| 1. |
- Yan, Jinci, et al.
(författare)
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Identification of FtfL as a novel target of berberine in intestinal bacteria
- 2023
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Ingår i: BMC Biology. - 1741-7007. ; 21:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Berberine (BBR) is a commonly used anti-intestinal inflammation drug, and its anti-cancer activity has been found recently. BBR can intervene and control malignant colorectal cancer (CRC) through intestinal microbes, but the direct molecular target and related mechanism are unclear. This study aimed to identify the target of BBR and dissectrelated mechanisms against the occurrence and development of CRC from the perspective of intestinal microorganisms. Results: Here, we found that BBR inhibits the growth of several CRC-driving bacteria, especially Peptostreptococcus anaerobius. By using a biotin-conjugated BBR derivative, we identified the protein FtfL (formate tetrahydrofolate ligase), a key enzyme in C1 metabolism, is the molecular target of BBR in P. anaerobius. BBR exhibits strong binding affinity and potent inhibition on FtfL. Based on this, we determined the crystal structure of PaFtfL(P.anaerobius FtfL)-BBR complex and found that BBR can not only interfere with the conformational flexibility of PaFtfL tetramer by wedging the tetramer interface but also compete with its substrate ATP for binding within the active center. In addition, the enzymatic activities of FtfL homologous proteins in human tumor cells can also be inhibited by BBR. Conclusions: In summary, our study has identified FtfL as a direct target of BBR and uncovered molecular mechanisms involved in the anti-CRC of BBR. BBR interferes with intestinal pathogenic bacteria by targeting FtfLs, suggesting a new means for controlling the occurrence and development of CRC.
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| 2. |
- Yang, Pengjie, et al.
(författare)
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A toolbox for genetic manipulation in intestinal Clostridium symbiosum
- 2024
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Ingår i: Synthetic and Systems Biotechnology. - 2405-805X. ; 9:1, s. 43-54
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Tidskriftsartikel (refereegranskat)abstract
- Gut microbes are closely related with human health, but remain much to learn. Clostridium symbiosum is a conditionally pathogenic human gut bacterium and regarded as a potential biomarker for early diagnosis of intestinal tumors. However, the absence of an efficient toolbox that allows diverse genetic manipulations of this bacterium limits its in-depth studies. Here, we obtained the complete genome sequence of C. symbiosum ATCC 14940, a representative strain of C. symbiosum. On this basis, we further developed a series of genetic manipulation methods for this bacterium. Firstly, following the identification of a functional replicon pBP1 in C. symbiosum ATCC 14940, a highly efficient conjugative DNA transfer method was established, enabling the rapid introduction of exogenous plasmids into cells. Next, we constructed a dual-plasmid CRISPR/Cas12a system for genome editing in this bacterium, reaching over 60 % repression for most of the chosen genes as well as efficient deletion (>90 %) of three target genes. Finally, this toolbox was used for the identification of crucial functional genes, involving growth, synthesis of important metabolites, and virulence of C. symbiosum ATCC 14940. Our work has effectively established and optimized genome editing methods in intestinal C. symbiosum, thereby providing strong support for further basic and application research in this bacterium.
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| 3. |
- Bolívar Caballero, José Juan, et al.
(författare)
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Advanced application of a geometry-enhanced 3D-printed catalytic reformer for syngas production
- 2023
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Ingår i: Energy Conversion and Management. - : Elsevier BV. - 0196-8904 .- 1879-2227. ; 287
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Tidskriftsartikel (refereegranskat)abstract
- Catalyst research on reforming processes for syngas production has mainly focused on the active metals and support materials, while the effect of the catalyst's geometry on the reforming reactions has been poorly studied. The application of 3D-printed materials with enhanced geometries has recently started to be studied in heterogeneous catalysis and is of interest to be implemented for reforming biomass and plastic waste to produce H2-rich syngas. In this study, a geometry-enhanced 3D-printed Ni/Al2O3/FeCrAl-based monolithic catalyst with a periodic open cellular structure (POCS) was designed and fabricated. The catalyst was used for batch steam reforming biomass pyrolysis volatiles for syngas production at different parameters (temperature and steam-to-carbon ratio). The results showed complete reforming of pyrolysis volatiles in all experimental cases, a high H2 yield of ≈ 7.6 wt% of biomass was obtained at the optimized steam-to-carbon ratio of 8 and a reforming temperature of 800 °C, which is a higher yield compared to other batch reforming tests reported in the literature. Moreover, CFD simulation results in COMSOL Multiphysics demonstrated that the POCS configuration improves the reforming of pyrolysis volatiles for tar/bio-oil reforming and H2 production thanks to enhanced mass and heat transfer properties compared to the regular monolithic single-channel configuration.
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| 4. |
- Cuvilas, Carlos Alberto
(författare)
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Mild Wet Torrefaction and Characterization of Woody Biomass from Mozambique for Thermal Applications
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mozambique has vast forestry resources and also considerable biomass waste material such as bagasse, rice husks, sawdust, coconut husks and shells, cashew nut shell and lump charcoal waste. The potential of the total residues from the agricultural sector and the forest industry is estimated to be approximately 13 PJ. This amount of energy covers totally the production of charcoal which amounted to approximately 12.7 PJ in 2006. Although biomass is an attractive renewable source of energy, it is generally difficult to handle, transport, storage and use due to its lower homogeneity, its lower energy density and the presence of non-combustible inorganic constituents, which leads to different problems in energy conversion units such as deposition, sintering, agglomeration, fouling and corrosion. Therefore, a pretreatment of the biomass to solve these problems could lead to a change of current biomass utilization situation. The aim of this study is to convert Mozambican woody biomass residue into a solid biochar that resembles low-grade coal.In this work the current energy situation in Mozambique has been reviewed, and the available and potential renewable sources including residues from agricultural crops and forest industry as energy have been assessed. It was found that the country is endowed with great potential for biofuel, solar, hydro and wind energy production. However, the production today is still far from fulfilling the energy needs of the country, and the majority of people are still not benefiting from these resources. Charcoal and firewood are still the main sources of energy and will continue to play a very important role in the near future. Additionally, enormous amounts of energy resources are wasted, especially in the agricultural sector. These residues are not visible on national energy statistics. The chemical composition and the fuelwood value index (FVI) showed that by failing to efficiently utilise residues from Afzelia quanzensis, Millettia stuhlmannii and Pterocarpus angolensis, an opportunity to reduce some of the energy related problems is missed. An evaluation of effect of a mild wet torrefaction pretreatment showed that the chemical composition of the biochar is substantially different than the feedstock. The use of diluted acid as catalysts improves the biochar quality, namely in terms of the energy density and ash characteristics; however, the increment of the S content in the final product should be considered for market acceptance (because the fuels have a maximum allowance for S concentration). The thermal behaviour of the untreated and treated biomass was also investigated. The pyrolytic products of umbila and spruce were affected by the treatment and catalyst in terms of yield and composition of the vapours.
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| 5. |
- Gulshan, Samina, et al.
(författare)
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Performance analysis and production of aromatics for ex situ catalytic pyrolysis of engineered WEEE
- 2024
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Ingår i: Journal of Analytical and Applied Pyrolysis. - : Elsevier BV. - 0165-2370 .- 1873-250X. ; 179
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Tidskriftsartikel (refereegranskat)abstract
- Ex situ catalytic pyrolysis of engineered waste electrical and electronic equipment (WEEE) was conducted in a two-stage reactor using HZSM-5 catalyst. The effect of the catalysis temperature and the catalyst-to-feedstock (C/F) ratio on products yield, gas and oil composition, and products characterization were investigated in this study. Results indicated that lower reforming temperature and C/F ratio favored organic fractions production. The highest yield of organic fraction was obtained at a catalysis temperature of 450 °C and at a C/F ratio of 0.15, corresponding to 28.5 and 27.4 wt %, respectively. The highest selectivity toward aromatic hydrocarbons and the lowest TAN value of the organic fraction were obtained at a catalysis temperature of 450 °C and a C/F ratio of 0.2, respectively. Most of the alkali and transition metals and 23 % of Br remained in the solid residue after the catalytic pyrolysis of low-grade electronic waste (LGEW).
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| 6. |
- Jin, Yanghao, et al.
(författare)
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Carbon and H-2 recoveries from plastic waste by using a metal-free porous biocarbon catalyst
- 2023
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Ingår i: Journal of Cleaner Production. - : Elsevier BV. - 0959-6526 .- 1879-1786. ; 404
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Tidskriftsartikel (refereegranskat)abstract
- Carbon and H2 recoveries from plastic waste enable high value-added utilizations of plastic waste while mini-mizing its GHG emissions. The objective of this study is to explore the use of a metal-free biocarbon catalyst for waste plastic pyrolysis and in-line catalytic cracking to produce H2-rich gases and carbon. The results show that the biocarbon catalyst exhibits a good catalytic effect and stability for various plastic wastes. Increasing the C/P ratio from 0 to 2, induce an increase in the conversion rate of C and H in plastics to carbon and H2 from 57.1% to 68.7%, and from 22.7% to 53.5%, respectively. Furthermore, a carbon yield as high as 580.6 mg/gplastic and an H2 yield as high as 68.6 mg/gplastic can be obtained. The hierarchical porous structure with tortuous channels of biocarbon extends the residence time of pyrolysis volatiles in the high-temperature catalytic region and thereby significantly promotes cracking reactions.
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| 7. |
- Jin, Yanghao, et al.
(författare)
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From Waste Biomass to Hard Carbon Anodes : Predicting the Relationship between Biomass Processing Parameters and Performance of Hard Carbons in Sodium-Ion Batteries
- 2023
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Ingår i: Processes. - : MDPI AG. - 2227-9717. ; 11:3
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Forskningsöversikt (refereegranskat)abstract
- Sodium-ion batteries (SIBs) serve as the most promising next-generation commercial batteries besides lithium-ion batteries (LIBs). Hard carbon (HC) from renewable biomass resources is the most commonly used anode material in SIBs. In this contribution, we present a review of the latest progress in the conversion of waste biomass to HC materials, and highlight their application in SIBs. Specifically, the following topics are discussed in the review: (1) the mechanism of sodium-ion storage in HC, (2) the HC precursor's sources, (3) the processing methods and conditions of the HCs production, (4) the impact of the biomass types and carbonization temperature on the carbon structure, and (5) the effect of various carbon structures on electrochemical performance. Data from various publications have been analyzed to uncover the relationship between the processing conditions of biomass and the resulting structure of the final HC product, as well as its electrochemical performance. Our results indicate the existence of an ideal temperature range (around 1200 to 1400 degrees C) that enhances the formation of graphitic domains in the final HC anode and reduces the formation of open pores from the biomass precursor. This results in HC anodes with high storage capacity (>300 mAh/g) and high initial coulombic efficiency (ICE) (>80%).
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| 8. |
- Lucas, Carlos, et al.
(författare)
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Mathematical model of biomass gasification using high temperature air in fixed beds
- 2007
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Ingår i: Progress in Computational Fluid Dynamics, An International Journal. - 1468-4349 .- 1741-5233. ; 7:1, s. 58-67
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Tidskriftsartikel (refereegranskat)abstract
- A mathematical model has been formulated for predicting the main chemical and physical processes taking place during the fixed-bed gasification of biomass fuels using high temperature air (up to 1000 degrees C). Predicted gas species concentrations profiles and their maximum values are in good agreement with measurements. The results also show that when the temperature of feed gas (air) is increased a higher gasification rate, higher molar fractions of fuel gases (CO, H-2 and CmHn) are obtained, thus resulting in a higher LHV. At a high flow rate of the feed gases, the peaks of the fuel gas concentrations are slightly increased, and the gasification rate is strongly increased. A smaller particle size of the biomass fuels leads to higher peak values of the fuel gas species molar fractions, and a more stable gasification zone for a relatively long period of time.
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| 9. |
- Shi, Ziyi, et al.
(författare)
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Bio-based anode material production for lithium–ion batteries through catalytic graphitization of biochar : the deployment of hybrid catalysts
- 2024
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Ingår i: Scientific Reports. - : Springer Nature. - 2045-2322. ; 14:1
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Tidskriftsartikel (refereegranskat)abstract
- Producing sustainable anode materials for lithium-ion batteries (LIBs) through catalytic graphitization of renewable biomass has gained significant attention. However, the technology is in its early stages due to the bio-graphite's comparatively low electrochemical performance in LIBs. This study aims to develop a process for producing LIB anode materials using a hybrid catalyst to enhance battery performance, along with readily available market biochar as the raw material. Results indicate that a trimetallic hybrid catalyst (Ni, Fe, and Mn in a 1:1:1 ratio) is superior to single or bimetallic catalysts in converting biochar to bio-graphite. The bio-graphite produced under this catalyst exhibits an 89.28% degree of graphitization and a 73.95% conversion rate. High-resolution transmission electron microscopy (HRTEM) reveals the dissolution–precipitation mechanism involved in catalytic graphitization. Electrochemical performance evaluation showed that the trimetallic hybrid catalyst yielded bio-graphite with better electrochemical performances than those obtained through single or bimetallic hybrid catalysts, including a good reversible capacity of about 293 mAh g−1 at a current density of 20 mA/g and a stable cycle performance with a capacity retention of over 98% after 100 cycles. This study proves the synergistic efficacy of different metals in catalytic graphitization, impacting both graphite crystalline structure and electrochemical performance.
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| 10. |
- Wang, Shule, 1994-, et al.
(författare)
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Renewable hydrogen production from the organic fraction of municipal solid waste through a novel carbon-negative process concept
- 2022
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Ingår i: Energy. - : Elsevier BV. - 0360-5442 .- 1873-6785. ; 252
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Tidskriftsartikel (refereegranskat)abstract
- Bioenergy with carbon capture and storage (BECCS) is one of the prevailing negative carbon emission technologies. Ensuring a hydrogen economy is essential to achieving the carbon-neutral goal. In this regard, the present study contributed by proposing a carbon negative process for producing high purity hydrogen from the organic fraction of municipal solid waste (OFMSW). This integrated process comprises anaerobic digestion, pyrolysis, catalytic reforming, water-gas shift, and pressure swing adsorption technologies. By focusing on Sweden, the proposed process was developed and evaluated through sensitivity analysis, mass and energy balance calculations, techno-economic assessment, and practical feasibility analysis. By employing the optimum operating conditions from the sensitivity analysis, 72.2 kg H2 and 701.47 kg negative CO2 equivalent emissions were obtained by treating 1 ton of dry OFMSW. To achieve these results, 6621.4 MJ electricity and 325 kg of steam were utilized during this process. Based on this techno-economic assessment of implementing the proposed process in Stockholm, when the negative CO2 equivalent emissions are recognized as income, the internal rate of return and the discounted payback period can be obtained as 26% and 4.3 years, respectively. Otherwise, these values will be 13% and 7.2 years.
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| 11. |
- Yang, Hanmin, 1992-, et al.
(författare)
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Carbon-negative valorization of biomass waste into affordable green hydrogen and battery anodes
- 2023
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Ingår i: International journal of hydrogen energy. - : Elsevier BV. - 0360-3199 .- 1879-3487.
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The global Sustainable Development Goals highlight the necessity for affordable and clean energy, designated as SDG7. A sustainable and feasible biorefinery concept is proposed for the carbon-negative utilization of biomass waste for affordable H2 and battery anode material production. Specifically, an innovative tandem biocarbon + NiAlO + biocarbon catalyst strategy is constructed to realize a complete reforming of biomass pyro-vapors into H2+CO (as a mixture). The solid residues from pyrolysis are upgraded into high-quality hard carbon (HCs), demonstrating potential as sodium ion battery (SIBs) anodes. The product, HC-1600-6h, exhibited great electrochemical performance when employed as (SIBs) anodes (full cell: 263 Wh/kg with ICE of 89%). Ultimately, a comprehensive process is designed, simulated, and evaluated. The process yields 75 kg H2, 169 kg HCs, and 891 kg captured CO2 per ton of biomass achieving approx. 100% carbon and hydrogen utilization efficiencies. A life cycle assessment estimates a biomass valorization process with negative-emissions (−0.81 kg CO2/kg-biomass, reliant on Sweden wind electricity). A techno-economic assessment forecasts a notably profitable process capable of co-producing affordable H2 and hard carbon battery anodes. The payback period of the process is projected to fall within two years, assuming reference prices of 13.7 €/kg for HCs and 5 €/kg for H2. The process contributes to a novel business paradigm for sustainable and commercially viable biorefinery process, achieving carbon-negative valorization of biomass waste into affordable energy and materials.
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| 12. |
- Yang, Hanmin, 1992-, et al.
(författare)
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Distributed electrified heating for efficient hydrogen production
- 2024
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Ingår i: Nature Communications. - : Nature Research. - 2041-1723. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- This study introduces a distributed electrified heating approach that is able to innovate chemical engineering involving endothermic reactions. It enables rapid and uniform heating of gaseous reactants, facilitating efficient conversion and high product selectivity at specific equilibrium. Demonstrated in catalyst-free CH4 pyrolysis, this approach achieves stable production of H2 (530 g h−1 L reactor−1) and carbon nanotube/fibers through 100% conversion of high-throughput CH4 at 1150 °C, surpassing the results obtained from many complex metal catalysts and high-temperature technologies. Additionally, in catalytic CH4 dry reforming, the distributed electrified heating using metallic monolith with unmodified Ni/MgO catalyst washcoat showcased excellent CH4 and CO2 conversion rates, and syngas production capacity. This innovative heating approach eliminates the need for elongated reactor tubes and external furnaces, promising an energy-concentrated and ultra-compact reactor design significantly smaller than traditional industrial systems, marking a significant advance towards more sustainable and efficient chemical engineering society.
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| 13. |
- Yang, Hanmin, 1992-, et al.
(författare)
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Distributed electrified heating for efficient hydrogen production
- 2024
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Ingår i: Nature Communications. - : Nature Research. - 2041-1723. ; 15
-
Tidskriftsartikel (refereegranskat)abstract
- This study introduces a distributed electrified heating approach that is able to innovate chemical engineering involving endothermic reactions. It enables rapid and uniform heating of gaseous reactants, facilitating efficient conversion and high product selectivity at specific equilibrium. Demonstrated in catalyst-free CH4 pyrolysis, this approach achieves stable production of H2 (530 g h−1 L reactor−1) and carbon nanotube/fibers through 100% conversion of high-throughput CH4 at 1150 °C, surpassing the results obtained from many complex metal catalysts and high-temperature technologies. Additionally, in catalytic CH4 dry reforming, the distributed electrified heating using metallic monolith with unmodified Ni/MgO catalyst washcoat showcased excellent CH4 and CO2 conversion rates, and syngas production capacity. This innovative heating approach eliminates the need for elongated reactor tubes and external furnaces, promising an energy-concentrated and ultra-compact reactor design significantly smaller than traditional industrial systems, marking a significant advance towards more sustainable and efficient chemical engineering society.
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| 14. |
- Yang, Hanmin, et al.
(författare)
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Evaluation of Engineered Biochar-Based Catalysts for Syngas Production in a Biomass Pyrolysis and Catalytic Reforming Process
- 2023
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Ingår i: Energy & Fuels. - : American Chemical Society. - 0887-0624 .- 1520-5029. ; 37, s. 5942-
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Tidskriftsartikel (refereegranskat)abstract
- Biochar, originating from biomass pyrolysis, has been proven a promising catalyst for tar cracking/reforming with great coke resistance. This work aims to evaluate various engineered biochar-based catalysts on syngas production in a biomass pyrolysis and catalytic reforming process without feeding extra steam. The tested engineered biochar catalysts include physical- and chemical-activated, nitrogen-doped, and nickel-doped biochars. The results illustrated that the syngas yields were comparable when using biochar and activated biochar as catalysts. A relatively high specific surface area (SSA) and a hierarchical porous structure are beneficial for syngas and hydrogen production. A 2 h physical-activated biochar catalyst induced the syngas with the highest H2/CO ratio (1.5). The use of N-doped biochar decreased the syngas yield sharply due to the collapse of the pore structure but obtained syngas with the highest LHVgas (18.5MJ/Nm3). The use of Ni-doped biochar facilitated high syngas and hydrogen yields (78.2 wt % and 26 mmol H2/g-biomass) and improved gas energy conversion efficiency (73%). Its stability and durability test showed a slight decrease in performance after a three-time repetitive use. A future experiment with a longer time is suggested to determine when the catalyst will finally deactivate and how to reduce the catalyst deterioration. © 2023 The Authors.
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| 15. |
- Yang, Hanmin, et al.
(författare)
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High-purity syngas production by cascaded catalytic reforming of biomass pyrolysis vapors
- 2022
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Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 322
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Tidskriftsartikel (refereegranskat)abstract
- A novel pyrolysis followed by in-line cascaded catalytic reforming process without additional steam was developed to produce high-purity syngas from woody biomass. The key to the proposed process is the construction of a cascaded biochar + NiAl2O4 catalytic reforming process in which biochar acts as a pre-reforming catalyst, and NiAl2O4 acts as a primary reforming catalyst. The large oxygenates in the pyro-vapors are deeply cracked in the biochar layer due to the increased residence time in the hot-biochar bed. The remaining small molecules are then reformed with the autogenerated steam from pyrolysis catalyzed by the reduced Ni0 species in the NiAl2O4 catalyst (NiAlO). The results showed that the yield of syngas for the optimized process was 71.28 wt% (including 44.44 mg-H2/g-biomass and 536.48 mg-CO/g-biomass), and the CO2 yield of the process was only 3 kg-CO2/kg-hydrogen. High-purity syngas with 89.47 vol% of (H2 + CO) was obtained, and the gas energy conversion efficiency (GECE) of the process reached 75.65%. The study shows that in the cascaded catalytic reforming process, cracking of the large oxygenates and reforming of the small molecules are promoted sequentially in separated biochar + NiAlO catalyst layers, which maximizes the syngas production and improves the activity and stability of the Ni-based catalyst. © 2022 The Author(s)
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| 16. |
- Yang, Hanmin, et al.
(författare)
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In situ catalytic fast pyrolysis of lignin over biochar and activated carbon derived from the identical process
- 2022
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Ingår i: Fuel processing technology. - : Elsevier B.V.. - 0378-3820 .- 1873-7188. ; 227
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a sustainable in situ catalytic fast pyrolysis (CFP) of lignin was developed by using biochar and activated carbon (AC) as catalysts, which is derived from the same CFP of lignin process. The results showed that using biochar as the catalyst mainly promoted the production of non-condensable gas, water, and guaiacol-rich oil regardless of the biochar-to-lignin ratio. The catalytic effect of the biochar was mainly attributed to the surface sodium and alkali metals. Using AC44.7% and AC48.6% as the catalyst resulted in a high yield of guaiacol-rich oil, whereas using AC64.3% induced a great decrease of the tarry oil yield and a significant increase of the phenol concentration in bio-oil. The diffusion efficiency of the reactive intermediates inside the catalysts determined by the pore size was believed to be the greatest determinant of the catalytic performance of the ACs. The mesopores were large enough to allow most of the reactive intermediates to diffuse quickly and react. Moreover, by using the same catalyst, char agglomeration was almost completely suppressed after in situ CFP. Two major problems, tar production and char agglomeration, which limit the large-scale application of fast lignin pyrolysis are believed to be solved. © 2021 The Authors
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| 17. |
- Yang, Hanmin, et al.
(författare)
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Influence of the porosity and acidic properties of aluminosilicate catalysts on coke formation during the catalytic pyrolysis of lignin
- 2022
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Ingår i: Journal of Analytical and Applied Pyrolysis. - : Elsevier B.V.. - 0165-2370 .- 1873-250X. ; 165
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Tidskriftsartikel (refereegranskat)abstract
- Five aluminosilicate catalysts with different textural and acidic properties are used to study the influence of their acidic and porous properties on the coke formation during the fast catalytic pyrolysis of lignin. The competition between coke formation and target product (hydrocarbons) formation in regard to different pore sizes and Si/Al ratios is classified via performing X-Ray Diffraction (XRD), nitrogen adsorption-desorption, pyrolysis–gas chromatography–mass spectrometry (Py-GCMS), kinetic calculations, and thermogravimetric (TG)/temperature programmed oxidation (TPO) measurements. The results indicated that a pore size consistent with the critical diameters of the pyrolysis products of lignin is a prerequisite for a catalyst to reach a high selectivity for the desired products with less coke formation. A relatively large pore size can cause severe coke formation; however, large pores are favorable for increasing the reaction rate by increasing the diffusion efficiency. A catalyst with sufficient acidity is also essential for high selectivity towards target products. © 2022 The Authors
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| 18. |
- Yang, Hanmin, 1992-
(författare)
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Sustainable valorization of Biomass into Syngas/H2 via Biocarbon catalyst
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Environmental issues stemming from the rapid growth in global energy demand and carbon dioxide emissions require urgent resolutions. Biomass represents a viable alternative for displacing fossil fuels, as its energy can be converted into electricity, heat, fuels, and chemical precursors, thus substituting petrochemicals. It is also the only carbon-containing renewable resource with substantial potential to mitigate environmental degradation, attain carbon-negative emissions, and drive sustainable development. Syngas production from biomass pyrolysis and in-line catalytic upgrading has attracted an increased attention, since it is a promising approach for further generating renewable bio-fuels, bio-chemicals, and bio-materials. Hydrogen isolated from bio-syngas is a clean and promising secondary energy source and carrier, capable of advancing a carbon-free energy system across technological, economic, and societal dimensions. This dissertation aims to realize a full valorization of biomass into renewable and affordable hydrogen-rich syngas and carbon-based battery anodes (hard carbons) through pyrolysis and in-line catalytic upgrading using biochar as the core of the catalyst strategy. Biochar, a carbon-enriched solid material with a carbon-neutral nature, emerges as a promising catalyst for promoting volatile upgrading owing to its extensively functionalized surface, porous structure, and resistance to coke deactivation.Optimization of the catalyst strategy using biochar-based catalysts in the catalytic upgrading process to enhance syngas quality is critical for scaling up the proposed process. This dissertation first investigated the effect of Ni-based, biochar, cascaded biochar+Ni-based, and engineered biochar catalysts on the catalytic performance in terms of the syngas yield, hydrogen yield, and gas energy conversion efficiency (GECE). Among them, the cascaded biochar+Ni-based catalyst and the Ni-doped biochar (NiBC) catalyst showed the most excellent catalytic performance. Using NiBC as a reforming catalyst introduced 78.2 wt. % of syngas consisting of an H2+CO proportion of 94.6 vol. % while applying cascaded biochar + NiAlO catalyst strategy resulted in 71 wt. % of syngas with a total H2+CO proportion of 89.5 vol. %. However, after a three-time test repetition, the Ni-doped biochar catalyst showed a slightly decreasing catalytic performance. In contrast, the cascaded biochar+NiAlO catalyst showed a stable promoting performance in terms of syngas and H2 yields after 15 feeding cycles. In addition, plastic waste, being a carbonaceous resource, was also applied in the pyrolysis and in-line catalytic upgrading process for hydrogen and high-value-added carbon production by using biochar as a cracking catalyst. In order to evaluate the techno-economic viability of the proposed process, a novel biorefinery concept was simulated and assessed based on the above results, aiming to produce affordable hydrogen and high-quality hard carbons from biomass and to realize negative carbon emissions. The proposed biorefinery was estimated to produce 75 kg of H2, 169 kg of hard carbon, and 891 kg of captured CO2 (95% purity) per metric ton of biomass while realizing a payback period (PBP) within two years at reference prices of 13.7 €/kg and 5 €/kg for HCs and H2. At the same time, a negative emission of the proposed biorefinery could be achieved with -0.89 kg CO2-eq/kg-biomass based on Sweden’s wind electricity, considering the captured CO2.A pilot-scale system using a continuous pyrolysis reactor was deployed to scale up the capacity of the proposed process. The catalytic performance of biochar was examined in terms of products’ distribution, gas composition and gas properties. Critical parameters, such as the weight hourly space velocity (WHSV), particle size and the morphology of the catalysts, and pressure drop of the catalyst bed, were evaluated. The results showed that a lower WHSV favours a higher syngas yield, a higher H2+CO proportion, and a higher hydrogen yield due to a longer residence time for volatiles-char contacts. Smaller catalyst particle sizes correspond to higher bed pressure drop, which resulted in a higher syngas and hydrogen yield. In addition, biochar particles with larger bulk density and more spherical and rounded shape introduced higher syngas yield, H2 +CO proportion, and H2 yield compared to the particles with elongated and angular shape. The stability of using biochar as a catalyst in a continuous feeding system was also examined and verified in this dissertation, which indicated its great anti-coking performance.
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| 19. |
- Yang, Hanmin, 1992-, et al.
(författare)
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Syngas production from biomass pyrolysis followed by in-line biochar-catalytic reforming : the effect of space velocity, particle size, and morphology
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- A syngas production based on a biomass pyrolysis followed by an in-line catalytic reforming process is a promising method to help curb greenhouse gas emissions. The use of biochar as the reforming catalyst is economically and technologically attractive. A continuous pyrolysis combined with an in-line biochar-catalytic reforming of the pyrolysis vapor was investigated in a comprehensive system consisting of an auger reactor and a downstream fixed-bed rector. The effect of the weight hourly space velocity (WHSV), particle size and morphology of biochar, and the pressure drop of the biochar bed on the catalytic performance were discussed. The results indicated that a higher syngas yield with a higher H2+CO proportion was obtained when using a lower WHSV, due to a longer residence time. The highest syngas and H2 yields were obtained when using biochar with the smallest particles sizes (0.6-1 mm), i.e. the highest bed pressure drops. The use of biochar particles, which are more spherical and rounded, resulted in higher syngas yields, H2 +CO proportions, and H2 yields due to the enhanced heat and mass transfer favored by the rounded shape. Up to 12 mmol H2/g-biomass was obtained, corresponding to a dry gas yield of 0.68 Nm3/kg , containing 39 vol. % H2 and 27 vol. % CO. The use of biochar as a reforming catalyst showed a relatively stable catalytic performance after during a 100-minutes of running the experimentexperimental run-time.
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| 20. |
- Alevanau, Aliaksandr, 1965-, et al.
(författare)
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Applicability of Scaling Approach for Analysis of Pyrolysis and Gasification of Porous Structures Composed of Solid Fuel Particles
- 2012
-
Ingår i: ISRN Mechanical Engineering. - : Hindawi Publishing Corporation. - 2090-5122 .- 2090-5130.
-
Tidskriftsartikel (refereegranskat)abstract
- Experimental research on the pyrolysis and gasification of randomly packed straw pellets was conducted with an emphasis on the reactive properties of the shrinking porous structure of the pellets. The apparent kinetics of such pyrolysis was approximated by the random pore, grain, and volumetric models. The best approximation results were obtained with the grain and random pore models. The self-organized oscillations of the pellet conversion rate during pyrolysis were observed. Two complementary explanations of the phenomenon are proposed.
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| 21. |
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| 22. |
- Alevanau, Aliaksandr, et al.
(författare)
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Parameters of high temperature steam gasification of original and pulverised wood pellets
- 2011
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Ingår i: Fuel processing technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 92:10, s. 2068-2074
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Tidskriftsartikel (refereegranskat)abstract
- Experiments on gasification of chars obtained from original and pulverised wood pellets were conducted in atmosphere of water steam and nitrogen under temperatures of 800, 900 and 950 degrees C. Molar flow rates of carbon containing product gases were measured and approximated using different models with respect to extents of carbon conversion in char of the pellets. Comparison of the random pore, grain and volumetric models revealed the best applicability for approximations of the random pore model. Apparent activation energies obtained as a result of application of the models to the data from experiments with char of original pellets were higher in comparison to those of pulverised pellets, except for a grain model. Approximations under 800 degrees C showed relatively big deviations from experimental data on the beginning of char gasification. This is attributed to catalytic effects from alkali metals in the pellets.
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| 23. |
- Alevanau, Aliaksandr, et al.
(författare)
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Prospective side effects of the heat and mass transfers in micro-porous structure of char during intermediate and final stages of the high-temperature pyrolysis
- 2013
-
Ingår i: Nonlinear Phenomena in Complex Systems. - 1561-4085 .- 1817-2458. ; 16:3, s. 287-301
-
Tidskriftsartikel (refereegranskat)abstract
- The general problem of a decrease of activation energy for reactions of thermal decomposition in ligno-cellulosic materials in the end of the high-temperature pyrolysis has been discussed. Experiments emphasizing the differences between the starting, intermediate and final stages of the process were conducted. A hypothesis to solve the problem from the point of view of a fundamental fractal theory was formulated. The conclusions of the discussions related to the hypothesis gave a description of new experiments to prove the fundamental theory on diffusion processes with naturally or artificially created conditions for self-organization.
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| 24. |
- Alevanau, Aliaksandr, 1965-
(författare)
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Study of pyrolysis and gasification of biomass from the self-organization perspective
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis focuses on the analysis of kinetics of i) low-temperature pyrolysis of gaseous hydrocarbons, ii) high-temperature steam gasification of char of wood pellets (>700oC), iii) high temperature pyrolysis of straw pellets in an atmosphere of argon and steam, and iv) high temperature pyrolysis of slices of transversally cut wooden sticks. The results of the kinetic measurements in the high-temperature cases are approximated using a least-square based optimization software, which was specially developed to analyse kinetics prone for deviation from the Arrhenius law.In the thesis a general analysis of the researched materials and kinetics of their pyrolysis and gasification is presented from the self-organization perspective. The energy transfer phenomena in both the pyrolysis and gasification processes of biomass are discussed with an emphasis on an analysis of basic phenomena involving the self-organized dynamics on fractal structures in the chosen biomass samples.
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| 25. |
- Alevanau, Aliaksandr, 1965-
(författare)
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Study of the Apparent Kinetics of Biomass Gasification Using High-Temperature Steam
- 2010
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Among the latest achievements in gasification technology, one may list the development of a method to preheat gasification agents using switched ceramic honey combs. The best output from this technology is achieved with use of water steam as a gasification agent, which is heated up to 1600 °C. The application of these temperatures with steam as a gasification agent provides a cleaner syngas (no nitrogen from air, cracked tars) and the ash melts into easily utilised glass-like sludge. High hydrogen content in output gas is also favourable for end-user applications.Among the other advantages of this technology is the presumable application of fixed-bed-type reactors fed by separately produced and preheated steam. This construction assumes relatively high steam flow rates to deliver the heat needed for endothermic reactions involving biomass. The biomass is to be heated uniformly and evenly in the volume of the whole reactor, providing easier and simpler control and operation in comparison to other types of reactors. To provide potential constructors and exploiters of these reactors with the kinetic data needed for the calculations of vital parameters for both reactor construction and exploitation, basic experimental research of high-temperature steam gasification of four types of industrially produced biomass has been conducted.Kinetic data have been obtained for straw and wood pellets, wood-chip charcoal and compressed charcoal of mixed origin. Experiments were conducted using two experimental facilities at the Energy and Furnace Division of the Department of Material Science and Engineering (MSE) at the School of Industrial Engineering and Management (ITM) of the Royal Institute of Technology (KTH) and at the Combustion Laboratory of the Mechanical Engineering Department of the University of Maryland (UMD), USA.The experimental facility at the Energy and Furnace Division has been improved with the addition of several constructive elements, providing better possibilities for thermo-gravimetric measurements.The obtained thermo-gravimetric data were analysed and approximated using several models described in the literature. In addition, appropriate software based on the Scilab package was developed. The implementation of the isothermal method based on optimisation algorithms has been developed and tested on the data obtained under the conditions of a slow decrease of temperature in experiments with the char gasification in small-scale experimental facilities in the Energy and Furnace Division.The composition of the gases generated during the gasification of straw and wood pellets by high-temperature steam has been recorded and analysed for different experimental conditions.
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| 26. |
- Alevanau, Aliaksandr, et al.
(författare)
-
Study of the effects of gaseous micro-expansion on the efficiency of convective heat transfer during pyrolysis
- 2013
-
Ingår i: Fuel processing technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 106, s. 253-261
-
Tidskriftsartikel (refereegranskat)abstract
- Measurements of temperature in the proximity of wood pellets (8 mm diameter) and thin wooden stick slices (5 cm diameter and 5 mm thickness) were conducted to estimate the effects of mixing between the evolving volatiles and hot steam (T > 700°C) flowing around the particles. Measurements of mass loss of the slices were conducted to estimate the apparent kinetic parameters of their pyrolysis. A simple kinetic model of the process (type II by Pyle and Zaror (1984) [20]) was investigated. The experiments showed a plateau-like part in the graphs of temperature measured in the proximity to the samples. The existence of this plateau-like part agrees with the general data of calorimetric measurements of pyrolysis, which show extensive energy consumption in the beginning of an active production of volatiles. A hypothesis regarding feedback on the process due to the micro-expansion and mixing of volatiles in the convective boundary layer is discussed.
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| 27. |
- Aragon-Briceno, Christian, et al.
(författare)
-
Integration of hydrothermal carbonization treatment for water and energy recovery from organic fraction of municipal solid waste digestate
- 2022
-
Ingår i: Renewable energy. - : Elsevier BV. - 0960-1481 .- 1879-0682. ; 184, s. 577-591
-
Tidskriftsartikel (refereegranskat)abstract
- Anaerobic digestion is an efficient way of using a wet fraction of municipal solid waste (MSW) for energy purposes as it can produce biogas. The moisture content of the digestate after application of mechanical dewatering is still high, and the amount of heat needed for drying is significant. Hydrothermal carbonization (HTC) is a process that can potentially offer great benefits by improved mechanical dewatering and valorization of the digestate into a better quality solid fuel. This study focuses on the determination of the optimum HTC process conditions to recover water from the MSW digestate. Different process conditions as temperature (180, 200, and 230 °C) and residence time (30, 60, and 120 min) were tested. Furthermore, a mass and energy balance was carried out and a process model in Aspen Plus was built. Results showed that HTC treatment increased the water recovery (40–48%) during the dewatering process compared with the original feedstock (18%). The process model showed a positive energy balance of 110 kWh per ton of MSW digestate treated with an electrical efficiency of 23.9%.
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| 28. |
- Biswas, Amit, et al.
(författare)
-
Change of pyrolysis characteristics and structure of woody biomass due to steam explosion pretreatment
- 2011
-
Ingår i: Fuel processing technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 92:10, s. 1849-1854
-
Tidskriftsartikel (refereegranskat)abstract
- Steam explosion (SE) pretreatment has been implemented for the production of wood pellet. This paper investigated changes in biomass structure due to implication of steam explosion process by its pyrolysis behavior/ characteristics. Salix wood chip was treated by SE at different pretreatment conditions, and then pyrolysis characteristic was examined by thermogravimetric analyzer (TGA) at heating rate of 10 K/min. Both pyrolysis characteristics and structure of biomass were altered due to SE pretreatment. Hemicellulose decomposition region shifted to low temperature range due to the depolymerization caused by SE pretreatment. The peak intensities of cellulose decreased at mild pretreatment condition while they increased at severe conditions. Lignin reactivity also increased due to SE pretreatment. However, severe pretreatment condition resulted in reduction of lignin reactivity due to condensation and re-polymerization reaction. In summary, higher pretreatment temperature provided more active biomass compared with milder pretreatment conditions. © 2011 Elsevier B.V. All rights reserved.
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| 29. |
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| 30. |
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| 31. |
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| 32. |
- Biswas, Amit Kumar, et al.
(författare)
-
Steam pretreatment of Salix to upgrade biomass fuel for wood pellet production
- 2011
-
Ingår i: Fuel processing technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 92:9, s. 1711-1717
-
Tidskriftsartikel (refereegranskat)abstract
- Steam explosion (SE) pretreatment is served to separate the main components of woody biomass. In general there is a noticeable gap in literature in terms of application of steam explosion process to upgrade biomass fuel for wood pellet production. In order to study the influence of steam explosion pretreatment on biomass fuel, Salix wood chips was used as raw material. Four different SE experiments were performed by varying two key process factors; time and temperature. Elementary quality and ash properties of the pretreated residue were investigated. Moreover, physical and thermochemical properties of the pellet, produced from the residue, were also investigated. Reduction in ash content especially in alkali metals was observed in steam treated residue. Pretreatment of biomass also enhanced carbon content and reduced oxygen amount in the fuel which enhanced the heating value of the fuel. Moreover, pretreatment enhanced pellet density, impact resistance, and abrasive resistance of pellet. However, small degradation in ash fusion characteristics and char reactivity was also observed as the severity of the process increased.
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| 33. |
- Biswas, Amit Kumar, 1984-
(författare)
-
Thermochemical behavior of pretreated biomass
- 2011
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Mankind has to provide a sustainable alternative to its energy related problems. Bioenergy is considered as one of the potential renewable energy resources and as a result bioenergy market is also expected to grow dramatically in future. However, logistic issues are of serious concern while considering biomass as an alternative to fossil fuel. It can be improved by introducing pretreated wood pellet. The main objective of this thesis is to address thermochemical behaviour of steam exploded pretreated biomass. Additionally, process aspects of torrefaction were also considered in this thesis. Steam explosion (SE) was performed in a laboratory scale reactor using Salix wood chips. Afterwards, fuel and thermochemical aspects of SE residue were investigated. It was found that Steam explosion pretreatment improved both fuel and pellet quality. Pyrolysis of SE residue reveals that alerted biomass composition significantly affects its pyrolysis behaviour. Contribution from depolymerized components (hemicellulose, cellulose and lignin) of biomass was observed explicitly during pyrolysis. When devolatilization experiment was performed on pellet produced from SE residue, effect of those altered components was observed. In summary, pretreated biomass fuel characteristics is significantly different in comparison with untreated biomass. On the other hand, Process efficiency of torrefaction was found to be governed by the choice of appropriate operating conditions and the type of biomass.
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| 34. |
- Blasiak, W., et al.
(författare)
-
Combustion performance improvement of grate fired furnaces using Ecotube system
- 2006
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Ingår i: Journal of the Energy Institute. - : Informa UK Limited. - 1743-9671 .- 1746-0220. ; 79:2, s. 67-74
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents the main features, advantages and an evaluation of applications of an 'Ecotube' technology for combustion improvement and emission reduction. The sensitivity of the Ecotube locations in a combustion chamber and the injection angle of jets on the Ecotube have been analysed numerically. A municipal solid waste incinerator and a coal fired boiler are the focus of this work. A definition of the heat release distribution ratio is proposed to identify the heat release inside the upper furnace of boilers or incinerators. Results show that an Ecotube system allows a far more uniform heat release, lower CO and NOx emissions, and a more uniform temperature distribution, thus a longer life of the furnace chamber. Additionally, the combustion reaction zone occupies as high as 45% of the whole combustion chamber using an Ecotube system, similar to 40% higher than a conventional multijet mixing system.
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| 35. |
- Blasiak, Wlodzimierz, et al.
(författare)
-
Evaluation of new combustion technologies for CO2 and NOX reduction in steel industries
- 2004
-
Ingår i: AIR POLLUTION XII. - 1853127221 ; , s. 761-771
-
Konferensbidrag (refereegranskat)abstract
- The paper presents state-of-the-art combustion technologies for heating applications in the steel industry. Two types of burners that exhibit dilution combustion were evaluated in this study carried out in a semi-industrial furnace. These were regenerative air-fuel burner and oxy-fuel burner. The tests with regenerative air-fuel were carried out applying operation both with and without oxygen-enrichment. The main parameters studied for the different types of burners and operations include heat flux, thermal efficiency, and NOX at different levels of in-leakage of air. The in-flame parameters were measured including temperature, gas composition, total and radiative heat fluxes. All the studied burners provide a high efficiency of fuel utilization, a large 'flame' with uniform temperature and heat flux profiles. The results also clearly indicate that NOX emissions can be maintained at low or even very low levels well (less than 100 mg/MJ of fuel) meeting the restrictions at industrial-scale operation.
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| 36. |
- Blasiak, W., et al.
(författare)
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Flameless oxyfuel combustion for fuel consumption and nitrogen oxides emissions reductions and productivity increase
- 2007
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Ingår i: Journal of the Energy Institute. - : Informa UK Limited. - 1743-9671 .- 1746-0220. ; 80:1, s. 3-11
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Tidskriftsartikel (refereegranskat)abstract
- In order to achieve very low emission of nitrogen oxides, a 'flameless' combustion process that uses oxygen, the so called 'flameless oxyfuel' combustion, has been developed. This new combustion technology is characterised by a lower temperature flame, more uniform temperature distribution and low concentrations of oxygen as well as nitrogen inside the combustion chamber. This work presents a description and the main features of the flameless oxyfuel combustion, the effect of flame structure and temperature on the heat transfer, the comparison of flameless oxyfuel and flameless air fuel combustion results of laboratory tests of new type of flameless oxyfuel burner, as well as examples of industrial applications. This newly developed and applied combustion technology guarantees fuel consumption reduction ( thus CO2 reduction), increase in productivity as well as drastic reduction of nitrogen oxides emission when applied, for example, to thermal treatment processes of wastes, and to the recovery of zinc bearing feed in a rotary kiln.
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| 37. |
- Blasiak, Włodzimierz, et al.
(författare)
-
Oxyfuel flameless combustion for fuel consumption and nitrogen oxides emissions reductions and productivity increase
- 2006
-
Ingår i: A and WM, Annual International Conference on Incineration and Thermal Treatment Technologies. - 0923204849 - 9780923204846 ; , s. 668-685
-
Konferensbidrag (refereegranskat)abstract
- During last years development of combustion technology focussed the following main aims: fuel consumption reduction, nitrogen oxides emission reduction, increase of productivity and product quality. Fuel savings up to 50%, thus also CO 2 emission reduction, was achieved by replacing combustion air with oxygen. To achieve very low emission of nitrogen oxides (NOx) the new combustion technology is characterised by: lower temperature of flame, more uniform temperature distribution and low concentration of oxygen as well as nitrogen inside combustion chamber. Because in such combustion a flame is replaced by a large chemical reaction zone and thus often is not visible the process was named as flameless combustion. Flameless combustion process with use of oxygen, so called oxyfuel combustion, as well as its technical application is subject of this work. This work presents description and main features of the flameless oxyfuel combustion, results of laboratory tests of new type of flameless oxyfuel burner, as well as examples of industrial applications. This newly developed and applied combustion technology guarantees fuel consumption reduction (thus CO 2 reduction), increase of productivity as well as drastic reduction of nitrogen oxides emission when applied for example to thermal treatment processes of wastes, and a recovery of zinc-bearing feed in a rotary kiln.
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| 38. |
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| 39. |
- Bolívar Caballero, José Juan, et al.
(författare)
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Reforming processes for syngas production : A mini-review on the current status, challenges, and prospects for biomass conversion to fuels
- 2022
-
Ingår i: Applications in Energy and Combustion Science. - : Elsevier BV. - 2666-352X. ; 10, s. 100064-
-
Tidskriftsartikel (refereegranskat)abstract
- Dedicated bioenergy combined with carbon capture and storage are important elements for the mitigation scenarios to limit the global temperature rise within 1.5 °C. Thus, the productions of carbon-negative fuels and chemicals from biomass is a key for accelerating global decarbonisation. The conversion of biomass into syngas has a crucial role in the biomass-based decarbonisation routes. Syngas is an intermediate product for a variety of chemical syntheses to produce hydrogen, methanol, dimethyl ether, jet fuels, alkenes, etc. The use of biomass-derived syngas has also been seen as promising for the productions of carbon-negative metal products. This paper reviews several possible technologies for the production of syngas from biomass, especially related to the technological options and challenges of reforming processes. The scope of the review includes partial oxidation (POX), autothermal reforming (ATR), catalytic partial oxidation (CPO), catalytic steam reforming (CSR) and membrane reforming (MR). Special attention is given to the progress of CSR for biomass-derived vapours as it has gained significant interest in recent years. Heat demand and efficiency together with properties of the reformer catalyst were reviewed more deeply, in order to understand and propose solutions to the problems that arise by the reforming of biomass-derived vapours and that need to be addressed in order to implement the technology on a big scale.
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| 40. |
- Boström, Mathias, et al.
(författare)
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Lithium atom storage in nanoporous cellulose via surface-induced Li-2 breakage
- 2013
-
Ingår i: Europhysics letters. - : IOP Publishing. - 0295-5075 .- 1286-4854. ; 104:6, s. 63003-
-
Tidskriftsartikel (refereegranskat)abstract
- We demonstrate a physical mechanism that enhances a splitting of diatomic Li-2 at cellulose surfaces. The origin of this splitting is a possible surface-induced diatomic-excited-state resonance repulsion. The atomic Li is then free to form either physical or chemical bonds with the cellulose surface and even diffuse into the cellulose layer structure. This allows for an enhanced storage capacity of atomic Li in nanoporous cellulose.
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| 41. |
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| 42. |
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| 43. |
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| 44. |
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| 45. |
- Cuvila, Carlos Alberto, et al.
(författare)
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The Impact of a Mild Sub-Critical Hydrothermal Carbonization of Pretreatment on Umbila Wood : A Mass and Energy Balance Perspective
- 2015
-
Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 8:3, s. 2165-2175
-
Tidskriftsartikel (refereegranskat)abstract
- Over the last years, the pretreatment of biomass as a source of energy has become one of the most important steps of biomass conversion. In this work the effect of a mild subcritical hydrothermal carbonization of a tropical woody biomass was studied. Results indicate considerable change in carbon content from 52.78% to 65.1%, reduction of oxygen content from 41.14% to 28.72% and ash slagging and fouling potential. Even though decarboxylation, decarbonylation and dehydration reactions take place, dehydration is the one that prevails. The mass and energy balance was affected by the treatment conditions than the severity of the treatment.
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| 46. |
- Cuvilas, Carlos Alberto, et al.
(författare)
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Spruce pretreatment for thermal application : Water, alkaline, and diluted acid hydrolysis
- 2012
-
Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 26:10, s. 6426-6431
-
Tidskriftsartikel (refereegranskat)abstract
- Hydrolysis a process that involves a separation of the main components of lignocellulosic material (LCM) primarily developed for ethanol production was applied in this work to upgrade biomass for thermal application. The purpose of the pretreatment was to remove hemicellulose and alkali metals and consequently increase the energy content of the biomass and improve the fuel properties. Freshly chopped (2-10 mm) spruce (Picea abies) samples were hydrolyzed (liquid/solid ratio of 800 mL/80 g), using water, diluted acid, and sodium hydroxide in a rotating autoclave at 180 2 ̊C for 150 and 350 min. Several analyses, such as proximate and ultimate analyses, ash composition and fusibility characteristics, and thermogravimetric analysis under pure nitrogen, were performed. Despite the reduction of mass and energy yields with increment of the severity factor, a significant increment of the higher heating value and ash quality was achieved, revealing that hydrolysis using water or diluted acid is a promising method to upgrade biomass as fuel. For alkaline treatment, a huge degradation on the quality of the ash was observed.
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| 47. |
- Danon, B., et al.
(författare)
-
EMISSION AND EFFICIENCY COMPARISON OF DIFFERENT FIRING MODES IN A FURNACE WITH FOUR HiTAC BURNERS
- 2011
-
Ingår i: Combustion Science and Technology. - : Informa UK Limited. - 0010-2202 .- 1563-521X. ; 183:7, s. 686-703
-
Tidskriftsartikel (refereegranskat)abstract
- Combustion in a furnace equipped with two HiTAC burner pairs, with a thermal power of 100kW(th) each, has been investigated experimentally and computationally. The objective of this study is (1) to observe differences in the performance of the furnace operating in two different firing modes, parallel and staggered, and (2) to explain these differences using detailed CFD simulations. Besides the permanent measurements of temperature, flow and pressure, in-furnace probe measurements of temperature, oxygen and emissions (NO and CO) have been performed. Experimental results show that the efficiency of the furnace was higher in parallel mode compared to staggered mode, 48% and 41% respectively. The values of CO emitted were equal for both firing modes. However, in parallel mode the NOx production was 39 ppm(v)@3%O-2, whereas in staggered mode 53 ppm(v)@3%O-2 NOx was produced. Considering both efficiency and emissions, parallel firing mode performs better than staggered mode. Next, CFD simulations of the furnace were performed in order to explain the observed differences. The simulations were validated with the in-furnace measurements. It was confirmed that the furnace firing in parallel mode achieved a higher efficiency. The radiative heat transfer was higher due to formation of a larger zone with gases with improved radiative properties. In addition, higher velocities along the cooling tubes, due to lower momentum destruction, led to higher convective heat transfer. Also, the lower production of NOx in parallel mode was reproduced by the simulations. This is due to the fact that in parallel mode the fuel jets are merging slower with the combustion air jet, leading to less intense combustion zones. Thus, lower peak temperatures and radical concentrations are achieved, and the NOx production via the thermal and N2O pathways was lower.
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| 48. |
- de Vries, Paul S., et al.
(författare)
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Comparison of HapMap and 1000 Genomes Reference Panels in a Large-Scale Genome-Wide Association Study
- 2017
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 12:1
-
Tidskriftsartikel (refereegranskat)abstract
- An increasing number of genome-wide association (GWA) studies are now using the higher resolution 1000 Genomes Project reference panel (1000G) for imputation, with the expectation that 1000G imputation will lead to the discovery of additional associated loci when compared to HapMap imputation. In order to assess the improvement of 1000G over HapMap imputation in identifying associated loci, we compared the results of GWA studies of circulating fibrinogen based on the two reference panels. Using both HapMap and 1000G imputation we performed a meta-analysis of 22 studies comprising the same 91,953 individuals. We identified six additional signals using 1000G imputation, while 29 loci were associated using both HapMap and 1000G imputation. One locus identified using HapMap imputation was not significant using 1000G imputation. The genome-wide significance threshold of 5x10(-8) is based on the number of independent statistical tests using HapMap imputation, and 1000G imputation may lead to further independent tests that should be corrected for. When using a stricter Bonferroni correction for the 1000G GWA study (P-value < 2.5x10(-8)), the number of loci significant only using HapMap imputation increased to 4 while the number of loci significant only using 1000G decreased to 5. In conclusion, 1000G imputation enabled the identification of 20% more loci than HapMap imputation, although the advantage of 1000G imputation became less clear when a stricter Bonferroni correction was used. More generally, our results provide insights that are applicable to the implementation of other dense reference panels that are under development.
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| 49. |
- Donaj, Pawel, et al.
(författare)
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Conversion of microwave pyrolysed ASR's char using high temperature agents
- 2011
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Ingår i: Journal of Hazardous Materials. - : Elsevier BV. - 0304-3894 .- 1873-3336. ; 185:1, s. 472-481
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Tidskriftsartikel (refereegranskat)abstract
- Pyrolysis enables to recover metals and organic feedstock from waste conglomerates such as: automotive shredder residue (ASR). ASR as well as its pyrolysis solid products, is a morphologically and chemically varied mixture, containing mineral materials, including hazardous heavy metals. The aim of the work is to generate fundamental knowledge on the conversion of the organic residues of the solid products after ASR's microwave pyrolysis, treated at various temperatures and with two different types of gasifying agent: pure steam or 3% (v/v) of oxygen. The research is conducted using a lab-scale, plug-flow gasifier, with an integrated scale for analysing mass loss changes over time of experiment, serving as macro TG at 950, 850 and 760 degrees C. The reaction rate of char decomposition was investigated, based on carbon conversion during gasification and pyrolysis stage. It was found in both fractions that char conversion rate decreases with the rise of external gas temperature, regardless of the gasifying agent. No significant differences between the reaction rates undergoing with steam and oxygen for char decomposition has been observed. This abnormal char behaviour might have been caused by the inhibiting effects of ash, especially alkali metals on char activity or due to deformation of char structure during microwave heating.
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| 50. |
- Donaj, Pawel, et al.
(författare)
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High temperature agent gasification of microwave pyrolysed chars from Automotive Shredder Residue
- 2010
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Ingår i: International Conference on Thermal Treatment Technologies and Hazardous Waste Combustors 2010. - 9781617386633 ; , s. 459-469
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Konferensbidrag (refereegranskat)abstract
- Presently, there is a growing need for handling Automobile Shredder Residues - ASR or "car fluff". One of the most promising methods of treatment ASR is pyrolysis. Apart of obvious benefits of pyrolysis: energy and metals recovery, there is serious concern about residues generated from that process which need to be recycled. Unfortunately, not much work has been reported providing solutions for handling pyrolysis waste's streams. The raw light fraction of ASR, containing mainly foam, textiles and light plastics was gravimetrically separated from the rest of ASR, and treated via microwave pyrolysis to generate 11% of gaseous, 30% of liquid and 59% of solid products, respectively. The resulting char has been characterized and gasified with either a pure steam or 3%vol. oxygen at temperatures between 950-750 °C, respectively, in a lab scale, fixed-bed reactor. The external temperature of gas and the mass loss of sample were continuously recorded. The activity of chars was investigated basing on carbon (ash free basis) conversion during gasification and pyrolysis stage. It was found the char activity decreases with the rise of external gas temperature and with the time of the process. No significant differences between the reactions undergoing with steam and oxygen. This abnormal char behaviour might have been caused the by the inhibiting effect of ash, especially alkali metals on char activity or due to deformation of char structure during microwave heating.
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