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Conversão termoquímica de esterco bovino em micro e macroescala com vistas a obtenção de biocombustíveis e produtos da química fina / Thermochemical conversion of cattle manure in micro and macroscale viewing the obtention of biofuels and fine chemical productsSantana, Kathamania Vanessa Rezende 16 February 2017 (has links)
The energy sources and oil derivatives necessities have increased over the last
years as well the mitigation of greenhouse gases (GHGs) emissions. These
concepts provided an increase on the use of residual lignocellulosic biomass as a
renewable source for the production of biofuels and chemical products. In this
study, the cattle manure was chosen as a biomass source considering their high
availability, as well as could be a major environmental pollutant residue when not
treated properly. Thus, we propose to produce and characterize the bio-oil and
biochar through of micro and macroscale pyrolysis. The work was divided into two
parts: biomass characterization and characterization of the pyrolysis products. The
cattle manure biomass presented 9.65% moisture after drying over ambient
temperature, 38.86% ash, 48.29% volatile matter and 3.20% fixed carbon; high
oxygen content (34.19%) and carbon (21.66%) by elemental analysis; and low
lignin content (6.09%) in comparison with the hemicellulose (18.24%) and cellulose
(14.24%). The thermogravimetric curve showed four mass loss stage between 25-
900
o C and a residual mass content of 39.58%; infrared analysis showed
characteristic bands of alcohols, phenols, carboxylic acids, nitrogenous
compounds and aliphatic groups. Concerning of bio-oils characterization,
presented as highly oxygenated liquid with predominant compounds from the
alcohols, phenols and carboxylic acid in micro and macroscale. Due to the high
calorific value of bio-oils (21.35–27.10 MJ kg -1 ), can be used as biofuel. Biochars
showed yields between 62.5% and 39.1%, the increase on pyrolysis temperature
has provided an increase in ash and pH values, as also decreasing in proportion
H/C, indicating increase on aromaticity of biochar the 600 ºC, also evidenced by
the infrared analysis. / O aumento da necessidade energética e de produtos derivados do petróleo, bem
como a necessidade de mitigação das emissões de gases de efeito estufa (GEE),
têm proporcionado um crescimento em pesquisas sobre a utilização da biomassa
lignocelulósica residual como fonte renovável para a obtenção de biocombustíveis
e produtos químicos de maior valor agregado. Diante destas problemáticas, o
esterco bovino foi escolhido como fonte de biomassa para este estudo devido a
sua alta disponibilidade, além de ser um resíduo que quando não tratado
adequadamente pode se tornar um grande poluente ambiental. Desta forma, este
trabalho propõe produzir e caracterizar o bio-óleo e o biocarvão obtidos a partir da
biomassa de esterco bovino através dos processos de pirólise em micro e
macroescala. O trabalho foi dividido em duas partes: caracterização da biomassa
e caracterização dos produtos das pirólises. A biomassa de esterco bovino
apresentou 9,65% de umidade, 38,86% de cinzas e 51,49% de matéria orgânica;
alto teor de oxigênio (34,19%) e carbono (21,66%); baixo teor de lignina (6,09%)
em comparação com a hemicelulose (18,24%) e a celulose (14,24%). A curva
termogravimétrica exibiu quatro estágios de perda de massa entre 25-900 o C e um
teor de massa residual de 39,58%; a análise do infravermelho apresentou bandas
características de álcoois, fenóis, ácidos carboxílicos, compostos nitrogenados e
grupos alifáticos. Com relação à caracterização do bio-óleo, apresentou-se como
líquido altamente oxigenado com predominância de compostos pertencentes às
classes de fenóis, álcoois e ácidos carboxílicos em micro e macroescala. Devido
ao alto valor do poder calorífico dos bio-óleos (21,35–27,10 MJ kg -1 ) pode-se
cogitar a possibilidade de seu uso como biocombustível. Quanto ao biocarvão,
mostrou rendimento que variou de 62,5% a 39,1%; o aumento da temperatura de
pirólise aumentou o teor de cinzas e concomitantemente os valores de pH, bem
como reduções em razões H/C, indicando um aumento do grau de aromaticidade
do biocarvão formado a 600 ºC, fato também evidenciado pela análise de
infravermelho.
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Impacto da diversidade bacteriana sob a degradação clorotalonil no solo manejado com biochar / Impact of bacterial diversity in the chlorothalonil degradation on soil handled with biocharAdijailton José de Souza 23 May 2016 (has links)
A diversidade microbiana é geralmente considerada por seu papel nos principais processos do ecossistema, tais como a decomposição da matéria orgânica e ciclos biogeoquímicos. No entanto, informações sobre o impacto da diversidade em funções menores, como degradação de xenobióticos são escassas. Nós estudamos a partir da abordagem da \'diluição para extinção\', o papel da diversidade sobre a capacidade da comunidade microbiana em degradar o fungicida clorotalonil (organoclorado). Também estudamos o comportamento da comunidade bacteriana após aplicação do pesticida no solo com e sem biochar. A diversidade microbiana do solo natural foi alterada artificialmente por diluição, constituindo um gradiente de diversidade (SN > 10-1 > 10-3 > 10-6), seguido pela inoculação em amostras de solo estéril e posterior reestruturação (15 dias). Após a reestruturação da comunidade, as amostras foram manejadas com biochar (1% m/m) e tratadas com a dose de campo do CHT. O comportamento da comunidade bacteriana foi estudo por PCR-DGGE e qPCR do gene 16S rDNA através de um experimento com molécula fria (não radiomarcada). Enquanto a capacidade de degradação do CHT foi estudada por radiorespirometria (14C-CHT). Inicialmente, a comunidade de bactérias foi influenciada pelo gradiente de diversidade obtido por diluição. A separação dos grupos bacterianos se mostrou bastante similar nos três primeiros períodos pré-aplicação do CHT (SN > 10-1 - 10-3 > 10-6), enquanto que no período de 15 dias, a dinâmica de grupos foi alterada (SN > 10-1 > 10-3 - 10-6). O fungicida e o biochar não exerceram efeitos na comunidade bacteriana no tempo zero (imediatamente após a aplicação), a modificação no perfil da comunidade foi atribuído à diluição. Nos períodos de 21 e 42 dias, o perfil comunidade bacteriana apresentou forte modificação. Os grupos bacterianos se mostraram mais dispersos quando considerado somente o CHT. Embora, a análise de ANOSIM indicou não haver diferença nas amostras com e sem biochar, sugerindo que o clorotalonil foi quem mais contribuiu na dispersão dos grupos bacterianos. No período de 42 d, a comunidade apresentou resposta positiva, sendo observado aumentos no número de bandas e no índice de Shannon em todos tratamentos. Isto possivelmente, devido a menor concentração do fungicida disponível na solução do solo, diminuindo assim, os efeitos deletérios sobre a comunidade. Os dados de qPCR não apresentaram alteração no número de copias do gene 16S rDNA em todos os tratamentos. A remoção da diversidade impactou fortemente a capacidade da comunidade bacteriana de degradar o clorotalonil. Apesar da capacidade de degradar não ter sido perdida, a mínima alteração na diversidade promoveu elevada redução na taxa de mineralização do CHT. A dissipação do CHT se mostrou rápida (D50 < 1 dia) em todos os tratamentos, além disso, a formação de 14C-resíduos não extraíveis foi constituiu um dos principais mecanismos de dissipação do CHT. A partir da degradação do fungicida, foram detectados três metabólitos. Conclui-se que a modificação por diluição da diversidade bacteriana promoveu impacto negativo na mineralização do clorotalonil. E que a formação de resíduos não extraíveis consistiu no principal mecanismo de dissipação do CHT em ambos solos. / Microbial diversity is generally considered for his role in key ecosystem processes, such as decomposition of organic matter and biogeochemical cycles. However, information about the impact of diversity on minor functions, such as degradation of xenobiotics is scant. We study from the approach of \'dilution to extinction\', the role of diversity on the capacity of microbial community to degrade the chlorothalonil (organochlorine). We also studied the behavior of bacterial community after applying the pesticide in the soil with and without biochar. Microbial diversity of the soil natural (control) was artificially altered by dilution, forming a gradient of diversity (SN > 10-1 > 10-3 > 10-6), followed by inoculation in sterile soil samples and subsequent restructuring (15 days). After of the community restructuring, the samples were handled with biochar (1% w/w) and treated with the chlorothalonil field dose. The behavior of the bacterial community was studied by PCR-DGGE and qPCR of the 16S rDNA gene through an experiment with cold molecule (no radiolabeled). While the CHT degradation capacity was studied by radiorespirometry (14C-CHT). Initially, the community of bacteria was influenced by the diversity gradient obtained by dilution. The separation of bacterial groups showed very similar in the first three pre-application periods of the CHT (SN > 10-1 - 10-3 > 10-6). While in the period of 15 days, the group dynamic has changed (SN > 10-1 > 10-3 e 10-6). During periods of 21 and 42 days, the profile bacterial community showed strong modification. The bacterial groups were more dispersed when only considered the CHT. Although, the ANOSIM analysis indicated no difference in samples with and without biochar, suggesting that chlorothalonil who has contributed the most in the dispersion of bacterial groups. In the period of 42 days, the community presented a positive response, being observed increases in the number of bands and Shannon-Weiner index in all treatments. This possibly due to less concentration of fungicide available in soil solution, thus reducing, the deleterious effects on the community. The qPCR dates showed no change in the number of copies of the 16S rDNA gene in all treatments. The removal of microbial strongly impacted the ability of the bacterial community to degrading chlorothalonil. Despite the ability to degrade not having been lost, the minimum change in diversity promoted high reduction in the rate of mineralization CHT. The dissipation of the CHT showed quick (D50 < 1 d) in all treatments, in addition, the formation of non-extractable 14C-residues was one of the main mechanisms of dissipation of the CHT. From the degradation of chlorothalonil, three metabolites were detected. We conclude that modification by dilution of the bacterial diversity had a negative impact on the mineralization of chlorothalonil. And the formation of non-extractable residues consisted in the main CHT dissipation mechanism in both soils.
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Stanovení organických sloučenin ve vzorcích biouhlu získaných mikrovlnou torefakcí biomasy / Determination of organic compounds in biochar produced by microwave torrefaction of biomassMeindl, Jiří January 2019 (has links)
The thesis is focused on a determination of polycyclic aromatic hydrocarbons (PAHs) contained in dried pelletized sewage sludge and pelletized biochar. Biochars were made in mild conditions by microwave torrefaction of prepared sewage sludge. There were analyzed and quantified the 34 of standardized PAHs compounds in two series. The first serie, also called “Sada 1”, has been aimed at comparison of extraction methods for the chosen sample of sewage sludge and the sample of biochar. In serie “Sada 1”, there were compared efficiencies of chosen type of solvent or solvent mixture by comparison of yields for 34 standardized analytes in a sample of biochar and a sample of sewage sludge. There were compared also to total yields of PAHs and to number of quantified compounds in analyzed samples. The most reliable extraction method has been used for the next analyses of samples in the second serie called “Sada 2”. In Sada 2, there were compared different samples of the same type (e.g. biochar, sludge). The origin of sewage sludge (small or big sewage treatment plant expressed as PE) and used additives (cellulose, chaff, hay) as modificators for torrefaction process were variables for different type of sample. The results of analysis were identification of the most suitable sewage sludge and additive to be used as modificator for microwave torrefaction process. The main goal of correctly chosen sludge and additive was to minimize production of PAH’s during torrefaction and in samples of biochar.
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Využití biouhlí jako sorpčního materiálu pro odstranění syntetických vonných látek z vod / The use of biochar as a sorption material for the removal of synthetic fragrances from waterKašparová, Jarmila January 2020 (has links)
Synthetic fragrances (musk) are artificially produced organic compounds. It is used as fragrance ingredient in personal care products. Substances from this group have the ability to withstand the cleaning process in wastewater treatment plants. The physico-chemical properties of musk compounds cause their accumulation in the living and non-living components of the ecosystem, where they behave as persistent pollutants. The adsorption process is considered to be one of the most widely used separation and purification processes. The adsorption processes of a solution of sixteen synthetic fragrances took place with biochar and activated carbon. Solid phase microextraction (SPME) was used as a method for extracting analytes. Gas chromatography coupled with mass spectrometry (GC-MS) was applied for final analysis, time of flight analyzer was used as detector. The data were fitted with adsorption isotherms.
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Analýza organických látek přítomných v biouhlu / Analysis of organic substances present in biocharBača, Ondřej January 2021 (has links)
This master's thesis deals with the analysis of organic substances, which are present in biochar. Biochar contains a number of organic compounds, that can be toxic and also carcinogenic to living organisms. In order for biochar to be used to improve soil quality or to be used for other applications, its safety must be declared by European or international certifications. Relevant European and international standards have been created for the determination of organic substances, that could be present in biochar. The theoretical part of the thesis was focused on selected organic substances, the process of pyrolysis and thermochemolysis, biochar characterisation and the used analytical methods. The experimental part of the thesis consisted of extraction with toluene and after that the determination of concentration of the 38 polycyclic aromatic hydrocarbons was performed. Qualitative analysis was performed by two-dimensional gas chromatography. Biochar samples were also subjected to thermochemolysis method and then they were analysed on GC-MS again. In both analytical methods, a large number of substances from groups such as PAHs, carboxylic acids, amines, substituted naphthalenes etc. was found, as well as smaller number of eg. polychlorinated biphenyls.
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Procena remedijacionog potencijala sedimenta zagađenog prioritetnim organskim zagađujućim materijama / Investigation of remediation potential of sediment polluted with priority organic pollutantsGrgić Marko 16 August 2019 (has links)
<p>Predmet istraživanja ove doktorske disertacije je procena potencijalno biodostupne frakcije odabranih prioritetnih organskih polutanata (pentahlorbenzena, heksahlorbenzena, lindana, trifluralina, 4-oktilfenola i 4-nonilfenola) u sedimentu, ispitivanje biodegradacionog potencijala ovih jedinjenja u sedimentu u različitim uslovima, kao i procena potencijala stabilizacije<br />sedimenta dodatkom ugljeničnih sorpcionih agenasa. U cilju razvoja metoda za određivanje biodostupnosti odabranih organskih polutanata ispitivane su i optimizovane metode višestepene i jednostepene parcijalne ekstrakcije primenom sledećih hemijskih agenasa: Tenaks smole, XAD-4 smole i rastvora ciklodekstrina (2-hidroksipropil-β-ciklodekstrina, β-ciklodekstrina i metil-β-ciklodekstrina). Optimalni agens za procenu biodostupne frakcije odabranih organskih zagađujućih materija sa sedimenta XAD-4 smola, a optimalno vreme ekstrakcije primenom jednostepenih ekstrakcija je oko 8 h. Procena biodegradacionog potencijala odabranih prioritetnih organskih zagađujućih materija u sedimentu ispitana je u različitim aerobnim i anaerobnim uslovima uz optimizaciju uslova putem biostimulacije i bioaugmentacije. Pokazano je da svih šest odabranih jedinjenja poseduju značajan potencijal biodegradacije u anaerobnoj sredini pri čemu u slučaju lindana i trifluralina dolazi do potpunog uklanjanja biodostupne količine jedinjenja primenom sva četiri ispitana inokuluma. Aerobni potencijal u ispitanim uslovima pokazali su samo alkil fenoli, gde je takođe uklonjena skoro celokupna količinabiodostupne frakcije jedinjenja u sedimentu (78-85%). Potencijal remedijacije sedimenta dodatkom ugljeničnih materijala ispitan je sa aspekta odabira ugljeničnih sorpcionih agenasa (aktivni ugalj, biougalj i humus); određivanja optimalne količine materijala; isptivanja dugoročnih i kratkoročnih efekata dodatka ovih agenasa na biodostupnost organskih zagađujućih materija kako bi se ispitao efekat starenja i toksičnosti dobijenih smeša. Rezultati stabilizacije zagađujućih supstanci u sedimentu pokazuju da: (1) povećanje doze sva tri sorpciona agensa dovodi do povećanja efikasnosti imobilizacije i smanjenja biodostupne frakcije odabranih organskih jedinjenja; (2) starenjem smeša sedimenta i sorbenata u toku prvih 90 dana dolazi do daljeg smanjenja biodostupne frakcije svih jedinjenja, nakon čega se biodostupna koncentracija ispitivanih jedinjenja primenom aktivnog uglja ne menja, dok primenom biouglja i humusa dolazi do porasta biodostupne frakcije jedinjenja. Testovi fitotoksičnosti su pokazali da je <em>Zea mays </em>akumulirao značajno veće količine ispitivanih jedinjenja iz netretiranog sedimenta u poređenju sa <em>Cucurbita pepo</em> i <em> Lactuca sativa. </em>Toksičnost smeša sedimenta sa aktivnim ugljom i humusom procenjena na osnovu inhibicije luminiscencije na <em>Vibrio fischeri</em> kao i ispitivanjem <em>Zea mays </em>germinacije i produkcije biomase je pokazala značajno smanjenje u odnosu na netretirani sediment. Akumulacija ispitivanih jedinjenja u biomasi <em>Zea mays </em>u netretiranom sedimentu je bila značajno veća u odnosu na sve smeše sedimenta i aktivnog uglja i humusa. Sva tri sorbenta pokazala su veliki remedijacioni potencijal za sediment zagađen organskim zagađujućim supstancama, ali je aktivni ugalj pokazao najbolje performance.</p> / <p>The aim of the research in this PhD dissertation is the assessment of the potentially biodegradable fraction of selected organic pollutants (pentachlorbenzene, hexachlorobenzene, lindane, trifluraline, 4-octylphenol and 4-nonylphenol) in the sediment, estimation of the biodegradation potential of these compounds in sediment in different conditions, as well as the assessment of the stabilization potential sediment by the sediment amendment with of carbon rich sorption agents. In order to develop and optimise methods for the bioavailability assessment of the selected organic pollutants, methods of multistage and single-step non exhaustive extraction were studied using the following chemical agents: Tenax resin, XAD -4 resin and a cyclodextrin solution (2-hydroxypropyl- β-cyclodextrin, β-cyclodextrin and methyl-β-cyclodextrin). Results showed that optimal agent for estimating the bioavailable fraction of selected organic pollutants from the sediment is XAD-4 resins, and that the optimum extraction time using single-step extraction is about 8 h. The assessment of the biodegradation potential of selected priority organic pollutants in the sediment was examined in various aerobic and anaerobic conditions, with the optimization of conditions through biostimulation and bioaugmentation. It has been shown that all six selected compounds possess significant biodegradation potential in the anaerobic environment, where in the case of lindane and trifluraline there is complete removal of the bioavailable amount of the compound using all four inoculum tested. Aerobic potential under the applied conditions has been showen only for alkyl phenols, where almost all of the bioavailable fraction of the compound in the sediment was removed (78-85%). The potential of sediment remediation with the amendment of sediment withcarbon rich materials was examined from the aspect of selecting carbon sorption agents (activated carbon, biochar and humus); estimation the optimal material doses; the long -term and short-term effects of the addition of these agents on the bioavailability of organic pollutants in order to examine the effect of aging and the toxicity of the resulting mixtures. The results of the stabilization of pollutants in the sediment show that: (1) increasing the dose of all three sorption agents leads to an increase in the immobilization efficiency and reduction of the bioavailable fraction of the selected organic compounds; (2) aging of the amended sediment during the first 90 days results in a further reduction of the biodegradable fraction of all compounds, after which the biodegradable concentration of the selected compounds remain the same in the case of activated carbon amendment, while the bioavailable fraction of the compound increases with the use of biohar and humus. Phytotoxicity tests showed that <em>Zea mays </em> accumulated significantly higher amount of selected organic pollutants from unamended sediment, comparing to <em>Cucurbita pepo </em> and <em>Lactuca sativa</em>. Toxicity of activated carbon and humus amended sediment assessed by <em>Vibrio fischeri </em> luminescence inhibition test and by measuring <em>Zea mays </em>germination and biomass yield was significantly reduced in the amended sediment samples. Accumulation of the selected organic pollutants in the <em>Zea mays</em> biomass in the unamended sediment were a significantly higher than in the humus and activated carbon amended sediment. Both sorbents show potential to be used as remediation agents for organically contaminated sediment, but activated carbon exhibited the better performance.</p>
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Phytoremediation using Lupinus mexicanus and biochar in arsenic contaminated soil an experimental study. / Fytoremediering med Lupinus mexicanus och biokol i arsenikkontaminerad jord en experimentell studie.Johansson, Elin, Ekström Hoonk, Jesper January 2020 (has links)
Soil contamination is one of the main threats affecting food and water safety and ecosystem services on a global scale. Contamination of toxic inorganic and organic pollutants in soils and its remediation is closely related to the implementation of Sustainable Development Goals. With phytoremediation as a method and biochar as a tool, we used a common plant type Lupin Mexicanus to remediate soil from arsenic contamination further, we wanted to study how biochar affects the phytoremediation of contaminants. The combination of biochar made from reeds and L. mexicanus was in this study tested for its suitability for phytoremediation of arsenic (As) in soil. Seeds from L. mexicanus was grown in 18 different pots spiked with As (80 mg kg-1, dry weight) and different percentage of biochar amendment (0, 1, 2, 3, 4,5%). Two additional pots were planted with seeds but completely without any arsenic or biochar. The plants were grown for 5 weeks. The highest concentration in roots was 3094 mg kg-1 found in the pots with 2% biochar. The highest concentration of arsenic in the aerial parts was at a level of 168 mg kg-1 and found in the pots with 5 % biochar. L.mexicanus showed a potential of bioaccumulating arsenic from soil with a bioconcentration factor of 40,6 (2%) and 29,4 (5%), the concentration in leaves was 1-2 times higher compared to that in the soil. The results showed that biochar affected the translocation ratio and uptake of As in L. mexicanus, However, the biochar amended soil did not show anything major to the pH-value at these proportions (5% of biochar or less). This study was limited in explaining the mechanisms responsible for the increase in As uptake but shows a promising application for potential remediation of soils contaminated with high As levels. / Markföroreningar och föroreningar har visat sig vara ett av de största hoten som påverkar mark- och ekosystemtjänster på global nivå. Arbetet med förebyggande av föroreningar i marken och reningsarbeten, såsom marksanering har en stark koppling till nästan alla mål för hållbar utveckling. Med fytoremediering som metod och biokol som medel använde vi växter för att extrahera arsenikförorening från jord. I ett försök att minska kunskapsklyftan kring hur biokol påverkar fytoremidering av föroreningar kombinerades dessa två. Kombinationen av biokol tillverkad av vass och L.mexicanus testades i denna studie för dess lämplighet för fytoremediering av As i jord. Frön från L.mexicanus odlades i 18 olika krukor spetsade med As (80 mg kg-1 torrsubstans) och i en variation av andelen biokol ändring (0,1,2,3,4,5%). Två ytterligare krukor planterades med frön men helt utan arsenik eller biokol. Dessa krukor fungerade som kontroll för att säkerställa grobarheten hos fröerna eller de förhållanden som växterna odlades i. Efter 5 veckor skördades växterna och den högsta koncentrationen av arsenik i rötter var på 3094 mg kg-1 och fanns i krukorna som hade 2% biokol. Den högsta koncentrationen av arsenik i plantdelar ovanjord var på 168 mg kg-1 och var i krukorna med 5% biokol. L. mexicanus visade sig kunna bioackumulera, och resultatet visade att bioconcentrations faktorn uppmätte 40,6 (2%) och 29,4 (5%), varav koncentrationen i löv och skälk var 1-2 gånger högre än vad som återfanns i jorden. Resultaten visade även att biokol påverkade translokeringsförhållandet och upptaget av arsenik i L. mexicanus, tillsättningen av biokol i jord gav inga stora förändringar i pH-värdet med tillsatt koncentration (5% av biokol eller mindre). Studien var begränsad i att förklara de mekanismer som är ansvarig för ökningen av As upptag men visar en lovande applikationspotential i arbetet med sanering av jordar från As.
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Pyrolysis based processing of biomass and shale gas resources to fuels and chemicalsAbhijit D Talpade (11150073) 19 July 2021 (has links)
<div>Thermochemical processing using fast-pyrolysis technology has been used to upgrade feedstocks like biomass and natural gas and more recently studied for plastic recycling. This work aims to improve the selectivity to desired products from a pyrolysis process through better catalysts and reactor design.</div><div>Fast-pyrolysis of biomass to fuels is considered a promising technology due to the higher yields to liquid fuel products. However, the process suffers from low carbon efficiency to hydrocarbon products due to carbon losses to biochar, accounting for 25-40 wt.% of the product stream depending on the biomass type. Using a combination of inorganic free-model compounds, biomass pretreatments and mass spectrometric analyses coupled with lab-scale reactor experiments, the char contribution from the lignocellulosic components (cellulose, hemicellulose, and lignin) and mineral content was investigated. The lignocellulosic components were found to follow the order: Lignin > Hemicellulose > Cellulose. Addition of inorganic salts (K, Na and Ca) to cellobiose, a model compound for cellulose, was found to catalyze additional dehydration reactions on primary pyrolysis products (e.g., levoglucosan) to yield secondary products (e.g., 5-HMF), and produce more char. This knowledge of char formation contributors can enable optimization of the bio-refining process sequencing using process system engineering tools and thus achieve higher carbon efficiency for biomass conversion.</div><div>While biomass has been viewed as a future energy source, there is a need for a transition fuel with the lowest possible greenhouse gas (GHG) footprint. Shale gas, consisting primarily of methane, is a potential candidate due to its large availability and high hydrogen to carbon ratio. Recently, single-atom catalysts have been studied as stable and non-coking catalysts for the non-oxidative coupling of methane (NOCM) to higher hydrocarbons (like ethylene). However, lack of post reaction catalyst characterization and rigorous kinetic testing have raised questions on the stability of these materials. This work combines homogenous (Chemkin simulations, gas phase kinetics) and heterogeneous reaction kinetic studies (reaction orders, steady state kinetics), coupled with microscopy (Scanning and Transmission Electron Microscopy (SEM, TEM)) and surface characterization tools (BET, TGA, Raman spectroscopy, CO-IR spectroscopy) to understand the role of the solid materials during NOCM. Post reaction catalyst characterization using transmission electron microscopy (TEM) analysis on the spent samples (CH4 treated at 975 deg C for 3 hours) reveals that the materials containing Pt single atoms (SA) and Pt nanoparticles (NP) are found to sinter to particles approximately 5-7 nm in size. Ethylene hydrogenation experiments, a kinetic probe for surface Pt, shows initial ethane formation rates that are four orders of magnitude lower on the isolated Pt+2 sites, found on Pt SAs, when compared to the rates obtained if all the surface Pt were assumed to be metallic. These results suggest that single atoms are not the active sites. However, under same reaction conditions (50 mL min-1 CH4 flow and 975 deg C), the ethylene formation rates (in mol h-1) on the solid materials are 2-7 times higher than the empty tube rates, indicating that the surface plays a role during NOCM. Addition of incremental amounts of the solid material increases methane conversion, extrapolating to the bare tube conversion at zero loading. This indicates that the solid materials improve the NOCM performance.</div><div>Experiments with pure methane feeds indicate that the solid materials are found to deactivate due to coking on the surface, evidenced by the coke buildup observed using thermogravimetric analysis (TGA) and the initial time-on-stream kinetic results showing rapid methane deactivation. Raman spectroscopy on the spent catalysts indicate at the development of a similar graphite-like surface intermediate under steady state conditions on all the materials. When compared under the same reaction conditions (975 deg C, 60 mL min-1 Pure CH4 with 10% UHP N2 feed, space velocity = 39.6 L h-1 gcat-1), these coked surfaces show a linear dependence for the ethylene formation rate (in mol h-1 gcat-1) with the spent surface area of the material (in m2 gcat-1). This observation is irrespective of the type of the material studied (alpha Al2O3, Davisil SiO2, 1 wt.% Pt/CeO2, Graphene, Graphite, etc.). In conclusion, these results prove that the spent surface area is critical for NOCM.</div><div>Similar experimental setup was used to study the dehydrogenation of methane, ethane, and propane mixture in the gas phase. Initial experiments at 1 bar pressure and reaction temperatures ranging from 650-850 deg C revealed that ethylene and hydrogen are the main gas phase products, with methane acting as a diluting agent under these reaction conditions. These results could enable direct processing of the shale gas without the use of a conventional ethane/propane separation step. These results were further studied by the system engineers using ANSYS ChemkinPro. For practical applications, these experiments were suggested to be performed at much higher operating pressures (~30 bar) and low residence time (~0.2 s), with a quick quenching step added after the reactor to prevent change in the exit stream compositions. A new reaction system was built to experimentally validate these recommendations.</div>
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Příprava čístírenských kalů pro proces pyrolýzy / Preprocessing of sewage sludge for pyrolysis processŠevčík, Jan Unknown Date (has links)
The concept of sludge management at the level of sludge treating technology of sewage treatment plants, as well as at national, continental or world level, requires fundamental improvement in the interest of sustainable development. Sewage sludge production is continuously increasing. Sewage sludge contains a number of pollutants but also a significant renewable resource for material transformation and / or energy recovery. Sewage sludge is composed of an inorganic mineral part and organic components. Its organic part is a source of energy and nutrients, but also contains harmful pollutants for exapmple heavy metals. However, there are technologies that offer the possibility of neutralizing pollutants while using other sludge components in terms of recycling energy, nutrients and other attractive sludge components. The mentioned technologies include mainly thermal methods of sewage sludge treatment and one of them is pyrolysis. Thessis focuses on sewage sludge prepartation for pyrolysis process, which includes mixing with additives and peletization of prepared mixture for purposes of agricultural or energetical utilisation. Technology for material transformation and energy utilization of sewage sludge, in particular the mentioned pyrolysis or torrefaction, require an insignificant degree of detailed research in order to expand it in the field of sludge management. Indeed, it is not only research that will enable direct correct use of this technology in practice. The results of such research are the basis for the drafting of the relevant legislation, which will subsequently enable the deployment of pyrolysis technologies in practice.
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Hydrothermal Synthesis and Characterization of Fluorescent Carbon-Based Materials Produced by Hydrogen Peroxide Oxidation of BiocharDavies, Bethany Ruth 01 September 2020 (has links)
No description available.
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