L'objectif de cette thèse est de développer un outil prédictif pour calculer les équilibres vapeur-liquide (VLE) associé à l'opération d'hydrotraitement à partir de biomasse pour la simulation de processus. La construction d'une base de données de solubilité fiables d'hydrogène et d'autres gaz d'hydrotraitement ont été réalisées. Le modèle utilisé a pour base l’équation Groupe Contribution- Polar Perturbed Chain - statistique Associer Fluid Theory (GC-PPC-SAFT), qui est version de PC-SAFT combiné avec la contribution de groupes proposé par Tamouza et un terme polaire développé par Nguyen Huynh. Des tests systématiques ont été effectué pour différents mélanges gaz + d'alcools, aldéhydes, esters, éthers, cétones, ... Une nouvelle contribution non-additif a été proposé sur la base des réflexions sur les interactions répulsives et l’effet de volume libre. Le modèle a été validé notamment par des simulations Monte Carlo. Ce terme non additif a été intégré dans GC-PPC-SAFT et testé pour les systèmes contenant de l'hydrogène. La méthode de contribution de groupes a été étendue au paramètre de ce nouveau terme. Des écarts moyens sur la constante de Henry sont en accord avec l'incertitude expérimentale (~ 10%). Nous avons également examiné la prédiction d’ autres gaz i.e. CO, H₂ S, NH₃ en utilisant GC-PPC-SAFT. Un paramètre associatif transversale a été utilisé pour des systèmes contenant H₂ S et NH₃. Les résultats sont tout à fait acceptable et cohérent avec l'incertitude expérimentale (~20%). / The main objective of this thesis is to develop a predictive tool to compute the vapor-liquid equilibria (VLE) associated with hydrotreating operation from biomass for process simulation. The construction of a reliable database of hydrogen and the other hydrotreating gases solubilities have been done. The model used based on the Group Contribution – Polar Perturbed Chain – Statistical Associating Fluid Theory (GC-PPC-SAFT), which is PC-SAFT combined with the group contribution proposed by Tamouza and a polar term developed by Nguyen Huynh. The systematic tests have been perform for mixtures of alcohols, aldehydes, esters, ethers, ketones,… A new non-additive contribution has also been proposed based on the reflections on the repulsive interactions and the free volume effect. The model development are validated by Monte Carlo simulations. This non-additive term has been integrated in GC-PPC-SAFT Equation of state and tested for systems containing hydrogen. Group contribution method has been extended to its parameter. Average deviations on Henry’s constant are within the experimental uncertainty (~10%). We also have performed the prediction of the other gases i.e. CO, H₂S, NH₃ solubility using GC-PPC-SAFT. A cross associative parameter has been used for systems containing H₂S and NH₃. The results are quite acceptable and within the experimental uncertainty (~20%).

No description available.

Dissertation (Ph.D.)--Auburn University, 2007. / Abstract. Includes bibliographic references (p.111-131).

</p> Part I The mass spectra of the seven isomeric monomethoxyquinolines, the seven monohydroxyquinolines, the two N-methylquinolones and six furoquinoline alkaloids have been recorded. Fragmentation mechanisms are proposed to account for the major peaks in all the spectra. Use has been made of intense metastable peaks found in most of the spectra to aid the interpretation of the fragmentation routes. In addition, deuterium and carbon-13 labelling have been employed in analyzing the fragmentation routes of the methoxyquinolines. </p> <p> Part II The Hofmann degradation of lobinaline is described. Examination of lobinaline, its derivatives and its Hofmann degradation products by mass spectrometry and other physical and chemical techniques has allowed a structure to be assigned to the alkaloid.</p> / Thesis / Doctor of Philosophy (PhD)

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: With worldwide emissions standards becoming more stringent over the last decade, the South African market seems set to follow suit. Older technology engines are however unable to attain these stringent standards and will require cleaner burning fuels. Biofuels like biodiesel and bioethanol-diesel blends are an attractive option as a result of their inherently oxygenated nature and renewable, low carbon footprint. Oxygenated fuels have been found to lower particulate and soot emissions without any significant increase in NOx, thus alleviating the usual particulate-NOx trade-off. In this study an existing diesel engine test facility has been upgraded to include emission equipment, and a low cost pressure indicating system. Fuel-to-fuel comparative testing was done with pump diesel and splash blended fuels consisting of pump diesel blended with varying amounts of ethanol and also biodiesel without including any cetane enhancing or blend stability additives. Emission analysis of the blended fuels showed a marked reduction in soot emission with little to no increase in NOx emission for all oxygenated fuels. This type of soot reduction without NOx increase is difficult to obtain through any other method. Blend stability was however a problem with the 15% ethanol-diesel blends. / AFRIKAANSE OPSOMMING: Met wêreldwye uitlaatgas standaarde wat al hoe strenger geword het oor die laaste dekade, lyk dit asof dit net ‘n kwessie van tyd is voor Suid-Afrika dieselfde roete volg. Ouer tegnologie binnebrandenjins kan egter nie hierdie streng standaarde handhaaf nie en sal dus vereis dat die brandstof skoner brand. Biobrandstowwe, soos biodiesel en bio-etanol-diesel mengsels, blyk ‘n aantreklike opsie te wees vanweë hul natuurlike inhoud van suurstof en as hernubare hulpbron. Wanneer suurstof houdende brandstowwe soos hierdie verbrand word, word daar gevind dat daar ‘n daadwerklike afname in rook uitlaat is sonder enige merkbare toename in NOx uitlaatgasse. Dit is teenstrydig met die gewoonlike wisselwerking wat daar tussen hierdie twee uitlaatgas produkte is. In hierdie studie word die bestaande diesel enjin toetssel opgegradeer om uitlaatgas analiese toerusting asook ‘n lae-koste silinderdruk meettoestel te bevat. Brandstof-tot-brandstof vergelykings toetse word gedoen met gewone diesel asook toets diesel wat gemengde konsentrasies biodiesel of bio-etanol bevat. Die toets diesel bevat egter geen aanvullings om mengselstabiliteit of cetaan te verbeter nie. Toetsresultate toon dat daar merkbare vermindering in rook uitlaat is met min tot geen toename in NOx. Hierdie tipe van resultaat met produkte van ontbranding is moeilik om op enige ander manier te bewerkstellig. Daar word ook gevind dat diesel met 15 % bio-etanol nie ‘n stabiele mengsel is nie en dat fase skeiding plaasvind.

D. Tech. Mechanical Engineering. / Discusses how to reduce the negative impacts of petroleum oil based fuels in reciprocating engines on the environment through the use of oxygenated (alcohol) blends, while not deteriorating engine performance. The specific objectives are as follows: To evaluate the performance characteristics of n-butanol-diesel blends: B5, B10 and B20, in a direct-injection turbo-charged diesel engine and to compare findings with a study that was carried out by others (Sayin, 2010). To compare the performance, combustion and emission characteristics of dual alcohol-gasoline with single alcohol-gasoline blends fired in a naturally-aspirated (NA) spark ignition (SI) engine. To compare the combustion and emission characteristics of dual alcohol (methanol-n-butanol-gasoline) blends with single alcohol (methanol-gasoline) blends in a single-cylinder SI engine. To evaluate the combustion and regulated emission characteristics of DF and n-butanol/diesel blends (B5, B10, and B20 where B5 represents 5 % shared volume of n-butanol to 95 % diesel fuel) fired in a high load turbo-charged diesel engine and to compare the findings with a study that was conducted by Raslavicius & Bazaras, (2010).

The behavior of Deepwater Horizon crude oil and other sources of oil were investigated when exposed to sunlight in aquatic systems under environmentally relevant conditions. This research decoupled the abiotic and biotic weathering modifications of oil by focusing solely on the photochemical transformations of oil in aquatic systems. Photochemical rates and mechanisms were measured through the determination of reactive transients. Total hydroxyl radical formation was studied using high benzoic acid concentrations and varying exposure time. Titanium dioxide (TiO2) nanomaterials were added to the system in an effort to determine if the photocatalyst would enhance oil photodegradation. Photochemical production of singlet oxygen from thin oil films over seawater and pure water was measured with furfuryl alcohol as a selective chemical probe. The loss of furfuryl alcohol and the formation of 6-hydroxy(2H)pyran-3(6H)-one were monitored. Photochemical production of organic triplets from 6 different compositions of petroleum was measured through the cis-trans isomerization of 1,3 pentadiene in Gulf water. The data correlate very well with previously measured singlet oxygen concentrations. The energies were measured in the range of 280-300 kJ/mol. Macondo Well Oil from the Deepwater Horizon (DWH) rig was mixed with pure water and seawater and irradiated with simulated sunlight. After irradiation, the water-soluble organics (WSO) from the dark and irradiated samples were extracted and characterized by ultrahigh resolution Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). Liquid-liquid extraction yielded two fractions from dark and irradiated water/oil mixtures: acidic WSOs (negative-ion electrospray (ESI)), and base/neutral WSOs (positive-ion ESI). These fractions were analyzed by FT-ICR MS to catalogue molecular-level transformations that occurred to oil-derived WSOs after solar irradiation. The increased abundance of higher-order oxygen classes in the irradiated samples relative to the dark samples indicates that photooxidized components of the Macondo crude oil become water-soluble after irradiation. Time series studies were performed to observe the changes in WSO composition. The predominance of higher-order oxygen classes indicates that multiple photochemical pathways exist that result in oxidation of petroleum compounds. More oxygenated compounds were observed in the WSO acid fraction of oils with higher API gravity.

The detection and identification of the oxygenated class of ignitable liquids is a complex issue for the fire debris analyst. The oxygenated compounds are difficult to recover using traditional analytical techniques since their chemical characteristics are vastly different from those of the petroleum products that compose the majority of the ignitable liquid classes. Previous research has demonstrated that the use of zeolite 13X as an adsorbent in heated passive headspace concentration provides increased recovery of oxygenated compounds in comparison to the conventional activated charcoal adsorbent. This hypothesis was further tested in this work using more realistic casework scenarios. Various carpet, carpet padding and wood types were utilized in a number of burn conditions in order to determine if any substrate interferences were present; as well as to monitor the recovery of oxygenated compounds from these substrates using the proposed zeolite extraction method. The substrates explored did not contribute significant background interference to complicate the identification of the oxygenated compounds. In addition, small volumes of the oxygenated ignitable liquids were easily recovered and identified from all burn states using the zeolite method. A dual-mode extraction with both zeolites and activated charcoal strips as adsorbents was utilized with mixtures of oxygenated compounds and petroleum products to determine if a variety of ignitable liquid classes could be detected and identified in the presence of a variety of substrate matrices within a single extraction protocol. The dual-mode extraction showed that both the oxygenated compounds and petroleum products could be detected and identified using a single extraction protocol in the presence of various substrate matrices. Lastly, an experiment was devised to compare the recovery of the oxygenated compounds using various total available surface areas of both zeolites and activated charcoal strips in order to determine which adsorbent exhibits a greater recovery when all other experimental conditions remain constant. When the surface areas were equalized between the zeolites and activated charcoal strips, the activated charcoal exhibited a greater recovery of the oxygenated compounds. However, the cost effectiveness of the zeolites allows for a greater amount of zeolite beads to be used in order to achieve the same recovery as the activated charcoal strips for a much lower price. Therefore, the findings from this work, in combination with previous research, continue to support the use of zeolite 13X as an alternative adsorbent for the recovery of oxygenated ignitable liquids from fire debris evidence.

As xantonas compreendem uma importante classe de heterocíclicos moleculares que possuem um esqueleto dibenzo-gama-pironas, podendo estes serem obtidos tanto por meios sintéticos quanto naturais. Estes constituintes têm sido freqüentemente isolados de plantas medicinais brasileiras e vêm recebendo atenção devido a seus aspectos fitoquímicos e suas propriedades biológicas. No entanto, poucos estudos são dedicados à abordagem estrutural mais aprofundada desses compostos no estado sólido, principalmente com relação a estudos cristalográficos. Uma justificativa para a escassez de trabalhos dessa natureza pode estar relacionada com a dificuldade de obtenção de cristais de qualidade. Com isso, a primeira etapa deste trabalho dedicou-se à obtenção de monocristais dos derivados xantônicos e, posteriormente, realizaram-se as medidas de difração de raios X por monocristal. Após a coleta de dados de difração de raios X, as estruturas cristalinas foram resolvidas e refinadas. Neste trabalho estudaram-se doze estruturas cristalinas de derivados xantônicos oxigenados, sendo que, uma das xantonas tetra-oxigenadas apresentou dois polimorfos. Portanto, onze constituintes quimicamente diferentes estão envolvidos (I-XI). Ressalta-se que das doze estruturas determinadas por difração de raios X apenas uma, III, trata-se de uma redeterminação, as demais foram estudadas pela primeira vez. Através da estrutura refinada estudou-se as geometrias moleculares de cada composto. Em relação aos aspectos intramoleculares, destacam-se as conformações dos anéis e substituintes, além dos efeitos causados pelos mesmos. Assim, observou-se que existe a tendência do sistema de anéis xantônicos apresentar uma conformação planar, e isso foi confirmado por cálculos de otimização de geometria. Na conformação molecular das xantonas 1-hidroxiladas, o efeito de ligação de hidrogênio assistida por ressonância (LHAR) foi exaustivamente estudado. As interações intermoleculares mostraram que a grande maioria das estruturas cristalinas são estabilizadas por ligações de hidrogênio fortes (OH...O) e fracas (CH...O). Além disso, as informações cristalográficas mostraram a existência de interações pi-pi, um importante contato hidrofóbico que contribui para manter o arranjo supramolecular. / Xanthones are a group of heterocyclic molecules having a dibenzo-gama-pyrone skeleton, and can be obtained as a synthetic or natural product. These compounds have often been afforded from Brazilian medicinal plants and have received special attention due to their phytochemical and biological properties. However, this compound class was seldom studied in the solid state, mainly with regard to the crystal structure. The lack of crystallographic studies can be explained due to the difficulties found in the production of single crystals. So, the goal of the first stage of this project was to obtain well shaped single crystals of the xanthones derivatives and then to perform X-ray diffraction measurements. After the data collection, the crystal structures were solved and refined. Here, twelve crystal structures of oxygenated xanthones derivatives were studied, in which one tetra-oxygenated xanthone presented two crystal forms. Hence, there are eleven chemically different constituents (I-XI) involved in the context of the xanthones. It is worth to emphasize that only the structure named III was a redetermination, being the others ones studied by X-ray diffraction for the first time. The molecular geometric parameters of each compound were provided by the refined structure. Despite the intramolecular aspects, the conformations of the rings and the substituents were highlighted, besides the effects caused by them. Usually, in the xanthone rings the preferred conformation is the planar, which was confirmed by theoretical calculations. The effect of the resonance assisted hydrogen bond (RAHB) on the molecular conformation was widely studied in the 1-hydroxylated xanthones derivatives. Finally, the intermolecular interactions and their meaning to the crystal structures stabilization were discussed, revealing that in almost all xanthones, the crystal packing are kept by strong (OH...O) and weak (CH...O) hydrogen bonds. In addition, the crystallographic analysis also pointed out to the presence of interactions pi-pi, an important hydrophobic contact for supramolecular assembly.

Ce travail de thèse a pour but de proposer des potentiels d'interaction et des méthodologies pour prédire, au travers de simulations Monte Carlo, les équilibres et propriétés de phases de systèmes oxygénés rencontrés dans les procédés de conversion de la biomasse. Le potentiel AUA4 a ainsi été étendu aux alcools, éthers, cétones, aldéhydes et esters carboxyliques. Une attention particulière a été portée à la transférabilité de ce champ de forces, afin de pouvoir simuler de manière prédictive un grand nombre de molécules oxygénées. Différentes propriétés d'équilibre de corps purs sont correctement prédites (masses volumiques, pressions de saturation, enthalpies de vaporisation, propriétés critiques, tensions de surface, structure de la phase liquide). De nombreux mélanges ont également été simulés dans le pseudo-ensemble point de bulle, qui a été étendu aux molécules polaires dans le cadre de ce travail. Les résultats de simulation de mélanges complexes comme des bioessences ont été validés par l'acquisition de nouvelles mesures expérimentales. Enfin, une nouvelle méthodologie pour le calcul des interactions électrostatiques intramoléculaires a été mise au point dans ce travail pour la simulation de molécules oxygénées multifonctionnelles (polyols, éthers de glycol, composés aromatiques oxygénés). L'utilisation de cette méthode, qui permet d'éviter l'emploi de paramètres empiriques additionnels, conduit à des résultats très encourageants, ce qui laisse entrevoir de nombreuses perspectives pour la prédiction de propriétés de mélanges industriels complexes. / The goal of this thesis work is to propose interaction potentials and numerical methods to predict through Monte Carlo simulations the phase equilibrium and properties of oxygenated systems involved in biomass conversion processes. The AUA4 potential was therefore extended to alcohols, ethers, ketones, aldehydes and carboxylic esters. A special care was paid to the transferability of this force field to allow the predictive simulation of a large number of oxygenated compounds. Various equilibrium properties of pure compounds are correctly predicted (densities, saturation pressures, vaporization enthalpies, critical properties, surface tensions, liquid phase structure). Many mixtures have also been simulated in the bubble point pseudo-ensemble which was extended in this work to polar molecules. The simulation results of complex mixtures such as biofuels have been validated through new experimental data acquisition. Finally, a new methodology for the intramolecular electrostatic energy interaction has been developed in this work to simulate multifunctional oxygenated molecules (polyols, glycol ethers, oxygenated aromatic compounds). The use of this method, which allows to avoid the use of additional empirical parameters, leads to promising results, giving thus future opportunities to predict properties of complex mixtures of industrial interest