Tesi sul tema "Liquide de pyrolyse"

Les résidus de biomasse, comme la bagasse de canne à sucre, ont un grand potentiel pour fournir des sources d’énergie renouvelables. Cependant, ses propriétés naturelles telles que sa faible densité, son faible pouvoir calorifique et sa sensibilité à la biodégradation peuvent limiter son utilisation. Pour améliorer son efficacité énergétique, la pyrolyse lente–processus de décomposition thermique dans un environnement pauvre en oxygène–peut être appliquée en transformant la biomasse en un charbon riche en carbone. Dans un scénario typique de pyrolyse lente, la biomasse est lentement chauffée pour produire principalement du charbon, dont les vapeurs organiques sont souvent considérées comme des produits secondaires. Cependant, il y a un intérêt à récupérer ce sous-produit en condensant la vapeur organique générée pendant la pyrolyse à des fins diverses. De plus, ce produit a une longue histoire en raison de ses avantages en tant que bio-pesticide utilisé par les agriculteurs traditionnels, notamment dans les pays asiatiques. Dans cette étude, la bagasse a été pyrolysée pour co-produire du charbon et du liquide de pyrolyse (huile de pyrolyse) en utilisant un réacteur de laboratoire à lit fixe. Différents paramètres ont été testés, tels que les températures (400 °C et 500 °C), la vitesse de chauffe (1 °C/min et 10 °C/min) et le temps de séjour (30 min et 60 min). Cette étude vise à évaluer le potentiel de valorisation de la bagasse dans le but de densifier l’énergie (conversion de la biomasse en charbon) et de valoriser l’utilisation de son sous-produit (liquide de pyrolyse) pour la protection du bois. Les résultats ont montré que le rendement en charbon diminue avec l’augmentation de la température de pyrolyse mais entraîne une amélioration favorable du pouvoir calorifique; tout en générant une masse élevée de rendement liquide. Les conditions de pyrolyse optimales pour co-produire le charbon et le liquide de pyrolyse étaient la température de 500 °C et la vitesse de chauffe de 10 °C/min, donnant 28,97% de charbon et 55,46% de liquide. Les principaux composés du liquid de pyrolyse étaient l’eau, l’acide acétique, le glycolaldéhyde, la 1-hydroxy-2-propanone, le méthanol, l’acide formique, le lévoglucosane, le furfural, suivis de quelques composés phéno- liques et de dérivés du guaiacol. Le liquid de pyrolyse présente également une activité anti-fongique et anti-termite à des concentrations relativement faibles dans les essais biologiques sur boîtes de Pétri. Lorsqu’il est traité au bois de hêtre et de pin, le liquid de pyrolyse indique une bonne protection contre les termites (Reticulitermes flavipes) et les champignons Basidiomycete (Coniophora puteana et Rhodonia placenta, une pourriture cubique et Trametes versicolor, une pourriture fibreuse) à une concentration de 50% et 100%. Cependant, il reste lessivée lorsqu’il est exposé à l’eau ou à une forte humidité, ce qui indique que des études futures devraient être menées pour trouver comment diminuer sa lessivabilité.Mots clés: biomasse, charbon, pyrolyse lente, bagasse de canne à sucre, liquide de pyrolyse, protection du bois
Biomass residue—such as sugarcane bagasse—has great potential in providing renewable energy sources. However, its natural properties such as low density, low calorific value, and biodegradation susceptibility can limit its utilization. To improve its energy efficiency, slow pyrolysis—the process of thermal decomposition in an oxygen-deficient environment—can be applied by transforming the biomass into carbon-rich char. In a typical slow pyrolysis scenario, biomass is slowly heated to produce mainly char, where the organic vapors are often considered secondary products. However, there is an interest to recover this by-product by condensing the organic vapor generated during pyrolysis for various purposes. Moreover, this product has a long history due to its benefits as a bio-pesticide used by traditional farmers, notably in Asian countries. In this study, bagasse was slow-pyrolyzed to co-produce char and pyrolysis liquid using a laboratory fixed bed reactor. Different parameters were tested, such as temperatures (400 °C and 500 °C), heating rate (1 °C/min and 10 °C/min), and holding time (30 min and 60 min). This study aims to evaluate the valorization potential of bagasse with the purpose of energy densification (conversion of biomass into char) and valorizing the utilization of its by-product (pyrolysis liquid) for wood protection.Results showed that the yield of char decrease with the increase of pyrolysis temperature but results in the favorable calorific value improvement; while at the same time generating a high mass of liquid yield. The optimum pyrolysis condition to co-produce char and pyrolysis liquid was at 500 °C temperature and 10 °C/min of heating rate, yielding 28.97% char and 55.46% liquid. The principal compounds of pyrolysis liquid were water, acetic acid, glycolaldehyde, 1-hydroxy-2-propanone, methanol, formic acid, levoglucosan, furfural, followed by some phenol compounds and guaiacol derivatives. Pyrolysis liquid also exhibits anti-fungal and anti-termite activity at relatively low concentrations in the Petri-dishes bioassays. When treated to beech and pine wood, pyrolysis liquid indicates good protection towards termites (Reticulitermes flavipes) and Basidiomycete fungi (Coniophora puteana and Rhodonia placenta, cubic rot and Trametes versicolor, a fibrous rot) at concentration 50% and 100%. However, it remains leachable when exposed to water or high humidity, which indicates that future studies should be conducted to find out how to decrease its leachability.Keywords: biomass, char, slow pyrolysis, sugarcane bagasse, pyrolysis liquid, wood protection

Une méthode d'analyse par chromatographie liquide haute performance échangeuse d'anions (Système Dionex) couplée à une détection par ampérométrie pulsée a été mise au point afin d'identifier et de quantifier les fructooligosaccharides (FOS) dans les fruits frais et les aliments à base de fruits. Trois FOS ont été détectés : 1-kestose, nystose et inulobiose. Leur teneur varie en fonction de l'espèce, de la variété, du degré de maturité du fruit. Le taux de 1-kestose diminue au cours du procédé de fabrication des compotes (pasteurisation, cuisson). En conséquence, la dégradation thermique (80ʿC-120ʿC) des solutions pures de FOS (pH 4,0, 7,0 et 9,0) a été suivie. Elle est d'autant plus rapide que la température est élevée et le pH bas. A pH 4, un mécanisme réactionnel est proposé. Par ailleurs, une étude réalisée sur la lignée cellulaire cancéreuse colique humaine HT29, a montré que les FOS n'ont pas d'effets toxiques sur ces cellules
We describe the suitability of high-performance anion-exchange chromatography coupled with pulsed amperometric detection to identify and quantify fructan in fresh fruits as well as in commercial stewed fruits. Three fructooligosaccharides (FOS) were detected: 1-kestose, nystose and inulobiose. FOS contents vary with species, variety, maturity of fruit. Amount of 1-kestose decreases during stewed fruit manufacturing (pasteurization, cooking). Thermic degradation (80ʿC-120ʿC) of FOS solutions (pH 4. 0, 7. 0 and 9. 0) was studied. FOS hydrolysis decreases at increasing pH values and increases with temperature. At pH 4, a reaction mechanism was proposed. In addition, a study realised on a human colon carcinoma cell-line HT-29 shows no toxicity of FOS on these cells

Cette étude s’inscrit dans le cadre du projet MINERVE de la région wallonne quivise notamment à valoriser les anciens centres d’enfouissement technique et leur contenuau travers de la production de matières premières et de sources d’énergie. Plus particulièrement,l’objectif de ce travail est d’étudier un procédé de co-pyrolyse de déchetsplastiques et d’huiles de lubrification usagées, ayant pour finalité la production d’uncombustible alternatif liquide pour l’industrie, en vue d’une future montée en échelledu procédé.Pour ce faire, différentes approches ont été poursuivies. Premièrement, nous avonsmis en place un réacteur de 5 litres, agité et scellé hermétiquement, permettant demener des essais de co-pyrolyse. Des essais de co-pyrolyse d’un mélange de déchetsplastiques excavés et d’huiles de lubrification usagées ont été menés dans le réacteur.L’influence des paramètres clés du procédé, tels que la température maximale, la fractionmassique de plastiques dans le mélange ainsi que la vitesse de refroidissement, surle procédé et la qualité du produit fini a été étudiée. Nous avons été en mesure deproduire un combustible alternatif liquide, possédant un pouvoir calorifique d’environ30 MJ/kg, par la co-pyrolyse d’un mélange contenant 60% de plastiques, en chauffantle mélange durant 13 h, en atteignant une température maximale de 387°C et enlaissant la pression au sein du réacteur monter jusqu’environ 30 bars. Les besoins énergétiquesdu procédé ont été évalués à environ 8 MJ/kg de déchets à pyrolyser, grâce àun modèle de transferts thermiques développé pour le système constitué du réacteur deco-pyrolyse. Ensuite, une méthode a été développée pour déterminer le temps de fonted’une particule de plastique en fonction de sa plus petite dimension. L’application decette méthode nous a permis de déterminer que la plus petite dimension maximale quepeuvent avoir les particules de plastiques dans le mélange plastique/huile, pour queleur fusion ne limite pas le procédé de co-pyrolyse, est d’environ 3 cm. Deux analysesthermiques, la thermogravimétrie isotherme et la calorimétrie différentielle à balayage,ont été combinées pour caractériser le craquage thermique et son influence sur plusieurspolymères. L’influence du craquage thermique sur les polymères a été évaluée sur basede l’analyse de la fusion ou de la transition vitreuse du polymère. Les protocole et dispositifexpérimentaux de co-pyrolyse de déchets plastiques et d’huiles de lubrificationusagées à l’échelle du laboratoire ont été adaptés pour pouvoir co-pyrolyser un mélangecontenant du PVC. Différents essais de co-pyrolyse par étapes ont été menés pour évaluerl’influence des paramètres comme l’évolution de la température pendant l’essai, lecontenu en PVC du mélange et le plastique en mélange avec le PVC (LDPE ou PS).Enfin, les interactions qui prennent place entre le LDPE ou le PS et une huile, lorsde leur co-pyrolyse, ont été mises en évidence à l’aide d’essais de thermogravimétriehaute résolution. Nous avons tenté d’expliquer les interactions mises en évidence, grâceà une combinaison d’analyses thermiques permettant de caractériser, voire d’identifier,les produits de décomposition de l’échantillon, en continu ou en fin de chauffe.This study takes part in the MINERVE (Walloon region) which aims at enhancingthe old landfills and valorize their content through the production of raw materials andenergy sources. Specifically, the objective of this work is to study a co-pyrolysis processof waste plastics and used lubrication oils, whose purpose is the production of a liquidalternative fuel for industry, in order to future scaling up the process.To do so, different approaches have been pursued. First, we set up a 5 liter reactor,stirred and hermetically sealed for performing co-pyrolysis tests. Co-pyrolysis tests ofa mixture of excavated plastic wastes and used lubrication oils were performed in thereactor. The influence of key parameters, such as maximum temperature, the massfraction of plastics in the mixture and the cooling rate, on the process and the qualityof the fuel was investigated. We were able to produce a liquid alternative fuel, witha calorific value of about 30 MJ/kg by co-pyrolyzing a mixture containing 60 % ofplastic, heating the mixture for 13 h, reaching a maximum temperature of 387°C anda maximum pressure of about 30 bar. The energy requirements of the process wereevaluated at about 8 MJ per kg of waste through a heat transfer model developed forthe system consisting of the co-pyrolysis reactor. In addition, a method was developedto determine the time of melting of a plastic particle according to its smallest size.The application of this method allowed us to determine that the maximum smallestsize that can have plastic particles in plastic/oil mixture, so that their melting willnot limit the co-pyrolysis process, is about 3 cm. Two thermal analysis techniques,isothermal thermogravimetry and differential scanning calorimetry, were combined tocharacterize the thermal cracking and its influence on several polymers. The influence ofthermal cracking of the polymers was evaluated based on the analysis of the melting orglass transition of the polymer. The experimental protocol and device of waste plasticsand used lubricating oils co-pyrolysis have been adapted to co-pyrolyze a mixturecontaining PVC. Two-step co-pyrolysis tests were performed to evaluate the influenceof parameters such as the evolution of the temperature during the test, the PVCcontent of the mixture and the plastic that is mixed with PVC (LDPE or PS). Finally,interactions that take place between the LDPE or the PS and an oil, when co-pyrolyzed,have been identified with high resolution thermogravimetry experiments. We tried toexplain the identified interactions through a combination of thermal analyzes thatcharacterized or identified the sample decomposition products, continuously duringthe thermal decomposition or at its end.
Doctorat en Sciences de l'ingénieur et technologie
info:eu-repo/semantics/nonPublished

Cette étude a pour objectif de contribuer au développement de la rmn du carbone-13 en tant qu'outil d'identification et de quantification des constituants des mélanges complexes naturels et d'appliquer cette technique a la caractérisation d'huiles essentielles du viet-nam et d'un liquide de pyrolyse de la biomasse. Les données chromatographiques et spectroscopiques (rmn du carbone-13) de composes linéaires non terpéniques diversement fonctionnalises (alcools, acetates et aldehydes, satures et insatures) ont ete determinees. Les valeurs de déplacements chimiques des carbones aliphatiques c4 et c5 des aldehydes α,β-insatures ont ete comparées a celles des alcools correspondants. Ces carbones présentent respectivement un léger deblindage et blindage du vraisemblablement a la conjugaison et indépendants de la longueur de la chaine carbonée. L'étude detaillee par rmn du carbone-13 d'une huile essentielle de piper bavinum du viet-nam a permis d'expliciter la méthode d'analyse. La composition chimique de diverses huiles essentielles vietnamiennes a ete déterminee par combinaison de la cpg(ir), de la cpg-sm et de la rmn du carbone-13. Certaines d'entre elles sont décrites pour la premiere fois et d'autres possedent une activité antibacterienne. Un liquide de pyrolyse de la biomasse a ete fractionne. Les fractions obtenues ont ete analysées par diverses techniques analytiques (analyse elementaire, ces, irtf, cpg-sm et rmn du carbone-13). La présence de trois grandes familles de composes a ete mise en évidence: des alcanes (satures et insatures), des sucres anhydres et des composes phénoliques (monomeres et oligomeres). Les oligomeres possedent une masse pouvant dépasser 5000 g. Mol-1. Enfin, une séquence quantitative par rmn du carbone-13 a ete mise en oeuvre pour déterminer la proportion d'hydroxyacetaldehyde (présent sous diverses formes monomeres et dimeres) dans les liquides de pyrolyse
The objective of this study was a contribution to the development of the 13c nmr as a tool for identification and quantitative determination of the components of natural mixtures. This technique was applied to the caracterization of essential oils from vietnam and a bio-oil. The chromatographic and spectroscopic data of acyclic, non terpenic compounds, bearing different fractions (alcohols, acetates and aldehydes, satured and unsatured) were determined. The signals of the c4 and c5 carbons of α,β-unsatured aldehydes were deshielded and shielded respectively, compared with those of the corresponding alcohols. These differences are probably the consequence of conjugation and are no dependant of the chain length. A detailed an alysis by 13c nmr of the essential oil of piper bavinum from vietnam allowed the direct identification of 38 components. The chemical composition of various essential oils from vietnam was determined by combination of gc(ri), gc-ms and 13c nmr. The composition of some of these oils was reported for the first time and some others oils exhibited an antibacterial activity. A bio-oil was fractionated and the fractions were analysed by complementary analytical techniques (gpc, irft, gc-ms and 13c nmr). Three families of components were distinguished: alcanes, anhydrosugars and phenolic compounds (monomers and oligomers). The oligomers have a mass up to 5000 g. Mol-1. Finally, a quantitative sequence was implemented to determine, by 13c nmr, the content of hydroxyacetaldehyde (monomeric and dimeric forms) in the bio-oils

L'objectif de ce travail était de synthétiser par pyrolyse laser des nanopoudres permettant d'élaborer des nanocomposites céramiques Si(3)N(4)-SiC présentant une forte ductilité à haute température. La synthèse de nanopoudres SiCN et SiCNYAlO stables thermiquement a été mise au point à partir d'un mélange de précurseurs liquides à base d'haxamétyldisilazane. Des nanocomposites denses Si(3)N(4)-SiC ont été élaborés par pressage uniaxial à chaud, à partir d'un mélange de nanopoudres SiCN et d'ajouts de frittage [Al(2)O(3) et Y(2)O(3], ou à partir de nanopoudres préalliées SiCNYAlO. L'étude de la densification a montré que la poudre préalliée présente une meilleure aptitude au frittage. De plus, l'utilisation de poudre préalliée simplifie le procédé d'élaboration en éliminant l'étape délicate de mélange des nanopoudres. Les matériaux nanostructurés élaborés à partir du mélange de poudres sont ductiles à haute température ; une déformation atteignant 45% a été obtenue en compression sous 180 MPa à 1350°

La chimie se doit de développer de nouveaux axes de recherche à la fois respectueux de la nature et s’inscrivant dans une démarche globale éco-compatible. Dans ce contexte, l’utilisation des polymères naturels, notamment les polysaccharides, permet de synthétiser des matériaux innovants des applications dans de nombreux secteurs industriels. L’objectif de ce travail est de valoriser les polysaccharides marins tels que le chitosane et le κ-carraghénane à travers l’exploration de deux axes de recherches. Le premier axe est consacré à l’amélioration des propriétés mécaniques, électriques et de sorption de biopolymères par l’incorporation de graphène. Un protocole original a permis de disperser très efficacement du graphène au sein du chitosane pour la conception de films et d’aérogels nanocomposites. L’analyse des films a mis en évidence une amélioration simultanée de la rigidité, de la résistance, et de l’élongation à rupture, pour de faibles teneurs en graphène. Le seuil de percolation permettant l’obtention d’une conductivité électrique n’a pas été atteint aux faibles taux de charges utilisés. L’étude des aérogels chitosane/graphène a, quant à elle, révélé que l’incorporation de graphène aux aérogels de chitosane permettait d’augmenter leur capacité d’adsorption de colorants.Le deuxième axe concerne l’introduction d’hétéroatomes dans la structure carbonée du graphène. Pour obtenir du graphène dopé en azote et en soufre, des aérogels de polysaccharides marins ont été synthétisés, puis pyrolysés dans des conditions contrôlées. Les aérogels carbonés obtenus sont ensuite exfoliés dans l’eau par l’utilisation d’ultrasons. Les groupements amine du chitosane ont permis d’obtenir avec un haut rendement un graphène dopé avec un taux de 5 % d’azote. De plus, il a été possible de moduler de 5 % à 11 %ce taux d’azote par l’emploi de liquide ionique tel que le [EMIm][dca]. De façon similaire, les groupements sulfate du κ-carraghénane ont permis de doper du graphène en soufre avec un taux d’atomes de soufre de 1,5 %
The chemistry have to develop new research axis both respectful of the nature and joining an eco-compatible global approach. In this context, use natural polysaccharides allow to synthesize innovative materials for applications in many industries fields. The aim of this work is add value to the marine polysaccharide such as chitosan and κ-carrageenan through two research axis.The first axis is consecrated to increase the mechanical, electrical and color sorption properties by introduce graphene filler in biopolymer matrice. An easy and original protocol allowed scattering very effectively graphene in chitosan to design films and aerogels nanocomposites. The analyse of nanocomposite films show an improvement of stiffness, tensile strength and elongation break at the same time with low content of graphene. However, the percolation threshold was not reach to bring electrics properties in films. The study of chitosan/graphene aerogel reveals that graphene allows an increase of color agent adsorbing power such as eosin Y compared with aerogels chitosan.The second axis concerns the introduction of heteroatom in graphene carbon structure. To obtain nitrogen-doped graphene and sulphur-doped graphene, it requires the synthesis of marine polysaccharide aerogel, and their pyrolysis under controlled conditions. The carbon aerogels are exfoliated in water with sonification. Amine groups in chitosan allowed through this process a nitrogen-doped graphene with high yield and nitrogen rate of 5 %. Moreover, it was possible to modulate nitrogen rate with ionic liquid such as [EMIm][dca]. So the nitrogen atom rate increases from 5% to 11%. In similar way, sulfate group in κ-carrageenan gives sulphur-doped graphene with sulphur rate of 1,5%

The current societal needs for fuels and chemical commodities strongly depend on fossil resources. This dependence can lead to economic instabilities, political problems and insecurity of supplies. Moreover, global warming, which is associated with the massive use of fossil resources, is a dramatic “collateral damage” that endangers the future of the planet. Biomass is the main renewable source available today that can, produce various liquid, gaseous and solid products. Due to their lignocellulosic origin are considered CO2 neutral and thus can generate CO2 credits. Biomass processing can meet to the challenge of reducing of fossil resources by producing a liquid feedstock that can lessen the “fossil dependence” and /or meet the increased demand via a rapidly emerging thermochemical technology: pyrolysis. The ultimate goal of this process is to produce liquid with improved properties that could directly be used as liquid fuel, fuel additive and/or feedstock in modern oil refineries and petrochemical complexes. However, the liquids derived from biomass thermal processing are problematic with respect to their handling and end use applications. Thus, alternative routes of advanced liquid feedstock production are needed. Heterogeneous catalysis has long served the oil refining and petrochemical industries to produce a wide range of fuels and products. The combination of biomass pyrolysis and heterogeneous catalysis (by bringing in contact the produced vapours/liquids with suitable catalysts) is a very promising route. In this dissertation, the exploitation of biomass to produce of liquid feedstock via pyrolysis over a multifunctional catalyst and in a steam atmosphere is investigated.  Steam pyrolysis in a fixed bed reactor demonstrated that steam can be considered a reactive agent even at lower temperatures affecting the yields and the composition of all the products. The devolatilisation accelerates and the amount of final volatile matter in the char. Fast pyrolysis in the presence of steam results in improved and controlled thermal decomposition of the biomass; higher liquid yields and slightly deoxygenated liquid products are also obtained. Steam pyrolysis over a bi-metallic Ni-V catalyst can produce liquids of improved quality (lower O content) and also provide routes for selective deoxygenation. However, a decrease in liquid yield was observed. The combination of metal and acid catalysts (Ni-V/HZSM5) shows enhanced deoxygenation activity and increased H preservation in the produced liquid. The final O content in the liquid was 12.83wt% at a zeolite (HZSM5) loading of~75wt%; however, the yield of the obtained liquid was substantially decreased. Moreover, increased coke formation on the catalyst was observed at highest zeolite rate. The increased catalyst space time (τ) results in a lower liquid yield with reduced oxygen (7.79 wt% at τ =2h) and increased aromatic content. The coke deposited per unit mass of catalyst is lower for longer catalyst space times, while the char yield seems to be unaffected. The evaluation of the stability of the hybrid catalyst showed no significant structural defects and activity loss when the catalyst was regenerated at a low temperature (550οC).
Det nuvarande samhällets behov av bränslen och kemiska produkter är starkt knutet till fossila resurser. Detta beroende kan leda till ekonomisk instabilititet, politiska svårigheter och osäker leveranssäkerhet. Dessutom riskeras allvarliga skador i framtiden på grund av global uppvärmning, vilket är relaterat till det ökande och massiva användandet av fossila bränslen.   Biomassa är en förnybar resurs som är tillgänglig idag, möjlig att utnyttja för produktion av diverse flytande, gasformiga och fasta produkter. Dessa produkter, beroende på biogeniskt ursprung, betraktas som koldioxidneutrala och kan därför generera koldioxidkrediter. Processande av biomassa kan möta utmaningen av minskad fossilbränsleanvändning, genom produktion av flytande råvara som kan reducera beroendet och/eller möta ökad efterfrågan, via en snabbt expanderande termokemisk teknik - pyrolys.    Det slutgiltiga målet med en sådan process är att producera en flytande produkt med förbättrade egenskaper som direkt skulle kunna användas som flytande bränslen, bränsleadditiv och/eller som råmaterial i moderna oljeraffinaderier och petrokemiska komplex. Vätskor som utvinns från termiska processer är problematiska med avseende på hantering och slutanvändningen i olika applikationer, därmed behövs olika spår för produktion av avancerade flytande råvaror. Heterogena katalysen har länge tjänat raffinaderi- och petrokemisk industri, som producerar ett brett utbud av bränslen och produkter, lämpliga för säker användning. Kombinationen av biomassapyrolys och heterogen katalys  (genom att bringa pyrolysångorna i kontakt med en lämplig katalysator) är ett väldigt lovande spår. I denna avhandling undersöks användningen av biomassa för produktion av flytande råvara, via pyrolys över en flerfunktionel katalysator i ångatmosfär. Ångpyrolys i en fastbäddsreaktor visade att ånga kan betraktas som ett reaktivt medium,  även vid låga temperaturer, som påverkar utbyten och sammansättning av alla produkter. Avgasningen sker snabbare och den slutliga flykthalten i kolresterna blir lägren vid användning av ånga. Snabbpyrolys i ångatmosfär resulterar i förbättrad och mer kontrollerad termisk nedbrytning av biomassa, vilket ger ett högre vätskeutbyte och en något deoxygenerad flytande produkten. ångpyrolys i kombination med bimetalliska NiV-katalysatorer, ger upphov till en flytande råvara med förbättrad kvalitet och selektiv deoxygenering. Dock med ett minskande utbyte som följd. Kombinationen av metall och en sur katalysator (Ni-V/HZSM5) visade förstärkt deoxygenering med bibehållen vätehalt i den flytande produkten. Den slutliga syrehalten i vätskan var 12.83 vikt% vid en zeolithalt (HZSM5) på 75 vikt%, dock med ett kraftigt minskande vätskeutbyte. Dessutom noterades ökad koksbildning på katalysatormaterialet med den högsta zeolithalten. Ökad rymd-tid  för katalysatorn (τ) ger ett lägre vätskeutbyte med reducerad syrehalt (7.79 vikt% vid τ=2h) och ökad aromathalt. Koksbildning på ytan, per massenhet katalysatormaterial, minskade vid längre rymd-tider medan utbytet av kolrester förblev opåverkat.  Undersökningen av stabiliteten hos hybridkatalysatorn visade inga strukturella defekter och ingen signifikant minskad aktivitet efter regenerering vid låg temperatur (550οC).
Οι σύγχρονες ανάγκες της κοινωνίας για παραγωγή υγρών καυσίμων και χημικών προϊόντων εξαρτώνται από τους ορυκτούς πόρους. Αυτή η εξάρτηση μπορεί να οδηγήσει σε οικονομικά προβλήματα, πολιτκή αστάθεια, όπως επίσης και αβεβαιότητα στις προμήθειες της ενεργειακής εφοδιαστικής αλυσίδας. Επιπροσθέτως, μια δραματική «παράπλευρη απώλεια» η οποία θέτει σε κίνδυνο το μέλλον του πλανήτη είναι η υπερθέρμανσή του, η οποία έχει συσχετισθεί με την εκτεταμένη χρήση ορυκτών πόρων. Σήμερα, η βιομάζα είναι η μόνη ανανεώσιμη πηγή από την οποία μπορούν να παραχθούν υγρά, αέρια και στερεά προϊόντα, που λόγω της λιγνοκυταρρινικής τους προελεύσεως, η συνεισφορά τους στις εκομπές CO2 θεώρειται μηδενική. Η θερμοχημική επεξεργασία της βιομάζας συνεισφέρει στον περιορισμό της χρήσης ορυκτών πόρων, με την παραγωγή υγρών προϊόντων, τα οποία μπορούν να μειώσουν την εξάρτηση ή /και την αυξημένη ζήτηση μέσω μιας ταχέως αναπτυσόμενης τεχνολογίας, της πυρόλυσης. Στόχος της διεργασίας είναι η παραγωγή υγρών προϊόντων με ιδιότητες, που επιτρέπουν την απευθείας χρήση τους ως υγρά καύσιμα ή ως πρώτη ύλη, για την παραγώγη χημικών προϊόντων σε συγχρονες μονάδες διύλισης πετρελαίου και σε πετροχημικά συγκτροτήματα. Εν τούτοις, τα υγρά προϊόντα της θερμικής διάσπασης (πυρόλυση) είναι προβληματικά στη διαχείρηση και στις τελικές τους εφαρμογές, λόγω της σύστασής τους. Ως εκ τούτου, απαιτούνται νέες τεχνικές για παραγωγή προηγμένων υγρών προοϊόντων. Η ετερογενής κατάλυση έχει επιτυχώς εφαρμοσθεί στην πετρελαϊκή και χημική βιομηχανία, παράγοντας ένα μεγάλο εύρος προϊόντων. Ο συνδυασμός της με την πυρόλυση (φέρνοντας σε επαφη τα υγρά/ατμούς με κατάλληλο καταλύτη) αποτελεί μια πολλά υποσχόμενη ενναλακτική. Στην παρούσα διατριβή μελετάται η αξιοποίηση βιομάζας για παραγωγή υγρών προϊόντων μέσω καταλυτικής πυρόλυσης, με χρήση πολυλειτουρικού καταλύτη (multi-functional catalyst) υπό την παρουσία ατμού. Η χρήση ατμου κατά τη διαρκειά πυρόλυσης βιομαζας σε αντιδραστήρα σταθερής κλίνης, μεταβάλει τη σύσταση των επιμέρους προϊόντων. Η παρουσία ατμού έχει ως αποτέλεσμα την ταχύτερη αποπτητικοποίηση του υλικού, ενώ παράλληλα η περιεκτικότητα του υπολειπόμενου εξανθρακώματος σε πτητικά είναι μικρότερη. Τα πειραματικά αποτελέσματα ταχείας πυρόλυσης σε αντιδραστήρα ρευστοστερεάς κλίνης δείχνουν ό,τι η χρήση ατμού βελτιώνει την θερμική διάσπαση της βιομαζας, αυξάνοντας την απόδοση σε υγρά προϊοντά, ενώ παράλληλα βοηθάει στην αποξυγόνωσή τους. Ο συνδυασμός της πυρόλυσης υπό την παρουσία ατμού και διμεταλλικού καταλύτη νικελίου–βαναδίου μπορεί να  βελτιώσει την ποιότητα των παραγόμενων υγρών (αποξυγόνωση) με παραλλήλη μείωση της απόδοσής τους, ενώ μπορεί να  παράγει προϊόντα εκλεκτικής αποξυγόνωσης. Συνδυασμός μεταλλικών και ζεολιθικών καταλυτών (Ni-V/HZSM5) εμφανίζει βελτιωμένη δραστικότητα στις αντιδράσεις αποξυγόνωσης, με παράλληλη συγκράτηση υδρογόνου (Η) στα υγρά προϊόντα. Η τελική περιεκτικότητα των υγρών προϊόντων σε οξυγόνου (Ο) μετά από 90 min αντίδρασης είναι 12.83 wt%, με περιεκτικότητα ζεόλιθου (ΗZSΜ5) ~75 wt% στον καταλύτη. Ωστόσο, η αυξηση της περεικτικότητας σε ζεόλιθο έχει ως αποτέλεσμα την αύξηση των επικαθήσεων άνθρακα επάνω στον κατάλυτη, καθώς και την σημαντική μειώση της απόδοσης των υγρών προϊόντων (24.35wt% επι ξηρής βιομάζας).  Η αύξηση του χώρου χρόνου του καταλύτη (τ) έχει ως αποτέλεσμα: τη μείωση των υγρών προϊόντων, τη μείωση του περιεχόμενου Ο στα υγρά προϊόντα (7.79 wt% at τ =2h), την αύξηση των αρωματικών υδρογονανθράκων και τη μείωση του επικαθήμενου κωκ ανά μονάδα μάζας καταλύτη. Η απόδοση του εξανθρακώματος παρέμεινε πρακτικά αμετάβλητη. Η αναγέννηση του υβριδικού καταλύτη σε χαμηλές θερμοκρασιές (550οC) δεν επέφερε σημαντικές δομικές αλλαγές και απώλεια δραστικότητας.

QC 20140306

The use of pyrolysis as a waste disposal method for waste plastics has been well established. However, the market value of the recycled plastic products and separate upgrading of the pyrolysis product liquid are some of the challenges facing the process. Therefore, the use of pyrolysis-catalysis of waste plastic in a two-stage pyrolysis-catalysis reactor system could bring a balance between sustainability and market value of the products generated. Hence, this work investigated the influence of different types of zeolite catalysts on the pyrolysis-catalytic upgrading of waste plastics for quality liquid fuels and valuable chemical production. Initially, two zeolite Y and ZSM-5 catalysts, in the form of pellets, were used for pyrolysis-catalysis of WEEE. Zeolite catalyst with a lower Si-Al ratio (Y zeolite) produced a higher conversion of the styrene to other aromatic products, particularly benzene and toluene. Thereafter, the influence of six zeolite catalysts with different surface areas and Si: Al ratios was investigated on the catalytic pyrolysis of waste high-density polyethylene (HDPE). Overall, the results suggest that the catalyst properties influenced the conversion of HDPE to more valuable products such as fuel-range hydrocarbons and chemicals. Similarly, pyrolysis of real-world mixed plastics, simulated mixed plastic (SMP), and virgin plastics were investigated in the presence of HZSM-5 catalyst. In addition, a sample of spent FCC catalyst was also tested for the pyrolysis of the plastic samples. Finally, the influence of spent FCC, fresh zeolite Y and ZSM-5 catalysts was investigated under different bed temperatures from 400 – 600 °C. This final work confirmed that the choice of a bed tempetrure of 500 °C, for most of this research was appropriately justified. Overall, the product oils gave fuel properties similar to gasoline, the aromatic content of the oil make them suitable as chemical feedstocks, the gas products with very high-calorific values can be used as fuel gas.

The overuse of antibiotics in agriculture is an emerging concern, due to their potential detrimental impact to the environment. This study focuses on exploring antimicrobial properties of lignin derived compounds. Lignin is of interest as a feedstock to replacing some petroleum-based chemicals and products because it is the most abundant source of renewable aromatic compounds on the planet. Two lignin rich streams, residues from the enzymatic hydrolysis of dilute acid and alkaline pretreated corn stover, were decomposed via pyrolysis and hydrogenolysis, respectively. The resulting liquid oils were subjected to sequential extractions using a series of solvents with different polarities. Chemical compositions of the extracted fractions were characterized through HPLC and GC/MS. These extracted compounds were screened against Saccharomyces cerevisiae (S. cerevisiae), Escherichia coli, and Lactobacillus amylovorus for antimicrobial properties. Six lignin model monomers: guaiacol, vanillin, vanillic acid, syringaldehyde, 2,6-dimethoxyphenol, and syringic acid were compared to the oils and extracted fractions for antimicrobial properties. Development of lignin-derived chemicals with antimicrobial properties could provide a novel use for this underutilized natural resource.

Lignocellulosic biomasses are considered promising feedstocks for the next generation of biofuels and chemicals; however, the recalcitrance of lignocellulose remains a barrier to its utilisation over conventional sources. Pyrolysis is the heating of biomass to several hundred degrees Celsius in the absence of oxygen, which can thermally depolymerise lignocellulose. Products of pyrolysis are a solid biochar, liquid bio-oil and syngas. Biochar has roles in both carbon sequestration and soil amendment however bio-oil has no defined use, despite a high concentration of fermentable sugars. Bio-oil is a complex organic microemulsion with a host of biocatalyst inhibitors that makes its microbial degradation a challenge. In this work, the use of aerobic cultures using microbial communities isolated from natural environments saw limited potential; however, the use of anaerobic digestion (AD) successfully generated a higher volume of biogas from reactors with bio-oil than controls. Biogas yield test reactors were set up with anaerobic digestate from a wastewater treatment plant as the substrate for degradation and conversion of bio-oils. Next-generation 16S rRNA gene sequencing was utilised to characterise the communities in the reactors while the ultrahigh resolution mass spectrometry technique of Fourier transform ion cyclotron resonance (FT-ICR) was used for characterisation of the chemical changes occurring during AD. Both sets of high-resolution data were additionally combined for multivariate analysis and modelling of the microbial genera that correlated best with the changes in digestate chemistry. This represents a novel analysis method for the microbial degradation of complex organic products. Bio-oil from common lignocellulosic feedstock was the most easily degradable by the AD communities, with significant inhibition observed when bio-oils from anaerobic digestate and macroalgae were used. Additionally it was found that the inclusion of biochars that were pre-incubated in anaerobic digestate prior to use in AD were capable of significantly reducing the lag time observed for biogas production in bio-oil-supplemented reactors. The addition of biochars that were not pre-incubated had no effect on biogas production. Specific inhibition of methanogenesis was also capable of causing the digestates to accumulate volatile fatty acids (VFAs) as a product of greater value than biogas. Scale-up experiments will be required to confirm the precise practicalities of the addition of bio-oil to AD as well as to establish the potential for isolation and purification of VFAs.

The aim of the present thesis is to model the conversion process of the fast pyrolysis vapours into liquid bio-oil in liquid collection systems. The study focuses on the two major types of condensation systems namely the indirect contact condensers and the direct contact condensers (quenching columns). In the first part of the research, the hydrodynamic and heat transfer characteristics of a bench scale quenching column are presented by conducting numerical simulations based on the immiscible Eulerian-Eulerian model. The simulations are compared with experimental observations on flooding phenomena and various design variants are proposed for their elimination. In the second part, a multiphase multi-component model, with the condensable vapours and non-condensable gases as the gaseous phase and the condensed bio-oil as the liquid phase, has been developed. Species transport modelling has been used to capture the detailed physical phenomena of 11 major compounds present in the pyrolysis vapours. The development of the condensation model relies on the saturation pressures of the individual compounds computed based on the corresponding state correlations. In the final part, detailed information is provided on the vapour phase change dynamics implemented on a disc and donut quenching column design obtained from the first part. The study investigates the effect of the different numbers of disc and donut pairs on the condensation performance of the column. The numerical simulations showed that different number of stages can significantly affect the final bio-oil composition. It is shown that heavy molecular weight compounds, condense rapidly even with a low number of stages, whereas an increased number of stages is needed to completely capture the heavier acidic fractions. The modelling results are in good agreement with data published in the existing literature.

Fast pyrolysis of biomass is a significant technology for producing pyrolysis liquids [also known as bio-oil], which contain a number of chemicals. The pyrolysis liquid can be used as a fuel, can be produced solely as a source of chemicals or can have some of the chemicals extracted and the residue used as a fuel. There were two primary objectives of this work. The first was to determine the fast pyrolysis conditions required to maximise the pyrolysis liquid yield from a number of biomass feedstocks. The second objective was to selectively increase the yield of certain chemicals in the pyrolysis liquid by pre-treatment of the feedstock prior to pyrolysis. For a particular biomass feedstock the pyrolysis liquid yield is affected by the reactor process parameters. It has been found that, providing the other process parameters are restricted to the values shown below, reactor temperature is the controlling parameter. The maximum pyrolysis liquid yield and the temperature at which it occurs has been found by a series of pyrolysis experiments over the temperature range 400-600°C. high heating rates > 1000°C/s; pyrolysis vapour residence times <2 seconds; pyrolysis vapour temperatures >400 but <500°C; rapid quenching of the product vapours. Pre-treatment techniques have been devised to modify the chemical composition and/or structure of the biomass in such a way as to influence the chemical composition of the pyrolysis liquid product. The pre-treatments were divided into two groups, those that remove material from the biomass and those which add material to the biomass. Component removal techniques have selectively increased the yield of levoglucosan from 2.45 to 18.58 mf wt.% [dry feedstock basis]. Additive techniques have selectively increased the yield of hydroxyacetaldehyde from 7.26 to 11.63 mf w.% [dry feedstock basis]. Techno-economic assessment has been carried out on an integrated levoglucosan production process [incorporating pre-treatment, pyrolysis and chemical extraction stages] to assess which method of chemical production is the more cost effective. It has been found that it is better to pre-treat the biomass in order to increase the yield of specific chemicals in the pyrolysis liquid and hence improve subsequent chemicals extraction.

The overall objective of this work was to compare the effect of pre-treatment and catalysts on the quality of liquid products from fast pyrolysis of biomass. This study investigated the upgrading of bio-oil in terms of its quality as a bio-fuel and/or source of chemicals. Bio-oil used directly as a biofuel for heat or power needs to be improved particularly in terms of temperature sensitivity, oxygen content, chemical instability, solid content, and heating values. Chemicals produced from bio-oil need to be able to meet product specifications for market acceptability. There were two main objectives in this research. The first was to examine the influence of pre-treatment of biomass on the fast pyrolysis process and liquid quality. The relationship between the method of pre-treatment of biomass feedstock to fast pyrolysis oil quality was studied. The thermal decomposition behaviour of untreated and pretreated feedstocks was studied by using a TGA (thermogravimetric analysis) and a Py-GC/MS (pyroprobe-gas chromatography/mass spectrometry). Laboratory scale reactors (100g/h, 300g/h, 1kg/h) were used to process untreated and pretreated feedstocks by fast pyrolysis. The second objective was to study the influence of numerous catalysts on fast pyrolysis liquids from wheat straw. The first step applied analytical pyrolysis (Py-GC/MS) to determine which catalysts had an effect on fast pyrolysis liquid, in order to select catalysts for further laboratory fast pyrolysis. The effect of activation, temperature, and biomass pre-treatment on catalysts were also investigated. Laboratory experiments were also conducted using the existing 300g/h fluidised bed reactor system with a secondary catalytic fixed bed reactor. The screening of catalysts showed that CoMo was a highly active catalyst, which particularly reduced the higher molecular weight products of fast pyrolysis. From these screening tests, CoMo catalyst was selected for larger scale laboratory experiments. With reference to the effect of pre-treatment work on fast pyrolysis process, a significant effect occurred on the thermal decomposition of biomass, as well as the pyrolysis products composition, and the proportion of key components in bio-oil. Torrefaction proved to have a mild influence on pyrolysis products, when compared to aquathermolysis and steam pre-treatment.

Ce travail qui s'inscrit dans le cadre de recherches à finalités appliquées, a pour objectif d'élaborer des matériaux carbonés à propriétés adsorbantes sélectives. Dans ce but, nous avons pyrolysé des mélanges brai de houille (ou charbon cokéfiant)-FeCI3 libre ou intercalé dans du graphite pulvérulent. L'effet des différents ajouts sur l'évolution thermique du brai de houille entraîne une accélération et une modification importante du mécanisme de développement de la mésophase. Dans le cas des précurseurs à base de charbon, il a été montré que l'ajout de l'halogénure entraîne une modification dans le dégagement des matières volatiles (résultat obtenu également dans le cas des précurseurs à base de brai), ainsi qu'une dégradation des propriétés mécaniques des semi-cokes résultants se traduisant par une diminution de la taille des domaines d'orientation moléculaire. FeCl3 provoque également une forte augmentation de l'ultramicroporosité dans les semi-cokes. L'analyse de la texture poreuse des semi-cokes activés à la vapeur d'eau montre que l'acide de Lewis initialement introduit dans les mélanges conduit à une augmentation de la mésoporosité dans les matériaux ex-brai et une augmentation de la microporosité dans les matériaux ex-charbon. Des essais de chimisorption sur les matériaux activés ont montré l'influence de la magnétite vis-à-vis des capacités de piégeage en H2S ou SO2. De plus, les propriétés catalytiques de ces échantillons vis-à-vis de la réduction de NO se traduisent par un taux de conversion (NO - > N2) de 45% à relativement basse température (I80a C).

Cette etude a pour objectif de contribuer a la valorisation de la biomasse, en tant que vecteur energetique et comme source de produits a forte valeur ajoutee. Or dans les deux cas, il s'agit de melanges complexes dont la caracterisation, recommandee, necessite l'analyse fine des constituants. Pour ce faire, nous avons developpe et utilise la methodologie d'analyse des melanges complexes par rmn du carbone-13 sans separation prealable des constituants, mise au point par notre equipe, et nous l'avons appliquee a trois types de melanges : les liquides de pyrolyse, l'huile essentielle de p. Lentiscus et les extraits du liege. En ce qui concerne les liquide de pyrolyse, apres avoir teste divers procedes de fractionnement, nous avons montre que l'extraction par des solvants de polarite croissante associee a l'analyse par rmn du carbone-13 des fractions obtenues, permet d'identifier pres d'une vingtaine de constituants et ainsi de caracteriser globalement le melange. Dans le but de caracteriser l'huile essentielle de lentisque de corse nous avons analyse par rmn du carbone-13 et par cpg plusieurs echantillons de population et plus d'une centaine d'echantillons individuels. Nous avons ainsi mis en evidence une variabilite chimique intraspecifique de cette huile essentielle, caracterisee par trois groupes d'inegale importance en fonction des proportions d'-pinene/terpinen-4-ol, de myrcene et de limonene. Enfin, nous avons mis au point un protocole experimental qui permet l'identification et la quantification par rmn du carbone-13, des triterpenes majoritaires des extraits dichloromethaniques du liege. L'analyse selon cette methode de 38 echantillons de sardaigne et de corse a montre une variabilite chimique des extraits ainsi qu'une correlation entre la composition chimique des echantillons et l'origine geographique du liege.

Alternative fuels are becoming more important as fossil fuels become more expensive. This thesis describes the production and properties of a bio-oil produced from waste biomass, in this case chicken litter. A higher quality fuel was produced through thermal and chemical upgrading of the raw bio-oil; this fuel is similar in some respects to fossil fuels, as it has a high hydrocarbon content and energy density comparable to gasoline. Combustion of liquid fuels commonly occurs in clouds of droplets, and studying the evaporation of single liquid drops provides information on the evaporation characteristics of the fuel as a whole. Droplet evaporation tests on the chicken litter fuel were carried out using the suspended droplet/moving furnace technique. For some tests, a fine wire thermocouple was used as the droplet suspension in order to measure the distillation characteristics of the fuel. An existing computational model based on continuous ther- modynamics was used to model the evaporation of the fuel. The modelled composition of the fuel was based on an existing pyrolysis field ionization mass spectrometry (Py-FIMS) analysis and used five major groups of compounds. The properties for these groups re- quired for the model were determined using several prediction methods and the values then used in a numerical model. Model predictions of droplet temperatures calculated for the fuel showed good agree- ment with the measured temperatures, indicating that the modelled composition gave an accurate picture of the fuel. Droplet evaporation histories also agreed well with mea- surements, but were not capable of reproducing the observed disruption of the droplet produced by internal boiling at higher temperatures, nor the formation of a solid residue at the end of evaporation. Further enhancements to the model should allow the prediction of residue formation.Model predictions of droplet temperatures calculated for the fuel showed good agree- ment with the measured temperatures, indicating that the modelled composition gave an accurate picture of the fuel. Droplet evaporation histories also agreed well with mea- surements, but were not capable of reproducing the observed disruption of the droplet produced by internal boiling at higher temperatures, nor the formation of a solid residue at the end of evaporation. Further enhancements to the model should allow the prediction of residue formation.

This thesis deals with sorption of selected drugs from model water by various sorption materials. Contamination of water resources by the pharmaceutical industry is a major problem today. Wastewater treatment plants, whose technological processes are unable to completely remove them, have a significant share in the penetration of these substances into the environment. At present, attention is paid to alternative materials that are capable of eliminating these substances. One of the potential sorption materials is biochar as one of the main pyrolysis products. This work focused on the assessment of the sorption properties of the different types of biochar and commercially used active charcoal. The sorption properties of the individual materials were compared with respect to the non-steroidal anti-inflammatory substance ibuprofen and the sulphonamide antibiotic sulfamethoxazole. The results of vial experiments were analysed on a liquid chromatograph with mass detection.

Thesis (Ph. D.)--Ohio State University, 2004.
Title from first page of PDF file. Document formatted into pages; contains xv, 214 p.; also includes graphics (some col.). Includes bibliographical references (p. 194-206). Available online via OhioLINK's ETD Center

Orientador: Caio Glauco Sanchez
Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica
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Resumo: Os processos de gaseificação e pirólise sofrem grande influência do tipo de biomassa que está sendo utilizada propiciando variações na distribuição dos produtos (alcatrão, cinzas, água, gás). No processo de gaseificação é obtido, principalmente, um gás combustível que pode variar seu poder calorífico de acordo com as temperaturas e agentes gaseificantes utilizados. A biomassa utilizada neste trabalho é a casca de castanha de caju proveniente da região nordeste do Brasil. Nesta região existem 23 grandes fábricas e aproximadamente 120 minifábricas de beneficiamento de castanha de caju. Essas fábricas geram grande quantidade de cascas que podem ser utilizadas como combustível. Através da conversão térmica da biomassa nos processos de gaseificação e pirólise foi quantificada a produção de resíduo carbonoso, alcatrão, água e gás variando a taxa de aquecimento, a temperatura final e o agente gaseificante (vapor de água, ar sintético ou nitrogênio). Foi verificado que a utilização de vapor de água (1,21 g/min) propicia a geração de um gás de síntese com grande quantidade de hidrogênio (0,99 g) e dióxido de carbono (12,06 g) e para a produção de gás combustível a pirólise com nitrogênio sem a presença de vapor apresenta um gás combustível com poder calorífico mais alto (13056 kJ/m3).
Abstract: Gasification and pyrolysis processes depend on biomass type used providing variations in the distribution of products (tar, ash, water, gas). In the gasification process is achieved mainly a fuel gas which can vary its calorific value according to the temperatures and gasifying agents used. The biomass used in this work is the shell of cashew nuts from the northeast region of Brazil. In this region there are 23 large factories and approximately 120 mini treaters of cashew nuts. These plants generate large quantities of shells that can be used as fuel. Through the thermal conversion processes of biomass gasification and pyrolysis was quantified the production of carbonaceous wastes, tar, water and gas by varying the heating rate, temperature final and gasifying agent (steam, nitrogen or synthetic air). It was found that the use of water vapor (1,21g/min) promotes the generation of a synthesis gas with large quantities of hydrogen (0,99 g) and carbon dioxide (12,06 g) and to produce a pyrolysis fuel gas with nitrogen without the presence of steam shows a fuel gas with heating value higher (13056 kJ/m3).
Doutorado
Termica e Fluidos
Doutor em Engenharia Mecânica

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
Com o passar do tempo, a população mundial vem se conscientizando mais sobre problemas ambientais. Isso fez surgir uma demanda por tecnologias novas que possam se encaixar no cenário de sustentabilidade. Instabilidades frequentes no cenário político-econômico global acabam por elevar o preço do barril do petróleo. Assim a indústria química começa a buscar por alternativas que tenham a mesma versatilidade do petróleo. Dentre as opções de combustíveis renováveis, destaca-se o bio-óleo de pirólise. Seu interesse em estudos científicos vem do fato de poder-se utilizar do rejeito de processos como matéria prima, não necessitando competir por espaço com a plantação de alimentos. Sua composição pode ser representada por ácidos e fenóis. Em especial destacamos o ácido acético e fenóis oxigenados como m-cresol, o-cresol, p-cresol e guaiacol por estarem presentes em grandes quantidades. Sua separação das frações menos polares do bio-óleo pode ser realizada por meio de extração com água que é um reagente abundante e de baixo custo. O conhecimento das propriedades desses componentes puros é amplamente disponível na literatura, porém dados de composições das fases corrosivas, como misturas ternárias de água-ácido acético-m-cresol/o-cresol/p-cresol/guaiacol nas temperaturas de (298,15, 310,65 e 323,15) K são escassos. Devido a isso, o uso de modelos termodinâmicos para simulação do comportamento desses sistemas torna-se interessante. Todavia, quando são testadas as capacidades dos modelos clássicos, como o UNIFAC e NRTL, percebe-se que os mesmos não conseguem reproduzir o comportamento da binodal dos componentes corrosivos. Sendo assim, essa dissertação investigou soluções para melhorar a descrição desses sistemas, assim como obteve dados experimentais para tais sistemas de misturas ternárias de água-ácido acético-m-cresol/o-cresol/p-cresol/guaiacol nas temperaturas de (298,15, 310,65 e 323,15) K; desenvolveu-se uma metodologia para estimar parâmetros do modelo NRTL a partir de dados de composição da binodal e verificou-se a possibilidade de utilizar o modelo UNIFAC para prever o comportamento de equilíbrio de fases. Como resultado foram obtidos 314 novos dados experimentais, obtiveram-se parâmetros para o modelo NRTL que conseguem reproduzir com acurácia a forma da binodal com a metodologia proposta e verificou-se a necessidade de aperfeiçoamento no estudo do modelo UNIFAC para otimizar sua utilização na previsão do comportamento dos sistemas estudados
Over time the world population has become increasingly aware of environmental problems. This started a demand for new technologies that are more environmentally friendly. Geopolitical instabilities exert a profound influence over oil prices, making the chemical industry search for alternative substances that can have the same versatility as oil. Among renewable fuels, pyrolysis bio-oil stands out as one of the most studied. Researchers were drawn to it because it can be obtained from process waste, thus not competing in space with food plantations. This biooil composition can be represented by acids and phenols. The acetic acid along with m-Cresol, o-Cresol, p-Cresol and Guaiacol are the main components in terms of amount. These substances can be separated from less polar fractions with water, a cheap and abundant solvent. Although knowledge on pure components is abundant in the literature, the opposite is true as regards data on phase composition of its corrosive components, such as ternary mixtures of water-acetic acid-m-cresol/o-cresol/p-cresol/guaiacol at (298.15, 310.65, and 323.15) K. In this case the use of the classical thermodynamic models which simulate the behavior of such systems is recommended. However, when one tests the accuracy of such models as NRTL and UNIFAC, it becomes clear that they cannot replicate the phase component behavior of the corrosive part. Hence, this thesis researched ways to improve knowledge of the ternary mixtures of water-acetic acid-m-cresol/o-cresol/p-cresol/guaiacol at (298.15, 310.65, and 323.15) K. A new methodology was developed to estimate/set parameters for the NRTL model obtained from binodal data. Also, possibility of use of the UNIFAC model to predict phase equilibrium behavior was verified. As a result, a new data set with 314 ternary system data was generated for the ternary mixtures containing acetic acid-water-m-cresol/o-cresol/p-cresol/guaiacol at (298.15, 310.65, and 323.15) K. Through the methodology proposed by this thesis, new parameters for the NRTL model were estimated, which can accurately replicate the binodal curve . Further studies are needed to optimize the UNIFAC model so it is able to predict phase behavior of the studied components

Le développement des technologies propulsives requiert la maîtrise de la régulation de poussée et parfois du refroidissement (propulsion hybride et hypersonique). Cet aspect de contrôle ne peut être abordé qu'après avoir développé une compréhension détaillée des phénomènes couplés mis en jeu (thermique, fluidique, cinétique chimique). La priorité est de proposer des moyens qui soient complémentaires entre eux (bancs d'essais, moyens de mesure, outils numériques) afin d'apporter de nouvelles connaissances scientifiques qui soient transposables à l'industrie. L'ensemble du travail mené dans cette optique est présenté ici en détaillant les applications visées. Ensuite, les similitudes identifiées entre celles-ci (couplage entre pyrolyse du carburant et combustion des produits, pilotage des phénomènes par la chimie) permettent de proposer une démarche globale de recherche portée par l'étude de certains verrous. Les connaissances ainsi développées sont assez larges pour être appliquées à d'autres systèmes, comme l'endommagement au feu des réservoirs de carburant en composite.

Les matériaux polymères sont de plus en plus utilisés pour remplacer d’autres types de matériaux tels que la céramique ou le métal. Cependant, la majorité des polymères ont un désavantage : ils doivent être ignifugés. Néanmoins, grâce à la recherche dans le domaine des matériaux, des polymères haute performance qui résistent à la chaleur et aux scénarios feu ont été conçus. Malgré l’avantage technique qu’apportent ces matériaux, ils sont extrêmement chers. Le but de ce travail est de comprendre la réaction au feu des matériaux hautes performances afin de concevoir des retardateurs de flamme qui réagiraient comme ces polymères hautes performances quand ils sont soumis à des températures élevées ou dans un scénario feu. Dans cette optique, le comportement à haute température et la réaction au feu de trois matériaux hautes performances ont été étudiés : polyetheretherketone (PEEK), polyimide (PI), et polybenzoxazole (PBO). Les mécanismes de décomposition de ces matériaux ont été évalués à travers différentes méthodes analytique telles que le pyrolyseur GCMS et l’ATG-FTIR. La cinétique de décomposition de ces matériaux a aussi été évaluée en utilisant l’ATG dynamique sous différentes atmosphères (azote, 2% oxygène, et air). Cela nous a permis d’acquérir du recul par rapport aux comportements thermiques de ces matériaux hautes performances, que nous avons pu exploiter pour définir des nouveaux retardateurs de feu. Ainsi, une série de retardateurs de flamme ont été synthétisés. Ces retardateurs de flamme font partie de la famille de bases de Schiff et comprennent le salen et ses dérivées, ainsi que certains de leurs complexes métalliques. Le comportement thermique et réaction au feu de ses retardateurs de flamme ont été évalués dans deux polymères : le polyuréthane thermoplastique, et le polyamide 6. Bien qu’une partie de ces retardateurs de feu aient montré peu d’effet au feu, certains ont montré une amélioration importante en termes de chaleur dégagée. Cette nouvelle approche vers la conception de charges ignifugeantes est prometteuse et peut être utilisée comme une méthode complémentaire pour la conception de matériaux haute performance à bas cout
Polymeric materials have been increasingly used as replacement for other types of materials such as ceramics or metals. However, most polymers have a serious drawback: they need to be fire retarded. Nevertheless, thanks to advanced research in the field, high performance materials that resist high temperatures and fire scenarios have been developed. While these materials have extremely enviable properties, they are also very expensive. The aim of this PhD is to understand the fire behavior of high-performance polymers and design fire retardants that would mimic these high-performance materials under extreme heat or fire. To do so, the thermal and fire behavior of three high performance materials were studied: polyetheretherketone (PEEK), polyimide (PI), and polybenzoxazole (PBO). Their thermal decomposition pathways were evaluated thanks to high temperature analytical techniques like pyrolysis-GC/MS and TGA-FTIR. Model based kinetics of the thermal decomposition of these polymeric materials were also elucidated by using dynamic TGA under three different atmospheres (nitrogen, 2% oxygen, and air). These provided insight regarding the thermal behavior high performance polymers, which were used to conceptualize novel potential fire retardants. Therefore, a series of fire retardants that have demonstrated similar behaviors as high performance polymers in fire scenarios were synthesized. These fire retardants include a Schiff base: salen and its derivatives, as well as some of their metal complexes. The thermal behavior and fire performances of these fire retardants were evaluated in two polymeric materials using a relatively low loading (< 10 wt%): thermoplastic polyurethane, and polyamide 6. While some of the fire retardants had little effect, in terms of fire retardancy, some candidates showed a significant improvement in terms of peak of heat release rate. This reverse approach towards designing fire retardants has shown some promise and can be used as a complementary method for the design of high-performance materials at lower cost

The main theme of this thesis is available and potential gaseous and liquid alternative biofuels made from biomass and waste. The thesis deals with their detailed description and comparison. The first part covers the basic distribution of biofuels and alternative fuels made from waste. The main part focuses then on the fuels themselves, their properties, production, use and environmental impact. Furthermore, thesis describes legislative issues and fuels are compared from different perspectives. Practical part includes testing of combustion of liquid fuels taken from waste sources. In the next chapters there is executed overview of basic atomization method of liquid fuels and a plan and running of the testing processed. Evaluation of results is based on point of view of suitability for use, the quality of combustion and emission limits.

Demand for energy and its resources, is increasing every day due to the rapid growth in population and urbanization. As the major conventional energy resources like coal, petroleum and natural gas are at the verge of getting extinct, biomass can be considered as one of the best environment friendly renewable energy options. Though there are many thermo-chemical conversion processes like pyrolysis, combustion, gasification, liquefaction, hydrogenation, Pyrolysis has gained special attention as it can convert biomass directly into solid, liquid and gaseous products by thermal decomposition of biomass in absence of oxygen. In this report, experiments on pyrolysis of sesame seed and groundnut seed was done and effect of temperature on pyrolysis of liquid product, char, volatiles and reaction time were studied. The liquid yield was highest at 500°C for sesame seed and groundnut seed. With increase in temperature, reaction time and weight of char decreased. Volatiles initially decreased and then increased with increase in temperature. The different FTIR spectra of sesame and groundnut oil show the presence of mostly alkane and alkenes. The results were found consistent when compared with the results of GC-MS. 1H NMR analysis of bio-oil proves that β- CH3, CH2 hydrogen protons are attached to an aromatic ring in higher proportions. Presence of pores shown by SEM-EDX analysis paves a path for using this char as an adsorbent.

Biomass pyrolysis is an advanced process in which an organic material is rapidly heated in a controlled environment and in the absence of oxygen to produce a liquid intermediate, the bio-oil, composed of hundreds of oxygenated compounds, which can be used directly to generate heat or further upgraded to a fossil-fuel substitute with improved properties, more suitable to be fed into a conventional oil refinery. This work deals with an experimental investigation in the production and use of biofuels and bioproducts from pyrolysis of several biomass species and alternative feedstock, for distributed energy generation or the production of chemical intermediates (biochemicals). Within the doctoral studies, a dedicated laboratory reactor was built for this scope and samples of pyrolysis oils have been produced from several biomasses, both lignocellulosic and microalgae, in sufficient amount to assess their properties as a fuel. Being a relatively novel bioliquid, material compatibility of microalgae bio-oil was addressed. Tests were carried out on selected metallic and elastomeric specimens to gain insight on handling and storage requirements and to compare the aggressiveness of pyrolysis oil from microalgae with the relatively more known pyrolysis oil from lignocellulosic biomasses. The results from the experimental test campaign, aimed at investigating the possibility of feeding pyrolysis oils to a modified micro gas turbine for power generation, are then presented in the final part of the work. The chapter “Pyrolysis for fuel, energy and chemicals” illustrates some generalities on the pyrolysis oil as a liquid intermediate, along with a brief state of the art of pyrolysis technologies and frontiers. The industrial perspective of generating energy from pyrolysis oils is also addressed, and examples of current demonstration activities in Europe are presented. A synthetic review of literature on two specialized subjects, microalgae and scrap tires pyrolysis, closes the chapter. The chapter “Bio-oil production in a pilot test bench” describes the experimental set-up that was used in this thesis for the production and collection of bio-oil samples. The chapter “Experimental results” discusses the results from production and analysis of pyrolysis oil from several biomass samples in a dedicated laboratory reactor. The yield and properties of the produced pyrolysis oils are presented, discussed and compared one against the other; a large quantity of microalgae from three distinct strains have been converted to pyrolysis oil for the first time in such amount. The chapter also reports the results from laboratory trials aimed at a preliminary assessment of the compatibility of pyrolysis oil from microalgae with 7 commercial specimens of metals and elastomers, commonly used in engineering practice for storage, handling and processing of fuels or organic fluids. Pyrolysis oil from microalgae was compared with pyrolysis oil from pine chips, which is almost commercially available, and for which larger data sets have been generated in the past. Finally, the results of the test campaign on the micro gas turbine are presented in chapter “Use of bio-oils in a modified micro gas turbine”. The possibility to feed a modified micro gas turbine, previously adapted to biofuels, was evaluated and the unit tested with two distinct pyrolysis oils; the first was of biogenic origin (pine chips), the second was obtained from the pyrolysis of scrap tires. Test results are discussed along with the challenges associated with feeding pyrolysis oils to a stationary engine for distributed power generation.

碩士
輔英科技大學
環境工程與科學系碩士班
93
The liquid crystal materials are hazardous to water and very difficult to be biodegraded. The production of liquid crystal wastes (the wastes contain liquid crystal materials) is increasing dramatically. This study investigated the kinetics and emission factor for 16 U.S. EPA priority polycyclic aromatic hydrocarbons (PAHs) in the liquid crystal pyrolysis/combustion. In addition, chemical characteristics and structure of the liquid crystal sample were also investigated. The evaporation of liquid crystals occurs in the early stage of the combustion process (at <545 K). Continuously, the liquid crystal molecules may be oxidized to form CO2, CO, CH4, C2H6 and PAHs. The activation energy (17.2 Kcal/mol), preexponential constant (2.21×106 min-1) and reaction order (0.63) of the liquid crystal combustion were also calculated in this study. On the other hand, the activation energy, pre-exponential constant and reaction order of the pyrolysis of liquid crystal sample are 17.0 Kcal mol-1, 2.15×108 min-1 and 1.15, respectively. The global rate equation for pyrolysis/combustion of the liquid crystal can be expressed as for liquid crystal pyrolysis: dX/dt= 2.15×108 [exp(-17.0/(RT))](1-X)1.15 for liquid crystal combustion: dX/dt= 2.21×106 [exp(-17.2/(RT))](1-X)0.63 (X denotes the reaction conversion). The analytic results indicated that the emission factor for 16 U.S. EPA priority PAHs in particulate and gas phase is n.d.- 57.34, n.d.- 15.55 and n.d.- 15.91, n.d.- 45.63μg/g, respectively, for the liquid crystal combustion and pyrolysis. The emission factor for the liquid crystal combustion is approximately 390 and 1520 times higher, respectively, than that of waste terephthalic acid and biological sludge combustion. Results from this work suggest that the liquid crystal wastes combustion should emphasize the air pollution control.

碩士
輔英科技大學
環境工程與科學系碩士班
96
The sludge produced from wastewater treatment and industry processes. The sludge could be reused because of the enrichment in their remaining resource. They can be derived energy by the enriched organic matter, prepared available adsorbent or construction material, so that the secondary pollution will be reduced from the environment. In this study, the bio-sludge was collected from wastewater treatment process of petrochemical plant and pyrolyzed in an electric thermal furnace or a pilot-scale plant. The effects on characteristics of pyrolytic product including solid, liquid and gas types for different pyrolytic temperature and duration time were examined. The results indicated that the specific surface area (from 56 to 307 m2/g) of residual solid increased with increasing temperature (from 400 to 600 ℃); heating values of liquid fuel derived from distillation by using liquid product ranged from 6731 to 9100 kcal/g; gas product concentration increased with increasing pyrolytic temperature, while some VOCs exhausted from pyrolysis were hazardous for human health. In addition, the air pollution control was investigated by using condensation method, and the effects to reduce the emission of organic gas product from bio-sludge pyrolysis were compared. The results indicated that the chain-forming compounds were reduced as 58% in its concentration; the cyclic-forming compounds were reduced as 47％ in its concentration; and the both were reduced as 49％ in the concentration of total organic compounds. In overview, pyrolysis of petro-derived sludge is appropriate for the purpose on resource reuse, but the air pollution control followed by process of pyrolysis is needed to further studied.

Energy is essential for development and the demand for energy is increasing continuously due to the rapid outgrowth of population and urbanization. Biomass is found to be the maost promising source of many renewable enrgy sources. Pyrolysis is one of the most recent renewable energy processes, has been introduced and offers the advantages of a liquid product – bio-oil – that can be readily stored and transported, and used as a fuel, an energy carrier and a source of chemicals. Catalyst can increase the yield and quality of liquid product oil. In this paper, catalytic pyrolysis of castor seed was performed at 400oC for different ratio of catalyst to biomass using zeolite catalyst. It was found that max yield of liquid was obtained at 1:5 ratio. Overall maximum yield of 62.73% was obtained in case of zeolite at the ratio of 1:5. As compared to the yield of thermal pyrolysis of castor seed without catalyst which was 64.4%, the yield of oil was significantly reduced after catalysis for the catalyzed reaction. It was also observed that the bio-oil contains compounds with carbon chain length in the range of C4–C24 which is similar to most of fuels used.

There are several procedures to extract the energy out of biomass. One of them, that has assumed particular importance is pyrolysis. In this work, cotton seed has been chosen as the material of interest and serves as biomass. These cotton seed samples have been subjected to pyrolysis and the effect of pyrolysis temperature on the yield of liquid product, char and volatile were studied. The main objective of this work was to determine the possibility of finding a product that may serve as a fuel or may be used as a valuable product. Pyrolysis experiments were carried out in the temperature range of 3500C to 6000C. The liquid product was characterized using methods like FTIR and GCMS and its physical properties were determined using standard procedure prescribed in literature.

碩士
國立臺灣大學
環境工程學研究所
105
Indium is a kind of rare metal because of its scarcity in the earth’s crust and difficulty in refining. The major application of indium is indium tin oxide (ITO), a transparent current-conductive material playing a critical role in the liquid crystal display (LCD) function. With the mass production of LCD screens, indium resource was estimated to be exhausted by 2025. Therefore, the recovery of indium from waste LCD is important and urgent. The indium recovery process in this study incorporates the microwave-induced pyrolysis in the hydrometallurgy to enhance the recovery efficiency of indium from waste LCD and get high purity and concentration of indium aqueous solution. The process include four steps: microwave-induced pyrolysis, leaching, extraction, and stripping. First, the microwave-induced pyrolysis process can remove the organics and make the separation between the layers of LCD panel to enhance the leaching rate in the following process. According to the thermal gravimetric analysis (TGA) results, the maximum decay rate of waste LCD occurred at 361.2 °C. Consequently, The microwave-induced pyrolysis process was carried out at the microwave power of 150 W for the processing time of 50 min. Secondly, in the leaching process, indium can be dissolved in the acid solution. 98.27 wt.% of the indium was leached out in 0.5M sulfuric acid with 1:10 solid/liquid ratio, 2 hr, 90 ℃ and stirring at 360 rpm. The purity and concentration of indium are 40.07 % and 25.97 ppm. Thirdly, di(2-ethylhexly)phosphoric acid (D2EHPA) can extract indium from the sulfuric acid solution to separate indium from the other metals and enrich the indium concentration. In the extraction process, the best condition for indium was 20 % (v/v) D2EHPA dissolved in the kerosene at organic-to-aqueous phase ratio (O/A) of 1:10. The purity, concentration and recovery rate of indium are 86.17 %, 228.23 ppm and 81.7 wt.%. Finally, indium in the loaded organic phase can be stripped by hydrochloric acid to separate and enrich indium again. In the stripping process, 68.99 wt.% of the indium was recovered in 6 M hydrochloric acid at O/A of 10:1. The purity and concentration of indium in the final production are 99.98 % and 1892.38 ppm. In this study, the final product (hydrochloric acid solution) containing high purity and high concentration of indium is beneficial to electrolytic refining or replacement to get indium metal. The result indicates that the recovery process of indium from waste LCD by microwave-induced pyrolysis is a promising technique.

Recent developments in converting biomass to bio-chemicals and liquid fuels provide a promising sight to an emerging biofuels industry. Biomass can be converted to energy via thermochemical and biochemical pathways. Thermal degradation processes include liquefaction, gasification, and pyrolysis. Among these biomass technologies, pyrolysis (i.e. a thermochemical conversion process of any organic material in the absence of oxygen) has gained more attention because of its simplicity in design, construction and operation. This research study focuses on comparative assessment of two types of pyrolysis processes and catalytic upgrading of bio-oil for production of transportation fuel intermediates. Slow and fast pyrolysis processes were compared for their respective product yields and properties. Slow pyrolysis bio-oil displayed fossil fuel-like properties, although low yields limit the process making it uneconomically feasible. Fast pyrolysis, on the other hand, show high yields but produces relatively less quality bio-oil. Catalytic transformation of the high-boiling fraction (HBF) of the crude bio-oil from fast pyrolysis was therefore evaluated by performing liquid-phase reactions at moderate temperatures using Pt/HZSM-5 catalyst. High yields of upgraded bio-oils along with improved heating values and reduced oxygen contents were obtained at a reaction temperature of 200°C and ethanol/HBF ratio of 3:1. Better quality, however, was observed at 240 °C even though reaction temperature has no significant effect on coke deposition. The addition of ethanol in the feed has greatly attenuated coke deposition in the catalyst. Major reactions observed are esterification, catalytic cracking, and reforming. Overall mass and energy balances in the conversion of energy sorghum biomass to produce a liquid fuel intermediate obtained sixteen percent (16 wt.%) of the biomass ending up as liquid fuel intermediate, while containing 26% of its initial energy.

Biomass fast pyrolysis liquid is a renewable fuel for stationary heat and power generation; however degradation of bio-oil by time, a.k.a. aging, has an impact on combustion performance and emissions. Moreover, the temperature at which bio-oil is stored has a strong effect on the degradation process. In this study, the same biooil-ethanol blends with different storage conditions are tested in a pilot stabilized spray burner under the same flow conditions. Measurements were made of the steady state gas phase emissions and particulate matter, as well as visual inspection of flame stability. The results confirm a relationship between room temperature storage time and storage at higher temperatures (accelerated aging). They also show that fuel aging increases the emissions of carbon monoxide, unburned hydrocarbon and the organic fraction of particulate matter. These emissions increase more rapidly as more time is allocated for aging. NOx emission shows a slight decrease with fuel aging.

A residential micro-cogeneration system based on a Stirling engine unit was modified to operate with wood derived fast pyrolysis liquid (bio-oil)-ethanol blend. A pilot stabilized swirl combustion chamber was designed to replace the original evaporative burner due to bio-oil’s nondistillable nature. This also required modifications of the engine’s control systems. Efficiencies for the bio-oil/ethanol blend were found be higher than those of diesel due to the higher heat loss incurred with diesel. Based on a modified efficiency, which disregarded the heat loss through the combustion chamber, power efficiencies were found to be comparable. The maximum time of operation with the bio-oil/ethanol blend was approximately 97 minutes due to the clogging of the narrow passages. Carbon monoxide emissions were higher for the bio-oil/ethanol blend due to the operation conditions of the combustion chamber. Oxides of nitrogen emissions were also higher for the bio-oil/ethanol blend due to its inherent nitrogen content.

A study was carried out into the computational fluid dynamic simulation of bio-oil combustion. Measurements were taken in an empirical burner to obtain information regarding the flow behaviour. A surrogate fuel was developed to mimic the unique chemical and physical properties of bio-oil combustion. The resulting computational model of the burner domain and surrogate fuel was compared with empirical data. The bio-oil model displayed a good agreement with the data in terms of the combustion behaviour, but was limited by the uncertain flow solution associated with the burner used.

In this thesis, a novel in-situ method for incorporating nanoscale ceramic particles into metal has been developed. The ceramic phase is introduced as an organic-polymer precursor that pyrolyzes in-situ to produce a ceramic phase within the metal melt. The environment used to shield the melt from burning also protects the organic precursor from oxidation. The evolution of volatiles (predominantly hydrogen) as well as the mechanical stirring causes the polymer particles to fragment into nanoscale dispersions of a ceramic phase. These “Polymer-based In-situ Process-Metal Matrix Composites” (PIP-MMCs) are likely to have great generality, because many different kinds of organic precursors are commercially available, for producing oxides, carbides, nitrides, and borides. Also, the process would permit the addition of large volume fractions of a ceramic phase, enabling nanostructural design, and production of MMCs with a wide range of mechanical properties, meant especially for high temperature applications. An important and noteworthy feature of the present process, which distinguishes it from other methods, is that all the constituents of the ceramic phase are built into the organic molecules of the precursor (e.g., polysilazanes contain silicon, carbon, and nitrogen); therefore, a reaction between the polymer and the host metal is not required to produce the dispersion of the refractory phase. The polymer precursor powder, with a mean particle size of 31.5 µm, was added equivalent to 5 and 10 weight % of the melt (pure magnesium) by a liquid metal stir-casting technique. SEM and OM microstructural observations show that in the cast structure the pyrolysis products are present in the dendrite boundary region in the form of rod/platelets having a thickness of 100 to 200 nm. After extrusion the particles are broken down into fine particles, having a size that is comparable to the thickness of the platelets, in the 100 to 200 nm range, and are distributed more uniformly. In addition, limited TEM studies revealed the formation of even finer particles of 10-50 nm. X-ray diffraction analysis shows the presence of a small quantity of an intermetallic phase (Mg2Si) in the matrix, which is unintended in this process. There was a significant improvement in mechanical properties of the PIP-MMCs compared to the pure Mg. These composites showed higher macro-and micro-hardness. The composite exhibited better compressive strength at both room temperature and at elevated temperatures. The increase in the density of PIP-composites is less than 1% of Mg. Five weight percent of the precursor produced a two-fold increase in the room-temperature yield strength and reduced the steady state creep rate at 723 K by one to two orders of magnitude. PIP-MMCs showed higher damping capacity and modulus compared to pure Mg, with the damping capacity increasing by about 1.6 times and the dynamic modulus by 11%-16%. PIP-composites showed an increase in the sliding wear resistance by more than 25% compared to pure Mg.

In this thesis, a novel in-situ method for incorporating nanoscale ceramic particles into metal has been developed. The ceramic phase is introduced as an organic-polymer precursor that pyrolyzes in-situ to produce a ceramic phase within the metal melt. The environment used to shield the melt from burning also protects the organic precursor from oxidation. The evolution of volatiles (predominantly hydrogen) as well as the mechanical stirring causes the polymer particles to fragment into nanoscale dispersions of a ceramic phase. These “Polymer-based In-situ Process-Metal Matrix Composites” (PIP-MMCs) are likely to have great generality, because many different kinds of organic precursors are commercially available, for producing oxides, carbides, nitrides, and borides. Also, the process would permit the addition of large volume fractions of a ceramic phase, enabling nanostructural design, and production of MMCs with a wide range of mechanical properties, meant especially for high temperature applications. An important and noteworthy feature of the present process, which distinguishes it from other methods, is that all the constituents of the ceramic phase are built into the organic molecules of the precursor (e.g., polysilazanes contain silicon, carbon, and nitrogen); therefore, a reaction between the polymer and the host metal is not required to produce the dispersion of the refractory phase. The polymer precursor powder, with a mean particle size of 31.5 µm, was added equivalent to 5 and 10 weight % of the melt (pure magnesium) by a liquid metal stir-casting technique. SEM and OM microstructural observations show that in the cast structure the pyrolysis products are present in the dendrite boundary region in the form of rod/platelets having a thickness of 100 to 200 nm. After extrusion the particles are broken down into fine particles, having a size that is comparable to the thickness of the platelets, in the 100 to 200 nm range, and are distributed more uniformly. In addition, limited TEM studies revealed the formation of even finer particles of 10-50 nm. X-ray diffraction analysis shows the presence of a small quantity of an intermetallic phase (Mg2Si) in the matrix, which is unintended in this process. There was a significant improvement in mechanical properties of the PIP-MMCs compared to the pure Mg. These composites showed higher macro-and micro-hardness. The composite exhibited better compressive strength at both room temperature and at elevated temperatures. The increase in the density of PIP-composites is less than 1% of Mg. Five weight percent of the precursor produced a two-fold increase in the room-temperature yield strength and reduced the steady state creep rate at 723 K by one to two orders of magnitude. PIP-MMCs showed higher damping capacity and modulus compared to pure Mg, with the damping capacity increasing by about 1.6 times and the dynamic modulus by 11%-16%. PIP-composites showed an increase in the sliding wear resistance by more than 25% compared to pure Mg.

Biomass fast pyrolysis liquid (bio-oil) is a cellulose based alternative fuel with the potential to displace fossil fuels in stationary heat and power applications. To better understand the combustion behavior and emissions of bio-oil, a 10 kW spray burner was designed and constructed. The effect of swirl, atomization quality, ignition source (pilot) energy, air/fuel preheat and equivalence ratio on the stability and emissions of bio-oil spray flames was investigated. A blend of 80% pyrolysis liquid and 20% ethanol by volume was used during the tests and the results were compared to burner operation with diesel. It is important to have good atomization, thorough mixing and high swirl in order to stabilize ignition, promote the burnout of bio-oil and decrease CO, hydrocarbon and particulate matter emissions. The total amount of primary air and atomizing air that can be used to improve turbulence, mixing, droplet burnout and overall combustion quality is limited by the distillable fraction and narrow lean blow-out limit associated with pyrolysis liquid. Air and fuel preheat are important for reducing hydrocarbon and CO emissions, although subsequent fuel boiling should be avoided in order to maintain flame stability. The NOx produced in bio-oil flames is dominated by the conversion of fuel bound nitrogen. The particulate matter collected during bio-oil combustion is composed of both carbonaceous cenosphere residues and ash. Under good burning conditions, the majority consists of ash. Pilot flame energy and air/fuel preheat have a weak effect on the total particulate matter in the exhaust. Generally, these results suggest that available burner parameters can be adjusted in order to achieve low hydrocarbon, CO and carbonaceous particulate matter emissions when using pyrolysis liquid. Total particulates can be further mitigated by reducing the inherent ash content in bio-oil. Comparative burner tests with diesel reveal much lower emissions for this fuel at most of the operating points considered. This is due to the fully distillable nature, better atomization and improved spray ignition characteristics associated with diesel. Because of its superior volatility, diesel can also operate over a much wider range of primary air and atomizing air flow rates compared to bio-oil.

Energy crisis have led to a vast research on various alternative sources of energy in order to cope up with the growth in standard of living of all human beings across the world. And Waste disposal poses a problem which is increasingly difficult to ignore. While the increasing volumes of generated waste are a problem, the types of waste being generated further complicate the challenge of disposal. Waste-to-energy is an obvious replacement for medical waste incinerators whose numbers are likely to decline due to more stringent emission standards. The high plastic content of medical waste is looked at as a potential feedstock for a novel pyrolytic reactor. Hence, various technologies and processes are evolved to utilize the waste resource efficiently. Pyrolysis is one of the latest technologies which have the potential to provide valuable liquid and gaseous fuels from these medical waste sources. In this work, thermal pyrolysis of plastic medical waste (plastic syringes) will be performed in a semi batch reactor at a temperature of 450°C for the production of pyrolytic oil. The physical properties analysis of liquid product is in comparable range with physical properties of commercial transportation fuels

Commercial liquid petroleum fuels are complex mixtures of various hydrocarbons. In multicomponent fuel modelling, these liquid fuels are represented typically with two components or up to ten discrete components. Even with ten components, there are limitations on the representation of real commercial fuels such as heavy fuel oil (HFO), which contains large numbers of hydrocarbons with a wide range of molecular weights and dissimilar structures. Continuous thermodynamics and pyrolysis chemical kinetics are used to model the behaviour of HFO in diesel spray combustion. The evaporation model is developed using the principle of continuous thermodynamics rather than discrete component modelling, to accurately cover the entire range of composition. Continuous thermodynamics reduces the computational simulation load compared to conventional discrete thermodynamics, without degrading the quality of prediction of the complex behaviours of such multicomponent fuels. In continuous thermodynamics modelling, liquid mixture compositions are simply represented by probability density functions (PDF). In the present study, HFO is represented by four fuel fractions: n-paraffins, aromatics, naphthenes and heavy residue. Each of these fractions is assigned a separate distribution function. In the evaporation model, both low-pressure and high-pressure formulations for the calculation of vapour-liquid equilibrium (VLE) at the droplet surface are provided. The formulations for high-pressure VLE are developed for a semicontinuous mixture and a generic approach to the equation of state (EOS) is used. Therefore, depending on the mixture compositions (continuous or semicontinuous) these formulations can be applied with any EOS. It is identified that in the high-pressure model, interaction coefficients between the liquid-liquid components and between the liquid component and air plays an important role during evaporation. Interaction coefficients help to improve the evaporation rate of heavy molecules. HFO is primarily composed of high molecular weight hydrocarbons which cannot evaporate but are pyrolised at high temperatures. Pyrolysis produces volatile gases and polymers through thermal cracking and polymerisation respectively. Baert’s pyrolysis model based on chemical kinetics for thermal cracking and polymerisation rate is developed. Results of this pyrolysis model show that polymer formation within a droplet is dependent on droplet heating rate and composition. Moreover, it is observed in Baert’s pyrolysis model results that the process of polymerisation starts prior to the thermal cracking. This order of thermal cracking and polymerisation is contradictory to the experimental evidence. Subsequently, Baert’s pyrolysis model parameters are modified. Results of the modified pyrolysis model did not show any significant dependency of polymer formation on droplet heating rate and in addition it showed thermal cracking beginning earlier than the polymerisation. The low and high-pressure evaporation models along with the modified pyrolysis model are applied to a single HFO droplet in a high pressure environment, showing good agreement with experimental results obtained by other researchers. A comparison of the low-pressure model with the high-pressure model for 100 micron and 30 micron droplets at high pressure and temperature show that evaporation of the volatile hydrocarbons (nparaffins, aromatics, naphthenes) from HFO occurs at a faster rate for the high-pressure model. However, this faster evaporation does not significantly affect the droplet lifetime because modelled HFO contains only 30% volatile hydrocarbons (cutter stock) by mass. Therefore, droplet lifetime is found to be similar for both models. Thus in sprays where droplets are generally small, the VLE calculation can be obtained with sufficient accuracy by the low-pressure model avoiding the use of the complex high-pressure EOS model. The low-pressure evaporation and modified pyrolysis models along with a heterogeneous liquid phase soot burnout model are implemented via subroutines in a diesel spray simulation in the CFD package StarCD. This simulation is applied to two different constant volume spray combustion chambers which are used to examine the combustion characteristics of HFO. The models are tested for two representative fuel samples; one with the good combustion quality and the other poor. Good qualitative agreement is shown between the computer simulations and the published experimental data. A sample of HFO is characterised in the laboratory using chemical characterisation procedures such as; sequential elution solvent chromatography (SESC), gaschromatography (GC), mass spectrometry (MS) and elemental analysis, to obtain the composition and mean molecular weights of HFO fractions required for continuous thermodynamics modelling. A CFD simulation of the characterised HFO is performed using the developed low-pressure evaporation and modified pyrolysis models.

The first part of this dissertation is focused on the dynamics and stability of thin liquid films flowing over heterogeneous surfaces, which are involved in numerous applications ranging from coating processes to microfluidics devices. Because of the small height-to-length ratio of the thin film, interfacial forces dominate the hydrodynamics in such flows. For thin films flowing over a locally heated substrate, the temperature gradient at the free surface induces a surface tension gradient, or Marangoni stress, at the liquid-gas interface. The flow due to this stress redistributes liquid from warmer to cooler regions, creating a pronounced bump in the film profile that is susceptible to a hydrodynamic instability that can cause a degradation in microdevice performance. Since a gradient in surface tension can also be induced by a surfactant concentration gradient, the thin film flowing over a locally heated substrate may behave markedly differently in the presence of surfactant. Utilizing the appropriate simplifications of lubrication theory, evolution equations are derived for the local film thickness and surfactant concentration, and predictions based on nonlinear and linearized equations of state for the surface tension are compared. Despite a localized accumulation of surfactant near the upstream edge of the heater, the predictions of the two models are found to be in good agreement. More significantly, a detailed linear stability analysis reveals that the surfactant stabilizes the film. The physical mechanism for this stabilization is discussed and linked to a qualitative change in the kinematics associated with the elimination of fluid recirculation near the heater. The effect of surfactant is also investigated for films over isothermal, inclined substrates with topographical features and for the dynamics of a film on a heated, horizontal substrate with topographical features. In the absence of surfactant, the effect of inertia on the stability of a liquid film flowing over a locally heated substrate is investigated by incorporating the leading-order term for inertia within the framework of lubrication approximation. The linear stability analysis and the energy analysis reveal that the inertial term destabilizes the film. The second part of this dissertation is focused on two fundamental studies relevant to the pyrolysis of biomass. The heating of a biomass particle produces a temperature gradient within the particle, which creates spatially varying reaction rates. A reaction-transport model is developed to investigate the significance of intra- and extra-particle heat transfer effects on the pyrolysis of nonporous particles of cellulose, a major component of lignocellulosic biomass. Recently measured kinetic parameters are incorporated. The explicit shrinkage of a biomass particle undergoing pyrolysis is related to the overall mass loss as gaseous products are formed. Numerical predictions for measurable properties, including the temporal evolution of the residual mass and the final yield of char, which is an undesired byproduct, are validated through comparison to experimental data for various particle sizes and external temperatures. The particles are found to be sufficiently non-isothermal during typical processing conditions that heat transfer influences the char and product yield. Extensions are made to the pyrolysis of porous biomass particles. In continuous flow processing, the catalytic pyrolysis of biomass typically occurs in a fluidized bed reactor. Solid biomass particles enter the reactor along with a carrier gas through a vertical standpipe, decompose, and produce condensable vapors that can be further processed into biofuel. Due to the coupling of the hydrodynamics to the rate of particle decomposition, the selection of appropriate operating conditions for the feed device can be challenging. For inert gas-solid flows, rich nonlinear dynamics can be observed due to momentum transfer between the phases through the drag force coupled to the compressibility of the gas. For decomposing solids as in pyrolysis, the exchange of mass between the phases further complicates the hydrodynamics. Using the approach of interacting and interpenetrating continua, a one-dimensional, steady-state model is developed for the gravity-driven flow of gas and decomposing particles through a vertical standpipe. The theory yields the particle and gas flow rates, the pressure profile, and the particle size and void fraction distributions. Preferred operating conditions are identified to produce steady flow, avoid a transition to moving bed flow, and provide desired values of the pressure, particle size, and solids flow rate at the pipe exit. Applications are made to the pyrolysis of wood particles. The admissible range of operating conditions is found to increase with the particle decomposition rate, which increases strongly with temperature.

About 8 tons of dry undigested solid waste is generated by the MixAlco process for every 40 tons of food residue waste fed into the process. This MixAlco process produces liquid fuels and the sludge generated can be further converted into synthesis gas using the process of pyrolysis. The hydrogen component of the product synthesis gas may be separated by pressure swing adsorption and used in the hydrogenation of ketones into fuels and chemicals. The synthesis gas may also be catalytically converted into liquid fuels via the Fischer-Tropsch synthesis process. The auger-type pyrolyzer was operated at a temperature between 630-770 degrees C and at feed rates in the range of 280-374 g/minute. The response surface statistical method was used to obtain the highest syngas composition of 43.9 +/- 3.36 v % H2/33.3 +/- 3.29 v % CO at 740 degrees C. The CH4 concentration was 20.3 +/- 2.99 v %. For every ton of sludge pyrolyzed, 5,990 g H2 (719.3 MJ), 65,000 g CO (660 MJ) and 21,170 g CH4 (1055.4 MJ) were projected to be produced at optimum condition. At all temperatures, the sum of the energies of the products was greater than the electrical energy needed to sustain the process, making it energy neutral. To generate internal H2 for the MixAlco process, a method was developed to efficiently separate H2 using pressure swing adsorption (PSA) from the synthesis gas, with activated carbon and molecular sieve 5A as adsorbents. The H2 can be used to hydrogenate ketones generated from the MixAlco process to more liquid fuels. Breakthrough curves, cycle mass balances and cycle bed productivities (CBP) were used to determine the maximum hydrogen CBP using different adsorbent amounts at a synthesis gas feed rate of 10 standard lpm and pressure of 118 atm. A 99.9 % H2 purity was obtained. After a maximum CBP of 66 % was obtained further increases in % recovery led to a decrease in CBP. The synthesis gas can also be catalytically converted into liquid fuels by the Fischer-Tropsch synthesis (FTS) process. A Co-SiO2/Mo-Pd-Pt-ZSM-5 catalyst with a metal-metal-acid functionality was synthesized with the aim of increasing the selectivity of JP-8 (C10-C17) fuel range. The specific surface areas of the two catalysts were characterized using the BET technique. The electron probe microanalyzer (with WDS and EDS capabilities) was then used to confirm the presence of the applied metals Co, Mo, Pd and Pt on the respective supports. In addition to the gasoline (C4-C12) also produced, the synthesis gas H2:CO ratio was also adjusted to 1.90 for optimum cobalt performance in an enhanced FTS process. At 10 atm (150 psig) and 250 degrees C, the conventional FTS catalyst Co-SiO2 produced fuels rich in hydrocarbons within the gasoline carbon number range. At the same conditions the Co-SiO2-Mo-Pd-Pt/HZSM-5 catalyst increased the selectivity of JP-8. When Co-SiO2/Mo-Pd-Pt-HZSM-5 was used at 13.6 atm (200 psig) and 250 degrees C, a further increase in the selectivity of JP-8 and to some extent diesel was observed. The relative amounts of olefins and n-paraffins decreased with the products distribution shifting more towards the production of isomers.

Biomass fast pyrolysis liquid, also known as bio-oil, is a promising renewable fuel for heat and power generation; however, implementing crude bio-oil in some current combustion systems can degrade combustion performance and emissions. In this study, optimizing fuel properties to improve combustion is considered. Various bio-oils with different fuel properties are tested in a pilot stabilized spray burner under very close flow conditions. Effects of solids, ash and water content of bio-oil as well as ethanol blending were examined. The results show the amount of solids and ash fractions of the fuel were correlated with combustion efficiency. The CO and unburned hydrocarbon emissions decreased with both water and ethanol content. Increasing the fuel’s volatile content by blending in ethanol has been shown to improve flame stability. Also, the organic fraction of particulate matter emissions was found to be a strong function of the thermogravimetric analysis residue of the fuel.

Thesis (PhD (Process Engineering))--University of Stellenbosch, 2010.
ENGLISH ABSTRACT: A techno-economic feasibility study was performed to compare biological and thermochemical process routes for production of liquid biofuels from sugarcane bagasse in South Africa using process modelling. Processing of sugarcane bagasse for the production of bioethanol, pyrolysis oil or Fischer-Tropsch liquid fuels were identified as relevant for this case study. For each main process route, various modes or configurations were evaluated, and in total eleven process scenarios were modelled, for which fourteen economic models were developed to include different scales of biomass input. Although detailed process modelling of various biofuels processes has been performed for other (mainly first world) countries, comparative studies have been very limited and mainly focused on mature technology. This is the first techno-economic case study performed for South Africa to compare these process routes using data for sugarcane bagasse. The technical and economic performance of each process route was investigated using the following approach: Obtain reliable data sets from literature for processing of sugarcane bagasse via biological pretreatment, hydrolysis and fermentation, fast and vacuum pyrolysis, and equilibrium gasification to be sufficient for process modelling. Develop process models for eleven process scenarios to compare their energy efficiencies and product yields. In order to reflect currently available technology, conservative assumptions were made where necessary and the measured data collected from literature was used. The modelling was performed to reflect energy-self-sufficient processes by using the thermal energy available as a source of heat and electricity for the process. Develop economic models using cost data available in literature and price data and economic parameters applicable to South Africa. Compare the three process routes using technical and economic results obtained from the process and economic models and identify the most promising scenarios. For bioethanol production, experimental data was collected for three pretreatment methods, namely steam explosion, dilute acid and liquid hot water pretreatment performed at pretreatment solids concentrations of 50wt%, 10wt% and 5wt%, respectively. This was followed by enzymatic hydrolysis and separate co-fermentation. Pyrolysis data for production of bio-oil via fast and vacuum pyrolysis was also collected. For gasification, data was generated via equilibrium modelling based on literature that validated the method against experimental data for sugarcane bagasse gasification. The equilibrium model was used to determine optimum gasification conditions for either gasification efficiency or syngas composition, using sugarcane bagasse, fast pyrolysis slurry or vacuum pyrolysis slurry as feedstock. These results were integrated with a downstream process model for Fischer-Tropsch synthesis to evaluate the effect of upstream optimisation on the process energy efficiency and economics, and the inclusion of a shift reactor was also evaluated. The effect of process heat integration and boilers with steam turbine cycles to produce process heat and electricity, and possibly electricity by-product, was included for each process. This analysis assumed that certain process units could be successfully scaled to commercial scales at the same yields and efficiencies determined by experimental and equilibrium modelling data. The most important process units that need to be proven on an industrial scale are pretreatment, hydrolysis and fermentation for bioethanol production, the fast pyrolysis and vacuum pyrolysis reactors, and the operation of a twostage gasifier with nickel catalyst at near equilibrium conditions. All of these process units have already been proven on a bench scale with sugarcane bagasse as feedstock. The economic models were based on a critical evaluation of equipment cost data available in literature, and a conservative approach was taken to reflect 1st plant technology. Data for the cost and availability of raw materials was obtained from the local industry and all price data and economic parameters (debt ratio, interest and tax rates) were applicable to the current situation in South Africa. A sensitivity analysis was performed to investigate the effects of likely market fluctuations on the process economics. A summary of the technical and economic performances of the most promising scenarios is shown in the table below. The bioethanol process models showed that the liquid hot water and dilute acid pretreatment scenarios are not energy self-sufficient and require additional fossil energy input to supply process energy needs. This is attributed to the excessive process steam requirements for pretreatment and conditioning due to the low pretreatment solid concentrations of 5wt% and 10wt%, respectively. The critical solids concentration during dilute acid pretreatment for an energy selfsufficient process was found to be 35%, although this was a theoretical scenario and the data needs to be verified experimentally. At a pretreatment level of 50% solids, steam explosion achieved the highest process thermal energy efficiency for bioethanol of 55.8%, and a liquid fuel energy efficiency of 40.9%. Both pyrolysis processes are energy self-sufficient, although some of the char produced by fast pyrolysis is used to supplement the higher process energy demand of fast compared to vacuum pyrolysis. The thermal process energy efficiencies of both pyrolysis processes are roughly 70% for the production of crude bio-oil that can be sold as a residual fuel oil. However, the liquid fuel energy efficiency of fast pyrolysis is 66.5%, compared to 57.5% for vacuum pyrolysis, since fast pyrolysis produces more bio-oil and less char than vacuum pyrolysis.
Centre for Renewable and Sustainable Energy Studies