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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Fabricating and Characterizing Physical Properties of Electrospun Polypeptide-based Nanofibers

Khadka, Dhan Bahadur 01 January 2013 (has links)
This dissertation has aimed to fabricate polypeptide based biomaterial and characterize physical properties. Electrospinning is used as a tool for the sample fabrication. Project focused on determining the feasibility of electrospinning of certain synthetic polypeptides and certain elastin-like peptides from aqueous feedstocks and to characterize physical properties of polymer aqueous solution, cast film and spun fibers and fiber mats. The research involves peptide design, polymer electrospinning, fibers crosslinking, determining the extent of crosslinking, fibers protease degradation study, fibers stability and self-organization analysis, structure and composition determination by various spectroscopy and microscopy techniques and characterization of mechanical properties of individual suspended fibers. Fiber mats of a synthetic cationic polypeptide poly(L-ornithine) (PLO) and an anionic co-polypeptide of L-glutamic acid and L-tyrosine (PLEY) of defined composition have been produced by electrospinning. Fibers were obtained from polymer aqueous solution at concentrations of 20-45% (w/v) in PLO and at concentrations of 20-60% (w/v) in PLEY. Applied voltage and spinneret-collector distance were also found to influence polymer spinnability and fibers morphology. Oriented fibers were obtained by parallel electrodes geometry. Fiber diameter and morphology was analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). PLO fibers exposed on glutaraldehyde (GTA) vapor rendered fiber mats water-insoluble. A common chemical reagent, carbodiimide was used to crosslink PLEY fibers. Fiber solubility in aqueous solution varied as a function of crosslinking time and crosslinker concentration. Crosslink density has been quantified by a visible-wavelength dye-based method. Degradation of crosslinked fibers by different proteases has been demonstrated. Investigation of crosslinked PLEY fibers has provided insight into the mechanisms of stability at different pH values. Variations in fiber morphology, elemental composition and stability have been studied by microscopy and energy-dispersive X-ray spectroscopy (EDX), following the treatment of samples at different pH values in the 2-12 range. Fiber stability has been interpreted with reference to the pH dependence of the UV absorbance and fluorescence of PLEY chains in solution. The data show that fiber stability is crucially dependent on the extent of side chain ionization, even after crosslinking. Self-organization kinetics of electrospun PLO and PLEY fibers during solvent annealing has been studied. After being crosslinked in situ, fibers were annealed in water at 22 °C. Analysis by Fourier transform infrared spectroscopy (FTIR) has revealed that annealing involved fiber restructuring with an overall time constant of 29 min for PLO and 63 min for PLEY, and that changes in the distribution of polymer conformations occurred during the first 13 min of annealing. There was a substantial decrease in the amount of Na+ bound to PLEY fibers during annealing. Kinetic modeling has indicated that two parallel pathways better account for the annealing trajectory than a single pathway with multiple transition states. Bacteria have been engineered to make novel 250-mer elastin-like polypeptides (ELPs). Each was predicted to have an absolute net charge of less than 0.05 electron charges per amino acid residue in aqueous solution at neutral pH. Polymer structure in solution has been assessed by Circular dichroism spectroscopy (CD) and dynamic light scattering (DLS). Suitability for materials manufacture has been tested by electrospinning. Here, we have also tested the hypothesis that blending polypeptides of radically different amino acid composition will enable the realization of novel and potentially advantageous material properties. Aqueous polymer feedstock solutions consisted of pure ELP or ELP blended with a synthetic polypeptide, PLEY, which is highly ionized at neutral pH and spinnable. Morphology analysis of blended fibers by SEM has revealed the formation of a surprising variety of structures that are not seen in fibers of ELP or PLEY alone, for example, hollow beads. Analysis of blended fibers by fluorescence microscopy showed that there was little or no phase separation, despite the large difference in electrical properties between ELP and the synthetic polymers. Structure and composition of PLO, PLEY, ELPs and blends and electrospun fibers made of these polymers have been determined and compared. CD and FTIR have been utilized to obtain structural information on these polymers in aqueous solution, cast films and fibers. Fiber composition has been analyzed by EDX. Protein adsorption has been analyzed by quantitative fluorescence microscopy. The polymers adopted random coil-like conformations in aqueous feedstocks at neutral pH and in dehydrated cast films and fibers on glass, and the fibers comprised numerous counterions, according to spectral analysis. Adsorption of model proteins and serum proteins onto hydrated and crosslinked fibers depended on the electrical charge of the proteins and the fibers. The surface charge density of the fibers will be comparable to, but less than, the charge density on the outer leaflet of the plasma membrane of usual eukaryotic cells. Mechanical properties of a series of as-spun and crosslinked PLO and PLEY nanofibers with various diameters have been analyzed by using the pure bending mode and AFM technique. Aligned nanofibers were deposited on top of a microsized groove etched on a glass substrate. AFM tip was used as a probe, which could apply a measurable deflection and force onto the suspended nanofiber at a force calibration mode, so that the Young's modulus of a single nanofiber can be calculated based on the basic beam bending theories. The Young's moduli of the studied peptide nanofibers increased significantly with decreased fiber diameters. This study has also demonstrated that crosslinked electrospun PLO and PLEY fibers have a higher Young's modulus compared with their as-spun counterparts. Taken together, the results will advance the rational design of polypeptides for peptide-based materials, especially materials prepared by electrospinning. It is believed that this research will increase basic knowledge of polymer electrospinning and advance the development of electrospun materials, especially in medicine and biotechnology. The study has yielded two advances on previous work in the area: avoidance of an animal source of peptides and avoidance of inorganic solvent. The present results thus advance the growing field of peptide-based materials. Non-woven electrospun fiber mats made of polypeptides are increasingly considered attractive for basic research and technology development in biotechnology, medicine and other areas.
12

Effects of Intercropping Switchgrass in Managed Pine Stands on Plant Communities and White-Tailed Deer Forage Production

Wheat, Bradley Robert 14 August 2015 (has links)
Interest in renewable energy and governmental mandates has motivated land managers to consider cellulosic feedstocks for bioenergy. I investigated plant community response to a system including switchgrass (Panicum virgatum) as a feedstock intercropped with loblolly pine (Pinus taeda). I estimated plant species evenness, richness, and diversity and biomass production, with emphasis on white-tailed deer (Odocoileus virginianus) forages. I detected 225 species in 2,220 1-m2 quadrats, and 7,495 biomass samples (96.4 kg dry weight) from 960 quadrats. Intercropping reduced plant species diversity, total non-pine tree biomass, and biomass of deer forages during switchgrass establishment. These effects were no longer apparent at treatment level two years after switchgrass establishment, except that deer browse and total deer forage biomass remained less in intercropped interbeds. Intercropping in managed pines may temporarily effect plant communities but further studies are needed to examine longer term effects and to quantify effects on nutritional carrying capacity for deer.
13

FRACTIONATION AND CHARACTERIZATION OF LIGNIN STREAMS FROM GENETICALLY ENGINEERED SWITCHGRASS

Liu, Enshi 01 January 2017 (has links)
Development of biomass feedstocks with desirable traits for cost-effective conversion is one of the main focus areas in biofuels research. As suggested by techno-economic analyses, the success of a lignocellulose-based biorefinery largely relies on the utilization of lignin to generate value-added products, i.e. fuels and chemicals. The fate of lignin and its structural/compositional changes during pretreatment have received increasing attention; however, the effect of genetic modification on the fractionation, depolymerization and catalytic upgrading of lignin from genetically engineered plants is not well understood. This study aims to fractionate and characterize the lignin streams from a wild-type and two genetically engineered switchgrass (Panicum virgatum) species (low lignin content with high S/G ratio and high lignin content) using three different pretreatment methods, i.e. dilute sulfuric acid, ammonia hydroxide, and aqueous ionic liquid (cholinium lysinate). The structural and compositional features and impact of lignin modification on lignin-carbohydrate complex characteristics and the deconstruction of cell-wall compounds were investigated. Moreover, a potential way to upgrade low molecular weight lignin to lipids by Rhodococcus opacus was evaluated. Results from this study provide a better understanding of how lignin engineering of switchgrass influences lignin fractionation and upgrading during conversion processes based on different pretreatment technologies.
14

Production of Bio-Based Chemicals and Polymers from Renewable Feedstocks: Bioprocesses Development

Bustamante Jaramillo, Daniel Arturo 29 October 2021 (has links)
Tesis por compendio / [ES] El aprovechamiento de subproductos para producir biocombustibles, energía y compuestos químicos básicos es cada vez más necesario en la situación actual de escasez de petróleo y preocupación por el medioambiente. Muchos compuestos que tradicionalmente han sido producidos a partir del petróleo pueden sintetizarse hoy día de forma biotecnológica empleando recursos renovables. En este contexto, los microorganismos pueden aprovecharse eficazmente como biocatalizadores para llevar a cabo estas transformaciones. Con este tipo de procesos se pueden aprovechar residuos o materias primas renovables para la obtención de productos de interés como bioplásticos de origen microbiano o productos químicos que pueden servir como monómeros para la síntesis de plásticos biodegradables u otro tipo de aplicaciones. La contaminación ambiental causada por los residuos de polímeros sintéticos no biodegradables es un problema en aumento debido a la estabilidad de los compuestos derivados de los combustibles fósiles. En contraste, los bioplásticos pueden obtenerse de fuentes renovables, lo que posibilita el desarrollo de procesos de producción sostenible. En este trabajo de investigación se han estudiado y desarrollado bioprocesos para la producción de polihidroxialkanoatos, 2,3-butanodiol y ácido D-láctico de forma sostenible empleando materias primas renovables como el suero lácteo de quesería, aceite de camelina, glicerina, fracción orgánica de residuos urbanos y residuos de naranja. La caracterización de las materias primas de partida se realizó mediante técnicas de análisis composicional, análisis en HPLC, cromatografía de gases y técnicas espectrofotométricas. Con estos resultados se hizo una selección de cepas bacterianas capaces de sintetizar los productos de interés a partir de los sustratos seleccionados. Una vez seleccionadas las cepas, el trabajo se centró en el desarrollo de los procesos para conseguir buenos rendimientos de fermentación y su escalado. Por lo tanto, este trabajo de investigación aporta conocimientos sobre la identificación y selección de biocatalizadores industriales para el uso de materias primas renovables y residuos industriales para la producción de productos químicos y polímeros de base biológica. Estos estudios allanan el camino para el futuro desarrollo de procesos biotecnológicos sostenibles en el marco de las biorrefinerías y de la bioeconomía circular. / [CA] L'aprofitament de bioproductes per produir biocombustibles, energia i compostos químics bàsics és cada vegada més necessari en la situació actual d'escassetat de petroli i preocupació pel medi ambient. Molts compostos que tradicionalment s'han produït a partir de petroli es poden sintetitzar hui en dia biotecnològicament utilitzant recursos renovables. En aquest context, els microorganismes es poden utilitzar eficaçment com a biocatalitzadors per dur a terme aquestes transformacions. Amb aquest tipus de processos es poden utilitzar residus o matèries primeres renovables per obtenir productes d'interès com bioplàstics d'origen microbià o químics que puguen servir de monòmers per a la síntesi de plàstics biodegradables o altres aplicacions. La contaminació ambiental causada per residus de polímers sintètics no biodegradables és un problema creixent a causa de l'estabilitat dels compostos de combustibles fòssils. Per contra, els bioplàstics es poden obtenir a partir de fonts renovables, permetent el desenvolupament de processos productius sostenibles. En aquest treball de recerca s'han estudiat i desenvolupat bioprocessos per a la producció de polihidroxialcanoats, 2,3-butanodiol i àcid D-làctic de manera sostenible utilitzant matèries primeres renovables com sèrum de llet, oli de camelina, glicerina, fracció orgànica de residus urbans i residus de taronges. La caracterització de matèries primeres inicials es realitza mitjançant tècniques d'anàlisi composicional, anàlisi HPLC, cromatografia de gasos i tècniques espectrofotomètriques. Amb aquests resultats es crea una selecció de soques bacterianes capaç de sintetitzar els productes d'interès dels substrats seleccionats. Una vegada seleccionades les soques, el treball es va centrar en el desenvolupament dels processos per aconseguir uns bons rendiments de fermentació i el seu escalat. Per tant, aquest treball de recerca aporta coneixements sobre la identificació i selecció de biocatalitzadors industrials per a l'ús de matèries primeres renovables i residus industrials per a la producció de productes químics i polímers de base biològica. Aquests estudis amplien el coneixement per al futur desenvolupament de processos biotecnològics sostenibles en el marc de la biorefineria i la bioeconomia circular. / [EN] The use of by-products to produce biofuels, energy and basic chemicals is increasingly necessary in the current situation of oil shortages and environmental concern. Many compounds that have traditionally been produced from oil can now be synthesised in a biotechnological way using renewable resources. In this context, microorganisms can be effectively used as biocatalysts to carry out these transformations. With this type of process, waste streams or renewable raw materials can be used to obtain products of interest such as bioplastics of microbial origin or chemical products that can serve as monomers for the synthesis of biodegradable plastics or other types of applications. Environmental pollution caused by non-biodegradable synthetic polymer waste is a growing problem due to the stability of compounds derived from fossil fuels. In contrast, bioplastics can be obtained from renewable sources, which enables the development of sustainable production processes. In this research work, bioprocesses for the production of polyhydroxyalkanoates, 2,3-butanediol and D-lactic acid using renewable raw materials such as cheese whey, camelina oil, glycerine, organic waste and orange waste were studied and developed. The characterisation of the raw materials was carried out using compositional analysis, HPLC analysis, gas chromatography and spectrophotometric techniques, among others. With these results, a selection of bacterial strains capable of synthesising the products of interest from the selected substrates was made. Once the strains were selected, the work was focused on process development in order to optimize fermentation yields and scale-up. Therefore, this research work provides knowledge on the identification and selection of industrial biocatalysts for the use of renewable feedstocks and industrial wastes for the production of bio-based chemicals and polymers. These studies pave the way for further development of sustainable biotechnological processes in the framework of biorefineries and circular bioeconomy. / Bustamante Jaramillo, DA. (2021). Production of Bio-Based Chemicals and Polymers from Renewable Feedstocks: Bioprocesses Development [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/175819 / TESIS / Compendio
15

Pyrolysis Strategies for Effective Utilization of Lignocellulosic and Algal Biomass

Maddi, Balakrishna January 2014 (has links)
No description available.
16

Determining biological roles of four unique Vernicia fordii acyl-CoA Binding Proteins

Pastor, Steven 20 May 2011 (has links)
High-value industrial oils are essential for many processes and have great economic and environmental impacts. The tung tree produces a high-value seed oil. Approximately 80% of tung oil is α-eleostearic acid, which has a high degree of unsaturation thus giving it properties as a drying oil. The identification of the biological components in tung is imperative to further the knowledge of its processes. Four unique tung acyl-CoA binding proteins, VfACBP3a, VfACBP3b, VfACBP4, and VfACBP6 were identified and the genes encoding them were cloned and analyzed to determine their biological roles. The VfACBPs were observed to be similar to other organisms' ACBPs, especially Arabidopsis thaliana. In addition, each gene was expressed in all tung tissues. They were shown to interact with VfDGAT1 and VfDGAT2, two known components of tung lipid metabolism. Finally, VfACBP3a and VfACBP6 were expressed in the seeds of transgenic plants to study the effects of VfACBP expression on seed lipid fatty acid content.
17

Catalysts and catalytic processes for the transformation of tars and other non-conventional feedstocks into fuels and chemicals

Raad, Zaher 03 December 2021 (has links)
[ES] Debido al agotamiento de las fuentes de petróleo, la mayor demanda de energía y combustibles para el transporte, y la necesidad de reducir las emisiones de gases de efecto invernadero y la dependencia de los recursos fósiles, la utilización de fuentes alternativas sostenibles para producir combustibles y productos químicos se vuelve esencial. En este contexto, la valorización de alquitranes ligeros (formados durante los procesos de refinación de petróleo y gasificación de biomasa) y otras fuentes no convencionales (es decir, ácidos grasos) y su conversión en productos químicos de alto valor agregado será una opción interesante y desafiante. En este trabajo se desarrollan catalizadores sólidos y procesos catalíticos para la transformación de alquitranes ligeros mediante el proceso de hidrotratamiento suave. Este proceso está estudiado empleando diferentes hidrocarburos aromáticos policíclicos (HAP) como moléculas modelo, representativas de materias primas de alquitrán ligero. Los compuestos de tipo alquitrán de esta mezcla modelo se transforman en hidrocarburos C9-C15 parcialmente hidrogenados, que podrían aplicarse como aditivos (mejoradores) del combustible de aviación, o como productos químicos y disolventes para la industria. Primero, se estudia el hidrotratamiento suave de alquitranes empleando Pd soportado sobre TiO2, que posee diferentes fases cristalinas. La actividad de hidrotratamiento y la selectividad hacia los productos hidrogenados deseados (es decir, tetralina y otros) aumentaron al aumentar tanto la acidez como el área superficial del catalizador, junto con la presencia de nanopartículas de Pd pequeñas y bien distribuidas. El catalizador Pd/TiO2 Nano revela una notable actividad de hidrotratamiento y estabilidad después de varios reusos sin prácticamente cambios en la estructura del TiO2. Además, no se observa prácticamente deposición de carbono, ni lixiviación de Pd, manteniéndose tanto el tamaño de partícula como la adecuada distribución del Pd, incluso después de la regeneración del catalizador. Además, el catalizador Pd/TiO2 Nano demuestra ser más eficaz para la producción de hidrocarburos C9-C15 que otros catalizadores de hidrotratamiento comerciales y reportados anteriormente. Además, el Pd soportado en el óxido mixto TiO2-Al2O3 preparado mediante el método de co-precipitación optimizado, se evalúa en el hidrotratamiento suave de alquitranes, mostrando buena actividad y estabilidad después de varios reusos. Su actividad de hidrotratamiento se compara con la de los catalizadores Pd/TiO2 Nano y Pd/Al2O3; mientras que su ámbito de aplicación se extiende a otras reacciones de hidrogenación más exigentes, como la aminación reductora de acetol bioderivado. Además, un nuevo catalizador desarrollado con Pd soportado sobre TiO2/Al2O3 (precursor de Ti impregnado sobre alúmina como soporte) demuestra una buena actividad en el hidrotratamiento suave de compuestos de tipo alquitrán. Finalmente, los catalizadores a base de Ni se preparan y prueban en el hidrotratamiento suave de alquitranes, siendo el catalizador Ni/TiO2/Al2O3 el más activo entre ellos. Además, los catalizadores de Ni muestran un excelente rendimiento catalítico cuando se aplican como catalizadores en la hidrogenación selectiva de ácidos grasos para producir hidrocarburos, catalizadores de Ni/TiO2/Al2O3 y Ni/TiO2/ZrO2, ofreciendo la más alta selectividad hacia n-heptadecano (C17). Curiosamente, se encuentra que el dopaje con Pt aumenta la actividad de los últimos catalizadores de Ni. En resumen, diferentes catalizadores soportados por metales desarrollados en este estudio son capaces de transformar alquitranes ligeros y ácidos grasos en condiciones de reacción suaves, ofreciendo así una opción viable y más sostenible para la producción de hidrocarburos útiles de otras fuentes no convencionales. / [CA] Degut a l'esgotament dels depòsits petrolífers, hi hagut un increment de la demanda d'energia i de combustibles; al mateix temps que la necessitat de reduir les emissions de gasos GHG i la dependència als recursos fòssils; esdevé essencial la utilització de fonts d'energia alternativa per a produir combustibles líquids i productes químics. En aquest context, la valorització de quitrans lleugers (formats durant els processos de refinament del petroli i de gasificació de la biomassa) i d'altres fonts d'energia no convencionals com per exemple àcids grassos; i la seva conversió en productes químics d'alt valor afegit són una opció interessant i prometedora. En aquest treball, es desenvoluparan catalitzadors sòlids i processos catalítics per a la transformació de quitrans lleugers a través del procés d'hidrotractament en condicions suaus. Aquest procés s'estudia utilitzant diferents hidrocarburs policíclics aromàtics (PAHs) com a molècules model representatives de la matèria prima que constitueixen els quitrans lleugers. Els quitrans d'aquesta mescla representativa es transformen a hidrocarburs C9-C15 parcialment hidrogenats que poden ser utilitzats com a querosè o com a productes químics i dissolvents per a la indústria. Primer, l'hidrotractament en condicions suaus dels quitrans va ser estudiat utilitzant materials de Pd suportat sobre TiO2 de diferents fases cristal·lines. L'activitat de l'hidrotractament i la selectivitat del procés als productes hidrogenats desitjats (i.e tetralina i altres) augmenta en augmentar l'acidesa i l'àrea superficial del catalitzador, junt amb la presència de petites nanopartícules de Pd adequadament distribuïdes. El catalitzador Pd/TiO2 Nano presenta una destacada activitat en la reacció d'hidrotractament i resulta estable després de reutilitzar-lo en diverses ocasions sense pràcticament canvis en l'estructura TiO2, malgrat que té lloc certa sedimentació de carboni, no es detecta lixiviació i es manté tan la distribució com les dimensions de les partícules després de la regeneració del catalitzador. A més a més, el catalitzador Pd/TiO2 Nano resulta ésser més efectiu per a la producció d'hidrocarburs C9-C15 que altres catalitzadors comercials i d'altres descrits prèviament en la bibliografia. A més a més, s'ha estudiat el Pd suportat en l'òxid mixt TiO2-Al2O3 preparat a través de l'optimització del mètode de la coprecipitació en la reacció d'hidrotractament de quitrans en condicions suaus. Aquest catalitzador mostra una bona activitat i estabilitat després de reutilitzar-lo en vàries ocasions. La seva activitat en dita reacció es compara a la que presenten els catalitzadors de Pd/TiO2 Nano i Pd/Al2O3; i també s'ha comprovat el seu abast en altres reaccions d'hidrogenació d'interès, com per exemple l'aminació reductiva d'acetol provinent de la biomassa. A més a més, s'ha desenvolupat un nou catalitzador de Pd suportat sobre TiO2/Al2O3 (on el precursor de Ti s'impregna sobre l'alúmina que actua com a suport) que mostra una bona activitat en la reacció d'hidrotractament de compostos tipus quitrans en condicions suaus. Finalment, els catalitzadors basats en Ni han estat preparats i testats en reaccions d'hidrotractament de quitrans en condicions suaus, sent el catalitzador Ni/TiO2/Al2O3 el més actiu de tots. Addicionalment, els catalitzadors de níquel mostren excel·lents activitats catalítiques quan s'utilitzen com a catalitzadors per a la hidrogenació selectiva d'àcids grassos per a la producció d'hidrocarburs. Els catalitzadors de Ni/TiO2/Al2O3 i Ni/TiO2/ZrO2 presenten la major selectivitat a n-heptadecà (C17). Cal mencionar, que el dopatge amb Pt tendeix a augmentar l'activitat de l'últim catalitzador de Ni. Resumint, s'ha demostrat que diferents catalitzadors basats en metall suportat que han estat desenvolupats durant aquest estudi són capaços de transformar els quitrans lleugers i els àcids grassos en condicions su / [EN] Because of the depletion of petroleum sources, the increased demand for energy and transportation fuels, and the need for both reduction of greenhouse gases (GHG) emissions and the dependence on fossil resources, the utilization of sustainable alternative sources to produce fuels and chemicals becomes essential. In this context, the valorization of light tars (formed during petroleum refining and biomass gasification processes) and other non-conventional sources (i.e., fatty acids), and their conversion into high-added value chemicals will be an interesting and challenging option. In this work, solid catalysts, and catalytic processes for the transformation of light tars via mild hydrotreatment process are developed. This process is studied by employing different polycyclic aromatic hydrocarbons (PAHs) as model molecules representative of light tars feedstocks. The tars-type compounds of this model mixture are transformed into C9-C15 partially hydrogenated hydrocarbons that could be applied as jet fuel additives (improvers) or as chemicals and solvents for industry. First, the tars mild hydrotreatment is studied over Pd supported on TiO2 possessing different crystalline phases. The hydrotreatment activity and selectivity towards the desired hydrogenated products (i.e., tetralin and others) increase by increasing both acidity and surface area of the catalyst, along with the presence of small and well distributed Pd nanoparticles. The Pd/TiO2 Nano catalyst reveals remarkable hydrotreatment activity and stability after several reuses with practically no changes in TiO2 structure, quite low carbon deposition, any Pd leaching detected and maintaining both small Pd particle size and their adequate distribution, even after regeneration of the catalyst. Additionally, Pd/TiO2 Nano catalyst demonstrates to be more effective to the production of C9-C15 hydrocarbons than other commercial and previously reported hydrotreatment catalysts. In addition, Pd supported on TiO2-Al2O3 mixed oxide, prepared via optimized co-precipitation method, is evaluated in the tars mild hydrotreatment, displaying good activity and stability after several reuses. Its hydrotreatment activityis compared with that of Pd/TiO2 Nano and Pd/γ-Al2O3 catalyst; while its application scope is extended to other demanding hydrogenation reactions, such as the reductive amination of bio-derived acetol with ethylenediamine to produce 2-methylpiperazine. Furthermore, a novel Pd supported on TiO2/γ-Al2O3 (Ti precursor impregnated onto alumina as support) developed catalyst demonstrates good activity in the mild hydrotreatment of tars-type compounds. Finally, Ni-based catalysts are prepared and tested in the tars mild hydrotreatment, Ni/TiO2/Al2O3 catalyst being the most active among them. Additionally, Ni catalysts show excellent catalytic performance when applied as catalysts in the selective hydrogenation of fatty acids to produce hydrocarbons, Ni/TiO2/Al2O3 and Ni/TiO2/ZrO2 catalysts offering the highest selectivity to n-heptadecane (C17). Interestingly, Pt doping is encountered to increase the activity of the latter Ni catalysts. Summarizing, different metal supported catalysts developed in this study are capable to transform light tars and fatty acids under mild reaction conditions, thus offering a viable and more sustainable option to produce useful hydrocarbons from other non-conventional sources. / Raad, Z. (2021). Catalysts and catalytic processes for the transformation of tars and other non-conventional feedstocks into fuels and chemicals [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/177954 / TESIS
18

Modélisation et optimisation de la production de cellulases par Trichoderma reesei pour les bioraffineries lignocellulosiques

Jourdier, Etienne 19 September 2012 (has links)
Dans le contexte énergétique et climatique mondial, le coût élevé des enzymes Cellulolytiques (cellulases) freine le développement des bioraffineries lignocellulosiques, pour produire des biocarburants et composés chimiques à partir d'une matière première végétale renouvelable. L'objectif de ce travail est de caractériser et de modéliser le métabolisme du micro-organisme Trichoderma reesei, afin d'optimiser le protocole industriel de production de cellulases. Cette étude a été réalisée sur des milieux modèles représentatifs de ceux attendus à l'échelle industrielle. Tout d'abord, la stoechiométrie des réactions de croissance et de production a été établie, puis une étude cinétique a été menée pour mesurer précisément le comportement du micro-organisme à forte induction de la production de cellulases. Le modèle résultant a été utilisé pour optimiser le protocole industriel de production. Ensuite, l'intégration de cette étape dans une bioraffinerie lignocellulosique a été étudiée, avec l'effet sur le métabolisme i) des mélanges de sucres disponibles, ii) des composés inhibiteurs issus de la dégradation de la lignocellulose, et iii) du changement d'échelle. Ces travaux ont fait progresser de façon substantielle les connaissances du métabolisme de T. reesei en ce qui concerne la production de cellulases, et les modèles développés sont des outils d'aide rationnelle à la définition d'un procédé de production de cellulases intégré dans une bioraffinerie lignocellulosique. / In the global energetic and climatic context, the high cost of the cellulolytic enzymes (cellulases) postpones the development of lignocellulosic biorefineries, dedicated to produce biofuels and chemical compounds from renewable vegetable feedstocks. The aim of this work was to measure and model the metabolism of the micro-organism Trichoderma reesei, in order to optimize the industrial protocol for the production of cellulase. This study was carried out using synthetic media representative of industrial ones. First, the stoichiometries of growth and protein production reactions were determined. Then, a kinetic study was conducted to precisely measure the specific rates of T. reesei at high induction of cellulase production. The resulting model was used to optimize the industrial production protocol. Finally the integration of this step in a lignocellulosic biorefinery was studied by determining the impacts on the metabolism of i) available sugar mixtures, ii) inhibitory compounds from lignocellulosic biomass degradation, and iii) scale-up. These results significantly contributed to improve the knowledge of T. reesei metabolism on cellulase production. The developed models are rational tools for the optimization of a cellulase production protocol suited to lignocellulosic biorefineries.
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Untersuchungen zum Freisetzungsverhalten von Störkomponenten aus Energierohstoffen unter reduzierenden und oxidierenden Bedingungen

Hommel, Caroline 03 July 2023 (has links)
Die vorliegende Dissertationsschrift beschreibt Experimente zur Weiterentwicklung der Methode der elektrothermischen Verdampfung mit induktiv gekoppeltem Plasma und optischer Emissionsspektroskopie (ETV-ICP OES). Ziel ist die Analyse der Mobilisierung einzelner Elemente in Verbrennungsgasatmosphären, um so das Verschmutzungs- und Verschlackungspotential von Energierohstoffen abschätzen zu können. Zur Simulation der Atmosphäre wird Sauerstoff zum Argon-Gasstrom der Verdampfungseinheit in verschiedenen Verhältnissen zugesetzt, weshalb einige Bauteile der ETV und alle Methodenparameter angepasst werden müssen. Der Einfluss der Gasatmosphäre sowie des Temperaturprogrammes auf die Freisetzung der Elemente wird anhand von drei Kohlen unterschiedlicher Inkohlung und Mineralstoffanteile untersucht und die Analysenmethode dementsprechend optimiert. Im Anschluss erfolgt die Anwendung der entwickelten Methode auf acht Argonne Premium Kohlen sowie auf verschiedene Biomassen und Klärschlämme.:1 Motivation und Aufgabenstellung 12 2 Stand der Technik 15 2.1 Energierohstoffe 15 2.2 Ansatzbildung und Korrosion im Kraftwerk 17 2.2.1 Ansatzbildungsmechanismen 17 2.2.2 Korrosion 20 2.2.3 Freisetzung von Störkomponenten 21 2.2.3.1 Schwefel 21 2.2.3.2 Chlor 21 2.2.3.3 Alkalien 22 2.2.4 Analysemethoden zur Ermittlung der Freisetzung von Störkomponenten 23 3 Eingesetzte Methoden und Parameter 27 3.1 ETV-ICP OES 27 3.2 Thermodynamische Gleichgewichtsberechnungen 31 4 Methodenentwicklung modifizierte ETV-ICP OES 33 4.1 Anpassung des ETV-Systems an simulierte Prozessbedingungen 34 4.1.1 Auswahl der Gasatmosphären 36 4.1.2 Vergleich Standardrohr und SiC-beschichtetes Rohr 38 4.1.3 Einfluss der Beschichtung der Probentiegel 39 4.1.4 Fazit 42 4.2 Temperaturprogramm 43 4.3 Linienauswahl 44 4.4 Kalibration für quantitative Analysen 46 4.5 Datenbearbeitung 49 4.5.1 Korrekturfaktor für Massenbilanz 50 4.5.2 Argon-Korrektur 51 4.5.3 Intensität und Freisetzungsverlauf 53 4.5.4 Zusammenfassung notwendiger Datenbearbeitung 56 4.6 Einfluss der modifizierten Methode auf die Kohlematrix 56 4.6.1 Probenauswahl und Charakterisierung 57 4.6.1.1 Bestimmung der Bindungsformen von Kalium und Natrium 59 4.6.2 Elementfreisetzungsverhalten – Analyse der Kohleproben 64 4.6.2.1 Mineralreiche Kohle – 4419 64 4.6.2.2 Mineralarme Braunkohle – 3922 73 4.6.2.3 Steinkohlestandard – 1632d 81 4.6.2.4 Sonderfall Chlor 87 4.7 Fehlerbetrachtung 89 4.8 Zusammenfassung der Methodenentwicklung 92 5 Anwendung der Methode 96 5.1 Argonne Premium Kohlen 96 5.1.1 Kalium 98 5.1.2 Natrium 101 5.1.3 Schwefel 103 5.1.4 Zusammenfassung der Analysen an den APCs 106 5.2 Klärschlamm 106 5.2.1 Probenauswahl 107 5.2.2 Kalium 108 5.2.3 Natrium 111 5.2.4 Schwefel 113 5.2.5 Phosphor 115 5.2.6 Zusammenfassung der Klärschlammanalysen 118 5.3 Biomasse 118 5.3.1 Probencharakterisierung 119 5.3.2 Freisetzungsverhalten der Elemente 120 5.3.3 Zusammenfassung der Analysen an den Biomassen 123 5.4 Rückschlüsse der Ergebnisse auf reale Prozesse 124 6 Zusammenfassung und Ausblick 126 7 Anhang 130 7.1 Analysenmethoden zur Probencharakterisierung 130 7.1.1 Brennstoffanalyse 130 7.1.2 Röntgenfluoreszenzspektroskopie 131 7.1.3 Röntgendiffraktometrie 132 7.1.4 Thermische Analysen 134 7.1.5 Weitere Parameter für die FactSageTM-Berechnungen 135 7.2 Zusatzinformationen zur Methodenentwicklung 136 7.2.1 Methodenparameter 136 7.2.2 Probencharakterisierung 140 7.3 Zusatzinformationen zur Anwendung der modifizierten Methode 147 7.3.1 APC 147 7.3.2 Klärschlämme 148 8 Referenzen 150 9 Veröffentlichungsliste 160 10 Verzeichnisse 161 10.1 Abbildungsverzeichnis 161 10.2 Tabellenverzeichnis 166 10.3 Abkürzungsverzeichnis 168 / This dissertation describes the development of a method to analyze the mobilization of individual elements in combustion gas atmospheres with the help of electrothermal evaporation in combination with inductively coupled plasma optical emission spectros-copy (ETV-ICP OES) to estimate the pollution and slagging potential of energy feed-stocks. To simulate the atmosphere, oxygen is added to the argon gas stream of the evaporation unit in different ratios. To that end, some components of the ETV unit and all method parameters have to be adjusted. The influence of the gas atmosphere as well as the temperature program on the release of the elements is investigated on the basis of three coals of different degree of carbonization and mineral content and the analysis method is optimized accordingly. Subsequently, the method is applied to analyze eight Argonne Premium coals as well as various biomasses and sewage sludges.:1 Motivation und Aufgabenstellung 12 2 Stand der Technik 15 2.1 Energierohstoffe 15 2.2 Ansatzbildung und Korrosion im Kraftwerk 17 2.2.1 Ansatzbildungsmechanismen 17 2.2.2 Korrosion 20 2.2.3 Freisetzung von Störkomponenten 21 2.2.3.1 Schwefel 21 2.2.3.2 Chlor 21 2.2.3.3 Alkalien 22 2.2.4 Analysemethoden zur Ermittlung der Freisetzung von Störkomponenten 23 3 Eingesetzte Methoden und Parameter 27 3.1 ETV-ICP OES 27 3.2 Thermodynamische Gleichgewichtsberechnungen 31 4 Methodenentwicklung modifizierte ETV-ICP OES 33 4.1 Anpassung des ETV-Systems an simulierte Prozessbedingungen 34 4.1.1 Auswahl der Gasatmosphären 36 4.1.2 Vergleich Standardrohr und SiC-beschichtetes Rohr 38 4.1.3 Einfluss der Beschichtung der Probentiegel 39 4.1.4 Fazit 42 4.2 Temperaturprogramm 43 4.3 Linienauswahl 44 4.4 Kalibration für quantitative Analysen 46 4.5 Datenbearbeitung 49 4.5.1 Korrekturfaktor für Massenbilanz 50 4.5.2 Argon-Korrektur 51 4.5.3 Intensität und Freisetzungsverlauf 53 4.5.4 Zusammenfassung notwendiger Datenbearbeitung 56 4.6 Einfluss der modifizierten Methode auf die Kohlematrix 56 4.6.1 Probenauswahl und Charakterisierung 57 4.6.1.1 Bestimmung der Bindungsformen von Kalium und Natrium 59 4.6.2 Elementfreisetzungsverhalten – Analyse der Kohleproben 64 4.6.2.1 Mineralreiche Kohle – 4419 64 4.6.2.2 Mineralarme Braunkohle – 3922 73 4.6.2.3 Steinkohlestandard – 1632d 81 4.6.2.4 Sonderfall Chlor 87 4.7 Fehlerbetrachtung 89 4.8 Zusammenfassung der Methodenentwicklung 92 5 Anwendung der Methode 96 5.1 Argonne Premium Kohlen 96 5.1.1 Kalium 98 5.1.2 Natrium 101 5.1.3 Schwefel 103 5.1.4 Zusammenfassung der Analysen an den APCs 106 5.2 Klärschlamm 106 5.2.1 Probenauswahl 107 5.2.2 Kalium 108 5.2.3 Natrium 111 5.2.4 Schwefel 113 5.2.5 Phosphor 115 5.2.6 Zusammenfassung der Klärschlammanalysen 118 5.3 Biomasse 118 5.3.1 Probencharakterisierung 119 5.3.2 Freisetzungsverhalten der Elemente 120 5.3.3 Zusammenfassung der Analysen an den Biomassen 123 5.4 Rückschlüsse der Ergebnisse auf reale Prozesse 124 6 Zusammenfassung und Ausblick 126 7 Anhang 130 7.1 Analysenmethoden zur Probencharakterisierung 130 7.1.1 Brennstoffanalyse 130 7.1.2 Röntgenfluoreszenzspektroskopie 131 7.1.3 Röntgendiffraktometrie 132 7.1.4 Thermische Analysen 134 7.1.5 Weitere Parameter für die FactSageTM-Berechnungen 135 7.2 Zusatzinformationen zur Methodenentwicklung 136 7.2.1 Methodenparameter 136 7.2.2 Probencharakterisierung 140 7.3 Zusatzinformationen zur Anwendung der modifizierten Methode 147 7.3.1 APC 147 7.3.2 Klärschlämme 148 8 Referenzen 150 9 Veröffentlichungsliste 160 10 Verzeichnisse 161 10.1 Abbildungsverzeichnis 161 10.2 Tabellenverzeichnis 166 10.3 Abkürzungsverzeichnis 168

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