| 1. |
- Di Francesco, Davide, et al.
(författare)
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Debottlenecking a Pulp Mill by Producing Biofuels from Black Liquor in Three Steps
- 2021
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Ingår i: ChemSusChem. - : Wiley. - 1864-5631 .- 1864-564X. ; 14:11, s. 2414-2425
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Tidskriftsartikel (refereegranskat)abstract
- By extracting lignin, pulp production can be increased without heavy investments in a new recovery boiler, the typical bottleneck of a pulp mill. The extraction is performed by using 0.20 and 0.15 weight equivalents of CO2 and H2SO4 respectively. Herein, we describe lignin esterification with fatty acids using benign reagents to generate a lignin ester mixable with gas oils. The esterification is accomplished by activating the fatty acid and lignin with acetic anhydride which can be regenerated from the acetic acid recycled in this reaction. The resulting mass balance ratio is fatty acid/lignin/acetic acid (2 : 1 : 0.1). This lignin ester can be hydroprocessed to generate hydrocarbons in gasoline, aviation, and diesel range. A 300-hour continuous production of fuel was accomplished. By recirculating reagents from both the esterification step and applying a water gas shift reaction on off-gases from the hydroprocessing, a favorable overall mass balance is realized.
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| 2. |
- Arora, Prakhar, 1987, et al.
(författare)
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The role of catalyst poisons during hydrodeoxygenation of renewable oils
- 2021
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Ingår i: Catalysis Today. - : Elsevier BV. - 0920-5861. ; 367, s. 28-42
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Tidskriftsartikel (refereegranskat)abstract
- Hydrodeoxygenation (HDO) activity of NiMo catalysts have been evaluated in the presence of catalyst poisons in bio-based feedstocks. An in-house synthesized NiMo/Al2O3 catalyst was placed in a refinery unit for biofuel production. Iron (Fe), phosphorus (P) and metals were identified as major contaminants. Calcination treatment was explored to recover the activity of spent catalysts. The effect of Fe, K and phospholipid containing P and Na on catalyst deactivation during hydrodeoxygenation of stearic acid was simulated at lab-scale. Fe caused the most deactivation where the highest feed concentration of the Fe compound resulted in 1480 ppm Fe deposited on the catalyst. Elemental distribution along the radial axis of spent catalysts indicated: Fe deposited only to a depth of 100 μm irrespective of concentration while P and Na from phospholipid and K penetrated deeper in catalyst particles with a distribution profile that was found to be concentration dependent.
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| 3. |
- Carlsson, Gunilla, 1962-, et al.
(författare)
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A model system for understanding the distribution of fines in a paper structure using fluorescence microscopy
- 2011
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Konferensbidrag (refereegranskat)abstract
- When making paper a sheet is formed by draining a specific amount of dilute water suspension of pulp and wet end additives through a wire-cloth. The procedure is well known but the underlying mechanisms are not fully understood. The pulp stock is composed by different particles such as fines, fibers, retention aids and other additives that interact with each other during the papermaking process. These interactions are important since they influence the properties of the formed paper. Pulp fibers have different sizes and the finest particle fraction is referred to as fines. In this study fines from bleached Kraft pulp were used.The fines were oxidized to some extent as a consequence of the Kraft pulp process.A model system containing fibers and latex was used together with fluorescence microscopyand image analysis to study the Brownian motion of a probe in different electrolyte concentrations. The model system was built up of:• A water suspension of 1 % fines, negatively charged. At this concentration the fines are interacting with each other, forming a gel like structure.• Negatively charged probes with three different sizes (radii 50, 100 and 500 nm).• Two types of electrolytes (NaCl and CaCl2). The electrolytes were used for altering the electrical double layer of the charged surfaces in the system.By studying the Brownian motion of the probes with different sizes in the network of fines more can be understood about this model system. The knowledge obtained from this model system can be used for further understanding of the paper chemistry mechanisms.ReferencesCarlsson G., Warszynski P., van Stam J., J. Colloid Interface Sci., 2003, 267, 500-508Carlsson G., van Stam J., Nord. Pulp Pap. Res. J., 2005, 20, 192-199Carlsson G., Järnström L., van Stam J., J. Colloid Interface Sci., 2006, 298, 162-171Rådberg W., Bachelor thesis, Karlstad University, 2010
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| 4. |
- Carlsson, Gunilla, et al.
(författare)
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Determination of Distribution of Fines in a Paper Structure using Fluorescence Microscopy and Image Analysis
- 2010
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Konferensbidrag (refereegranskat)abstract
- When making paper a sheet is formed by draining a specific amount of dilute water suspension of pulp through a wire-cloth. The procedure is well known but the underlying mechanisms are not fully understood. The different particles such as fines, fibers, retention aids and other additives interact with each other during the process. These interactions are important since they impact the properties of the formed paper. The fibers have different sizes and the finest particle fraction is called fines. The fines used in this study are from bleached kraft pulp and are therefore oxidized to some extent. By labelling the fines with a fluorophore the movements of individual fines can be followed with video-based fluorescence microscopy even if the size of the fines is below the microscopes resolution limit. [1-3] The fluorophores that has been used are N-Methylisatoic anhydride and fluorescein-5-thiosemicarbazide. N-Methylisatoic anhydride reacts directly with hydroxyl groups on the cellulose chain. Fluorescein-5-thiosemicarbazide reacts with groups like aldehydes and ketones in the cellulose chain, so the chain has to be oxidized before the labeling process. These two fluorephores have different absorption and emission wavelengths. [4]The methods for labeling the fibers are easy to perform. The labeled fiber can be seen in the microscope. One problem is that the fibers aggregate, probably due to the method used for labeling. Another problem can be the fading of the flourophores. Both problems will be further investigated. [5]The elevated drying process in the paper machine makes it difficult to understand the mechanisms involved. Within this project the understanding will be built up in many steps. The first step is to study the labeled fibers in water. A model system containing fibers and latex will be used to study the behavior in different environments such as different electrolyte concentration and pH. References[1] Carlsson G., Warszynski P., van Stam J., J. Colloid Interface Sci., 2003, 267, 500-508[2] Carlsson G., van Stam J., Nord. Pulp Pap. Res. J., 2005, 20, 192-199[3] Carlsson G., Järnström L., van Stam J., J. Colloid Interface Sci., 2006, 298, 162-171[4] DeAngelis P. L., Analytical Biochemistry, 2000, 284, 167-169 [5] Rådberg W., Bsc thesis, Karlstad university, 2010
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| 5. |
- Jafri, Yawer, 1988-, et al.
(författare)
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Combining expansion in pulp capacity with production of sustainable biofuels – Techno-economic and greenhouse gas emissions assessment of drop-in fuels from black liquor part-streams
- 2020
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Ingår i: Applied Energy. - : Elsevier Ltd. - 0306-2619 .- 1872-9118. ; 279
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Tidskriftsartikel (refereegranskat)abstract
- Drop-in biofuels from forest by-products such as black liquor can help deliver deep reductions in transport greenhouse gas emissions by replacing fossil fuels in our vehicle fleet. Black liquor is produced at pulp mills that can increase their pulping capacity by upgrading some of it to drop-in biofuels but this is not well-studied. We evaluate the techno-economic and greenhouse gas performance of five drop-in biofuel pathways based on BL lignin separation with hydrotreatment or black liquor gasification with catalytic synthesis. We also assess how integrated biofuel production impacts different types of pulp mills and a petroleum refinery by using energy and material balances assembled from experimental data supplemented by expert input. Our results indicate that drop-in biofuels from black liquor part-streams can be produced for ~80 EUR2017/MWh, which puts black liquor on the same footing (or better) as comparable forest residue-based alternatives. The best pathways in both production routes have comparable costs and their principal biofuel products (petrol for black liquor gasification and diesel for lignin hydrotreatment) complement each other. All pathways surpass European Union's sustainability criteria for greenhouse gas savings from new plants. Supplementing black liquor with pyrolysis oil or electrolysis hydrogen can improve biofuel production potentials and feedstock diversity, but better economic performance does not accompany these benefits. Fossil hydrogen represents the cheaper option for lignin hydrotreatment by some margin, but greenhouse gas savings from renewable hydrogen are nearly twice as great. Research on lignin upgrading in industrial conditions is recommended for reducing the presently significant performance uncertainties. © 2020 The Authors
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| 6. |
- Janosik, Tomasz, et al.
(författare)
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Derivatizing of Fast Pyrolysis Bio-Oil and Coprocessing in Fixed Bed Hydrotreater
- 2022
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Ingår i: Energy & Fuels. - : American Chemical Society. - 0887-0624 .- 1520-5029. ; 36:15, s. 8274-8287
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Tidskriftsartikel (refereegranskat)abstract
- In several countries forest-based biofuels are being developed and to some extent also deployed. Fast pyrolysis bio-oil produced from, for example, sawdust, has now been coprocessed in fluid catalytic cracking refinery units in a number of commercial trials. However, this application is limited to about 10% of the total feed, and coprocessing in conventional fixed bed hydrotreaters is necessary to reach the high potential with this feedstock. Feeding and upgrading of fast pyrolysis bio-oil in a fixed bed reactor configuration is still problematic due to the inherent bio-oil properties. Stabilization of reactive compounds in fast pyrolysis bio-oil and mild hydrotreatment in a separate refining unit prior to refinery integration has therefore been developed the past decade. Another approach, presented here, involves complete dewatering of fast pyrolysis bio-oil by azeotropic distillation using mesityl oxide as the solvent, followed by conversion of the abundant hydroxyl compounds via mixed anhydride esterification methodology using an external source of mixed carboxylic acids of different chain lengths originating from renewable tall oil fatty acids, providing a lipophilic feed component. Dewatering and derivatizing were carried out in reactors up to 50 dm3 with a mass ratio of fast pyrolysis bio-oil to tall oil fatty acid of 10:13. The produced lipophilic oils were miscible with a petroleum light gas oil fraction and exhibited superior stability even after accelerated aging at elevated temperature (80 °C). The derivatized oils were thus mixed with light gas oil, with a proportion of 30 wt % derivatized oil in final blends and hydrotreated continuously in pilot fixed bed reactors for 14 days at 4 operating conditions without plugging or excessive exotherms. The test conditions were varied; the reactor pressure was either 55 or 80 bar, temperature 380 or 400 °C, and liquid hourly space velocity either 1 or 2 h-1 during the hydrotreatment. Successful hydrodeoxygenation and desulfurization were accomplished, whereas an increasing nitrogen concentration could be observed in the liquid products with the particular catalyst and reaction conditions employed. The observed hydrogen consumption (15-20 g/kg feed) was compared with the stoichiometric consumption for direct deoxygenation and with typical consumptions for industrial hydrotreated vegetable oil processing. The measured biogenic carbon content in hydrotreated liquid products (26.7%) agreed extremely well with the calculated biogenic carbon content in the hydrotreating feed (26.6%) that consisted of the blend of derivatized oil and petroleum light gas oil. The overall results are very promising since simple unit operations can be used to produce derivatized fast pyrolysis bio-oils that do not need additional standalone hydrotreating units but can be coprocessed in existing ones
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