Stickoxide NOx werden von Menschenhand in verschiedenen Verbrennungsprozessen emittiert. Die selektive katalytische Reduktion mit Ammoniak (NH3-SCR) hat sich weltweit als wichtigste Methode zur Minderung von NOx-Emissionen etabliert. Derzeit erhältliche Katalysatoren für die NH3-SCR werden bei Temperaturen unterhalb von 473 K stark in Gegenwart von Wasser desaktiviert, welches unvermeidbar in Abgasen aus der Verbrennung von organischen Stoffen enthalten ist. In dieser Arbeit werden drei verschiedene Arten der Modifikation von SCR-Katalysatoren diskutiert, die eine gesteigerte H2O-Resistenz bewirken. Eine Methode ist die Verwendung von mischoxidischen Trägermaterialien, eine Andere ist eine mischoxidische aktive Komponente und schließlich eine postpräparative Oberflächenmodifikation mit Organosilylgruppen. Die Katalysatoren wurden sowohl auf ihre katalytische Aktivität als auch auf ihre adsorptiven, redox und andren Oberflächeneigenschaften untersucht. Die Wechselwirkungen zwischen H2O und der Katalysatoroberfläche wurden mittels temperaturprogrammierter Desorption (TPD), isothermaler Adsorption bei erhöhtem Druck und einer gravimetrischen Methode untersucht. Besonders die H2O-TPD hat sich als eine leistungsstarke Methode für diesen Zweck herausgestellt. Jede der drei Modifikationen bewirkte eine Verminderung der Wechselwirkungen zwischen H2O und der Katalysatoroberfläche. Neben einer allgemeinen Erhöhung der Aktivität eines SCR-Katalysators, wird die gezielte Verminderung dieser Wechselwirkungen als Schlüsselrolle in der Entwicklung von Katalysatoren mit verbesserter H2O-Resistenz angesehen. Jedoch gibt es zur Zeit kaum Publikationen, die diesen Zusammenhang behandeln. Daneben wurde auch die Bildung von N2O als ungewünschtes Nebenprodukt bei der SCR-Reaktion untersucht. Dessen Treibhauspotential entspricht ungefähr dem 300-fachen von CO2. Die Verwendung von einem mischoxidischem Trägermaterial kann die Freisetzung von N2O während der SCR verringern, was größtenteils auf die Unterdrückung der Bildung nach einem ER-Mechanismus zurückgeführt wurde. Auch die N2O-Bildung wird in vielen Publikationen über die Entwicklung von SCR-Katalysatoren nicht betrachtet.:0.1 Abbreviations 0.2 Symbols 1 Introduction and Objectives 2 Literature Overview 2.1 NH3-SCR 2.1.1 NH3-SCR Catalysts 2.1.2 Mechanisms of NH3-SCR Reaction 2.1.3 N2O-Formation under SCR-Conditions 2.2 Deactivation of NH3-SCR Catalysts 2.2.1 Deactivation by H2O 2.2.2 Deactivation by SO2 2.3 Low-Temperature NH3-SCR 2.3.1 Requirements and Challenges of LT-SCR 2.3.2 LT-SCR Catalysts 2.4 Silylation of Metal Oxide Surfaces 3 Experimental Section 3.1 Catalyst Preparation 3.1.1 Support Modification with Different Metal Oxides 3.1.2 Deposition of Active Component 3.1.3 Catalyst Modification with Organosilyl Groups 3.2 Catalyst Characterization 3.2.1 Texture Analysis 3.2.2 Phase Analysis 3.2.3 Elementary Analysis 3.2.4 Adsorption Properties 3.2.5 Surface Spectroscopy 3.2.6 Redox Properties 3.3 Catalytic Experiments 4 Results and Discussion 4.1 Impact of Mixed-Oxide Support on Catalyst Activity 4.1.1 Impact in Dry Gas-Flow: Reduced N2O-Emission 4.1.1.1 Catalytic Activity 4.1.1.2 Catalyst Characterization 4.1.1.3 Discussion 4.1.2 Impact in Wet Gas-Flow: Higher H2O-Resistance 4.1.2.1 Catalytic Activity 4.1.2.2 Catalyst Characterization 4.1.2.3 Discussion 4.1.3 Summary of SiO2-Impact 4.2 Mn-Ce Mixed-Oxide as Active Component 4.2.1 Catalytic Activity 4.2.2 Catalyst Characterization 4.2.3 Discussion and Summary 4.3 Catalyst Modification with Organosilyl Groups 4.3.1 Stability of Organosilyl Groups 4.3.2 Impact of Organosilyl Modification on H2O-Adsorption 4.3.3 Impact of Organosilyl Modification on Catalytic Activity in Pre- and Absence of H2O 4.3.3.1 Catalytic Activity 4.3.3.2 Catalyst Characterization 4.3.3.3 Discussion 4.3.4 Summary of Organosilyl Modification 4.4 Discussion on the Investigation of H2O-Adsorption 5 Conclusions and Outlook 5.1 Conclusions 5.2 Outlook 6 References 7 Appendix 7.1 Evaluation of H2O-Sorption Data through BET-Theory 7.2 Evaluation of Kinetic SCR Investigation 7.3 Calculation of the Average Oxidation State of Mnz+ from H2-TPR 7.4 Calculation of the Surface-Density of Mn 7.5 Supplementary Data 7.6 Scientific Contributions 7.7 Curriculum Vitae 8 Summary (german) 8.1 Einleitung 8.2 Experimentelles 8.3 Ergebnisse und Diskussion 8.3.1 Einfluss eines mischoxidischen Trägermaterials auf die katalytische Aktivität 8.3.2 Mn-Ce-Mischoxide als aktive Komponente 8.3.3 Modifikation von Katalysatoren mit Organosilyl-Gruppen 8.4 Schlussfolgerungen / Nitrogen oxides NOx were anthropogenically emitted by various combustion processes. The selective catalytic reduction with ammonia (NH3-SCR) has been established worldwide as the most important technique for the abatement of NOx . Currently available catalysts for NH3-SCR become strongly deactivated at temperatures below 473 K in presence of H2O which is unavoidable present in the exhaust gas arising from the combustion of organic matter. In this work three different kinds of a modification of an SCR-catalyst were discussed that cause a higher H2O-resistance. One is the application of a mixed-oxide support material, the other is a mixed-oxide active component and finally a post-preparative surface modification with organosilyl-groups. The catalysts were assessed for their catalytic activity as well as their adsorptive, redox and other surface properties. The interactions between H2O and the catalyst surface were investigated by means of temperature programmed desorption (TPD), isothermal adsorption at elevated pressure and a gravimetric method. Especially the H2O-TPD turned out to be a powerful method for this purpose. Each of the three modifications caused a reduction in the H2O-catalyst interactions. Beside a general increase of the activity of an SCR-catalyst, the purposeful reduction of these interactions is considered to play a key role in the development of catalysts with an enhanced H2O-resistance. However, there is a lack of publications that deal with this correlation. Also the formation of the unwanted by-product N2O was investigated. Its global warming potential is about 300-times that of CO2. The application of a mixed-oxide support can reduce the release of N2O during SCR which was attributed mainly to the suppression of the ER-type formation pathway. Also the N2O-formation is not considered in many publications dealing with the development of SCR-catalysts.:0.1 Abbreviations 0.2 Symbols 1 Introduction and Objectives 2 Literature Overview 2.1 NH3-SCR 2.1.1 NH3-SCR Catalysts 2.1.2 Mechanisms of NH3-SCR Reaction 2.1.3 N2O-Formation under SCR-Conditions 2.2 Deactivation of NH3-SCR Catalysts 2.2.1 Deactivation by H2O 2.2.2 Deactivation by SO2 2.3 Low-Temperature NH3-SCR 2.3.1 Requirements and Challenges of LT-SCR 2.3.2 LT-SCR Catalysts 2.4 Silylation of Metal Oxide Surfaces 3 Experimental Section 3.1 Catalyst Preparation 3.1.1 Support Modification with Different Metal Oxides 3.1.2 Deposition of Active Component 3.1.3 Catalyst Modification with Organosilyl Groups 3.2 Catalyst Characterization 3.2.1 Texture Analysis 3.2.2 Phase Analysis 3.2.3 Elementary Analysis 3.2.4 Adsorption Properties 3.2.5 Surface Spectroscopy 3.2.6 Redox Properties 3.3 Catalytic Experiments 4 Results and Discussion 4.1 Impact of Mixed-Oxide Support on Catalyst Activity 4.1.1 Impact in Dry Gas-Flow: Reduced N2O-Emission 4.1.1.1 Catalytic Activity 4.1.1.2 Catalyst Characterization 4.1.1.3 Discussion 4.1.2 Impact in Wet Gas-Flow: Higher H2O-Resistance 4.1.2.1 Catalytic Activity 4.1.2.2 Catalyst Characterization 4.1.2.3 Discussion 4.1.3 Summary of SiO2-Impact 4.2 Mn-Ce Mixed-Oxide as Active Component 4.2.1 Catalytic Activity 4.2.2 Catalyst Characterization 4.2.3 Discussion and Summary 4.3 Catalyst Modification with Organosilyl Groups 4.3.1 Stability of Organosilyl Groups 4.3.2 Impact of Organosilyl Modification on H2O-Adsorption 4.3.3 Impact of Organosilyl Modification on Catalytic Activity in Pre- and Absence of H2O 4.3.3.1 Catalytic Activity 4.3.3.2 Catalyst Characterization 4.3.3.3 Discussion 4.3.4 Summary of Organosilyl Modification 4.4 Discussion on the Investigation of H2O-Adsorption 5 Conclusions and Outlook 5.1 Conclusions 5.2 Outlook 6 References 7 Appendix 7.1 Evaluation of H2O-Sorption Data through BET-Theory 7.2 Evaluation of Kinetic SCR Investigation 7.3 Calculation of the Average Oxidation State of Mnz+ from H2-TPR 7.4 Calculation of the Surface-Density of Mn 7.5 Supplementary Data 7.6 Scientific Contributions 7.7 Curriculum Vitae 8 Summary (german) 8.1 Einleitung 8.2 Experimentelles 8.3 Ergebnisse und Diskussion 8.3.1 Einfluss eines mischoxidischen Trägermaterials auf die katalytische Aktivität 8.3.2 Mn-Ce-Mischoxide als aktive Komponente 8.3.3 Modifikation von Katalysatoren mit Organosilyl-Gruppen 8.4 Schlussfolgerungen

The electronic and vibrational spectra of Ni+(H2O) were measured using photofragment spectroscopy. In the electronic spectrum, photodissociation is observed at photon energies above 16875 cm-1. The only fragment observed is Ni+. The electronic spectrum consists of well-resolved peaks spaced by ~340 cm-1, due to a vibrational progression in the excited electronic state. These peaks have complex sub-structure, consisting of a triplet, spaced by ~30 cm-1. The sub-structure is due to rotational structure in a perpendicular transition of a prolate top molecule. In addition to this major progression, there is a series of less intense, single peaks spaced by ~340 cm-1. These may be due to a vibrational progression in a second electronic state, this time due to a parallel transition. The O-H stretching vibrations of Ni+(H2O) were measured using vibrationally mediated photodissociation (VMP) in a depletion experiment, only monitoring transitions from K’’=1. This revealed a O-H symmetric stretch at 3629 cm-1 and antisymmetric O-H stretch at 3692 cm-1. Several electronic structure calculations complement the experiments using the BHandHLYP hybrid density functional and the 6-311++G(3dp, f) basis set. At this level of theory, Ni+(H2O) is predicted to have C2v symmetry and 2A1 ground state. The Ni-O bond length is 1.95, the O-H bond lengths are .955 and the H-O-H angle is 108.2˚ The molecule is a near-prolate top, with rotational constants A=13.98 cm-1, B=0.297 cm-1 and C=0.296 cm-1 . Analysis of the electronic and vibrational spectra reveals that binding to Ni+ removes electron density from the oxygen lone pairs, increasing the H-O-H bond angle from its value in bare H2O. The electronic and vibrational spectra corresponds to 4s ¬3d transistion in Ni+. As a result of electronic excitation, the Ni-O bond stretches by .20 Å, and the H-O-H bond angle is reduced.

Currently there is no known method for accurately measuring the temperature of the gas phase of combustion products within a solid fuel flame. The industry standard is a suction pyrometer and thermocouple which is intrusive, both spatially and temporally averaging, and difficult to use. In this work a new method utilizing the spectral emission from water vapor is investigated through modeling and experimental measurements. This method was demonstrated along a 0.75m line of sight, averaged over 1 minute in the products of a natural gas flame but has the potential to produce a spatial resolution on the order of 5 cm and a temporal resolution of less than 1 millisecond. The method employs the collection of infrared emission from water vapor over discrete wavelength bands and then uses the ratio of those emissions to infer temperature. A 12.5 mm lens has been positioned within a water cooled probe to focus flame product gas emission into an optical fiber where the light is transmitted to a Fourier Transform Infrared Spectrometer (FTIR). The same optical setup was also used to collect light from a black body cavity at a known temperature in order to calibrate the spectral sensitivity of the optical system and FTIR detector. Experiments were conducted in the product gas of a 150 kWth methane flame comparing the optical emission results to a suction pyrometer with type K thermocouple. The optical measurement produced gas temperatures approximately 1 - 4% higher than the suction pyrometer. Broadband background emission was also seen by the optical measurement and was removed assuming grey body radiation. This background emission can be used to determine particle emission temperature and intensity. Additional work will be needed to demonstrate the method under conditions with significant particle emission. Additional work is also needed to demonstrate the work over a smaller path length and shorter time scale.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第24237号 / 工博第5065号 / 新制||工||1791(附属図書館) / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 田中 庸裕, 教授 佐藤 啓文, 教授 阿部 竜 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

名古屋大学年代測定総合研究センターシンポジウム報告

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第19000号 / 工博第4042号 / 新制||工||1622 / 31951 / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 田中 庸裕, 教授 今堀 博, 教授 阿部 竜 / 学位規則第4条第1項該当

The gas phase etching of thermal silicon dioxide films was investigated with in situ Fourier Transformed Infrared Spectroscopy (FTIR) and ex situ X-ray Photoelectron Spectroscopy (XPS). The initiation process, the bulk etching of the oxide, and the termination mechanism were characterized as a function of reactant concentration, temperature, and pressure. The experiments were carried out in a custom made vessel with a gas panel and a data acquisition and control system (DA&C) capable of lowering flow and pressure disturbances originated by reactant introduction. The FTIR technique used to monitor the reaction in real time allowed distinguishing reactions that initiated in a gas/solid regime from reactions that started in a gas/liquid/solid regime. This study was focused on the gas/solid initiation process in order to expand the general assumption in published works that a condensed layer is previously required to initiate and sustain the reaction. It was found in this investigation that, depending on the experimental parameters, the water layer is not always a requisite for the initiation of the reaction but a consequence of the etching process. The FTIR data also showed the role in the initiation process of gas phase heterogeneous associated species, specifically (HF)H₂O and (HF)₂H₂O. After the initiation period, the experimental conditions determined the amount of water present on the surface of the sample, which in turn determined the local environment of the reaction and by extension the etching species. Reactions developing in a gas/solid regime were found to be slow, with etching rates of less than 1 °A/sec. Contrarily, reactions taking place in a gas/liquid/solid regime reached etching rates of 100 °A/sec, a maximum value determined by transport limitations. The condensed layer was found to be especially sensitive to temperature since a variation of 15 ° C changed the local environment from gas/liquid/solid to gas/solid. Finally, it was corroborated through the XPS analysis that the removal process in the gas phase leaves the silicon surfaces with high fluorine and oxygen concentrations in the form of SiFₓ and SiOH.

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Mecânica, 2007. / Submitted by wesley oliveira leite (leite.wesley@yahoo.com.br) on 2009-10-02T19:28:32Z No. of bitstreams: 1 2007_EnioNascimentoCarvalho.pdf: 2105502 bytes, checksum: 65813f4b4858c9fa351308e192c9ae35 (MD5) / Approved for entry into archive by Guimaraes Jacqueline(jacqueline.guimaraes@bce.unb.br) on 2009-10-05T12:57:08Z (GMT) No. of bitstreams: 1 2007_EnioNascimentoCarvalho.pdf: 2105502 bytes, checksum: 65813f4b4858c9fa351308e192c9ae35 (MD5) / Made available in DSpace on 2009-10-05T12:57:08Z (GMT). No. of bitstreams: 1 2007_EnioNascimentoCarvalho.pdf: 2105502 bytes, checksum: 65813f4b4858c9fa351308e192c9ae35 (MD5) Previous issue date: 2007-11 / A finalidade deste trabalho é a modelagem física e simulação numérica de unidades resfriadoras de Líquidos por absorção a H2O-LiBr, nas configurações a simples e duplo efeito, com análise do efeito da utilização de aditivos na solução de H2O-LiBr e da influência do clima local sobre o desempenho e consumo energético da unidade. O modelamento físico de cada um dos componentes do sistema foi adotado baseando-se nos princípios clássicos da conservação de energia, junto com as correlações aplicáveis da transferência de calor e massa e equações que descrevem as propriedades dos fluidos de trabalho. O modelo adota um conceito semi-empírico, ou seja, parâmetros característicos para cada componente do sistema são utilizados. A aplicação do modelamento e simulação é realizada para quatro estudos de caso. No primeiro estudo de caso é simulada a operação de uma unidade resfriadora de líquido, de simples efeito, para as 8760 horas do ano, com aplicação em um edifício comercial. A simulação de uma unidade por absorção de duplo efeito, com estimativa do consumo de gás natural, durante o período de um ano de operação da máquina, é o objeto do estudo de caso dois. No terceiro estudo de caso, o consumo anual de combustível e desempenho de uma unidade de resfriamento de duplo efeito é comparado, para duas localidades climáticas diferentes. Finalmente, a avaliação da influência do uso de aditivos à solução H2O-LiBr, sobre o desempenho da unidade resfriadora é analisado no quarto estudo de caso, onde, se obteve um ganho no coeficiente de performance de até 5,5%, se comparado ao desempenho com uso da solução convencional de H2O-LiBr. Dessa forma, os resultados obtidos nesse trabalho permitem uma avaliação sobre a influência de vários fatores, no desempenho de unidades resfriadoras de líquidos por absorção e por conseqüência em seu consumo energético. _____________________________________________________________ ABSTRACT / The purpose of this work is the physical modeling and simulation of H2O-LiBr absorption chillers, in the single and double effect settings, with analysis of the effect of the use of additives in the solution of H2O-LiBr, and the influence of local climate on the performance and energy consumption of the unit. The physical modeling of each component of the system was adopted based on the classical principles of the energy conservation, along with the correlations for the heat and mass transfer or equations that describe the properties of the fluids of work. The model adopts a semi-empirical approach, where characteristic parameters for each component of the system are used. The application of physical modeling and simulation is carried out for four case studies. In the first case study is simulated the operation of a single effect chiller unit, for 8760 hours of the year, with implementation in a commercial building. The simulation of a double effect absorption machine with estimated consumption of natural gas during the period of one year of operation of the machine is the subject of the second case study. In case study three, the annual consumption of fuel and performance of a double effect absorption machine is compared for two different climatic areas. Finally, the evaluation of the influence of the use of additives to the solution H2O-LiBr, on the performance of the absorption chiller is analyzed in the fourth case study, where, was obtained an improvement in the COP of the system up to 5.5%, when compared with the COP of the conventional solution of H2O-LiBr. Thus, the results obtained in this work provide an assessment on the influence of various factors in the absorption chiller performance and result in their energy consumption.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第21574号 / 理博第4481号 / 新制||理||1643(附属図書館) / 京都大学大学院理学研究科物理学・宇宙物理学専攻 / (主査)教授 嶺重 慎, 教授 太田 耕司, 准教授 栗田 光樹夫 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19000号 / 工博第4042号 / 新制||工||1622(附属図書館) / 31951 / 京都大学大学院工学研究科分子工学専攻 / (主査)教授 田中 庸裕, 教授 今堀 博, 教授 阿部 竜 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM