Pretreatment of waste activated sludge (WAS) and the subsequent near-critical water gasification (NCWG) is a potential avenue to convert WAS into value added products. Part one of the research investigated thermal and thermochemical pretreatments. No difference was observed in the percentage of sludge liquefied beyond 10min between 200°C to 300°C. It was found that pretreated activated sludge supernatant (PASS) doubled the gas yield compared to untreated sludge when gasified. The order of effectiveness for sludge treatment was thermo-alkali > thermal > thermo-acid for hydrogen production in NCWG. Part two investigated NCWG parameters to identify optimal conditions. High gasification yields were obtained using a commercial catalyst (Raney nickel), with hydrogen content of 65-75% of the gas phase products. Thermo-alkali treated PASS was found to perform well at subcritical temperatures with 25% higher yields than thermally treated PASS. Increased catalyst loading had little additional effect on gas yields above 0.075g.

Pretreatment of waste activated sludge (WAS) and the subsequent near-critical water gasification (NCWG) is a potential avenue to convert WAS into value added products. Part one of the research investigated thermal and thermochemical pretreatments. No difference was observed in the percentage of sludge liquefied beyond 10min between 200°C to 300°C. It was found that pretreated activated sludge supernatant (PASS) doubled the gas yield compared to untreated sludge when gasified. The order of effectiveness for sludge treatment was thermo-alkali > thermal > thermo-acid for hydrogen production in NCWG. Part two investigated NCWG parameters to identify optimal conditions. High gasification yields were obtained using a commercial catalyst (Raney nickel), with hydrogen content of 65-75% of the gas phase products. Thermo-alkali treated PASS was found to perform well at subcritical temperatures with 25% higher yields than thermally treated PASS. Increased catalyst loading had little additional effect on gas yields above 0.075g.

Supercritical water gasification (SCWG) is an innovative hydrothermal technique, employing supercritical water (SCW, T≥374oC, P≥22.1 MPa) as the reaction media, to convert wet biomass or aqueous organic waste directly into hydrogen (H2)-rich synthetic gas (syngas). In the first stage of this research, a secondary pulp/paper-mill sludge (SPP, provide by AbitibiBowater Thunder Bay Operations) was gasified at temperatures of 400-550oC for 20 to 120 min in a high-pressure batch reactor for H2 production. The highest H2 yield achieved was 14.5 mol H2/kg SPP (on a dry basis) at 550oC for 60 min. In addition, SPP exhibited higher H2-generation potential than sewage sludges, likely attributed to its higher pH and higher volatile matter and alkali salt contents. In the second stage, a novel two-step process for sludge treatment was established. The first step involved the co-liquefaction of SPP with waste newspaper in a batch reactor at varying mixing ratios, aimed at converting the organic carbons in the feedstocks into valuable bio-crude and water-soluble products. The highest heavy oil (HO) yield (26.9 wt%) was obtained at 300oC for 20 min with a SPP-to-newspaper ratio of 1:2. This co-liquefaction process transformed 39.1% of the carbon into HOs, where 16.3% of the carbon still remained in the aqueous waste. Next, an innovative Ru0.1Ni10/γ-Al2O3 catalyst (10 wt% Ni, Ru-to-Ni molar ratio=0.1), with long-term stability and high selectivity for H2 production, was developed for the SCWG of 50 g/L glucose, where no deactivation was observed after 33 h on stream at 700oC, 24 MPa and a WHSV (weight hourly space velocity) of 6 h-1. The H2 yield was maintained at ~50 mol/kg feedstock. The addition of small amounts of Ru to Ni10/γ-Al2O3 was found to be effective in enhancing Ni dispersion and increasing the reducibility of NiO. Finally, the Ru0.1Ni10/γ-Al2O3 catalyst together with an activated carbon (AC) supported catalyst (Ru0.1Ni10/AC) were utilized for treating the aqueous by-product from sludge-newspaper co-liquefaction using a continuous down-flow tubular reactor. More than 90% of the carbon in the waste was destroyed at 700oC with the highest H2 yield of 71.2 mol/kg carbon noted using Ru0.1Ni10/AC. / Thesis (Ph.D, Civil Engineering) -- Queen's University, 2011-04-27 17:20:49.193

In this work, SCWG of glucose, cellulose and pinewood was studied at different operating conditions with and without catalyst. Three parameters studied included temperature (400, 470, 500 and 550oC), water to biomass weight ratio (3:1 and 7:1) and catalyst (Ni/MgO, Ni/activated carbon, Ni/Al2O3, Ni/CeO2/Al2O3, dolomite, NaOH, KOH, activated carbon and olivine), which were varied for gasification of glucose, cellulose and pinewood. By comparing the results from model compound (glucose and cellulose) with that from real biomass (pinewood), the mechanism of how the individual compounds are gasified was explored. For catalytic runs with glucose, NaOH had the best activity for improving H2 formation. H2 yield increased by 135% using NaOH compared to that for run without catalyst at 500oC with a water to biomass weight ratio of 3:1. At the same operating conditions, the presence of Ni/activated carbon (Ni/AC) contributed to an 81% increase in H2 yield, followed by 62% with Ni/MgO, 60% with Ni/CeO2/Al2O3 and 52% with Ni/Al2O3. For catalytic runs with cellulose, the H2 yield increased by 194% with KOH compared to that for run without catalyst at 400oC with a water to biomass ratio of 3:1. At the same operating conditions, the presence of Ni/CeO2/Al2O3 contributed to a 31% increase in H2 yield followed by a 28% increase with dolomite. When the water to biomass ratio was increased from 3:1 to 7:1, H2 yield from glucose gasification was increased by 40% and 33% at 400 and 500oC, respectively, and the H2 yield of cellulose gasification was increased by 44%, 11% and 22% at 400, 470 and 550oC, respectively. The higher heating value of the oil products derived from SCWG of both glucose and cellulose incresed in the presence of catalysts. As real biomass, pinewood was gasified in supercritical water at the suitable operation conditions (550oC with water to biomass ratio of 7:1) obtained from previous experiments, using three kinds of catalyst: Ni/CeO2/Al2O3, dolomite and KOH. At the same operating conditions, the gasification of pinewood had smaller yields of H2 (20 to 41%) compared with that from cellulose. The effect of the catalyst on H2 production from SCW in the absence of biomass was studied. The results showed that a trace amount of H2 was formed with Ni based catalyst/dolomite only while some CO2 was formed with Ni/AC. Most of the runs presented in this report were repeated once, some of the runs had been triplicated, and the deviation of all results was in the range of ±5%.

La pyrolyse et la gazéification sont les deux procédés les plus prometteurs pour une valorisation thermique des déchets organiques solides en réponse aux objectifs énergétiques environnementaux actuels et futurs. Si pour la pyrolyse, les déchets traités sont aussi synthétiques (plastiques, composites) que naturels (biomasse), pour la gazéification c'est la biomasse qui est la matière première la plus rencontrée. Les travaux expérimentaux de cette thèse ont été réalisés dans deux types d'installations : une installation à échelle laboratoire (analyseur thermique : TG, ATD, EGA) et une installation à échelle pilote (nommée four « Aubry »). Les traitements thermiques ont été effectués dans les conditions spécifiques pour la pyrolyse (atmosphère d'azote) et la gazéification (vapeurs d'eau). Les matériaux testés ont été le polychloroprène, les composés de la biomasse (hémicellulose, lignine, cellulose), seuls où en mélange, ainsi qu'un bois naturel (le bouleau) et son « modèle » (mélange en proportions équivalents de ses constituants). Deux modèles cinétiques pour la pyrolyse du polychloroprène ont été choisis de littérature et testés. La différence primordiale entre les deux modèles est leur degré de complexité. Le premier est un modèle empirique simplifié, tandis que le deuxième, très détaillé, est un modèle radicalaire Le modèle cinétique utilisé pour modéliser le processus de pyrolyse de la cellulose, pris aussi de la littérature, a montré une concordance très bonne avec nos résultats expérimentaux. L'étude hôte de la gazéification à la vapeur d'eau a nécessité des modifications de nos installations expérimentales, tout particulièrement à l'échelle pilote, pour assurer une atmosphère confinée en vapeur d'eau. Les expériences réalisées en conditions expérimentales spécifiques ont données des résultats excellents pour la composition finale du gaz de synthèse. La simulation, à l'échelle pilote, de la gazéification a été obtenue par adaptation d'un modèle existant, à la réalisation de nos conditions opératoires, prenant en compte les transferts matières et basé sur l'évolution de la porosité d'une particule sphérique équivalente. Le modèle a montré une concordance raisonnable avec nos données expérimentales. La dernière partie de cette thèse présente une étude dans lequel on compare les analyses thermiques pour les constituants purs, un modèle de bois et un bois naturel afin d'établir les interactions possibles entre ces composants lors de la dégradation thermique du bois naturel. Les résultats ont montré que pour les mélanges cellulose-lignine et lignine-hémicellulose, le premier composé inhibe la dégradation du dernier tandis que, pour les mélanges cellulose-hémicellulose, cet effet se manifeste à l'inverse. Tous les modèles testés et les résultats enregistrés dans cette thèse représentent des instruments très utiles pour l'aide au dimensionnement des installations de pyrolyse à échelle laboratoire ainsi que pour des installations de gazéification à la vapeur d'eau à échelle pilote. / The pyrolysis and gasification are the most actual techniques used for valorization of organic wastes. If for pyrolysis the raw materials are both synthetic (plastics) and natural (biomass), in the case of gasification mainly the biomass is used. The experiments presented in this thesis were carried out in two type of plants: a laboratory scale plant (thermal analyses: TGA, DTA, EGA) and a pilot scale plant (so-called “Aubry” furnace). The thermal treatments implemented both the conditions of pyrolysis (nitrogen atmosphere) and gasification (water vapors). The materials tested in the experimental part were: polychloroprene, biomass constituents (hemicelluloses, lignin and cellulose), alones and in mixture, and a natural wood (the birch) with it's “model” (a mixture of it's components in different proportions). For the polychloroprene pyrolysis, two kinetic models chosen from the published literature were tested. The difference in the two models is given by their degree of complexity. The first one was a simplified empirical model. The second one was a free-radical model. For the cellulose pyrolysis was also tested a model proposed in the literature and the model showed a good accuracy in representing our experimental data. The study of gasification at pilot scale needed an appropriate modification of the experimental set-up to create a saturated atmosphere in water vapor inside the Aubry furnace. The experimental work concerning the gasification followed a specific protocol and gave excellent results for the syngas composition. A gasification mathematical model for pilot scale was proposed and tested. This model, based on the evolution of equivalent spherical particles porosity, take supplementary into account the mass transfer. The results given by the last model were in reasonable agreement with our experimental results. The last part of this thesis presents a comparative study of the thermal analyses of pure biomass components, of a wood model and also of a natural wood. The goal is to identify the interactions that could take place between these compounds during the thermal degradation of the natural wood. Our results showed that for the mixtures cellulose-lignin and lignin-hemicelluloses the first compound inhibits the second one. For the mixtures cellulose-hemicelluloses this effect is inverse. All the kinetic models tested in this thesis are useful tools for dimensioning laboratory scale pyrolysis plants and pilot scale set-up for water vapors gasification.

Des nouveaux procédés éco-efficients basés sur une meilleure utilisation des ressources renouvelables sont nécessaires pour assurer la continuité du développement énergétique. La thèse étudie le procédé de gazéification en eau supercritique (T>374°C et P>22,1 MPa) de la biomasse très humide pour l’obtention de l’hydrogène, molécule ayant un potentiel énergétique très intéressant à valoriser avec un impact environnemental très favorable. L’étude porte sur l’application du procédé à la biomasse modèle (solutions de glucose, glycérol et leur mélange) ainsi qu’au bioglycérol, résidu de la fabrication du biodiesel. Les propriétés du solvant et les mécanismes prépondérants développés par l’eau en phase souset supercritique peuvent être contrôlés par les paramètres opératoires imposés au processus : température, pression, concentration en molécules organiques et catalyseur alcalin, temps de réaction... Les études paramétriques des systèmes réactionnels ont été menées dans des réacteurs batch à deux échelles différentes, les phases résultantes étant caractérisées par des protocoles analytiques élaborés et validés dans le cadre de l’étude. Le suivi du milieu réactionnel en batch lors de son déplacement vers l’état supercritique a mis en évidence une conversion avancée des molécules organiques et une identification de certains intermédiaires générés. Parmi les paramètres étudiés, la température et le temps de réaction influent le plus le rendement à l’obtention d’hydrogène en présence de catalyseur (K2CO3) dans les réacteurs batch, rendements de 1,5 et 2 mol d’H2 respectivement par mol de glycérol et de glucose introduites. Les gaz obtenus contiennent des proportions variables d’hydrocarbures légers et du CO2. Environ 75% du carbone est converti en phase gaz et liquide (sous forme de carbone organique et inorganique), le restant étant déposé sous forme solide ou huileuse. L’analyse du solide généré (plus de 90% de C) laisse apparaître différentes phases, y compris la formation de nanoparticules sphériques. Enfin, la gazéification en réacteur continu du glycérol préchauffé a montré de meilleurs rendements en hydrogène que le procédé batch, pendant que celle du bioglycérol demande une évolution du procédé à cause de la précipitation en phase supercritique des sels contenus dans le réactant. En conclusion, la gazéification en eau supercritique de la biomasse peut être considérée comme une alternative intéressante à d’autres procédés physico-chimiques de production de l’hydrogène. L’amélioration du procédé sera possible par son intensification menée en parallèle avec l’utilisation de matériaux plus performants et le contrôle de la salinité de la phase réactante. / Supercritical water (T > 374 ° C and P > 22.1 MPa) gasification of wet biomass for hydrogen production is investigated. This process converts a renewable resource into a gas, which is mainly composed of hydrogen and hydrocarbons with interesting energy potential, and which can be separated at high pressure. In addition, the greenhouse gas effect of the process is zero or negative. Model biomasses (glucose, glycerol and their mixture) and bio-glycerol, residue from bio-diesel production, have been gasified by different processes: two-scale batch reactors (5 mL and 500 mL) and a continuous gasification system. Supercritical water acts as a reactive solvent, its properties can be adjusted by the choice of the experimental (P, T) couple. The operating parameters, e.g. temperature, pressure, concentration of biomass and alkaline catalysts, reaction time… allow favoring certain reaction mechanisms. In order to characterize the processes, specific analytical protocols have been developed and validated. The intermediates, formed during the heating time in the batch reactors, have been identified. Among the investigated operating parameters, temperature and reaction time have the greatest influence on the hydrogen production in batch reactors. In the presence of catalyst (K2CO3), H2 yields of 1.5 mol/mol glucose and 2 mol/mol glycerol have been respectively observed. The obtained gas contains different proportions of light hydrocarbons and CO2. About 75% of the carbon is converted into gas and liquid (in form of organic and inorganic carbon). The conversion leads also to a solid or oily residue. In the generated solid phase (composed over 90% of C), spherical nanoparticles are observed via electronic microscopy. The hydrogen production from glycerol is improved in the continuous process compared to batch reactors, however, bio-glycerol supercritical water gasification requests process improvement due to the precipitation of the salt contained in the reactant. In conclusion, supercritical water gasification of biomass can be considered as an promising alternative process for hydrogen production. The process should be improved by more performing equipments and by the control of the salinity content of the crude biomass.

Submitted by Liliane Ferreira (ljuvencia30@gmail.com) on 2018-10-15T15:41:01Z No. of bitstreams: 2 Dissertação - Jarbas Almeida de Melo - 2018.pdf: 7287109 bytes, checksum: 8e33ba1a3ef2d679e03ecdb4e368b53c (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2018-10-16T10:13:44Z (GMT) No. of bitstreams: 2 Dissertação - Jarbas Almeida de Melo - 2018.pdf: 7287109 bytes, checksum: 8e33ba1a3ef2d679e03ecdb4e368b53c (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) / Made available in DSpace on 2018-10-16T10:13:44Z (GMT). No. of bitstreams: 2 Dissertação - Jarbas Almeida de Melo - 2018.pdf: 7287109 bytes, checksum: 8e33ba1a3ef2d679e03ecdb4e368b53c (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2018-09-28 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / In this work the synthesis of catalysts was carried out with the objective of H2 production from gasification of ethanol in medium containing water under supercritical conditions. Based on reports from the literature, Cu, Ni and Mg were selected as components for the active phase, alumina (Al2O3) as catalysts support. The catalysts were prepared from aqueous solutions of nitrate salts precursors of Cu, Ni and Mg. The catalysts were characterized by X-ray fluorescence (FRX), scanning electron microscopy, thermogravimetric and thermal differential analysis (TG/ATD), X-ray diffraction (DRX) and textural analysis by N2 adsorption / desorption isotherms at -196 ° C. The TG/ATD analysis indicated that the calcination of the catalytic precursors was sufficient for the removal of water and decomposition of the nitrates of the metal salts precursors of the active phase. In the FRX analysis, the increase in the concentration of the metals in relation to the nominal values after the synthesis of the catalysts was characterized, with an increase of 20 to 40% depending on the metal due to the loss of water from the alumina support. The FRX analysis of the catalysts used in the catalytic tests shows that there was no significant leaching during the gasification process. DRX analysis have characteristic results that the metals are in amorphous form or dispersed in the form of small crystallites. Textural analysis of N2 adsorption / desorption isotherms indicated a reduction of approximately 60% in the specific surface area between the alumina and the calcined alumina and the specific area values between the alumina and the metal catalysts were kept close. The catalytic tests were performed at a pressure of 25 MPa and at temperatures of 400 to 650 ° C. A 10/1 molar water / ethanol solution was fed. In the catalytic tests H2, CH4, CO, CO2, C2H4, C2H6, C2H4O were obtained. The highest ethanol conversions were obtained at the temperature of 650 ° C for the catalysts NiO/Al2O3 and NiO-MgO/Al2O3, both 81%. The highest yield was 0.41 mol H2 / mol ethanol fed to the NiO / Al2O3 catalyst, at a temperature of 600 ° C. The highest selectivity at the temperature of 600 ° C was 39%, obtained by the NiO/Al2O3 catalyst. / Neste trabalho foi realizada a síntese de catalisadores com o objetivo da produção de H2 a partir da gaseificação de etanol em meio contendo água em condições supercríticas. A partir de relatos da literatura, foram selecionados Cu, Ni e Mg como componentes para a fase ativa e a alumina (Al2O3) como suporte dos catalisadores. Os catalisadores foram preparados a partir de soluções aquosas de sais de nitrato precursores de Cu, Ni e Mg. Os catalisadores foram caracterizados por fluorescência de raios X (FRX), microscopia eletrônica de varredura (MEV), análises termogravimétrica e térmica diferencial simultânea (TG/ATD), difração de raios X (DRX) e análise textural por isotermas de adsorção/dessorção de N2 a -196°C. As análises de TG/ATD indicaram que a calcinação dos precursores catalíticos foi suficiente para a remoção da água e decomposição dos nitratos dos sais metálicos precursores da fase ativa. Nas análises de FRX ficou caracterizado o aumento da concentração dos metais em relação aos valores nominais, após a síntese dos catalisadores, com acréscimo de 20 a 40 % dependendo do metal, devido à perda de água do suporte de alumina. As análises FRX dos catalisadores utiilzados nos testes catalíticos mostraram que não houve lixiviação considerável durante o processo de gaseificação. Análises de DRX apresentaram resultados característicos de que os metais se encontram na forma amorfa ou dispersos na forma de pequenos cristalitos. Os resultados foram coerentes com as imagens de microscopia eletrônica de varredura. Análises textural por isotermas de adsorção/dessorção de N2 indicaram uma redução de aproximadamente 60% na área superficial específica entre a alumina e a alumina calcinada e mantiveram-se próximos os valores de área específica entre a alumina e os catalisadores metálicos. Os testes catalíticos foram realizados a uma pressão de 25 MPa e nas temperaturas de 400 a 650 °C. Foi alimentada uma solução de água/etanol na razão de 10/1 molar. Nos testes catalíticos foram obtidos H2, CH4, CO, CO2, C2H4, C2H6, C2H4O. As maiores conversões de etanol foram obtidas na temperatura de 650 °C para os catalisadores de NiO/Al2O3 e NiO-MgO/Al2O3, ambas 81 %. O maior rendimento obtido foi de 0,41 mol H2/mol etanol alimentado para o catalisador de NiO/ Al2O3, na temperatura de 600 °C. A maior seletividade na temperatura de 600 °C foi de 39 %, obtida pelo catalisador de NiO/Al2O3.