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The Investigation of Nickel-Based Catalysts for the Oxidative Dehydrogenation of Ethane Justin Lane ParkDepartment of Chemistry & Biochemistry, BYU Doctor of Philosophy Chemistry The advancement of creating ethylene from ethane via oxidative dehydrogenation (ODH) rather than the traditional direct dehydrogenation is right on the cusp of commercialization. The oxidative pathway provides a novel route that reduces the operating temperature of this reaction by 400-500°C. A variety of metals including Mo, V, and Ni that have redox properties suitable for the partial oxidation of small chain alkanes have been investigated. Currently, a MoVNbTe oxide is the most promising catalyst but it suffers from a long and difficult preparation method and the combination of four expensive metals. Nickel based catalysts have also shown great promise but are limited by the reactivity of the oxygen species on the surface of the catalyst. In this manuscript, the details for improving the activity of the nickel and altering the activation mechanism are outlined.Bulk CeNiNb oxide catalysts were shown to almost double the rate of ethylene yields at temperatures as low as 300°C. This is partially related to the improved rate of oxygen adsorption and transfer to the active oxygens on the nickel oxide via the ceria additive. However, with further characterization of these materials, it was shown that there is likely an interaction between the Ce and Nb, forming a Ce-O- Nb linkage that is also selective towards ethylene. This facilitates a higher activity of the catalyst by creating two redox active sites. The improved rates of ethylene formation observed with these catalysts led to the initial development of a commercially viable nickel based catalyst. The support interactions of NiO with a novel silica doped alumina support show higher yields than previously reported studies of NiO on alumina for ODH. These initial metal support interactions show that the addition of the niobium and ceria to this catalyst should give ethylene yields that are satisfactory for the commercialization of this catalyst.

This report deals with the mathematical model of the transient behaviour of an existing ethane dehydrogenation furnace which is composed of two main sections: a preheating convection section and a radiant-heated section. The correlation of pressure drop with time has been found from the available data. The fractional carbon deposition and the multiplier coefficient of a pressure drop equation have been determined by the direct search optimization technique of Hooke and Jeeves. An optimal policy for the cyclic operation of the furnace was determined by considering plant temperature profile and hydrocarbon/ steam ration as parameters for maximizing average ethylene produced per day. The effect of temperature profile on the distribution of carbon deposited along the reactor was also predicted and discussed. / Thesis / Master of Engineering (ME)

The reaction barrier and heat of formation of the various dehydrogenation reactions involved in the steam reforming of ethane is a critical concern in the applications and understanding of these reactions. Focusing on Ir-based catalyst, we report a comprehensive reaction network of dehydrogenation of ethane on Ir(100) based on extensive density functional theory calculations performed on 10 C-H bond cleavage reactions, utilizing the Vienna Ab Initio Package codes. The geometric and electronic structures of the adsorption of C2Hx species with corresponding transition-state structures is reported. We found that the C-H bond in CH3C required the most energy to activate, due to the most stable four-fold hollow adsorption site configuration. Ethane can easily dissociate to CH3CH and CH2CH2 on Ir(100) and further investigation of surface temperature dependence will contribute to the research effort in this area. By using the degree of dehydrogenation of the reactant species as a variable to correlate the C-H bond cleavage barrier as well as reaction energy. DFT studies reveal that the surface Ir(100) to a great extent promotes ethane dehydrogenation when compared to other surfaces.

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京都大学 / 新制・課程博士 / 博士(工学) / 甲第23925号 / 工博第5012号 / 新制||工||1782(附属図書館) / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 村上 正浩, 教授 杉野目 道紀, 教授 中尾 佳亮 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 新制・課程博士 / 博士(工学) / 甲第24639号 / 工博第5145号 / 新制||工||1983(附属図書館) / 京都大学大学院工学研究科合成・生物化学専攻 / (主査)教授 杉野目 道紀, 教授 中尾 佳亮, 教授 藤原 哲晶 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

Ethyl iodide and ethyl chloride have been used as reactants to produce ethyl fragments on the stoichiometric α-Cr₂O₃ (1012) surface by means of thermal dissociation. Ethyl iodide is dissociated giving iodine adatoms and ethyl fragments bound to surface Cr cation sites, while ethyl chloride is dissociated giving chlorine adatoms and ethyl fragments. No oxygenated products are observed in thermal desorption, suggesting the 3-coordinate lattice oxygen on the stoichiometric α-Cr₂O₃ (1012) surface is very stable, and no nucleophilic attack occurs at the carbon atoms on surface ethyl fragments. For both reactants, the only reaction products observed are ethylene gas (CH₂=CH₂), ethane gas (CH₃-CH₃), hydrogen gas (H₂) and halogen adatoms (Cl_ads or I_ads). In thermal desorption experiments, all the gas phase products from ethyl chloride are produced in a reaction-limited, high temperature desorption feature attributed to a rate limiting β-hydride elimination from surface ethyl fragments. Similar product desorption features are observed for the reaction of ethyl iodide. However, the reaction of ethyl iodide also produces ethylene and ethane via a low temperature, desorption-limited reaction channel. It is postulated that I adatoms produced in the reaction of ethyl iodide thermal desorption might somehow promote a low temperature route to products that Cl adatoms do not. / Master of Science

Rh(III) and Ir(III) dimeric complexes with tunable cyclopentadienyl (Cp) rings have proven versatile for both catalysis and as synthetic precursors. An efficient microwave method to synthesize Rh(III) and Ir(III) dimeric complexes [(η5-ring)MCl]2(μ2-Cl)2, (where (η5-ring)MCl = (η5-Me4C5R)Rh(III)Cl or (η5-Me4C5R)Ir(III)Cl) was developed. A modular design for the substituted cyclopentadienes HC5Me4R was based on Grignard reactions of 2,3,4,5-tetramethylcyclopent-2-en-1-one (R = alkyl, 12 examples; R = aryl, 3 examples) or by SNAr reactions of potassium tetramethylcyclopentadienide with perfluoroarenes (R = perfluoroaryl, 3 examples). Reaction of the Me4CpHR ligands with [M(COD)](μ2-Cl)2 (M = Rh, Ir; COD = 1,5-cyclooctadiene) produced the dimeric complexes [Cp*RMCl]2(μ2-Cl)2 in moderate to excellent yield. The resulting dimers were characterized by nuclear magnetic resonance (NMR) spectroscopy, single-crystal X-ray diffraction (XRD), high-resolution mass spectrometry (HRMS), elemental analysis, and examined as catalysts for oxidative lactonization of 1,4- and 1,5-diols. Oxidative lactonization of 1,4-butanediol to afford γ-butyrolactone proceeded selectively and efficiently using [(η5-Me4C5R)IrCl]2(μ2-Cl)2 as the catalyst. Several R substituents were tested to assess electronic substituent effects. The most active complex contained an electron donating group, R = CHMe2 and successfully catalyzed the formation of diols to lactones across a range of 1,4- and 1,5-diols, generally in high yield. Computational analysis of the rate-determining b-hydrogen elimination reactions provided an atomistic account of observed trends in reaction yield and selectivity as a function of substrate structure, while accounting neatly for the observed selective formation of lactones (vs. succinaldehyde) in the transfer dehydrogenation of 1,4-butyrolactone. / Doctor of Philosophy / Rhodium(III) and iridium(III) complexes are useful synthetic precursors, catalysts, and biologically active compounds. This dissertation explores a rapid synthesis of these metal complexes and their subsequent catalytic applications with 1,4- and 1,5-diols. The oxidative lactonization of diols with rhodium and iridium complexes is an attractive one-pot synthesis, opening a variety of lactones to be produced. Structural studies involving novel fluorinated rhodium and iridium chloro-bridged dimers are discussed in detail.