Made available in DSpace on 2016-06-02T19:56:52Z (GMT). No. of bitstreams: 1 5331.pdf: 11740082 bytes, checksum: e8f5288e8c937187089b53d5c0ebd1c9 (MD5) Previous issue date: 2013-04-26 / Financiadora de Estudos e Projetos / The combustion of petroleum fuels produces large emissions of NOX, SOX and other strong atmospheric pollutants. The abatement of NOX can be achieved by the nonselective catalytic reduction of NO with CO, for that, supported noble metals have been the most commonly used, with high cost as disadvantage. Transition metal oxides show good activity for this reaction, however, they have poor performance in the presence of SO2, O2 and water steam. Thus, this study aimed to prepare, characterize and evaluate catalysts based on CuO, Fe2O3 and CuO-Fe2O3 supported on TiO2, ZrO2 and their mixtures, in the reduction of NO to N2 with CO in the presence or absence of water steam. XRD data, N2 adsorption and H2-TPR showed that mixed oxides and their catalysts, prepared by sol-gel in-situ, presented specific surface areas between 30 to 60 m2/g, with Cu or Fe species highly distributed, having the last greater interaction with titanium. Rietveld refinement showed preferential formation of zirconium titanate, then showing a close interaction of these species in the mixed supports. All catalysts were highly active in the reduction of NO to N2. At temperatures below 500 °C a CuO catalysts were more active and selective for the formation of N2 than Fe2O3, with the formation of N2O being favored with the increase of zirconium in the support. At 600 °C, the high conversion of NO to N2 on CuO was not influenced by the content of TiO2 in the support. Also at 600 °C, an increasing in the content of titanium in the Fe2O3 catalysts resulted in a significant drop in the conversion of NO to N2. The presence of water steam during the reduction of NO with CO at 600 °C caused a significant decrease in the conversion of NO to N2 and CO to CO2 on the CuO catalyst on the support with higher titanium content. The water steam completely eliminates the activity for the reduction of NO to N2 on Fe2O3 catalysts, but keeping a high conversion of CO to CO2. The CuO and CuO-Fe2O3 catalysts on zirconium-rich supports showed high potential for the abatement of NOX in the presence of water steam at temperatures above 500 ºC. / A combustão de derivados do petróleo gera grandes emissões de NOX, SOX e outros fortes poluentes da atmosfera. O abatimento de NOX pode ser realizado por meio da redução catalítica não seletiva com CO, onde os metais nobres suportados têm sido os mais empregados, com a desvantagem de seu elevado custo. Óxidos de metais de transição apresentam boa atividade nessa reação, no entanto, têm baixo desempenho na presença de SO2, O2 e vapor de água. Assim, este trabalho teve como objetivo preparar, caracterizar e avaliar catalisadores a base de CuO, Fe2O3 e CuO-Fe2O3 suportados em TiO2, ZrO2 ou suas misturas, na redução de NO a N2 com CO na presença ou ausência de vapor de água. Dados de DRX, adsorção de N2 e RTP-H2 mostraram que os suportes mistos e seus catalisadores, que foram preparados via síntese sol-gel in-situ, apresentaram áreas superficiais específicas entre 30 e 60 m2/g, com as espécies de Cu ou Fe altamente distribuídas, tendo essas últimas maior interação com a titânia. Refinamento de Rietveld mostrou formação preferencial de titanato de zircônia, evidenciando a estreita interação dessas espécies nos suportes mistos. Todos os catalisadores foram altamente ativos na redução de NO a N2. Em temperaturas inferiores 500 ºC os catalisadores de CuO foram mais ativos e seletivos à formação de N2 que o Fe2O3, com a formação de N2O sendo favorecida com o aumento de zircônia no suporte. A 600 ºC, a alta conversão de NO a N2 sobre CuO não foi influenciada pelo conteúdo de TiO2 no suporte. Nessa temperatura, o aumento do teor de titânia provocou nos catalisadores de Fe2O3 uma queda significativa na conversão de NO a N2. A presença de vapor de água durante a redução de NO com CO a 600 ºC provocou sobre CuO queda significativa da conversão de NO a N2 e de CO a CO2 sobre o suporte com maior conteúdo de titânia. Nos catalisadores de Fe2O3 puro, o vapor de água anulou completamente a atividade para a redução de NO a N2, mas manteve-se a conversão de CO a CO2. Os catalisadores de CuO e CuO-Fe2O3 sobre suporte contendo alto teor de zircônia apresentaram alto potencial para o abatimento de NOx na presença de vapor de água em temperaturas superiores a 500 ºC.

In recent years, rules and regulations regarding fuel consumption of vehicles and the amount of emissions produced by them are becoming stricter. This has led the automotive industry to develop more advanced solutions to propel vehicles to meet the legal requirements. The Hybrid Electric Vehicle is one of the solutions that is becoming more popular in the automotive industry. It consists of an electrical driveline combined with a conventional powertrain, propelled by either a diesel or petrol engine. Two power sources create the possibility to choose when and how to use the power sources to propel the vehicle. The strategy that decides how this is done is referred to as an energy management strategy. Today most energy management strategies only try to reduce fuel consumption using models that describe the steady state behaviour of the engine. In other words, no reduction of emissions is achieved and all transient behaviour is considered negligible.  In this thesis, an energy management strategy incorporating engine dynamics to reduce fuel consumption and nitrogen oxide emissions have been designed. First, the models that describe how fuel consumption and nitrogen oxide emissions behave during transient engine operation are developed. Then, an energy management strategy is developed consisting of a model predictive controller that combines the equivalent consumption minimization strategy and convex optimization. Results indicate that by considering engine dynamics in the energy management strategy, both fuel consumption and nitrogen oxide emissions can be reduced. Furthermore, it is also shown that the major reduction in fuel consumption and nitrogen oxide emissions is achieved for short prediction horizons.

A lot of research effort is spent worldwide in order to reduce the environmental impact of the transportation and power generation sector. To minimize the environmental pollution the role of hydrogen fuelled gas turbines is intensively discussed in several research scenarios, like the IGCC-technology or the application of hydrogen as large scale storage for renewable energy sources. The adaptation of the applied gas turbine combustion chamber technology and control technology is mandatory for a stable and secure low NOx operation of a hydrogen fuelled gas turbine.<p>The micromix combustion principle was invented at Aachen University of Applied Sciences and achieves a significant reduction of the NOx-emissions by the application of multi miniaturized diffusion-type flamelets. Based on the research experiences, gained during the two European hydrogen research programs EQHHPP and Cryoplane at Aachen University of Applied Sciences, the intention of this thesis was to continue the scientific research work on low NOx hydrogen fuelled gas turbines. This included the experimental characterization of the micromix combustion principle, the design of an improved combustion chamber, based on the micromix combustion principle, for industrial gas turbine applications and the improvement of the gas turbine’s control and metering technology.<p>The experimental characterization of the micromix combustion principle investigated the impact of several key parameters, which influence the formation of the NOx-emissions, and allows therefore the definition of boundary conditions and design laws, in which a low NOx operation of the micromix combustion principle is practicable. In addition the ability of the micromix combustion principle to operate at elevated energy densities up to 15 MW/(m2bar) was successfully demonstrated. The improved combustion chamber design concept includes the experiences gained during the experimental characterization and covers the industrial needs regarding scalability and manufacturability.<p>The optimization and testing is done with an Auxiliary Power Unit GTCP 36-300. The original kerosene fuelled gas turbine was modified for the hydrogen application. Therefore several hardware and software modifications were realized. The improved gas turbine’s control and metering technology enables stable and comparable operational characteristics as in kerosene reference. An improved hydrogen metering unit, which is controlled by the industrial Versatile Engine Control Box, was successfully implemented. <p>The combination of the micromix combustion technology and of the optimized control and metering technology allows a stable, secure and low NOx hydrogen fuelled gas turbine operation.<p> / Doctorat en Sciences de l'ingénieur / info:eu-repo/semantics/nonPublished

Poor air quality has been projected to be the world’s top cause of environmental premature mortality by 2050 surpassing poor sanitation and dirty water (IGBP / IGAC press release, 2012 ). One of the major challenges of air quality management is how to adequately quantify both the spatial and temporal variations of pollutants for the purpose of implementing necessary mitigation measures. The work described in this thesis aims to address this problem using novel electrochemical based air quality (AQ) sensors. These instruments are shown to provide cost effective, portable, reliable, indicative measurements for urban air quality assessment as well as for personal exposure studies. Three principal pollutants CO, NO and NO2 are simultaneously measured in each unit of the AQ instrument including temperature / RH measurements as well as GPS (for time and position) and GPRS for data transmission. Laboratory studies showed that the electrochemical sensor nodes can be highly sensitive, showing linear response during calibration tests at ppb level (0-160 ppb). The instrumental detection limits were found to be < 4 ppb (CO and NO) and < 1 ppb for NO2 with fast response time equivalent to t90 < 20 s. Several field studies were carried out involving deployment of both the mobile and static electrochemical sensor nodes. Results from some short-term studies in four different cities including Cambridge (UK), London (UK), Valencia (Spain) and Lagos (Nigeria) are presented. The measurements in these cities represent snapshot of the pollution levels, the stark contrast between the pollution level especially CO (mean mixing ratio of 16 ppm over 3 hrs) in Lagos and the other three cities is a reflection of the poor air quality in that part of the world. Results from long-term AQ monitoring using network of 46 static AQ sensors were used to characterise pollution in different environments ranging from urban to semi-urban and rural locations. By coupling meteorological information (wind measurements) with pollution data, pollution sources, and phenomena like the street canyon effect can be studied. Results from the long-term study also revealed that siting of the current fixed monitoring stations can fail to represent the actual air quality distribution and may therefore be unrepresentative. This work has shown the capability of electrochemical based AQ sensors in complementing the existing fixed site monitors thus demonstrating an emerging measurement paradigm for air quality monitoring and regulation, source attribution and human exposure studies.

No description available.

The thesis deals with an analyses of emission and harmful particles of exhaust fumes of automobiles with an environmental impact. More precisely, it describes the basic characteristics of current fuel types and emission produced by internal combustion engines. Next, it deals with the measures and possibilities of decreasing car traffic emission with respect to environmental impact. It also describes the current European standards for emission and the systems of the cars that are able to decrease emission. The work also deals with the measuring of emission and the methods that are used. According to the measuring methods, the analysis of exhalation is done and it is based on the data of the real car fleet. Values of the emission analyses are compared. The financial aspect is a part of the analyses.

This diploma thesis deals with selected abatement techniques of nitrogen oxides (NOx) developed for large combustion plants. The first part describes selected NOx, their properties and explains the formation during combustion. Furthermore, there is an analysis of current legal legislation regulating the issue of emission limits. The third part presents selected primary and secondary measures that are widely used. The emphasis is placed on the description of selective catalytic (SCR) and non-catalytic reduction (SNCR). Finally, the basic design of these technologies for model combustion equipment is performed. The consumption of reducing medium and the volume of the catalyst for the mentioned techniques are calculated here. The estimate of selected operating and investment costs is a part of the basic scheme.

The main aim of the work was the investigation of the effect of operational parameters of the combustion process (combustion air excess, primary fuel ratio) and burner constructional parameters (the pitch angle of secondary nozzles, tangential orientation of secondary nozzles towards the axis of the burner) on the formation of NOx and CO, flue gas temperature, the shape, dimensions and stability of the flame, in-flame temperatures in the horizontal symmetry plane of the combustion chamber and the amount of heat extracted from the hot combustion gases in the combustion chamber’s shell. Experimental activities were carried out in the laboratory of the Institute of Process and Environmental Engineering, which is focused on burners testing. The combustion tests were performed with the experimental low-NOx type burner, namely the two-gas-staged burner. Mathematical model developed based on the experimental data describes the dependency of NOx on the operating parameters of the combustion process and burner constructional parameters. The model shows that increasing air excess and increasing angle of tangential orientation of the secondary nozzles reduce the formation of NOx. The temperature peaks in the horizontal symmetry plane of the combustion chamber decreases with increasing combustion air excess. The thermal load to the combustion chamber’s wall along the length of the flame was evaluated for selected settings. It was validated that the thermal efficiency of is reduced when higher air excess is used.

In order to improve the air quality in Uppsala, a proposition to introduce one of two new emission zones (EZ), starting in the year 2020, has been proposed. In what is called Environment Zone Class 2 (EZ2), only cars that meet emission class Euro 5 and higher are allowed and in Environment Zone Class 3 (EZ3), only electric, fuel cell and gas vehicles are allowed. The purpose of this thesis is to examine how EZ: s would affect the air quality, regarding nitrogen oxides (NOx) and particles (PMx), within the zone of the city of Uppsala. Using the traffic simulation software PTV Vissim and the emissions modeling software EnViver, four scenarios have been created, two representing today's fleet of vehicles and two examining a modified fleet. Scenario 1 examines an exclusion of all non EZ2 vehicles (Euro 4 and lower) within the zone and scenario 2 examines an EZ2 solely on the road Kungsgatan. Scenario 3 and 4 examine an EZ2 and EZ3 where all cars that do not currently meet the requirements for each EZ are replaced with ones that do. The results indicate that all proposals, except scenario 2, lead to a reduction of NOx and PM2 within the zone. Scenario 1 shows a decrease by 51% for NOx and 57% for PM10, scenario 3 shows a decrease by 17% and 24% respectively and scenario 4 shows a decrease by 66% and 43% respectively. For scenario 2 the emissions show an increase by 10% and 7% each within the zone.

<div>Metal-zeolites are promising materials for passive adsorber technologies for the abatement of nitrogen oxides (NOx, x = 1,2) and aldehydes during low-temperature operation in automotive exhaust aftertreatment systems. The aqueous-phase exchange processes used commonly to prepare metal-zeolites typically require mononuclear, transition metal complexes to diffuse within intrazeolite pore networks with their solvation shells and replace extra framework cations of higher chemical potential. When metal complexes are larger than the zeolite pore-limiting diameter, this imposes intracrystalline transport restrictions; thus, complexes and agglomerates tend to preferentially deposit near the surfaces of crystallites, requiring post-synthetic treatments to disperse metal species more uniformly throughout zeolite crystallites via solid-state ion-exchange processes. Here, we address the influence of post-synthetic gas treatments and zeolite material properties on the structural interconversion and exchange of extra framework Pd in CHA zeolites with a focus on the thermodynamic, kinetic, and mechanistic factors that dictate the Pd site structures and spatial distributions that form.<br></div><div><br></div><div>Pd-amine complexes introduced via incipient wetness impregnation on CHA zeolites were found to preferentially site near crystallite surfaces. Post-synthetic treatments in flowing air results in Pd-amine decomposition and agglomeration to metallic Pd0and supersequent oxidation to PdO, before converting to mononuclear Pd²⁺cations through an Ostwald ripening mechanism at high temperatures (>550 K). Progressively higher air treatment temperatures (up to 1023 K) were found to (1) thermodynamically favor the formation of mononu-clear Pd²⁺cations relative to agglomerated PdO particles, (2) increase the apparent rate of structural interconversion to mononuclear Pd²⁺, and (3) facilitate longer-range mobility of molecular intermediates involved in Ostwald ripening processes that allow Pd cations to form deeper within zeolite crystallites to form more uniformly dispersed Pd-zeolite materials. Additionally, the controlled synthetic variation of the atomic arrangement of 1 or 2Al sites in the 6-membered ring of CHA was used to show a thermodynamic preference to form mononuclear Pd2+cations charge-compensated by 2 Al sites over [PdOH]⁺complexes at 1 Al site. Colloidal Pd nanoparticle syntheses and deposition methods were used to prepare monodisperse Pd-CHA materials to isolate the effects of Pd particle size on structuralinterconversion to mononuclear Pd²⁺under a range of external environments. Consistent with computational thermodynamic predictions, smaller Pd particle sizes favor structural interconversion to mononuclear Pd²⁺under high-temperature air treatments (598–973 K),while adding H2O to the air stream inhibits the thermodynamics but not the kinetics of mononuclear Pd²⁺formation, demonstrating that water vapor in exhaust streams may be deleterious to the long-term stability of Pd-zeolite materials for passive NOx adsorption.<br></div><div><br></div><div>The influence of metal-zeolite material properties on the adsorption, desorption, and conversion of formaldehyde, a government-regulated automotive pollutant, under realistic conditions was investigated to identify beneficial material properties for this emerging application in mobile engine pollution abatement. A suite of Beta zeolite materials was synthesized with varied adsorption site identity (Brønsted acid, Lewis acid, silanol groups, and extra framework metal oxide) and bulk site densities. All materials stored formaldehyde and converted a large fraction of formaldehyde to more environmentally benign CO and CO₂, demonstrating the efficacy of silanol defects and zeolitic supports for the storage of formaldehyde. Sn-containing zeotypes, containing either Lewis acidic framework Sn sites or extra framework SnO_x particles, resulted in the greatest selectivity to CO and CO₂ formed during formaldehyde desorption, suggests that Sn species are a beneficial component in metal-zeolite formulations for the abatement of formaldehyde in automotive exhaust streams.<br></div><div><br></div><div>This work demonstrates how combining precise synthesis of metal-zeolites of varied bulk and atomic properties with site-specific characterization and titration methods enables systematically disentangling the influence of separate material properties (e.g., Pd particle size, zeolite framework Al arrangement, silanol density, heteroatom identify) and external environment on changes to metal structure, speciation, and oxidation state. This approach provides thermodynamic, kinetic, and mechanistic insights into the factors that influence metal re-structuring under the practical conditions encountered in automotive exhaust after treatment applications and guidance for materials design and treatment strategies to form desired metal structures during synthesis and after regeneration protocols.<br></div>