Dissertations / Theses on the topic 'Gas Poisoning'

Abstract The aim of this thesis project was to gain new knowledge on the effect of phosphorus on the catalytic activity and characteristics of automotive exhaust gas catalyst components. The simultaneous roles of phosphorus and calcium were also studied. The first test series of powdery catalyst samples contained Rh and oxide (Test series 1) and the second, Pt and oxide or ZSM-5 (Test series 2). The catalysts were analyzed when fresh and after two ageing and phosphorus poisoning procedures developed in this work. The procedures consisted of adding poison via impregnation in an aqueous solution (for Test series 1) and in the gaseous phase under hydrothermal conditions (for Test series 2). The poison compounds formed and the changes in the washcoat were studied by using physisorption analyses, SEM, TEM, XRD, and FTIR-ATR. The poison content of the samples was determined by ICP-OES and XRF. Laboratory-scale activity measurements were done to investigate the catalytic activity. Thermodynamic calculations were used to obtain information about ageing conditions and phosphorus compounds formed during ageing. Phosphorus decreased the catalytic activity and the characteristic surface areas of the catalysts. Addition of calcium to a phosphorus-poisoned catalyst was found to have even a regenerating effect on the catalysts' activity. The poisoning methods developed in this study resulted in the same phosphorus compounds as can be found in vehicle-aged catalysts. Phosphorus was identified as cerium, zirconium, aluminium, and titanium phosphates. Phosphorus was detected in zeolites, but phosphorus-containing compounds were not observed. Phosphorus poisoning takes place in the gas phase at high operating temperatures and with high oxygen and water contents. It was also shown that the role of phosphorus poisoning was more pronounced than the role of hydrothermal ageing alone. Phosphorus poisoning mainly affects the oxide components used in this study, not the noble metals. The results can be utilized in the development of catalytic materials and catalyst compositions that can better tolerate phosphorus poisoning under hydrothermal conditions. The results can also be applied in evaluating the effects of phosphorus on different catalyst compositions and in estimating the age of commercial catalysts.

This work provides a detailed characterization study on H2S poisoning of Pd and Pd/Au alloy composite membranes to obtain fundamental understandings of sulfur poisoning phenomena and preparation of sulfur tolerant membranes. The enhancement of the sulfur tolerance by alloying Pd with Au has been confirmed by both permeation test and microstructure analysis (SEM and XRD). While pure Pd membranes exhibited the permeance decline in the presence of H2S due to both sulfur adsorption and bulk Pd4S formation, Pd/Au alloy membranes showed the permeance loss merely resulted from the surface sulfur adsorption without bulk sulfide formation up to 55 ppm H2S. The XPS study confirmed that the H2S adsorption on the Pd/Au alloy surfaces was dissociative, and both surface Au and Pd sulfides were formed with the preferential Au-S bonding. The adsorption type of sulfur on the Pd/Au alloy surfaces was monolayer with a limited coverage, which increased with decreasing temperature. The permeance loss of Pd/Au membranes was essentially fully recoverable in H2, and the integrity of the membranes remained unaltered after the poisoning/recovery tests. Increasing Au composition in the Pd/Au membranes increased the sulfur tolerance. A Pd/Au alloy membrane of 16.7 wt% Au exhibited a permeance over 50% of its original value in the presence of 5 ppm H2S at 400°C, while a Pd membrane showed 85% permeance loss. The Pd/Au alloy membranes were fabricated by the Au displacement deposition, which had an empirical reaction order of 3.2 determined by the AAS. The HT-XRD study verified that the formed Pd/Au alloy layers were thermally stable up to 500°C.

[EN] Several major problems have to be solved before Solid Oxide Fuel Cells (SOFC) can operate continuously using hydrocarbon fuels such as natural gas. The risk of low catalytic behavior for fuel reforming, the carbon formation/deposition on the anode material at high operating temperatures and the presence of impurities in the fuel (in particular sulfides) can dramatically reduce the performance and durability of the cells. Taking all this into account, new anode materials with adequate (electro)catalytic properties are required. Recently, manganite compounds with Ruddlesden-Popper (RP) structure have been studied as potential new anode materials in INTERFASE group at Universidad Industrial de Santander (UIS). Their electrochemical performance have been described in previous works with promising results, but a fundamental knowledge was missing concerning the catalytic properties of such materials and the way to improve them by the addition of nickel metallic particles on the electrode surface. The current Ph.D. thesis was focused on the synthesis, characterization and catalytic study for steam reforming in SOFC anode conditions (low steam content) of a new RP manganite (La1.5Sr1.5Mn1.5Ni0.5O7±δ), which, in reducing atmosphere at high operating temperatures promotes via an exsolution mechanism the formation of two phases, i.e. an RP manganite of composition LaSrMnO4±δ decorated with metallic active Ni nanoparticles embedded in the surface; such strategy can be viewed as an original way to improve the (electro)catalytic properties of the anode materials and then a promising option for future SOFC systems operating with Colombian natural gas. The first chapter deals with the synthesis and characterization of the RP n= 2 phase La1.5Sr1.5Mn1.5Ni0.5O7±δ using the Pechini method. In agreement with SOFC operating temperature, Ni exsolution has been studied in diluted H2 at different temperatures (750, 800 and 850 °C) and reduction times. Ni nanoparticles decorating an RP n= 1 manganite is confirmed by XRD, TEM-EDS analysis and the size of the metallic particles on the oxide surface, below 100 nm, is characterized as a function of the exsolution conditions. The second chapter presents the catalytic behavior for the methane steam reforming reaction of the exsolved material applying the Gradual Internal Reforming concept adapted to SOFC operation (i.e. low water content, steam to carbon ratio equal to 0.15) at different reaction temperatures (750, 800 and 850 °C). The catalytic properties of Ni impregnated samples using a similar (La,Sr)2MnO4±δ ceramic support are also presented for comparison. The exsolved material exhibits better performance than the impregnated manganite for the reaction, especially at 850 °C, with higher conversion, conversion rate, and H2 production rate. Concerning the steam reforming of light alkane gas mixtures (CH4-C2H6, and CH4-C3H8), the behavior is affected due to the competition between the molecules and low available metallic active sites, but without affecting the H2 production. In addition, at long reaction times, the activity over the exsolved material is stable even with 100 h of reaction, without formation of carbonaceous species on the Ni particles, as confirmed by TEM and TGA/MS analysis. In the third and last chapter, the possible coke formation and sulfide poisoning are presented. Despite the high and stable catalytic behavior for methane steam reforming reaction with considerable carbon formation resistance, the exsolved material exhibits a high level of sensitivity to H2S poisoning, similar to the case of state-of-the-art Ni/YSZ anodic cermet and or Ni impregnated catalyst, with a drop of the activity to almost zero. Nevertheless, the exceptional overall results obtained for the exsolution-based material are promising for a possible use as SOFC anode operating with sulfur-free Colombian natural gas.
[ES] Muchos son los problemas que deben resolverse antes de que las celdas de combustible de óxido sólido (SOFC por sus siglas en inglés) puedan operar continuamente usando combustibles hidrocarbonados como por ejemplo el gas natural. El riesgo de una baja actividad catalítica para el reformado del combustible, la formación y depósito en el material de ánodo a elevadas temperaturas de operación y la presencia de impurezas en el combustible empleado (en particular de sulfuros) pueden reducir dramáticamente el desempeño y la durabilidad de las celdas. Teniendo todo esto en cuenta, nuevos materiales de ánodo con adecuadas propiedades (electro)catalíticas son necesarios. Recientemente, en el grupo INTERFASE de la Universidad Industrial de Santander (UIS), compuestos de tipo manganita con estructura Ruddlesden-Popper (RP) han sido estudiados como potenciales materiales de ánodo. Su desempeño electrocatalítico ha sido descrito en trabajos previos con promisorios resultados, pero el conocimiento fundamental sobre las propiedades catalíticas de dichos materiales y la forma de mejorarlos mediante la adición de partículas metálicas de níquel en la superficie del electrodo aún faltaba. La presente tesis doctoral se enfocó en la síntesis, caracterización y estudio catalítico en el reformado con vapor en condiciones de ánodo de celdas SOFC (bajo contenido de vapor) de una nueva manganita de tipo RP (La1.5Sr1.5Mn1.5Ni0.5O7±δ), la cual, en atmósfera reductora y a elevadas temperaturas de operación, promueven a través del mecanismo de exsolución la formación de dos fases: una manganita tipo RP de composición LaSrMnO4±δ decorada con nanopartículas metálicas y activas de Ni incrustadas en la superficie; dicha estrategia puede ser vista como una manera muy original de mejorar las propiedades (electro)catalíticas de los materiales de ánodo y por lo tanto ser consideradas como una opción prometedora para sistemas SOFC operados con gas natural colombiano. El primer capítulo trata sobre la síntesis de la fase RP n= 2 La1.5Sr1.5Mn1.5Ni0.5O7±δ usando el método de Pechini y su caracterización. De acuerdo con la temperatura de operación de las celdas SOFC, la exsolución del Ni en atmósfera de H2 diluido a diferentes temperaturas (750, 800 y 850 °C) y tiempos de reducción fue estudiada. Las nanopartículas de Ni decorando la manganita de estructura RP n= 1 es confirmada a través de análisis de DRX, MET-EDS y el tamaño de las partículas metálicas en la superficie del óxido, inferiores a 100 nm, es caracterizado en función de las condiciones de exsolución. El segundo capítulo presenta el comportamiento catalítico del material exsuelto en la reacción de reformado de metano aplicando el concepto de reformado interno gradual (GIR por sus siglas en inglés) adaptado a celdas SOFC (en otras palabras, bajo contenido de agua, relación vapor carbono igual a 0.15) a diferentes temperaturas de reacción (750, 800 y 850 °C). Las propiedades catalíticas de las muestras impregnadas con Ni utilizando como soporte un material cerámico similar (La,Sr)2MnO4±δ, son también presentados como comparación. El material exsuelto exhibe un mejor desempeño catalítico en la reacción de reformado que la manganita impregnada, especialmente a 850 °C, mostrando una más alta conversión, velocidad de conversión y de producción de H2. Con respecto al reformado de la mezcla de alcanos ligeros (CH4 -C2H6, y CH4 -C3H8), el comportamiento catalítico es afectado debido a la competición entre moléculas y la baja disponibilidad de sitios activos metálicos, sin afectar la producción de H2. Adicionalmente, a tiempos de reacción prolongados, la actividad en el material exsuelto es estable incluso con 100 h de reacción, sin formación de especies carbonáceas sobre las partículas de Ni como lo confirman las imágenes MET y el ATG/MS. En el tercer y último capítulo, la posible formación y depósito de carbón y el envenenamiento con sulfuros son presentados. Sin embargo, a pesar de la elevada y estable actividad catalítica en la reacción de reformado de metano con vapor con una considerable resistencia a la formación de carbón, el material exsuelto tiene un alto nivel de sensibilidad al envenenamiento con H2S, similar al Ni/YSZ (material de referencia de la literatura) o al material impregnado con Ni, con una disminución de la actividad catalítica a prácticamente cero No obstante, el excepcional resultado global obtenido en el material exsuelto es prometedor para un posible uso como material de ánodo en sistemas SOFC alimentados con gas natural colombiano libre de H2S.
[CA] Molts són els problemes que han de ser resolts abans que les cel·les de combustible d'òxid sòlid (SOFC per les seues sigles en anglès) puguen operar contínuament usant combustibles hidrocarbonats com per exemple el gas natural. El risc d'una baixa activitat catalítica per al reformat del combustible, la formació i depòsit en el material d'ànode a elevades temperatures d'operació i la presència d'impureses en el combustible emprat (en particular de sulfurs) poden reduir dramàticament l'acompliment i la durabilitat de les cel·les. Tenint tot això en compte, nous materials d'ànode amb propietats (electro)catalítiques adequades són necessaris. Recentment, en el grup d'investigació INTERFASE de la Universitat Industrial de Santander (UIS), compostos de tipus manganita amb estructura Ruddlesden-Popper (RP) han sigut estudiats com a potencials materials anòdics. El seu acompliment electroquímiques ha sigut tractades en treballs previs amb resultats promissoris, però el coneixement fonamental sobre les característiques catalítiques d'aquests materials i la manera de millorar-los mitjançant l'addició de partícules metàl·liques de níquel en la superfície de l'elèctrode encara faltava. La present tesi de doctorat es va enfocar en la síntesi, caracterització i estudi d'activitat catalítica en el reformat amb vapor en condicions d'ànode de cel·les SOFC (sota contingut de vapor) d'una nova manganita de d'estructura RP (La1.5Sr1.5Mn1.5Ni0.5O7±δ), la qual, en atmosfera reductora i a elevades temperatures d'operació, promouen, a través del mecanisme de exsolució; la formació de dues fases: una manganita de composició LaSrMnO4±δ decorada amb nanopartícules metàl·liques i actives de Ni incrustades en la superfície; aquesta estratègia pot ser vista com una manera molt original de millorar les propietats (electro)catalítiques dels materials d'ànode i per tant, ser considerades com una prometedora opció per a futurs usos en sistemes SOFC alimentats amb gas natural colombià. El primer capítol tracta sobre la síntesi de la fase RP n= 2 La1.5Sr1.5Mn1.5Ni0.5O7±δ usant el mètode de Pechini i la seua caracterització. D'acord amb la temperatura d'operació de les cel·les SOFC, la exsolució del Ni en atmosfera d'H2 diluït a diferents temperatures (750, 800 i 850 °C) i temps de reducció va ser estudiada. Les nanopartícules de Ni decorant la manganita d'estructura RP n= 1 és confirmada a través d'anàlisi de DRX, MET-EDS i la grandària de les partícules metàl·liques en la superfície de l'òxid, inferiors a 100 nm, és caracteritzat en funció de les condicions de exsolució. El segon capítol presenta el comportament catalític del material d’exsolució en la reacció de reformat de metà amb vapor aplicant el concepte de reformat gradual intern (GIR per les seues sigles en anglès) adaptat a cel·les SOFC (en altres paraules, sota contingut de vapor, relació vapor-carboni de 0.15) a diferents temperatures de reacció (750, 800 i 850 °C). Les propietats catalítiques de les mostres impregnades amb Ni utilitzant com a suport un material ceràmic similar (La,Sr)2MnO4±δ, són també presentats com a comparació. El material d’exsolució exhibeix un millor resultat catalític en la reacció de reformat que la manganita impregnada, especialment a 850 °C, mostrant una més alta conversió, velocitat de conversió i de producció d'H2. En el reformat de la mescla d'alcans lleugers (CH4 -C2H6, i CH4 -C3H8), el comportament catalític és afectat per la competició entre molècules i la baixa disponibilitat de llocs actius metàl·lics, sense afectar la producció d'H2. Addicionalment, a temps de reacció llargs, l'activitat en el material d’exsolució és estable fins i tot desprès de 100 h de reacció, sense formació d'espècies carbòniques sobre les partícules de Ni, com ho confirmen les imatges MET i el ATG/MS. En el tercer i últim capítol, la possible formació i depòsit de carbó i l'enverinament amb sulfurs són presentats. No obstant això, malgrat l'elevada i estable activitat catalítica en la reacció de reformat de metà amb vapor amb una considerable resistència a la formació de carbó, el material d’exsolució té un alt nivell de sensibilitat a l'enverinament amb H2S, similar al Ni/YSZ (material de referència de la literatura) o el material impregnat amb Ni, amb una disminució de l'activitat catalítica a pràcticament zero No obstant això, l'excepcional resultat global obtingut aquest nou material és prometedor per a un possible ús futur com a material d'ànode en sistemes SOFC alimentats amb gas natural colombià lliure d'H2S.
Al Departamento Administrativo de Ciencia, Tecnología e Innovación (COLCIENCIAS) por la beca de estudios de Doctorados Nacionales Conv. 647 y el proyecto # 110265842833 “Symmetrical high temperature Fuel Cell operating with Colombian natural gas”. Al Consejo Superior de Investigaciones Científicas por el apoyo con la ayuda económica para la estancia mediante la convocatoria I-coop Project # COOPA20112.
Vecino Mantilla, JS. (2020). Nickel exsolution effect on the catalytic behavior of ruddlesden-popper manganites in sofc conditions using colombian natural gas [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/149474
TESIS

The goal of current solid oxide fuel cell (SOFC) research is to design electrode materials and other system components that permit the fuel cell to be operated in the 400-700ºC range. Cell performance in this lower temperature range is limited by the oxygen reduction process at the SOFC cathode and by multiple contamination processes. The work presented demonstrates that Raman spectroscopy, a form of vibrational spectroscopy, can provide structural and compositional information complementary to that from traditional characterization methods. Initial experiments into the oxygen reduction mechanism on SOFC cathodes were unable to detect surface oxygen species on selected perovksite-based SOFC cathode materials. However, the Raman signal from the cathode surface was able to be enhanced by depositing silver or gold nanoparticles on the cathode, creating the so-called surface-enhanced Raman scattering (SERS) effect. The Raman sample chamber was also used to study two possible electrode contamination processes. First, the deposition of carbon on nickel and copper anodes was observed when exposed to different hydrocarbon fuel gases. Second, the poisoning of an SOFC cathode by chromium-containing vapor (usually generated by stainless steel SOFC system components) was monitored. Overall, Raman spectroscopy was shown to be useful in many areas crucial to the development of practical, cost-effective SOFCs. The techniques developed here could also be applied to other high temperature electrochemical and catalytic systems.

Climate change has become a discussion topic of exponentially increasing urgency and importance amoung world leaders of all disciplines. These changes are brought about by the emission of so-called Greenhouse gases from various human activities. The primary cause of CO2 emissions is the burning of the Earth’s supply of nonrenewable natural fossil fuels like coal, oil and natural gas. The world first agreed on the prevention of “dangerous” climatic changes at the Earth Summit in 1992. The Kyoto Protocol of 1997 was the first step toward protection of the atmosphere and prescribes restrictions on emission pollutants. Since then the vehicle gas emissions are being controlled by means of different gas emissions norms, like the European Union Norm in Europe. The automotive manufacturers and suppliers are collectively working on reducing overall vehicle emissions. They are focusing on several different emission limiting possibilities, for example improved engine design, special fuel development and exhaust gas treatment systems. The exhaust gas treatment process requires continuous controlling and management of the exhaust gas emissions while driving a vehicle. Certain factors such as high emission temperatures have a negative influence on the life span of these systems. Their functionality and durability is also known to be reduced by the presence of chemical poisoning species like sulphur, phosphorus, zinc and calcium. The chemical poisoning species are produced during combustion of fuel and engine oil. They are therefore contained in the exhaust emissions and can poison the catalyst when passing over it. Phosphorous poisoning is particularly problematic and should be reduced considerably. This study involves the investigation of the phosphorous poisoning process and aims to provide clarity regarding the influences of different fuel and oil compositions on the severity of the process. Engine oil and biodiesel are two major sources of phosphorous poisoning. The phosphorus contained in biodiesel fuel is a natural component and can be minimized during the refining procedure. In contrast to others studies, the biodiesel fuel used during this project was SME (Soya Methyl Ester) with a 20% biodiesel content. This choice of fuel was made because of the increasingly important role that this type of biodiesel is playing in the European market and the future tendency to increase the percentage of biodiesel in the mixture with standard diesel fuel. The phosphorus contained in engine oil is a necessary additive to retain the antioxidant and anti-wear properties of the oil. This study examined the poisoning influences from the most commonly used phosphorus containing oil additive, Zinc Dithiophosphates (ZDDP), as well as a Zn-free, phosphorus containing anti-wear oil additive. This formulation provides information about the phosphorus poisoning process as caused by the engine oil in the absence of Zn in the oil additives. The results show how the phosphorus content in biodiesel fuel affects the functionality of the exhaust gas treatment systems and the importance of reducing the permitted content of phosphorus contained in the fuel. Reducing the phosphorus content in the fuel will conserve the functionality of the exhaust gas treatment systems during their operational life and thereby protect the environmental from emission pollutants. It also provides insight into the differences in the poisoning processes when the phosphorus deposited on the catalyst comes from biodiesel fuel and when it comes from the engine oil. Finally the results also illustrate the influence of different phosphorous forms contained in engine oil additives on the catalyst poisoning process. This information could be used for the development of new oil additive formulations.

Abstract The combustion of fuels in motor vehicles is one of the most significant causes of air emissions. The use of oxidation catalysts in exhaust gas emission treatment can reduce hydrocarbons (HCs) and carbon monoxide (CO) emissions by more than 90%. Fuels and engine lubricants contain impurities like sulphur (S) and phosphorus (P), which can have a significant effect on the activity and durability of oxidation catalysts. This thesis aims at increasing the current knowledge of the deactivation phenomena caused by sulphur and phosphorus in diesel and natural/bio gas oxidation catalysts. Accelerated laboratory scale sulphur, phosphorus and thermal treatments in gas-phase conditions were carried out for alumina (Al2O3) based platinum (Pt) and platinum-palladium (PtPd) metallic monolith diesel and natural gas oxidation catalysts. In addition, a vehicle-aged natural gas oxidation catalyst and an engine-bench-aged diesel oxidation catalyst were studied and used as a reference for the laboratory-scale-aged catalysts. BET-BJH, FESEM, TEM, XPS and DRIFT were used as characterization techniques to determine changes on the catalysts. The effect of accelerated deactivation treatments on the catalyst activity was determined using laboratory scale measurements in CO, HC and nitric oxide (NO) oxidation. Sulphur and phosphorus were found to cause morphological and chemical changes on the studied catalysts. Sulphur was found to be adsorbed vertically throughout the entire catalyst support from the catalyst surface to the metallic monolith, while phosphorus accumulated on the surface region of the precious metal containing catalysts. Both, sulphur and phosphorus, slightly increased the average size of the precious metal particles size and are adsorbed onto the alumina by chemical bonds. In addition, a partial transformation from PdO to Pd and a change in the shape of the precious metal particles due to phosphorus were detected. Due to the detected structural and chemical changes on the catalysts, sulphur and phosphorus treatments reduced the catalytic activity of the studied diesel and natural-gas-oxidation catalysts. Correspondence between real and simulated ageing was found and thus the used accelerated laboratory scale aging method can be stated to be a good tool to simulate sulphur and phosphorus exposure
Tiivistelmä Moottoriajoneuvot ovat merkittäviä ilmapäästöjen aiheuttajia. Hapetuskatalyyttejä käyttämällä hiilimonoksidi- ja hiilivetypäästöistä pystytään poistamaan yli 90 %. Polttoaineet ja voiteluaineet sisältävät epäpuhtauksia kuten rikkiä ja fosforia, jotka voivat merkittävästi heikentää hapetuskatalyyttien aktiivisuutta ja kestävyyttä. Väitöskirjan tavoitteena on tuottaa uutta tietoa rikin ja fosforin aiheuttamasta diesel- ja maakaasukatalyyttien deaktivoitumisesta. Metalliseen monoliittiin tuettuja alumiinioksidipohjaisia platina- ja palladiumkatalyytteja ikäytetiin tekemällä niille rikki-, fosfori- ja lämpökäsittelyjä. Maantieikäytettyä maakaasuhapetuskatalyyttiä ja moottoripenkki-ikäytettyä dieselhapetuskatalyyttiä käytettiin laboratorioikäytettyjen katalyyttien referensseinä. Ikäytyskäsittelyjen aiheuttamat muutokset analysoitiin BET-BJH-, FESEM-, TEM-, XPS- ja DRIFT-menetelmillä. Käsittelyjen vaikutus katalyyttien hiilimonoksidin, hiilivetyjen ja typenoksidien hapetusaktiivisuuteen tutkittiin laboratoriomittakaavan aktiivisuuslaitteella. Rikki ja fosfori aiheuttivat rakenteellisia ja kemiallisia muutoksia tutkittuihin katalyytteihin. Rikki adsorboitui koko tukiaineeseen (tukiaineen pinnalta pohjalle), kun taas fosfori adsorboitui vain pinnan alueelle. Sekä rikki että fosfori kasvattivat jalometallipartikkeleiden kokoa sekä muodostivat alumiinioksidin kanssa yhdisteitä. Lisäksi fosforikäsittelyjen havaittiin osittain pelkistävän PdO:n Pd:ksi ja muuttavan jalometallipartikkelien muotoa. Havaitut rikin ja fosforin aiheuttamat rakenteelliset sekä kemialliset muutokset laskivat diesel- ja maakaasukatalyyttien hapetusaktiivisuutta. Laboratorioikäytyksillä havaittiin olevan hyvä korrelaatio todellisissa olosuhteissa tehtyjen ikäytysten kanssa ja tästä syystä työssä käytetyn laboratoriomittakaavan ikäytysmenetelmän voidaan todeta olevan hyvä työkalu simuloimaan rikin ja fosforin aiheuttamaa deaktivoitumista

Car exhaust catalysts were introduced in the early 1980’s, to limit the release of pollutants such as hydrocarbons, carbon monoxides and nitrogen oxides. These catalysts contain noble metals such as palladium (Pd), platinum (Pt) and rhodium (Rh) and are able to simultaneously abate all three of the above-mentioned pollutants, hence the name three-way catalyst (TWC). The exposure to high temperatures (800-1000 °C) during operation and the presence of additives in petrol such as lead, calcium, silicon, magnesium, manganese, chromium, sulphur and phosphorus will after a certain time start to lower the overall effectiveness of the catalyst. These effects are either of a mechanical or a chemical nature. High temperatures reduce the active area by causing the noble metals to agglomerate and sinter whereas the additives alter the activity by either fouling the pores of the support material (phosphorus) or by interacting with the metals (sulphur and lead).

The main objective of this work was to develop a method to redisperse the catalytically active sites, comprising Pd, Pt and Rh on the washcoat surface, in an effort to regain lost catalyst activity. For this purpose, a wide spectrum of different commercial car exhaust catalysts containing varying noble metal loadings, aged under various driving conditions and with mileages ranging from 30 to 100 000 km were evaluated.

The influence of a thermal treatment in a controlled gas atmosphere, such as oxygen or hydrogen and a redispersing agent, e.g. chlorine, on the activity of TWC was investigated by means of laboratory-scale activity measurements. Several complementary characterisation methods such as SEM/TEM, XRD, BET and TPR were used to verify the effects of the regeneration treatments on the catalyst morphology (Paper I). Partial regeneration of catalyst activity and noble metal dispersion was achieved after thermal treatment in an oxygen-chlorine rich atmosphere at temperatures below 500 °C.

Finally, an investigation of the effects of an oxy-chlorine thermal treatment for regeneration of a ‘full-scale’ commercial automotive three-way catalyst was performed. Catalyst activity and performance prior to and after the oxy-chlorine thermal treatment was measured on a test vehicle in accordance with the European driving cycle (EC2000). The catalyst surface was further characterised using XRD and EDX (Paper II). Improved catalyst activity for a high mileage catalyst could be observed, with emissions lowered by approximately 30 to 40 vol% over the EC2000 driving cycle

A estatística das principais causas das intoxicações mostra que os depressores do sistema nervoso central (SNC) têm uma participação significativa. No Centro de Controle de Intoxicações da Unicamp, em 1995, 30% das intoxicações foram por medicamentos, sendo a metade por depressores do SNC. A avaliação do paciente intoxicado, freqüentemente inclui, além de exames clínicos, análises laboratoriais para identificação de agentes tóxicos presentes em amostras biológicas. Os procedimentos analíticos com esta finalidade utilizam diversas técnicas, entre elas as cromatográficas. O objetivo do presente trabalho foi desenvolver e otimizar um método de triagem para diagnóstico laboratorial das intoxicações por medicamentos que causam depressão do SNC, através da cromatografia em fase gasosa, para ser utilizado em análises de urgência em Centros de Controle de Intoxicações. Foram selecionados 21 fármacos depressores do SNC a partir de critérios de freqüência e importância clínico-toxicológica. As técnicas de extração apresentaram recuperação relativa entre 66,4 e 92,6% para a urina e entre 36,7 e 82,6% para o plasma. O estudo de precisão apresentou coeficiente de variação entre 4,3 e 13,7% para as amostras de urina e entre 7,8 e 19,4% para o plasma. A sensibilidade foi testada para concentrações próximas aos níveis terapêuticos (1 a 5 µg/mL) tendo sido considerada satisfatória e a análise de extratos de \"brancos\" de referência apresentou cromatograma sem interferentes. O tempo de análise foi compatível com a necessidade clínica (menor que duas horas) para análise concomitante dos 21 fármacos. Pode-se concluir que o método de triagem por cromatografia gasosa proposto foi adequado para o diagnóstico laboratorial das intoxicações agudas por medicamentos que causam síndrome de depressão do SNC.
Drugs that cause Central Nervous System Depression Syndrome (CNSDS) have an important role in poisons. At the Poison Control Center of University of Campinas, in 1995, 30% of poisons were due to medicines and a half of that was due to CNS depressants. The evaluation of the poisoned patient includes, in addition to clinical examinations, laboratorial screenings to identify toxic agents in biological samples. The analytical procedures with this endpoint use several methods, including chromatographic analyses. The objective of this study was to develop and to optimize a procedure for screening drugs that cause CNSDS, through gas chromatography, to be used in emergency assays at the Poison Control Center. Twenty one drugs were selected using frequency and clinical-toxicology importance criteria. The extraction technique presented relative recuperation between 66.4 and 92.6% for urine and 36.7 and 82.6% for plasma. The intra-assay coefficient of variation was between 4.3 and 13.7% for urine and 7.8 and 19.4% for plasma. The sensibility was tested for concentrations near therapeutical levels (1 to 5 µg/ml) and was considered satisfactory. The chromatogram of blank sample extract presented no interferences. The time required to screen 21 drugs in plasma and urine samples was less than 2 hours, making this method appropriate for use in poison control center in hospitals.

Le silicium est connu pour être un poison sévère des catalyseurs d'hydrotraitement (HDT). L’objectif de la thèse a donc été de mettre en place des outils analytiques pour la spéciation du silicium afin d'identifier toutes les molécules silicées réellement formées dans les charges d'HDT. Différents outils analytiques de pointe basés sur des couplages entre la chromatographie en phase gazeuse et la spectrométrie de masse (MS et ICP/MS) ont été développés. Étant donnée la réactivité de certaines espèces silicées, des échantillons représentatifs de la dégradation du PDMS ont été produits dans des conditions de craquage thermique d'un mélange heptane/xylène. L'application à ces échantillons de la stratégie analytique, développée initialement, a démontré la présence du silicium sous différentes formes chimiques. Plus d’une centaine de molécules réparties en 10 familles comprenant un nombre d’atomes de silicium entre 1 et 1500 a été caractérisée. Ces composés silicés vont donc pouvoir être présents dans toutes les coupes pétrolières, des fractions gaz aux fractions les plus lourdes, couvrant ainsi un domaine de coupes pétrolières beaucoup plus vaste que celui des essences. Les siloxanes cycliques (Dn) ont été confirmés comme produits majoritaires de dégradation du PDMS. Les autres composés silicés, jamais caractérisés pour la plupart, sont présents à l’état de traces mais possèdent des groupements réactifs de type hydroxy, métoxy, hydropéroxy susceptibles d’interagir fortement avec le support du catalyseur (Al2O3) et donc de conduire à sa désactivation
Silicon is known to be a severe poison for hydrotreatment (HDT) catalysts especially in naphtha and gasoline samples. The objective of the PhD was to develop analytical methods for silicon speciation in order to characterize silicon molecules formed during refining steps which potentially affects HDT catalysts. For the analytical strategy, different high-technology analytical tools based on gas chromatography coupled to mass spectrometry (MS and ICP/MS) were developed. Due to the high reactivities of several silicon species, representative samples of PDMS degradation were produced under thermal cracking of a mixture of heptane/xylene (500°C) using a pilot plant. The previously developed analytical strategy was applied to these samples and demonstrated the occurrence of silicon under a wide array of chemical forms. More than a hundred of silicon species belonging to 10 chemical families with a number of silicon atoms ranging from 1 to 1,500 were characterized. These silicon compounds could be present in all petroleum cuts, from the gas fractions to the heavier fractions. Therefore, the investigated range of boiling points was inevitably more important than for naptha and gasoline cuts. Cyclic siloxanes (Dn) were confirmed as the major PDMS degradation products. The other silicon compounds, almost never characterized before, were recovered at trace levels but consisted of reactive groups such as hydroxy, methoxy and hydroperoxy. These silicon species were able to strongly react with the catalytic support (Al2O3) and led to its deactivation

Ricin je prirodni protein, toksin koji spada među najpristupačnije i najsmrtonosnije otrove. Nalazi se u biljci Ricinus (Ricinus communis), sa najvećim sadržajem u semenu (1-5 %). Ricin se smatra potencijalnim bioterorističkim oružjem i prema riziku za ljudsko zdravlje svrstan je u B kategoriju biološkog oružja. U novije vreme korišćen je za konstruisanje imunotoksina protiv tumorskih ćelija u terapiji maligniteta. Dokumentovana su mnoga trovanja ricinom, kako zadesna, tako i samoubilačka i ubilačka. U tu svrhu koristilo se intaktno seme ricinusa ili ekstrahovani ricin. Osim ricina, u semenu ricinusa je prisutan toksični alkaloid ricinin u količini 0.3-0.8 %. Ricinus je jedini poznati prirodni izvor ricinina, koji se ko-ekstrahuje sa ricinom iz semena biljke. Ricinin se jednostavno detektuje u kliničkim uzoracima metodom tečne hromatografije i masene spektrometrije i, s obzirom na komplikovanu identifikaciju ricina u biološkim uzorcima, smatra se biomarkerom za intoksikaciju ricinusom, odnosno ricinom. Osnovni ciljevi ovog istraživanja su da se uz pomoć HS-GC metode i patohistološkom  analizom dokaže prisustvo ricinina u krvi laboratorijskih pacova u odnosu na vremenski interval koji je protekao od oralne aplikacije suspenzije do vremena žtvovanja, da se odredi distribucija i koncentracija ricinina u organima laboratorijskih pacova u različitim vremenima žrtvovanja, kao i da se utvrdi da li postoji značajna razlika u razvoju patomorfoloških promena na organima laboratorijskih pacova u različitim vremenima žrtvovanja. Istraživanje je bilo otvoreno, randomizirano i prospektivnog tipa. Laboratorijski pacovi su u istom vremenu oralno tretirani suspenzijom koja je sadržaja subletalnu koncentraciju ricina. Nakon žrtvovanja u precizno definisanim vremenskim intervalima uzeti su uzorci krvi i unutrašnjih organa radi daljih analiza. Odgovarajući uzorci su analizirani metodom HC-GS u cilju određivanja koncentracije i distribucije ricinina, kao pouzdanog markera trovanja ricinom, u krvi i unutrašnjim organima. Takođe je izvršena patohistološka analiza uzoraka tkiva unutrašnjih organa u cilju utvrđivanja promena izazvanim delovanjem ricina u odnosu na vreme proteklo od aplikacije suspenzije. Dobijeni rezultati su obrađeni odgovarajućim statističkim metodama. Rezultati istraživanja omogućavaju standardizaciju postupaka odabira reprezentativnih uzoraka prilikom sumnje na trovanje ricinusom i metode dokazivanja akutnog trovanja. Na taj način može se pouzdano i efikasno dokazati trovanje ricinusom.
Ricin is a naturally occurring protein, a toxin which belongs to the category of the most accessible and the most lethal poisons. It is obtained from the castor oil plant ( Ricinus communis), whose seeds contain its highest content (1-5%). Ricin is also thought to be a potential weapon of bioterrorism and taking into account the risk for human health, it is classified as a biological weapon category B. Lately it has been used for the construction of the immunotoxins against tumor cells in the therapy of malignant diseases. Numerous poisonings using ricin have been documented, not only accidental poisoning, but also in case of suicides and homicides. In those cases, intact ricin seeds or extracted ricin were used. Apart from ricin, castor oil plants also contain a toxic alkaloid ricinine (0.3-0.8%). Castor oil plants are the only known natural source of ricinine, which is co-extracted with ricin from the seeds of this plant. Ricinine is simply detected in clinical samples by using the method of liquid chromatography and mass spectrometry. Taking into account a complicated identification of ricin in biological samples, it is considered to be a biomarker for the intoxication by castor oil plant, or ricin itself. The main aim of this research is to use the HS-GC method and pathohistological analysis in proving the existence of ricinine in the blood of experimental rats in relation to the time interval between the oral application of solution of castor seeds in water and the time of sacrificing, to determine the distribution and concentration of ricinine in the organs of experimental rats, as well as to establish whether there was a significant difference in the development of pathomorphological changes on the organs of experimental rats at various points of sacrificing. The research was open, randomised and prospective. Experimental rats were simultaneously orally tested by the solution which contained sublethal concentration of ricin. After sacrificing, blood samples were taken from inner organs in specifically defined intervals of time and used for further analysis. The appropriate samples were analysed by HC-GS method in order to determine the concentration and distribution of ricinine as a reliable marker of ricin poisoning in blood and inner organs. Also, pathohistological analysis of the samples of inner organ tissues was made with the purpose of establishing the changes caused by the effects of ricinine in relation to time which passed from the application of the solution. The obtained results were processed by appropriate statistical methods. The results of this research allow for the standardisation of the actions in selecting the representative samples in case there is a possibility of ricin poisoning and the method of proving the acute poisoning. Following these steps, ricin poisoning can be proved in a reliable and an efficient way.

碩士
國立交通大學
機械工程系所
101
This study numerically investigates the effects of window position、window area and aheap stuff on the formation of carbon monoxide in a balcony with gas water heater. Simulations are carried out with a transient and multicomponent combustion model, using Fire Dynamics Simulator (FDS). The model is validated by the comparison with experiment. The simulated results show that a good agreement between predicted data of present model and the experimental results. The following conclusions are obtained by this research: 1. The balcony is considered to be safe within 20 minutes if it’s empty and the window-width is equal or more than to 0.2m. 2. Hanging clothes in front of the window will reduce exhaust-efficiency, therefore, the window have to open more widely than 0.25m to keep the balcony safe. 3. Heaping stuff on the floor restricts the region of oxygen water heater can absorb, which makes the balcony with window opened for 0.2m no more safe. Otherwise, to raise the stuff can help the water heater absorb oxygen and keep the balcony safe with the same window opened width 0.2m. 4. The water heater in balcony should not be higher than windows and the position should not be right above or right below the window. 5. Using water heater of forced exhaust can make carbon monoxide concentration to be zero in balcony within 20 minutes.

Little is known of tissue carbon monoxide (CO) changes after acute exposure because tissue levels are in the order of picomoles per milligram and the technology to measure such low concentrations has only become available relatively recently. This study tested three hypotheses: That tissue CO levels (1) vary among tissues after acute poisoning; (2) change over time; but (3) cannot be predicted by measuring carboxyhaemoglobin (COHb) levels. Twenty four healthy male Sprague-Dawley rats were exposed to 2500 ppm CO in air for 45 min. This non-lethal exposure achieved reproducible COHb values of 66 to 72%. Animals were allowed to recover breathing air and were sacrificed at 30 minute intervals for 150 minutes. An additional nine male animals served as unexposed controls. Accurate measurements of tissue CO levels were made in blood, brain, heart, and skeletal muscle samples. All samples were prepared using the validated technique described by Vreman et al., and Reduction Gas Analysis was used to determine the pmol CO per wet weight tissue. Co-oximetry and gas chromatography were performed on all blood samples. Predictably, blood CO content dropped following exposure, but tissue CO content did not follow the same trend in all tissues. This study supports the hypothesis of (1) tissue and (2) time-related variability of CO concentration in three body tissues after exposure and (3) documents lack of utility of COHb for predicting tissue CO tissue values.
Dissertation (MSc)--University of Pretoria, 2007.
Nuclear Medicine
Unrestricted

碩士
中華科技大學
土木防災工程研究所在職專班
105
The prevention of carbon monoxide poisoning is one of the most important duties of firefighters. In order to complete this task, fire departments of cities have increased the home visit service of gas-operated geyser by every winter for recent years. Although firemen have been dedicating to visit houses by houses and guide people to be aware of the carbon monoxide poisoning, deadly cases still happen a lot. By analyzing the statistic data of recent years, the cause of carbon monoxide poisoning cases is mostly from the gas-operated geyser which is wrongly istalled indoors or at raletively airtight space, like baconies with bad ventilation (ex. hanging clothes or illegal buildings). Therefore, It’s necessary to study how to improve the prevention of carbon monoxide poisoning. While firemen of the responsible area visit houses and instruct some guideline of preventing carbon monoxide poisoning, they will suggest the resident, who lives with the potential causes of carbon monoxide poisoning, to move the gas-operated geyser or to replace it by a new model. Within the period of Fire Department subsidizing, which is from January to April, people tend to agree to move or to replace the gas-operated geyser. Relatively, people tend to remain original rather than changing while the period without subsidizing, which is from May to December, that causes an ineffective result of preventing carbon monoxide poisoning. So it is necessary to come up with some plan to improve the willing of people to be aware of the potential causes of carbon monoxide poisoning, and the willing to correct immediately. This study, consults with the home-visiting experience of firemen from different organizational level, expects to find the best way through Analytic Hierarchy Process(AHP) to prevent carbon monoxide poisoning. This study finds the most important factor of choosing a way to prevent carbon monoxide poisoning is cost, followed by safety, time, human resources and diversity. Considering these factors, preferential offers by gas-operated geyser manufacturers, replacement of old geyser and legislative punishment is the best solution. This study may contribute to the enhancement of preventing carbon monoxide poisoning in the future. Keywords：Home visits, Gas heater, Prevent carbon monoxide poisoning, Analytic Hierarchy Process