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Dissertation (Ph. D.)--University of Akron, Dept. of Chemical Engineering, 2007. / "December, 2007." Title from electronic dissertation title page (viewed 03/12/2008) Advisor, Steven S. C. Chuang; Committee members, Lu-Kwang Ju, Edward Evans, W. B. Arbuckle, Stephen Z. D. Cheng; Department Chair, Lu-Kwang Ju; Dean of the College, George K. Haritos; Dean of the Graduate School, George R. Newkome. Includes bibliographical references.

Thesis (M.S.)--Ohio University, November, 2000. / Title from PDF t.p.

Includes bibliographical references.

The partial oxidation of propene (CH₂=CHCH3) to acrolein (CH₂=CHCHO) has been studied over Cu₂0(100) and (111) single crystal surfaces. Propene adsorption under ultrahigh vacuum conditions yields no significant oxidation products, but the propene desorption temperatures are sensitive to the structural differences in the surfaces. Propene adsorption at atmospheric pressure followed by thermal desorption in ultrahigh vacuum demonstrates that propene may be activated at higher pressures. Over the nonpolar Cu₂0(111) surface, lattice oxygen insertion occurs at 300 K and 1 atm. with the formation of the σ-bonded allyl intermediate. Once formed, this specie is stable in ultrahigh vacuum and produces acrolein during TDS via a reaction-limited process. A comparison of these data with studies of allyl alcohol decomposition over Cu₂O surfaces indicate that the σ-bonded intermediate is surface allyloxy (CH₂=CH-CH₂0-) which dehydrogenates to acrolein via hydride elimination on the carbon α to the oxygen. Thus, oxygen insertion precedes the final hydrogen abstraction in the partial oxidation pathway. Propene is also observed during allyl alcohol decomposition indicating that the transformation of the π-allyl to the σ-allyl (allyloxy) during propene oxidation is reversible. The structure sensitivity of the propene oxidation reaction is demonstrated by the lack of acrolein production from the Cu-terminated, Cu₂0(100) surface following 1 atm. propene exposures. The origin of the structure sensitivity is related to the absence of coordinately-unsaturated lattice oxygen anions on the (100) surface. / Ph. D.

Thesis (Ph. D.)--University of Washington, 2001. / Vita. Includes bibliographical references (leaves 173-183).

The aim of the present work was to determine operational parameters of methanol conversion to formaldehyde using nanolayer copper catalysts.

Thesis (Ph. D.)--University of Massachusetts Amherst, 2009. / Includes bibliographical references (p. 153-161). Print copy also available.

Orientadores: Gustavo Paim Valença, Ricardo Vieira / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-21T00:05:40Z (GMT). No. of bitstreams: 1 Oliveira_NataliaMairaBraga_M.pdf: 2188373 bytes, checksum: 7d467de1163b278869ab8a52ee898f4f (MD5) Previous issue date: 2012 / Resumo: A reação de deslocamento de gás d'água, também conhecida como water gas shift reaction (WGSR), é muito utilizada na produção de hidrogênio, por meio da conversão do monóxido de carbono em CO2 e da água em H2. No presente trabalho, catalisadores de cobre e níquel suportados em alumina ou nanofibras de carbono (NFC) foram utilizados para estudo da WGSR. Os catalisadores foram preparados através da impregnação de nitrato do metal nos suportes, sendo 5% em massa o valor nominal de teor metálico empregado. Os materiais foram secados, calcinados e caracterizados através de Microscopia Eletrônica de Varredura (MEV), Difração de Raios X (DRX), Adsorção Física de Nitrogênio e Espectrometria de Emissão Óptica por Plasma Indutivamente Acoplado (ICP OES). Depois de calcinados, os catalisadores foram carregados no reator, reduzidos e então testados na WGSR a baixas temperaturas (125 - 300 °C). Os gases que saíram do reator foram analisados online por Cromatografia Gasosa (CG). Houve produção de CO2, H2 e, provavelmente, de coque em pequenas quantidades. A pressão parcial de CO variou entre 4,64 e 11,35 kPa, e a pressão parcial de água variou entre 20,01 e 47,44 kPa. As condições de reação mais favoráveis para 5% Cu/Al2O3 foram pH2O = 38,64 kPa e pCO = 11,35 kPa, em todas as temperaturas reacionais empregadas. Já para 5% Cu/NFC as condições mais favoráveis foram pH2O = 20,01 kPa e pCO = 6,56 kPa, correspondendo a uma razão molar H2O:CO de 3,05. Outra variável testada foi corrente elétrica aplicada em 5% Ni/NFC, com o objetivo de verificar sua influência na atividade do catalisador. Entretanto, diferentes intensidades de corrente elétrica (entre -1,4 e 1,4 A) não alteraram a taxa ou a seletividade da WGSR. Dentre os catalisadores testados, 5% Cu/Al2O3 foi o mais ativo em todas as condições reacionais, devido à alta dispersão das partículas metálicas no suporte. Níquel suportado em Al2O3 se mostrou pouco ativo, porque as partículas metálicas estavam muito dispersas e, provavelmente, não foram reduzidas pelo H2. Ni/NFC e Cu/NFC apresentaram baixas conversões de CO, devido à hidrofobicidade do suporte. A energia de ativação aparente calculada para a WGSR foi de 86,05 kJ/mol para 5% Cu/Al2O3 e de 69,80 kJ/mol para 5% Cu/NFC. O mecanismo de reação proposto para Cu/NFC foi redox de cooperação e as ordens aparentes de reação obtidas foram 0,64 em relação ao CO e aproximadamente zero em relação à água / Abstract: The water gas shift reaction (WGSR) is widely used in the production of hydrogen, by the conversion of carbon monoxide into CO2 and of water into H2. In the present work, copper and nickel catalysts supported on alumina or carbon nanofibers (CNF) were used to study the WGSR. The catalysts were prepared by impregnating metal nitrate in the supports, with a nominal mass metallic content of 5%. The solids were dried, calcined and characterized by Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), Nitrogen Adsorption and Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES). After calcination, the catalysts were loaded into the reactor, reduced and then tested in the WGSR at low temperatures (125 - 300 °C). The gases from reactor were analyzed online by Gas Chromatography (GC). The products were CO2, H2 and, probably, small amounts of coke. The CO partial pressure varied between 4.64 and 11.35kPa, and the water partial pressure varied between 20.01 and 47.44 kPa. The most favorable reaction conditions for 5% Cu/Al2O3 were pH2O = 38.64 kPa and pCO = 11.35 kPa, for all reaction temperatures used in this work. For 5% Cu/CNF the most favorable conditions were pH2O = 20.01kPa and pCO = 6.56 kPa, corresponding to a molar ratio H2O:CO of 3.05. In a different experiment, electrical current was used in the 5% Ni/CNF bed, in order to verify its influence on the catalyst activity. The electrical current was varied between -1.4 and 1.4 A and no change was observed in the rate or selectivity of the WGSR. Among the catalysts tested, 5%Cu/Al2O3 was the most active under all conditions used in this work, due to the high dispersion of the metal particles on the support. Nickel supported on Al2O3, under reaction conditions studied, was less active, because the metal particles were widely dispersed and, probably, were not reduced by H2. Ni/CNF and Cu/CNF had low CO conversions, due to the support hydrophobicity. The apparent activation energy calculated for the WGSR was 86.05kJ/mol for 5% Cu/Al2O3 and 69.80 kJ/mol for 5% Cu/CNF. For Cu/CNF a co-operative redox reaction mechanism was proposed, and apparent reaction orders were 0.64 in relation to CO and approximately zero in relation to water / Mestrado / Desenvolvimento de Processos Químicos / Mestra em Engenharia Química

The study of normal N-heterocyclic carbenes (NHCs), which probably represent one of the most important families of ligands in organometallic chemistry and homogeneous catalysis, has indubitably led to the usage of other related ligands beyond di-amino carbenes. So far, such species are only marginally used as ligands due to their relative novelty and stability. The following chapters describe the exciting journey into the development of new synthetic accesses of various abnormal, remote N-heterocyclic, mesoionic and carbocyclic carbene transition metal complexes. The uses of a number of these ruthenium- and copper-based complexes as catalysts in several applications are also disclosed. Halfway between the study of the electronic effect of mixed NHC/phosphite ruthenium in olefin metathesis reactions (Chapter 1) and NHC copper-catalysed transformations (Chapters 5 and 6), resides the core of this dissertation that links the book end chapters. Indeed, the NHC-Cuᴵ transfer or “transmetalation” reaction is disclosed as a powerful and reliable tool to access new transition metal catalysts in a relatively general manner. The syntheses of a series of various non-conventional NHC-Cu complexes as precursors for the transmetalation reaction are also described in Chapter 2. The dissertation finally closes with some preliminary results on what represents the first experimental and theoretical evidence for the mechanism of the NHC transfer by transmetalation. The exploration of the reaction by exchange from copper to platinum has begun to reveal what was so far unknown through the isolation of reactive intermediate species formed during the process.