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- Co-liquefaction of wastes and coal mixtures to produce added value liquid compoundsPublication . Pinto, Filomena; Costa, Paula; Paradela, Filipe; Silva, Pedro; Meredith, Will; Stevens, Lee; Snape, ColinABSTRACT: Nowadays there is an increasing need to find alternative fuels to reduce the dependency on imported ones and to decrease the negative environmental impact of wastes accumulation. Plastics are an important components of urban biowaste, thus their conversion into liquid fuels, in mixtures with other solid fuels still remains an important research goal. After the large experience obtained from coal gasification, it was found that co-liquefaction of coal and wastes may be a good solution to produce liquid fuels and raw materials for several industries. Co-liquefaction of coal blended with biomass gave unfavourable results, but co-liquefaction of coal mixed with PE (polyethylene) wastes led to encouraging results. The results obtained showed that the rise of PE content in coal blends led to an increase in liquid yield. As the main objective was the formation of liquid products, the mixture of coal with 50 wt% of PE was selected, as substantial total liquid yields were obtained, while using significant coal content. This blend was used to study the effect of initial hydrogen pressure, reaction temperature and time on products yields, using Response Surface Methodology (RSM) approach. Liquid yields were most affected by reaction temperature and pressure. The rise of temperature decreased liquid yields, while pressure had a positive effect, but the interaction between these two parameters showed a negative influence. Theoretical equations were used to calculate total and direct liquids yield (%daf). Total liquids are the sum of the liquids directly recovered from the autoclave (direct liquids) and the liquids extracted from the solid product. Both the theoretical model and the experimental results showed that the highest total liquids yields were obtained at 380 ºC, 1.4 MPa and 90 minutes.
- Recovery of wastes by pyrolysis: effect of experimental conditionsPublication . Paradela, Filipe; Pinto, Filomena; Ramos, Ana M.; Gulyurtlu, Ibrahim; Cabrita, IsabelThis work aimed to study the recovery of three types of waste by the process of pyrolysis: biomass, plastics and used tyres. The effects of experimental conditions in products yield and composition were studied. The increase of reaction time increased alkane content both in gas phase from 53% to 70% v/v and in liquid fraction from 48% to 60% w/w. The rise of reaction temperature led to a decrease of liquid yield (from 82% to 73% w/w), which was followed by the increase of solids and gases. The increase of reaction temperature also allowed the increase of the alkane content in gas phase from 39% to 70% v/v. The increase of initial pressure did not lead to appreciable variations in product yields or composition. The parameter that most affected products yield and composition was plastics content on the wastes initial mixture. The enhancement of this parameter increased liquids yield from 33% to 92% w/w, at the expenses of solids and gases contents and also decreased aromatics contents from 52% to 28% w/w.
- Estudo da pirólise de misturas de resíduos plásticos e de biomassaPublication . Paradela, FilipeA forte dependência da sociedade moderna das fontes de energia fósseis poderá ter consequências graves num futuro próximo se não forem adoptadas medidas. Com efeito, o esgotamento das suas reservas (principalmente de petróleo), as consequências ambientais do seu uso, e a excessiva dependência energética da maioria dos países são problemas que a sociedade terá que enfrentar. Outra vertente problemática actual é a elevada produção de resíduos e o seu deficiente reaproveitamento. Casos específicos destes resíduos são os plásticos (cujo consumo tem vindo a aumentar exponencialmente no último quarto de século) e a biomassa (produzida por exemplo, na indústria da pasta de papel e cuja acumulação nas áreas florestais contribui como fonte combustível de incêndios). O presente trabalho procurou integrar o tratamento destes dois tipos de resíduos pelo processo de pirólise. Este processo de decomposição térmica na ausência de oxigénio foi usado tradicionalmente na produção de carvão a partir da biomassa, ou como técnica de análise da constituição de polímeros. Mas face ao cenário actual, existe um interesse crescente na aplicação deste processo a resíduos, de modo a gerar produtos com interesse como combustíveis ou como matérias-primas para indústrias químicas. Verificou-se que a adição de uma mistura dos principais plásticos presentes nos resíduos sólidos urbanos permitiu melhorar a pirólise da biomassa em condições de pirólise lenta, ao criar uma fase líquida que melhorou a transferência de massa e de calor na mistura reaccional. Foram deste modo obtidos produtos líquidos com conteúdo energético apreciável, semelhante ao do gasóleo de aquecimento, bem como gases com poder calorífero superior ao do gás de cidade, e sólidos com conteúdo energético superior ao de alguns carvões. Para além disso foram identificados compostos típicos da pirólise rápida de biomassa com valor comercial como matéria-prima em várias indústrias. Foi também estudado o efeito das condições experimentais (tempo e temperatura de reacção, pressão inicial e teor de pinho na mistura inicial) no rendimento das três fracções de produtos e na sua composição. Verificou-se que o teor de pinho na mistura inicial foi o parâmetro que mais afectou os resultados, quer em termos de rendimento das três fracções (ao favorecer a formação de gases e sólidos em detrimento da fracção líquida), quer em termos da composição da fase gasosa, favorecendo a produção de CO e CO2. Outros parâmetros que tiveram também influência no processo foram (com o aumento do parâmetro): o tempo de reacção na composição da mistura gasosa (aumento do teor de alcanos) e da mistura dos líquidos (aumento do teor de aromáticos); a temperatura de reacção nos rendimentos das fracções (diminuição da fracção líquida em favor da de sólidos e de gases) e na composição dos gases (aumento da produção de alcanos); e a pressão inicial na composição dos líquidos (aumento do teor de aromáticos). ABSTRACT: Energy requirements of the modern society are increasing, and the main sources that are used in developed countries to provide that energy are fossil ones. This fact, seeing that their reserves are ending (especially oil), that these reserves are situated in small (and sometimes pollitically unstable) areas and that their use raises pollution and global warming issues, might have serious repercussions if appropriatte measures are not taken. Another problematic issue in modern day societies is the increasing production of wastes and their inadequate recovery. Plastics and biomass wastes are two specific types of waste that are not properly recovered, the majority of them being landfilled. This work aimed to study the recovery of these two types of waste by the process of pyrolysis. The attained results show that the adding of a plastics mix improves the overall efficiency of the slow pyrolysis of pine, by creating a liquid phase that improves heat and mass transfer processes. Therefore, it was possible to achieve higher liquid yelds and less solid product than in the classic slow pyrolysis carbonisation of biomass. The obtained liquids showed heating values similar to that of heating fuel oil. The gas products had energetic contents superior to that of town gas, and the obtained solid fractions showed heating values higher than some coals. There were also identified some typical products of fast biomass pyrolysis used as raw material in several industries. The effects of experimental conditions in products yield and composition were also studied. The parameters that showed higher influence were (with its increase): reaction time on gas product composition (increase of the alkane content) and on liquid composition (increase in aromatics content); reaction temperature on products yield (decrease of liquid yield with increase of solids and gases) and on gas product composition (increase in alkane content); initial pressure on liquid composition (increase in the aromatics content) and mainly the pine content of the initial mixture on products yield (increase of gas and solid yield with a decrease in liquids) and on the gas product composition (favouring CO and CO2 formation).
- Production of liquid compounds by co-pyrolysis of different pre-treated biomasses mixed with plastic wastesPublication . Pinto, Filomena; Duarte, Luís C.; Carvalheiro, Florbela; Paradela, Filipe; Costa, Paula; Marques, Joana; Andre, Rui N.; Marques, Paula; Costa, Diogo; Sampaio, BrunoABSTRACT: As an innovation to conventional biomass pyrolysis to produce liquid biofuels, different types of biomass wastes were pre-treated by autohydrolysis, prior to pyrolysis. Eucalyptus forestry waste, corn cobs agricultural residue, and miscanthus (an energy crop) were autohydrolysed. Autohydrolysis led to valuable sugar-rich stream that may be used in fermentation and to solids rich in lignin that were pyrolysed. Pyrolysis of autohydrolysed eucalyptus led to an increase in liquids yields of 24 % in relation to untreated eucalyptus, as autohydrolysis weakened initial macromolecular structure and thus helped chemical bonds breakdown during pyrolysis. However, similar pyrolysis liquid yields were obtained by autohydrolysed or untreated corn cobs and miscanthus, thus feedstock composition is an important issue. Nevertheless, the production of added value products by autohydrolysis may still justify this pre-treatment. Otherwise, more severe pre-treatments of these biomasses might improve co-pyrolysis as it happened with eucalyptus. As polyethylene (PE) is easier to pyrolyse than biomass and greatly favours the production of liquid hydrocarbons, autohydrolysed and untreated biomass was mixed with PE wastes to be used in co-pyrolysis. The rise of PE content in the blend clearly favoured the production of liquid products of pre-treated and untreated biomass. 75 %wt. of PE in the blend led to liquid yields of 72 %wt. for untreated eucalyptus and of 82 %wt. for autohydrolysed eucalyptus.
- Study of the slow batch pyrolysis of mixtures of pin, plastics and tiresPublication . Paradela, Filipe; Pinto, Filomena; Ramos, A. M.; Gulyurtlu, Ibrahim
- Study of the slow batch pyrolysis of mixtures of plastics, tyres and forestry biomass wastes. Effect of experimental conditions in the liguid compoundsPublication . Paradela, Filipe; Pinto, Filomena; Ramos, Ana M.; Gulyurtlu, Ibrahim; Cabrita, IsabelIn this work was studied the effect of experimental conditions in the production of liquid compounds from slow batch pyrolysis of mixtures of plastics, tires and pines wastes. The major compounds formed were toluene, ethylbenzene, and linear alkanes from C5 to C10 (each reaching yields around 5% w/w of the initial waste mixture). The pyrolysis reaction time and temperature improved the production of those species, while decreasing heavier alkanes formation. An increase of plastics content in waste mixture seemed to favour the production of lighter alkanes, although this effect was not as notorious as the ones just mentioned. The styrene production decreased regularly with the decrease of tyres content in the mixture. Autoclave initial pressure variation did not seem to affect significantly the formation of the major compounds.
- The role of solvent and catalysts on co-liquefaction of coal and wastePublication . Pinto, Filomena; Paradela, Filipe; Costa, Paula; Andre, Rui N.; Rodrigues, Tiago; Snape, Colin; Herrador, José M. Hidalgo; Fratczak, JakubABSTRACT: It is predictable that liquid fuels will be needed for long distance transport sector for quite some years. Thus, it is imperative to find alternative fuels to reduce the dependency on petroleum derived fuels and to decrease the negative environmental impact. Co-liquefaction of coal and wastes, like plastics, to produce liquid fuels and raw materials for several industries may play an important role in the near future, because it will decrease the problems associated with the dependency of only one raw material and also it will allow taking profit of the suitable properties of each one, while diluting the disadvantageous characteristics of coal. The use of plastics, namely polyethylene (PE) favoured coal liquefaction, as PE macromolecules are easier to break down and to form smaller liquid molecules than coal. To improve the production of liquid compounds by coal liquefaction solvents with different hydrogen donor capabilities were tested, such as: methylnaphthalene and tetralin. Tetralin led to the highest liquid yields and conversion, due to its hydrogen donor capacity. Some commercial available catalysts, like FCC (Fluid Catalytic Cracking) and Co-Mo based were also tried. Coal impregnated with some metals like iron (Fe) and molybdenum (Mo) was also tested. Impregnated coal, especially with Mo showed to have a better performance than the commercial catalysts. Liquid yield obtained during co-liquefaction of coal and PE when coal was impregnated with Mo was around 66 wt%. The use of tetralin allowed increasing this value around 44 %.
- Pressurized pyrolysis of mattress residue: An alternative to landfill managementPublication . Serrano, Daniel; Horvat, Alen; Mata, Ricardo M.; Costa, Paula; Paradela, FilipeABSTRACT: Mattresses are a difficult waste to manage in landfills due to their large volume and low density. Pyrolysis treatment could reduce its volume while producing fuel or products valuable for the chemical industry. Pressurized pyrolysis at 400, 450, and 500 degrees C is carried out in a lab-scale autoclave at initial pressures 4.2, 8.4, and 16.8 bar. Product gas yield increases slightly along with elevated pressure as well as temperature. However, beyond 8.4 bar the initial pressure makes no discernible differences. CO and CO2 are the major gas species followed by CH4. CO contributes the most to the product gas energy content followed by C-3 species, C2H6, and H-2. Calculated energy content (heating value) is between 2 and 15 MJ.Nm(-3). In terms of product gas energy content, low pressure pyrolysis is favorable over high pressure pyrolysis. According to integration areas of chromatographic measurements the liquid phase contains up to 25 % of N-compounds, with benzonitrile being the most abundant, followed by toluene, o-xylene, and ethylbenzene. The solid char maintains constant properties across operating conditions, with carbon and energy contents of approximately 75 wt% and 30 MJ.kg(-1), respectively.
- Slow pyrolysis of cork granules under nitrogen atmosphere: by-products characterization and their potential valorizationPublication . Costa, Paula; Barreiros, M. Alexandra; Mouquinho, Ana; Silva, P. Oliveira e; Paradela, Filipe; Oliveira, Fernando Almeida CostaABSTRACT: Cork granules (Quercus suber L.) were slowly pyrolyzed at temperatures between 400-700 degrees C and under N-2 flow. While preserving its structure, some cells of the cork biochar became interconnected, allowing such carbon residue to be used as templates for manufacturing ceria redox materials. The pyrolytic char morphology was similar to that of the natural precursor. The produced cork biochar belonged to Class 1 (C > 60%) and possessed a high heating value of 32 MJ kg(-1). Other pyrolysis-derived compounds were identified and quantified through GC-FID and GC-MS analyses. The yield of gases released during cork pyrolysis was strongly dependent on the temperature used due to the thermal decomposition reactions involved in the degradation of cork. In particular, rising pyrolysis temperature from 500 to 700 T resulted in reducing the total hydrocarbon gases from 74 to 24 vol%. On the other hand, the yield of H-2 increased from 0 to 58% by increasing the pyrolysis temperature from 400 to 700 T. Due to the presence of suberin in cork, the composition and yield of bio-oil could be regulated by the pyrolysis temperature. Cork bio-oil was found to consist of long-chain hydrocarbons (from C11 to C24). The bio-oil resulting from the slow pyrolysis of cork residues is suitable as an appropriate feedstock for producing aliphatic-rich pyrolytic biofuels or as a source of olefms. Overall, the findings of this study suggest that Quercus suber L. could be a promising feedstock for biochar and biofuel production through the pyrolytic route and could contribute to the environmental and economic sustainability of the cork production industry.
- Hydrothermal Co-Liquefaction of Food and Plastic Waste for Biocrude ProductionPublication . Feuerbach, Silvan; Toor, Saqib Sohail; Costa, Paula; Paradela, Filipe; Marques, Paula; Castello, DanieleABSTRACT: In this study, hydrothermal co-liquefaction of restaurant waste for biocrude production was conducted. The feedstock was resembled using the organic fraction of restaurant waste and low-density polyethylene, polypropylene, polystyrene, and polyethylene terephthalate, four plastic types commonly present in municipal solid waste. Using design of experiment and a face-centered central composite design, three factors (feedstock plastic fraction, temperature, time) were varied at three levels each: feedstock plastic fraction (0, 0.25, 0.5), temperature (290 degrees C, 330 degrees C, 370 degrees C), and reaction time (0 min, 30 min, 60 min). The literature reports positive synergistic interactions in hydrothermal co-liquefaction of biomass and plastics; however, in this work, only negative synergistic interactions could be observed. A reason could be the high thermal stability of produced fatty acids that give little room for interactions with plastics. At the same time, mass might transfer to other product phases.