneous separation and reaction leads to complex interactions between vapor-liquid equilibrium, vapor-liquid mass transfer and chemical kinetics. Hence, reactive distillation processes are highly nonlinear in nature. Application of reactive distillation for the production of ethyl acetate is considered for this dissertation. A detailed steady-state and dynamic mathematical model of reactive distillation is developed. This model is used for control studies of the reactive distillation column. Nonlinear Model Predictive Control algorithm is developed for centralized multivariable control of reactive distillation column. The performance of NLMPC is compared with decentralized PI control structure.Item Reactions of electrophiles with transition metal carbonyl anions(Texas Tech University, 2002-08) Park, Eun JungThe chemistry of compounds containing metal-metal bonds has attracted many inorganic chemists' interest. This research is based on reactions between metal carbonyl anions (Na2Fe(CO)4, Na2Cr(CO)5, and KFe(ç^5-C5H5)(CO)2) and transition metal halides in an attempt to make polynuclear metal cluster compounds via salt elimination reactions. Except metal-metal compound synthesis in the reaction between metal carbonyl anion and metal halides, oxidation and reduction is also a reaction of importance in chemistry. As it devised to make a metal-metal bonded compound, it shows few trace of the metal-metal compound. After initial metal-metal bond formation, products mainly proceed to characteristic of red-ox reactions by electron transfer. Between the acceptor (metal halide cation) and donor (metal carbonyl anion) metal of intermediate mixed metals, rapid electron transfer occurs by the condition depending on the reactant and environment.Item The reactivity of nucleophiles toward and the site of nucleophilic attack on thiolsulfinates(Texas Tech University, 1979-08) Liu, Chao-Chuin AnthonyNot available