| 1. |
- Bergvall, Niklas, et al.
(författare)
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Corefining of Fast Pyrolysis Bio-Oil with Vacuum Residue and Vacuum Gas Oil in a Continuous Slurry Hydrocracking Process
- 2020
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Ingår i: Energy & Fuels. - : American Chemical Society. - 0887-0624 .- 1520-5029. ; 34:7, s. 8452-8465
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Tidskriftsartikel (refereegranskat)abstract
- Integration of renewable raw materials in existing refineries is most likely the shortest way for the successful, large-scale introduction of biofuels in the transport sector in the short term and medium term. One possible renewable raw material for this application is fast pyrolysis bio-oil (FPBO), which in this study has been coprocessed (at 0 and 20 wt %) with vacuum residue (VR, 50 wt %) and vacuum gas oil (VGO, balance) in a continuous, as well as a semibatch, slurry hydrocracking process. Experiments both with and without FPBO were performed at 450°C and 150 bar with a continuous hydrogen flow through the reactor. Oil-soluble molybdenum hexacarbonyl and molybdenum 2-ethylhexanoate were used as catalyst precursors, to be sulfided in situ. The continuous trials resulted in reactor walls completely free of coking, and they resulted in a low overall coke yield (about 1 wt %). The hydrodeoxygenation reached almost 92%, and the total acid number was reduced by nearly 99% in the FPBO experiment A mass balance of the renewable carbon from FPBO, based on the performed experiments, showed that the fossil CO2 emissions can be lowered by 1.35 kg per kg of processed FPBO if all renewable carbon in gaseous and liquid hydrocarbons is used to replace its fossil counterparts, and all methane formed from FPBO is used to produce hydrogen. Semibatch experiments gave less successful results when upgrading FPBO-containing feedstock, with a high coke yield (8 wt %) as well as a high gas yield (24 wt %). The results of this study demonstrate that FPBO can be successfully coprocessed with heavy fossil oils in a continuous slurry hydrocracking process without neg. affecting the processing of the fossil components of the feed and that a continuous process is preferred over batch or semibatch processes when studying coprocessing of bio-oils.
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| 2. |
- Bergvall, Niklas, et al.
(författare)
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Slurry Hydroconversion of Solid Kraft Lignin to Liquid Products Using Molybdenum- and Iron-Based Catalysts
- 2022
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 1520-5029 .- 0887-0624. ; 36:17, s. 10226-10242
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Tidskriftsartikel (refereegranskat)abstract
- Kraft lignin is an abundantly available and largely underutilized renewable material with potential for production of biobased fuels and chemicals. This study reports the results of a series of slurry hydroprocessing experiments with the aim of converting solid Kraft lignin to liquid products suitable for downstream refining in more conventional reactors. Experiments reported in this study were conducted by feeding a lignin slurry to an already hot, liquid-filled reactor to provide momentaneous heating of the lignin to the reaction temperature. This modified batch procedure provided superior results compared to the regular batch experiments, likely since unwanted repolymerization and condensation reactions of the lignin during the heating phase was avoided, and was therefore used for most of the experiments reported. Experiments were performed using both an unsupported Mo-sulfide catalyst and Fe-based catalysts (bauxite and hematite) at varied reaction temperatures, pressures, and catalyst loadings. The use of Mo-sulfide (0.1% Mo of the entire feed mass) at 425 °C and 50 bar resulted in complete conversion of the Kraft lignin to nonsolid products. Very high conversions (>95%) could also be achieved with both sulfided bauxite or hematite at the same temperature and pressure, but this required much higher catalyst loadings (6.25% bauxite or 4.3% hematite of the total feed mass), and around 99% conversion could be achieved at higher temperatures but at the expense of much higher gas yields. Although requiring much higher loadings, the results in this study suggest that comparatively nonexpensive Fe-based catalysts may be an attractive alternative for a slurry-based process aimed at the hydroconversion of solid lignin to liquid products. Possible implementation strategies for a slurry-based hydroconversion process are proposed and discussed.
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| 3. |
- Bergvall, Niklas, et al.
(författare)
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Upgrading of fast pyrolysis bio-oils to renewable hydrocarbons using slurry- and fixed bed hydroprocessing
- 2024
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Ingår i: Fuel processing technology. - : Elsevier B.V.. - 0378-3820 .- 1873-7188. ; 253
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Tidskriftsartikel (refereegranskat)abstract
- Liquefaction of lignocellulosic biomass through fast pyrolysis, to yield fast pyrolysis bio-oil (FPBO), is a technique that has been extensively researched in the quest for finding alternatives to fossil feedstocks to produce fuels, chemicals, etc. Properties such as high oxygen content, acidity, and poor storage stability greatly limit the direct use of this bio-oil. Furthermore, high coking tendencies make upgrading of the FPBO by hydrodeoxygenation in fixed-bed bed hydrotreaters challenging due to plugging and catalyst deactivation. This study investigates a novel two-step hydroprocessing concept; a continuous slurry-based process using a dispersed NiMo-catalyst, followed by a fixed bed process using a supported NiMo-catalyst. The oil product from the slurry-process, having a reduced oxygen content (15 wt%) compared to the FPBO and a comparatively low coking tendency (TGA residue of 1.4 wt%), was successfully processed in the downstream fixed bed process for 58 h without any noticeable decrease in catalyst activity, or increase in pressure drop. The overall process resulted in a 29 wt% yield of deoxygenated oil product (0.5 wt% oxygen) from FPBO with an overall carbon recovery of 68%.
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| 4. |
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| 5. |
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| 6. |
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| 7. |
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| 8. |
- Carlsson, Per, et al.
(författare)
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Slag Formation During Oxygen Blown Entrained-Flow Gasification of Stem Wood
- 2014
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 28:11, s. 6941-6952
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Tidskriftsartikel (refereegranskat)abstract
- Stem wood powders were fired in a mullite-lined pilot-scale oxygen-blown pressurized entrained-flow gasifier. During repeated campaigns involving increases in fuel load and process temperature, slag formations that eventuated in the blockage of the gasifier outlet were observed. These slags were retrieved for visual and chemical characterization. It was found that the slags had very high contents of Al and, in particular, high Al/Si ratios that suggest likely dissolution of the mullite-based refractory of the gasifier lining due to interactions with the fuel ash. Possible causes for the slag formation and behavior are proposed, and practical implications for the design of future stem wood entrained-flow gasifiers are also discussed
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| 9. |
- Carlsson, Per, et al.
(författare)
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Spatially resolved measurements of gas composition in a pressurised black liquor gasifier
- 2009
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Ingår i: Environmental Progress & Sustainable Energy. - : Wiley. - 1944-7442 .- 1944-7450. ; 28:3, s. 316-323
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Tidskriftsartikel (refereegranskat)abstract
- Black liquor gasification is a new process for recovery of energy and chemicals in black liquor from the Kraft pulping process. The process can be combined with catalytic conversion of syngas into motor fuels. The potential for motor fuel production from black liquor in Sweden is to replace about 25% of the current consumption ofgasoline and diesel. For Finland the figure is even higher while for Canada it is about 14% and for the USA about 2%. © 2009 American Institute of Chemical Engineers Environ Prog, 28: 316-323, 2009.
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| 10. |
- Carvalho, Lara, et al.
(författare)
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Alkali enhanced biomass gasification with in situ S capture and a novel syngas cleaning : Part 2: Techno-economic analysis
- 2018
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Ingår i: Energy. - : Elsevier. - 0360-5442 .- 1873-6785. ; 165:Part B, s. 471-482
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Tidskriftsartikel (refereegranskat)abstract
- Previous research has shown that alkali addition has operational advantages in entrained flow biomass gasification and allows for capture of up to 90% of the biomass sulfur in the slag phase. The resultant low-sulfur content syngas can create new possibilities for syngas cleaning processes. The aim was to assess the techno-economic performance of biofuel production via gasification of alkali impregnated biomass using a novel gas cleaning systemcomprised of (i) entrained flow catalytic gasification with in situ sulfur removal, (ii) further sulfur removal using a zinc bed, (iii) tar removal using a carbon filter, and (iv) CO2 reductionwith zeolite membranes, in comparison to the expensive acid gas removal system (Rectisol technology). The results show that alkali impregnation increases methanol productionallowing for selling prices similar to biofuel production from non-impregnated biomass. It was concluded that the methanol production using the novel cleaning system is comparable to the Rectisol technology in terms of energy efficiency, while showing an economic advantagederived from a methanol selling price reduction of 2–6 €/MWh. The results showed a high level of robustness to changes related to prices and operation. Methanol selling prices could be further reduced by choosing low sulfur content feedstocks.
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| 11. |
- Cheah, You Wayne, 1993, et al.
(författare)
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Role of transition metals on MoS 2 -based supported catalysts for hydrodeoxygenation (HDO) of propylguaiacol
- 2021
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Ingår i: Sustainable Energy and Fuels. - : Royal Society of Chemistry (RSC). - 2398-4902. ; 5:7, s. 2097-2113
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Tidskriftsartikel (refereegranskat)abstract
- Transition metal sulfides (TMSs) are typically used in the traditional petroleum refining industry for hydrodesulfurization (HDS) and hydrodenitrogenation (HDN) applications. Bio-oils require an upgrading process like catalytic hydrodeoxygenation (HDO) to produce advanced biofuels and chemicals. Herein, MoS /γ-Al O promoted by transition metals like nickel (Ni), copper (Cu), zinc (Zn), and iron (Fe) was evaluated for the HDO of a bio-oil model compound, 4-propylguaiacol (PG) in a batch reactor at 340 °C under 50 bar H pressure. The catalyst screening results showed that the sulfided Ni-promoted catalyst gave a high 94% yield of deoxygenated cycloalkanes, however for the sulfided Cu-promoted catalyst, 42% of phenolics remain in the reaction medium after 5 h. The results also revealed that the sulfided Zn and Fe-promoted catalysts gave a final yield of 16% and 19% at full PG conversion, respectively, for deoxygenated aromatics. A kinetic model considering the main side reactions was developed to elucidate the reaction pathway of demethoxylation and dehydroxylation of PG. The developed kinetic model was able to describe the experimental results well with a coefficient of determination of 97% for the Ni-promoted catalyst system. The absence of intermediates like 4-propylcyclohexanone and 4-propylcyclohexanol during the reaction implies that direct deoxygenation (DDO) is the dominant pathway in the deoxygenation of PG employing sulfided catalysts. The current work also demonstrated that the activity of the transition metal promoters sulfides for HDO of PG could be correlated to the yield of deoxygenated products from the hydrotreatment of Kraft lignin. 2 2 3 2
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| 12. |
- Cheah, You Wayne, 1993, et al.
(författare)
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Slurry co-hydroprocessing of Kraft lignin and pyrolysis oil over unsupported NiMoS catalyst: A strategy for char suppression
- 2023
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Ingår i: Chemical Engineering Journal. - 1385-8947. ; 475
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Tidskriftsartikel (refereegranskat)abstract
- Pyrolysis oil (PO) assisted Kraft lignin (KL) liquefaction over an unsupported NiMoS catalyst in a paraffin solvent was explored in this work. A paraffin solvent was used to represent hydrogenated vegetable oil (HVO) which is a biofuel. We have for the first time showed that when co-processing Kraft lignin with pyrolysis oil in a paraffin solvent the char formation could be completely suppressed. The complex composition of PO, containing various compounds with different functional groups, was able to aid the depolymerization pathways of lignin by obstructing the condensation path of reactive lignin derivatives. To further understand the role of different functional groups present in pyrolysis oil during lignin liquefaction, we investigate the co-hydroprocessing of Kraft lignin with various oxygenate monomers using unsupported NiMoS. 4-propylguaiacol (PG) was found to be the most efficient monomer for stabilizing the reactive lignin intermediates, resulting in a low char yield (3.7%), which was 4 times lower than the char production from Kraft lignin hydrotreatment alone. The suppressed rate of lignin fragment repolymerization can be attributed to the synergistic effect of functional groups like hydroxyl (-OH), methoxy (-OCH3), and propyl (-C3H7) groups present in PG. These groups were found to be able to stabilize the lignin depolymerized fragments and blocked the repolymerization routes enabling efficient lignin depolymerization. It was found that the presence of a co-reactant like PG during the heating period of the reactor acted as a blocking agent facilitating further depolymerization routes. Finally, a reaction network is proposed describing multiple routes of lignin hydroconversion to solid char, lignin-derived monomers, dimers, and oligomers, explaining why the co-processing of pyrolysis oil and Kraft lignin completely suppressed the solid char formation.
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| 13. |
- Cheah, You Wayne, 1993, et al.
(författare)
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Thermal annealing effects on hydrothermally synthesized unsupported MoS2 for enhanced deoxygenation of propylguaiacol and kraft lignin
- 2021
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Ingår i: Sustainable Energy and Fuels. - 2398-4902. ; 5:20, s. 5270-5286
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Tidskriftsartikel (refereegranskat)abstract
- Catalytic hydrodeoxygenation (HDO) is an important hydrotreating process that is used to improve the quality of bio-oils to produce biomass-derived fuel components and chemicals. Molybdenum disulfide (MoS2) has been widely used as a catalyst in hydrodesulfurization (HDS) applications for several decades, which can be further improved for effective unsupported catalyst synthesis. Herein, we studied a universally applicable post-annealing treatment to a hydrothermally synthesized MoS2 catalyst towards developing efficient unsupported catalysts for deoxygenation. The effect of the annealing treatment on the catalyst was studied and evaluated for HDO of 4-propylguaiacol (PG) at 300 °C with 50 bar H2 pressure. The annealing of the as-synthesized catalyst under nitrogen flow at 400 °C for 2 h was found to enhance the HDO activity. This enhancement is largely induced by the changes in the microstructure of MoS2 after the annealing in terms of slab length, stacking degree, defect-rich sites and the MoS2 edge-to-corner site ratio. Besides, the effect of hydrothermal synthesis time and acid addition combined with the annealing treatment on the MoS2 catalytic activity was also studied for the same model reaction. The annealed MoS2 with a synthesis time of 12 h under an acidic environment was found to have improved crystallinity and exhibit the highest deoxygenation degree among all the studied catalysts. An acidic environment during the synthesis was found to be crucial in facilitating the growth of MoS2 micelles, resulting in smaller particles that affected the HDO activity. The annealed unsupported MoS2 with the best performance for PG hydrodeoxygenation was further evaluated for the hydrotreatment of kraft lignin and demonstrated a high deoxygenation ability. The results also indicate a catalyst with high activity for deoxygenation and hydrogenation reactions can suppress char formation and favor a high lignin bio-oil yield. This research uncovers the importance of a facile pretreatment on unsupported MoS2 for achieving highly active HDO catalysts.
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| 14. |
- Cheah, You Wayne, 1993, et al.
(författare)
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Upgrading of triglycerides, pyrolysis oil, and lignin over metal sulfide catalysts: A review on the reaction mechanism, kinetics, and catalyst deactivation
- 2023
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Ingår i: Journal of Environmental Chemical Engineering. - : Elsevier BV. - 2213-3437 .- 2213-2929. ; 11:3
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Forskningsöversikt (refereegranskat)abstract
- Human activities such as burning fossil fuels for energy production have contributed to the rising global atmospheric CO2 concentration. The search for alternative renewable and sustainable energy sources to replace fossil fuels is crucial to meet the global energy demand. Bio-feedstocks are abundant, carbon-rich, and renewable bioresources that can be transformed into value-added chemicals, biofuels, and biomaterials. The conversion of solid biomass into liquid fuel and their further hydroprocessing over solid catalysts has gained vast interest in industry and academic research in the last few decades. Metal sulfide catalysts, a common type of catalyst being used in the hydroprocessing of fossil feedstocks, have gained great interest due to their low cost, industrial relevance, and easy implementation into the current refining infrastructures. In this review, we aim to provide a comprehensive overview that covers the hydrotreating of various bio-feedstocks like fatty acids, phenolic compounds, pyrolysis oil, and lignin feed using sulfided catalysts. The main objectives are to highlight the reaction mechanism/networks, types of sulfided catalysts, catalyst deactivation, and reaction kinetics involved in the hydrotreating of various viable renewable feedstocks to biofuels. The computational approaches to understand the application of metal sulfides in deoxygenation are also presented. The challenges and needs for future research related to the valorization of different bio-feedstocks into liquid fuels, employing sulfided catalysts, are also discussed in the current work.
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| 15. |
- Eriksson, D., et al.
(författare)
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Characterization of Scots pine stump-root biomass as feed-stock for gasification
- 2012
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 104, s. 729-736
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Tidskriftsartikel (refereegranskat)abstract
- The main objective was to explore the potential for gasifying Scots pine stump-root biomass (SRB). Washed thin roots, coarse roots, stump heartwood and stump sapwood were characterized (solid wood, milling and powder characteristics) before and during industrial processing. Non-slagging gasification of the SRB fuels and a reference stem wood was successful, and the gasification parameters (synthesis gas and bottom ash characteristics) were similar. However, the heartwood fuel had high levels of extractives (≈19%) compared to the other fuels (2-8%) and thereby ≈16% higher energy contents but caused disturbances during milling, storage, feeding and gasification. SRB fuels could be sorted automatically according to their extractives and moisture contents using near-infrared spectroscopy, and their amounts and quality in forests can be predicted using routinely collected stand data, biomass functions and drill core analyses. Thus, SRB gasification has great potential and the proposed characterizations exploit it. © 2011 Elsevier Ltd.
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| 16. |
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| 17. |
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| 18. |
- Grahn, Mattias, et al.
(författare)
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Small ZSM-5 crystals with low defect density as an effective catalyst for conversion of methanol to hydrocarbons
- 2020
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Ingår i: Catalysis Today. - : Elsevier B.V.. - 0920-5861 .- 1873-4308. ; 345, s. 136-146
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Tidskriftsartikel (refereegranskat)abstract
- This work presents the synthesis of nearly defect-free ZSM-5 nanosized crystals, prepared in fluoride medium by seeding with silicalite-1. This material was carefully characterized and its catalytic performances in the methanol to hydrocarbons (MTH) reaction were assessed. Such fluoride-based material was compared to a reference ZSM-5, produced through a conventional alkaline synthesis but from the same seeding. Despite both the materials show closely identical morphology and they have a comparable acid site population, the catalyst prepared using the fluoride route showed significantly longer lifetime in MTH compared to the catalyst prepared using conventional synthesis at high pH. The slower deactivation for the samples prepared using the fluoride route was ascribed, thanks to a thorough in situ IR spectroscopy study, to its lower density of internal defects. According to the UV-Raman characterization of coke on the spent catalyst, the fluoride-based ZSM-5 catalyst produces less molecular coke species, most probably because of the absence of enlarged cavities/channels as due to the presence of internal defects. On the basis of these observations, the deactivation mechanism in the ZSM-5 synthesized by fluoride medium could be mostly related to the deposition of an external layer of bulk coke, whereas in the alkali-synthesized catalyst an additional effect from molecular coke accumulating within the porous network accelerates the deactivation process.
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| 19. |
- Hedlund, Jonas, et al.
(författare)
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Controlling diffusion resistance, selectivity and deactivation of ZSM-5 catalysts by crystal thickness and defects
- 2022
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Ingår i: Journal of Catalysis. - : Elsevier. - 0021-9517 .- 1090-2694. ; 410, s. 320-332
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Tidskriftsartikel (refereegranskat)abstract
- A systematic investigation of two sets of defect free and defective ZSM-5 crystals with controlled thickness (T) between 30 and 400 nm and of their performances in methanol conversion was reported for the first time in the present work. The defect free ZSM-5 crystals with a thickness of 35 nm are by far the smallest ever reported and displayed superior activity, stability and selectivity to slower diffusing compounds, which resulted in high yield of e.g. gasoline and the 1,2,4-trimethylbenzene isomer with high octane number, as compared to the other studied catalysts. Almost only products forming in the zeolite pores were detected and consequently, the external surface must be nearly inactive. Strong correlations between T and deactivation rate were observed. Thick crystals deactivated much faster than thin crystals, probably due to formation of carbon species in the zeolite pores, which results in pronounced percolation effects and faster deactivation of the former. At comparable thickness, crystals with defects deactivated much faster than defect free crystals, due to formation of additional small molecular coke species in the former. Strong correlations between T and selectivity were also observed and assigned to control of diffusion resistance by crystal thickness.
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| 20. |
- Hedlund, Jonas, et al.
(författare)
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The synthesis and testing of thin film ZSM-5 catalysts
- 2004
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Ingår i: Chemical Engineering Science. - : Elsevier BV. - 0009-2509 .- 1873-4405. ; 59:13, s. 2647-2657
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Tidskriftsartikel (refereegranskat)abstract
- The synthesis and catalytic testing of thin ZSM-5 films on glass and alumina beads is described. The thickness of the ZSM-5 films was controlled to 150, 350, 800 and 2300 nm. The samples were characterised by SEM, gas adsorption and p-xylene isomerisation and 1,3,5-tri-isopropyl benzene cracking test reactions. A reaction–diffusion model adequately described the p-xylene isomerisation data. Estimates of model parameters were obtained by fitting the model to the experimental data. In both cases, the reaction rate constant increased with increasing film thickness. The xylene reaction data showed that secondary reaction products increased as expected with increasing diffusion limitations, but the increase was less than that predicted by the variation of thickness only. The trends in the reaction data could be explained by more defects in the thicker films and/or partial poisoning of the zeolite by mobile support cations in thinner films and/or orientation effects.
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| 21. |
- Häggström, Caroline, et al.
(författare)
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Catalytic methanol synthesis via black liquor gasification
- 2012
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Ingår i: Fuel processing technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 94:1
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Tidskriftsartikel (refereegranskat)abstract
- Biofuel production from gasified black liquor is an interesting route to decrease green house gas emissions. The only pressurised black liquor gasifier currently in pilot operation is located in Sweden. In this work, synthesis gas was taken online directly from this gasifier, purified from hydrocarbons and sulphur compounds and for the first time catalytically converted to methanol in a bench scale equipment. Methanol was successfully synthesised during 45 h in total and the space time yield of methanol produced at 25 bar pressure was 0.16-0.19 g methanol/(g catalyst h). The spent catalyst exposed to gas from the gasifier was slightly enriched in calcium and sodium at the inlet of the reactor and in boron and nickel at the outlet of the reactor. Calcium, sodium and boron likely stem from black liquor whereas nickel probably originates from the stainless steel in the equipment. A slight deactivation, reduced surface area and mesoporosity of the catalyst exposed to gas from the gasifier were observed but it was not possible to reveal the origin of the deactivation. In addition to water, the produced methanol contained traces of hydrocarbons up to C 4, ethanol and dimethyl ether. © 2011 Elsevier B.V. All rights reserved.
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| 22. |
- 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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| 23. |
- Johansson, Ann-Christine, et al.
(författare)
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Characterization of pyrolysis products produced from different Nordic biomass types in a cyclone pilot plant
- 2016
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Ingår i: Fuel processing technology. - : Elsevier. - 0378-3820 .- 1873-7188. ; 146, s. 9-19
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Tidskriftsartikel (refereegranskat)abstract
- Pyrolysis is a promising thermochemical technology for converting biomass to energy, chemicals and/or fuels. The objective of the present paper was to characterize fast pyrolysis products and to study pyrolysis oil fractionation. The products were obtained from different Nordic forest and agricultural feedstocks in a pilot scale cyclone pyrolysis plant at three different reactor temperatures. The results show that the main elements (C, H and O) and chemical compositions of the products produced from stem wood, willow, forest residue and reed canary grass are in general terms rather similar, while the products obtained from bark differ to some extent. The oil produced from bark had a higher H/Ceff ratio and heating value which can be correlated to a higher amount of pyrolytic lignin and extractives when compared with oils produced from the other feedstocks. Regardless of the original feedstock, the composition of the different pyrolysis oil fractions (condensed and aerosol) differs significantly from each other. However this opens up the possibility to use specifically selected fractions in targeted applications. An increased reactor temperature generally results in a higher amount of water and water insoluble material, primarily as small lignin derived oligomers, in the produced oil.
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| 24. |
- Johansson, Ann-Christine, et al.
(författare)
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Co-pyrolysis of woody biomass and plastic waste in both analytical and pilot scale
- 2018
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Ingår i: Journal of Analytical and Applied Pyrolysis. - : Elsevier BV. - 0165-2370 .- 1873-250X. ; 134, s. 102-1113
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Tidskriftsartikel (refereegranskat)abstract
- Earlier studies show that co-pyrolysis of biomass and plastics can improve the quantity and quality of the produced pyrolysis oil compared to pyrolysis of the separate feedstocks. In this work three relevant plastic wastes; paper reject, shredder light fraction and cable plastics; were evaluated together with woody biomass (stem wood from spruce and pine) using analytical pyrolysis, Py-GC–MS/FID. One verification experiment was also conducted in a cyclone pyrolyser pilot plant at industrially relevant conditions. The addition of plastic waste to woody biomass pyrolysis was found to significantly affect the composition and properties of the produced pyrolysis products. In analytical pyrolysis experiments, positive synergetic effects were observed in the co-pyrolysis of paper reject and cable plastics together with the stem wood. The yield of reactive oxygenated compounds (ketones, aldehydes and acids) was suppressed while more stable alcohols and esters were promoted. The formation of hydrocarbons was also promoted in the co-pyrolysis of plastics from paper reject and stem wood. The results from the analytical pyrolysis were partly verified in the pilot scale experiment by co-pyrolysing stem wood and paper reject. However, the co-pyrolysis also affected other parameters that cannot be detected in analytical pyrolysis such as higher acidity and viscosity of the oil which highlights the need for undertaking experiments at different scales. The product yields in pilot scale were about the same for the co-pyrolysis case as for pure stem wood. However, a high volatile content of the solid product indicated that the process conditions can be further optimized for co-pyrolysing cases.
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| 25. |
- Johansson, Ann-Christine, et al.
(författare)
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Experiences of pilot scale cyclone pyrolysis
- 2017
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Ingår i: European Biomass Conf. Exhib. Proc.. - : ETA-Florence Renewable Energies. ; , s. 952-955
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Konferensbidrag (refereegranskat)abstract
- Fast pyrolysis is a promising thermochemical technology for converting biomass to energy, chemicals, and fuels. At RISE ETC, an industrially relevant pyrolysis pilot plant has been designed, constructed, and operated since 2011. The pilot plant is based on an externally heated cyclone reactor where both the pyrolysis reaction and the separation of products take place. The reactor design has shown to be beneficial since it produces oil with relatively low concentrations of inorganics. Pyrolysis of different Nordic biomasses, both forestry and agricultural, have been studied using the pilot plant and the results indicate that it is especially suitable for low grade fuels. The oil is collected in two separate steps, and the received two oil fractions have different chemical and physical properties, which opens up the possibility to use selected fractions in targeted applications. Oil fractionation has also been studied further in a separate fractional condensation system and the results show that it is possible to separate larger energy-rich lignin-derived material; medium-sized; and light water soluble compounds already in the oil collection step. The pilot plant has worked as a platform for pyrolysis research and for building up competence in the pyrolysis area.
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| 26. |
- Johansson, Ann-Christine, et al.
(författare)
-
Fractional condensation of pyrolysis vapors produced from Nordic feedstocks in cyclone pyrolysis
- 2017
-
Ingår i: Journal of Analytical and Applied Pyrolysis. - : Elsevier BV. - 0165-2370 .- 1873-250X. ; 123, s. 244-254
-
Tidskriftsartikel (refereegranskat)abstract
- Pyrolysis oil is a complex mixture of different chemical compounds with a wide range of molecular weights and boiling points. Due to its complexity, an efficient fractionation of the oil may be a more promising approach of producing liquid fuels and chemicals than treating the whole oil. In this work a sampling system based on fractional condensation was attached to a cyclone pyrolysis pilot plant to enable separation of the produced pyrolysis vapors into five oil fractions. The sampling system was composed of cyclonic condensers and coalescing filters arranged in series. The objective was to characterize the oil fractions produced from three different Nordic feedstocks and suggest possible applications. The oil fractions were thoroughly characterized using several analytical techniques including water content; elemental composition; heating value, and chemical compound group analysis using solvent fractionation, quantitative 13C NMR and 1H NMR and GC x GC − TOFMS. The results show that the oil fractions significantly differ from each other both in chemical and physical properties. The first fractions and the fraction composed of aerosols were highly viscous and contained larger energy-rich compounds of mainly lignin-derived material. The middle fraction contained medium-size compounds with relatively high concentration of water, sugars, alcohols, hydrocarbonyls and acids and finally the last fraction contained smaller molecules such as water, aldehydes, ketones and acids. However, the properties of the respective fractions seem independent on the studied feedstock types, i.e. the respective fractions produced from different feedstock are rather similar. This promotes the possibility to vary the feedstock depending on availability while retaining the oil properties. Possible applications of the five fractions vary from oil for combustion and extraction of the pyrolytic lignin in the early fractions to extraction of sugars from the early and middle fractions, and extraction of acids and aldehydes in the later fractions.
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| 27. |
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| 28. |
- Korelskiy, Danil
(författare)
-
Development of permporometry for analysis of MFI membranes
- 2011
-
Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Zeolite membranes exhibiting high flux and high selectivity are of major interest for potential future applications. In order to achieve high flux and high selectivity, the zeolite film must be thin (< 1 µm) and free from flow-through defects. The development of thin defect free zeolite membranes requires powerful tools for characterization of flow-through defects in the membranes. Permporometry is one of the most straightforward and powerful techniques for characterization of flow-through pores in ceramic membranes. In permporometry, the flow of a non-condensable gas, e.g., helium, through the membrane is monitored as a function of the activity of a strongly adsorbing compound, e.g., hydrocarbon.In the present work, MFI membranes prepared by a seeding method were characterized by permporometry using helium as the non-condensable gas and n-hexane or benzene as the adsorbing compound. In order to appreciate permporometry data, the membranes were also characterized by scanning electron microscopy (SEM), single gas permeation and separation experiments. The permporometry data were then compared to the SEM morphology of the membranes, permeances of different probe molecules and membrane separation performance.In order to determine the conditions of the permporometry experiment leading to blocking of zeolite pores, a model describing helium transport in the zeolite pores in the presence of n-hexane or benzene was developed. The model is based on percolation theory and knowledge of the adsorption isotherms and adsorption sites for n-hexane and benzene in the zeolite pores. Parameters needed in the model were estimated by Density Functional Theory (DFT) using a Local-Density Approximation (LDA), the most sophisticated theory yet applied to this system. Based on the permporometry data, it was demonstrated that the model could adequately describe helium transport in zeolite pores in the presence of the hydrocarbons.The sensitivity of the permporometry technique towards the defect size has been improved considerably. It was revealed that high quality MFI membranes prepared in the present work contained mainly micropore defects which are most like the defects in the zeolite crystal lattice (intracrystalline defects).The work has shown how permporometry data could be used to estimate the area distribution of the flow-through defects in the membranes. The results on the defect distribution were corroborated by the SEM observations and the separation experiments. The width of cracks, including support cracks, and open grain boundaries observed by SEM was in excellent agreement with the defect width estimated from permporometry data. A straightforward correlation was observed between separation data and permporometry data, i.e. membranes of higher quality according to permporometry analysis exhibited greater separation performance. Also, the permeance of molecules diffusing through defects in the membrane in the separation experiment was found to scale with the permeance of helium through the defects measured in the permporometry experiment. In addition, this work showed that single gas permeance ratios could not detect slight variations in the membrane quality. For membranes with similar however slightly different amount of defects, the ratios are mainly affected by the membrane thickness and support morphology.To summarise, the present work demonstrates that permporometry data adequately reflect membrane quality and that permporometry is a very powerful technique for MFI membrane characterization.
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| 29. |
- Landälv, Ingvar, et al.
(författare)
-
Two years experience of the BioDME project : A complete wood to wheel concept
- 2014
-
Ingår i: Environmental Progress & Sustainable Energy. - : Wiley. - 1944-7442 .- 1944-7450. ; 33:3, s. 744-750
-
Tidskriftsartikel (refereegranskat)abstract
- Dimethyl ether (DME), is an excellent diesel fuel that can be produced through gasification from multiple feedstocks. One particularly interesting renewable feedstock is the energy rich by-product from the pulping process called black liquor (BL). The concept of utilizing BL as gasifier feed, converting it via syngas to DME and then compensating the withdrawal of BL energy from the pulp mill by supplying biomass to a conventional combined heat and power plant, is estimated to be one of the most efficient conversion concepts of biomass to a renewable fuel on a well-to-wheel basis. This concept has been demonstrated by the four-year BioDME project, including field tests of DME-fueled heavy-duty trucks that are operated commercially. Up till the summer of 2013 more than 500 tons of BioDME has been produced and distributed to 10 HD trucks, which in total has run more than 1 million km in commercial service
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| 30. |
- Leijenhorst, Evert J., et al.
(författare)
-
Entrained flow gasification of straw- and wood-derived pyrolysis oil in a pressurized oxygen blown gasifier
- 2015
-
Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 79, s. 166-176
-
Tidskriftsartikel (refereegranskat)abstract
- Fast pyrolysis oil can be used as a feedstock for syngas production. This approach can have certain advantages over direct biomass gasification. Pilot scale tests were performed to investigate the route from biomass via fast pyrolysis and entrained flow gasification to syngas. Wheat straw and clean pine wood were used as feedstocks; both were converted into homogeneous pyrolysis oils with very similar properties using in-situ water removal. These pyrolysis oils were subsequently gasified in a pressurized, oxygen blown entrained flow gasifier using a thermal load of 0.4 MW. At a pressure of 0.4 MPa and a lambda value of 0.4, temperatures around 1250 °C were obtained. Syngas volume fractions of 46% CO, 30% H2 and 23% CO2 were obtained for both pyrolysis oils. 2% of CH4 remained in the product gas, along with 0.1% of both C2H2 and C2H4. Minor quantities of H2S (3 vs. 23) cm3 m−3, COS (22 vs. 94) cm3 m−3 and benzene (310 vs. 532) cm3 m−3 were measured for wood- and straw derived pyrolysis oils respectively. A continuous 2-day gasification run with wood derived pyrolysis oil demonstrated full steady state operation. The experimental results show that pyrolysis oils from different biomass feedstocks can be processed in the same gasifier, and issues with ash composition and melting behaviour of the feedstocks are avoided by applying fast pyrolysis pre-treatment.
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| 31. |
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| 32. |
- Lestander, Torbjörn, et al.
(författare)
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Characterization of fast pyrolysis bio-oil properties by near-infrared spectroscopic data
- 2018
-
Ingår i: Journal of Analytical and Applied Pyrolysis. - : Elsevier BV. - 0165-2370 .- 1873-250X. ; 133, s. 9-15
-
Tidskriftsartikel (refereegranskat)abstract
- Pyrolysis transforms bulky and heterogeneous lignocellulosic biomass into more easily-handled oils that can be upgraded into bio-based transportation fuels. Existing systems for monitoring pyrolysis processes and characterizing their products rely on slow and time-consuming wet chemical analyses. On-line near-infrared (NIR) spectroscopy could potentially replace such analyses, providing real-time data and reducing costs. To test the usefulness of NIR methods in characterizing pyrolysis oils and processes, biomass from conifers, Salix, and reed canary grass was milled and pyrolyzed at 675, 750, and 775 °C. Two separate pyrolytic fractions (aerosol and condensed) were produced in each experiment, and NIR spectra were collected for each fraction. Multivariate modelling of the resulting data clearly showed that the samples’ NIR spectra could be used to accurately predict important properties of the pyrolysis oils such as their energy values, main organic element (C, H and O) contents, and water content. The spectra also contained predictive information on the samples’ origins, fraction, and temperature treatment, demonstrating the potential of on-line NIR techniques for monitoring pyrolytic production processes and characterizing important properties of pyrolytic oils from lignocellulosic biomass.
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| 33. |
- Molinder, Roger, et al.
(författare)
-
Characterization and cleanup of wastewater from pressurized entrained flow biomass gasification
- 2014
-
Ingår i: ACS Sustainable Chemistry and Engineering. - : American Chemical Society (ACS). - 2168-0485. ; 2:8, s. 2063-2069
-
Tidskriftsartikel (refereegranskat)abstract
- Wastewater produced during pressurized entrained flow biomass gasification (PEBG) was characterized and cleaned in order to raise the technology readiness level of the PEBG concept. Scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) and thermogravimetric analysis (TGA) were used to study material found in the water. The material was removed using filtration and the concentration of dissolved organic carbon (DOC), polyaromatic hydrocarbons (PAHs) and metals in filtered water was studied using standardized methods. Water was sampled during operation at three oxygen equivalence ratios (λ) and the results were compared to concentrations of gaseous hydrocarbons in the syngas. As λ increased, the amount of soot in the wastewater and the amount of soot precursors in the syngas was reduced. As a result the concentration of particles in the water was reduced and their composition shifted toward a higher percentage of inorganics (ash). PAH concentration trends in the water and in the syngas correlated and dissolved organic material in the water was reduced with increased λ. A particle removal efficiency of 98-99% was achieved using sedimentation and filtration while the DOC was reduced from ≈2.5 mg L-1 to below detection limit using granular activated carbon (GAC). © 2014 American Chemical Society.
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| 34. |
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| 35. |
- Mosca, Alessandra, et al.
(författare)
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NO2 and N2 sorption in MFI films with varying Si/Al and Na/Al ratios
- 2009
-
Ingår i: Microporous and Mesoporous Materials. - : Elsevier BV. - 1387-1811 .- 1873-3093. ; 120:3, s. 195-205
-
Tidskriftsartikel (refereegranskat)abstract
- MFI crystals or films with controlled thicknesses and different Si/Al ratios were grown on seeded cordierite monoliths using a clear synthesis mixture with template or a template-free gel. The materials were analyzed by scanning electron microscopy, X-ray diffraction, inductively coupled plasma-atomic emission spectrometry, X-ray photoelectron spectroscopy, thermogravimetric analysis and sorption experiments using N 2 or NO 2 adsorbates. The films were uniformly distributed over the support surface. As expected, the specific monolayer N 2 adsorption capacity (mol/g zeolite ) was constant and independent of film thickness. The specific molar NO 2 adsorption capacity was significantly lower than the specific molar monolayer N 2 adsorption capacity, indicating that NO 2 is adsorbed at specific sites rather than evenly distributed in a monolayer. A number of NO 2 adsorption sites with varying strengths were observed by TPD experiments. At 30 °C, the amount of adsorbed NO 2 in the MFI films increased with increasing Al and Na content as opposed to the N 2 adsorption capacity, which was independent of these parameters. At 200 °C, the adsorbed amount of NO 2 was lower than at 30 °C and apparently independent on Al concentration in the Na-MFI films. These results indicate that different mechanisms are involved in NO 2 adsorption. NO 2 may adsorb weakly on Na + cations and also react with silanol groups and residual water in the zeolite, the latter two results in more strongly bound species. Upon NO 2 adsorption, formation of NO was observed. This work represents the first systematic study of the effects of Al and Na content on NO 2 adsorption in MFI films. © 2008 Elsevier Inc. All rights reserved.
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| 36. |
- Möller, K.P., et al.
(författare)
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The catalytic evaluation of structured zeolite catalysts
- 2004
-
Ingår i: International Journal of Chemical Reactor Engineering. - : Walter de Gruyter GmbH. - 1542-6580. ; 2:1
-
Tidskriftsartikel (refereegranskat)abstract
- ZSM-5 films, with thicknesses between 150 and 2300 nm, supported on 3 mm diameter alumina beads are characterised in terms of their catalytic activity and selectivity for tri-isopropylbenzene cracking and para-xylene isomerisation at 450°C. A reaction-diffusion model adequately represents the experimental data and is used to estimate intrinsic reactivity and diffusion properties of the zeolite films. Results show that the external activity, overall activity and the diffusivity increase with increasing film thickness. The variation in reactivity and diffusivity, when compared to physio-chemical data, are a result of structural defects and non-homogeneities of the zeolite film. The measured diffusivities are within an order of magnitude of those extrapolated from literature. Thick zeolite films have the largest Thiele modulus as the increase in zeolite film thickness dominates over the structural defects. The largest selectivity improvements are observed for thick zeolite films
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| 37. |
- Nejadmoghadam, Elham, 1984, et al.
(författare)
-
Stabilization of bio-oil from simulated pyrolysis oil using sulfided NiMo/Al 2 O 3 catalyst
- 2023
-
Ingår i: Fuel. - 0016-2361. ; 353
-
Tidskriftsartikel (refereegranskat)abstract
- Pyrolysis oil comprises compounds with a broad range of functional groups making its thermal/catalytic upgrading challenging due to the formation of undesired char. In this context, the current contribution addresses the thermal and catalytic hydrotreatment of a simulated pyrolysis oil containing all the representative groups of compounds under bio-oil stabilization conditions (180–300 °C, 60 bar, 4 h) using sulfided NiMo/Al2O3. The effect of reaction conditions and different oxygenated organic compounds on the yields and properties of products was compared thoroughly. Interestingly, a correlation between the presence/absence of oxygenated furan and sugar compounds was found to significantly affect the yield of liquid product containing stabilized compounds. The presence of such compound groups significantly enhances the solid formation via oligomerization and polymerization reactions. To gain further insight, the solid products were analyzed/characterized in detail to elucidate their characteristics by extracting them into a dimethyl sulfoxide (DMSO) soluble and insoluble solid fraction. It was found that in the presence of NiMo/Al2O3, increasing temperature from 180 to 300 °C enhances the formation of liquid product due to transformation of some of the soluble solids, while for experiments without the catalyst, the formation of solids was significantly higher. Oppositely, during heating up to 180 °C, no solids were found in the case without the catalyst, however the presence of the catalyst during heating resulted in solid formation due to various catalytic reactions that promoted char formation. Analysis of solids revealed that the structure of soluble solids at lower temperatures (180 °C) using the catalyst was closely related to sugar derivatives, whereas the corresponding insoluble solids with higher molecular weight were not fully char-like developed. However, at higher temperatures, the soluble and insoluble solid compositions were found to contain aliphatic compounds and fully developed char, respectively. Therefore, the stabilization of furan particularly with attached carbonyl groups and sugars derivatives in pyrolysis oil is of great importance to improve upgrading efficiency.
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| 38. |
- Nejadmoghadam, Elham, 1984, et al.
(författare)
-
Stabilization of fresh and aged simulated pyrolysis oil through mild hydrotreatment using noble metal catalysts
- 2024
-
Ingår i: Energy Conversion and Management. - 0196-8904. ; 313
-
Tidskriftsartikel (refereegranskat)abstract
- The nature and reactivity of the oxygenates, containing different functional chemical groups, and especially carbonyl compounds, render pyrolysis oil unstable. Alterations in physical and chemical properties of pyrolysis oil during storage and the catalytic stabilization of this oil is therefore critical and is the objective of the current work. In this study, Pd/Al2O3, Pt/Al2O3, Rh/Al2O3, Re/Al2O3 and sulphided NiMo/Al2O3 catalysts were employed in the hydrotreatment (180 °C, 60 bar H2, 4 h) of simulated pyrolysis oil to examine their effect on stabilization and potential polymerization routes. Of all the catalysts used, Pd/Al2O3 with well-dispersed metal particles, and a high char-suppressing potential was the most effective catalyst. It had the highest bio-liquid yield and the highest selectivity to low molecular weight stabilized oxygenates and deoxygenated products. In addition, the acidity in the light fraction was low and a very low solid product formation was found that consisted mainly of soluble polymers composed predominantly of aliphatic compounds and sugars, whereas insoluble polymers were not fully developed char. The solid yield increased in the following order: Pd (3.3 wt%) < Rh (13.3 wt%) < NiMo (13.6 wt%) < Pt (21.5 wt%) < Re (25.8 wt%) < Blank (27.4 wt%). This trend was also accompanied by an enhanced yield of heavy oligomers in the corresponding liquid phase abundant in phenolic compounds compared to carboxylic acids and aliphatic compounds based on GPC and P-NMR analyses. The Pd loading necessary to obtain a high-quality product was also assessed, and the lower carbon loss when using catalysts with smaller contents of metal was revealed. Based on the results a detailed reaction network was proposed regarding the reactions during stabilization of sugars, aldehydes, ketones, furans, acids and phenols present in pyrolysis oil. To delve deeper into the simulated pyrolysis oil properties, it was subjected to accelerated aging. Interestingly as much as 79 % of the feed was converted during aging. According to GC/MS analysis only large oligomers were formed that could not be detected. When removing the most reactive components from the feed, i.e. the sugar and furan, the conversion was lowered to 53 %. Catalytic stabilization was conducted on the aged oil and compared with stabilization followed by aging. The results showed that the solid formation increased from 5.1 to 9.1 % when the pyrolysis oil was first aged, followed by stabilization. A suggested reason for this is the large amount of oligomers that were formed during the aging. Thus, aging before stabilization is very negative for an industrial process.
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| 39. |
- Olsson Månsson, Emma, 1992, et al.
(författare)
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Removal of Inorganic Impurities in the Fast Pyrolysis Bio-oil Using Sorbents at Ambient Temperature
- 2024
-
Ingår i: Energy & Fuels. - 1520-5029 .- 0887-0624. ; 38:1, s. 414-4254
-
Tidskriftsartikel (refereegranskat)abstract
- Fast pyrolysis bio-oil (FPBO) sourced from residual biomass waste (such as sawdust) is a promising feedstock that may be used for biofuel production. Their inorganic elements may, however, vary and cause deactivation of the catalysts in the hydrodeoxygenation (HDO) upgrading biorefinery unit. It was found that the use of zeolite Y and strong acidic ion-exchange resins as adsorbents was almost equally efficient in lowering the concentrations of Ca from <10 to <1 ppm and of Fe, K, and Mg to <0.3 ppm in FPBO at 30 °C, atmospheric pressure, and 4 h adsorption time. The removal efficiency of zeolite and resins exceeded 85–98% (detection limit) of these particular elements. For the first time for the FPBO, phosphorus was reported as being successfully targeted by aluminum oxide, being lowered from 1 ppm to <0.1 ppm, which is a reduction of at least 90%. Characterization of the oil and sorbents suggests that the surface acidity affects the removal efficiency of these elements from FPBO. Organic compounds in the pyrolysis oil, including isopropanol, lactic acid, hydroxy acetone, furfural, guaiacol, and levoglucosan, were semiquantified using two-dimensional gas chromatography coupled with mass spectrometry (GCxGC-MS). Compared to the fresh oil, the compositions and contents of these organic compounds were not impacted significantly by the sorbents under these mild operating conditions. This research indicates that inorganic impurities present in bio-oils can be removed, and thus, they may be considered feedstocks for producing biofuels with less deactivation of HDO catalysts.
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| 40. |
- Perdana, Indra, 1973, et al.
(författare)
-
A comparison of NOx adsorption on Na, H and BaZSM-5 films
- 2007
-
Ingår i: Applied Catalysis B: Environmental. - : Elsevier BV. - 0926-3373 .- 1873-3883. ; 72, s. 82-91
-
Tidskriftsartikel (refereegranskat)abstract
- NOx adsorption in ZSM-5 films containing Na+, H+ or Ba2+ as counter ions was studied. NaZSM-5 films showed a superior NOx adsorption capacity over the entire temperature range (30-350ºC) in comparison with the other films. Besides the possibility to form strongly bound surface nitrate species, the presence of the Na ions in ZSM-5 resulted in a large enhancement of various weakly adsorbed species. In the HZSM-5 film, the NOx adsorption was mainly due to physisorption, surface nitric acid and nitrosium ion (NO+) formation. Besides weakly adsorbed species and surface nitric acid, the NOx adsorption in BaZSM-5 films also resulted in formation of strongly bound surface nitrate species. The nitrate species in the BaZSM-5 film were found to be resistant to NO exposure and were mainly formed through an NO2 disproportionation pathway.
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| 41. |
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| 42. |
- Perdana, Indra, et al.
(författare)
-
NOx adsorption over a wide temperature range on Na-ZSM-5 films
- 2005
-
Ingår i: Journal of Catalysis. - : Elsevier BV. - 0021-9517 .- 1090-2694. ; 234:1, s. 219-229
-
Tidskriftsartikel (refereegranskat)abstract
- NOx adsorption over a wide temperature range (30–350 °C) on monolith supported Na-ZSM-5 films were studied with a gas flow reactor. The nature of the adsorbed species was further investigated by in situ infrared spectroscopy. Depending on the adsorption temperature, three different ranges of thermally stable species were observed on Na-ZSM-5 films. In addition to the role of cationic sites and residual hydroxyl groups in zeolite frameworks, it was found that the formation of nitric acid plays an important role in NO2 adsorption. Nitrate species were formed during adsorption by two mechanisms. The nitrates formed via nitric acid and involving NO formation had lower thermal stability than those formed through an NO2 disproportionation reaction
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| 43. |
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| 44. |
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| 45. |
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| 46. |
- Risberg, Mikael, et al.
(författare)
-
Influence from fuel type on the performance of an air-blown cyclone gasifier
- 2014
-
Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 116, s. 751-759
-
Tidskriftsartikel (refereegranskat)abstract
- Entrained flow gasification of biomass using the cyclone principle has been proposed in combination with a gas engine as a method for combined heat and power production in small to medium scale (<20 MW). This type of gasifier also has the potential to operate using ash rich fuels since the reactor temperature is lower than the ash melting temperature and the ash can be separated after being collected at the bottom of the cyclone. The purpose of this work was to assess the fuel flexibility of cyclone gasification by performing tests with five different types of fuels; torrefied spruce, peat, rice husk, bark and wood. All of the fuels were dried to below 15% moisture content and milled to a powder with a maximum particle size of around 1 mm. The experiments were carried out in a 500 kWth pilot gasifier with a 3-step gas cleaning process consisting of a multi-cyclone for removal of coarse particles, a bio-scrubber for tar removal and a wet electrostatic precipitator for removal of fine particles and droplets from the oil scrubber (aerosols). The lower heating value (LHV) of the clean producer gas was 4.09, 4.54, 4.84 and 4.57 MJ/Nm3 for peat, rice husk, bark and wood, respectively, at a fuel load of 400 kW and an equivalence ratio of 0.27. Torrefied fuel was gasified at an equivalence ratio of 0.2 which resulted in a LHV of 5.75 MJ/Nm3 which can be compared to 5.50 MJ/Nm3 for wood powder that was gasified at the same equivalence ratio. A particle sampling system was designed in order to collect ultrafine particles upstream and downstream the gasifier cleaning device. The results revealed that the gas cleaning successfully removed >99.9% of the particulate matter smaller than 1 μm.
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| 47. |
- Rownaghi, Ali, et al.
(författare)
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Yield of dimethyl ether and gasoline as a function of size of ZSM-5 crystals
- 2011
-
Ingår i: 2010 AIChE annual meeting conference proceedings. - New York : American Institute of Chemical Engineers. - 9780816910656
-
Konferensbidrag (refereegranskat)abstract
- In this work we have studied different acidic zeolitic solid catalysts ZSM-5 with different crystal size, measuring their physical-chemical properties and correlating this with the activity, selectivity at different process condition during the conversion of methanol to dimethyl ether (DME) and gasoline boiling range hydrocarbons. The catalytic properties of these catalysts depended mainly on the crystal size and surface properties. Methanol feed in the DME and gasoline process is derived from black liquor-based syngas. The methanol to DME and gasoline process involves the conversion of black liquor syngas to crude methanol and methanol to DME and gasoline
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| 48. |
- Salam, Muhammad Abdus, 1983, et al.
(författare)
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Elucidating the role of NiMoS-USY during the hydrotreatment of Kraft lignin
- 2022
-
Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947. ; 442
-
Tidskriftsartikel (refereegranskat)abstract
- Major hurdles in Kraft lignin valorization require selective cleavage of etheric and C–C linkages and subsequent stabilization of the fragments to suppress repolymerization reactions to yield higher monomeric fractions. In this regard, we report the development of efficient NiMo sulfides and ultra-stable Y zeolites for the reductive liquefaction and hydrodeoxygenation of Kraft lignin in a Parr autoclave reactor at 400 °C and 35 bar of H2 (@25 °C). Comparing the activity test without/with catalyst, it is revealed that NiMo sulfides over ultra-stable Y zeolites (silica/alumina = 30) achieved a significant reduction (∼50 %) of the re-polymerized solid residue fraction leading to a detectable liquid product yield of 30.5 wt% with a notable monocyclic and alkylbenzenes selectivity (∼61 wt%). A physical mixture counterpart, consisting of hydrothermally synthesized unsupported NiMoS and Y30, on the other hand, shows lower selectivity for such fractions but higher stabilization of the lignin fragments due to enhanced access to the active sites. Moreover, an extended reaction time with higher catalyst loading of the impregnated NiMoY30 facilitated a remarkable alkylbenzene (72 wt%) selectivity with an increased liquid yield of 38.9 wt% and a reduced solid residue of 16.4 wt%. The reason for the high yield and selectivity over NiMoY30, according to the catalyst characterization (H2-TPR, XPS, TEM) can be ascribed to enhanced stabilization of depolymerized fragments via H2-activation at a lower temperature and high hydrodeoxygenation ability. In addition, the better proximity of the acidic and deoxygenation sites in NiMoY30 was beneficial for suppressing the formation of polycyclic aromatics.
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| 49. |
- Sandström, Linda, et al.
(författare)
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Pyrolysis of Nordic biomass types in a cyclone pilot plant — Mass balances and yields
- 2016
-
Ingår i: Fuel processing technology. - : Elsevier BV. - 0378-3820 .- 1873-7188. ; 152, s. 274-284
-
Tidskriftsartikel (refereegranskat)abstract
- Fast pyrolysis of biomass results in a renewable product usually denoted pyrolysis oil or bio-oil, which has been suggested to be used as a direct substitute for fuel oil or as a feedstock for production of transportation fuels and/or chemicals. In the present work, fast pyrolysis of stem wood (originated from pine and spruce), willow, reed canary grass, brown forest residue and bark has been performed in a pilot scale cyclone reactor. The experiments were based on a biomass feeding rate of 20 kg/h at three different reactor temperatures. At the reference condition, pyrolysis of stem wood, willow, reed canary grass, and forest residue resulted in organic liquid yields in the range of 41 to 45% w/w, while pyrolysis of bark resulted in lower organic liquid yields. Two fractions of pyrolysis oil were obtained, denoted as the condensed and the aerosol fraction. Most of the water soluble molecules were collected in the condensed fraction, whereas the yield of water insoluble, heavy lignin molecules was higher in the aerosol fraction. Based on the results of the present work, willow, reed canary grass and forest residue are considered as promising raw materials for production of pyrolysis oil in a cyclone reactor.
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| 50. |
- Shafaghat, Hoda, et al.
(författare)
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Customized Atmospheric Catalytic Hydropyrolysis of Biomass to High-Quality Bio-Oil Suitable for Coprocessing in Refining Units
- 2024
-
Ingår i: Energy & Fuels. - : American Chemical Society. - 0887-0624 .- 1520-5029. ; 38:6, s. 5288-5302
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to investigate the critical elements of the biomass ex situ catalytic hydropyrolysis (CHP) concept to improve the quality of fast pyrolysis bio-oil (FPBO) for further coprocessing in a fluid catalytic cracking (FCC) refining unit. Generally, the high oxygen and low hydrogen contents of biomass result in a bio-oil with low quality, necessitating its upgrading, which can be performed as integrated in the pyrolysis process via in situ or ex situ configuration. In this work, the quality of stem wood-derived pyrolyzates (520 °C) was improved via ex situ CHP (400 °C) using a continuous bench-scale drop tube pyrolyzer (60 g h-1), and then the produced FPBO was coprocessed with vacuum gas oil (VGO) fossil oil using a lab-scale FCC unit (525 °C). CHP of stem wood was carried out using different metal-acid catalysts such as Ni/HZSM-5, Ni/HBeta, Mo/TiO2, and Pt/TiO2 at atmospheric pressure. FCC runs were performed using an equilibrium FCC catalyst and conventional fossil FCC feedstock cofed with 20 wt % stem wood-derived bio-oil in a fluidized bed reactor. Cofeeding the nonupgraded FPBO with fossil oil into the FCC unit decreased the generation of hydrocarbons in the range of gasoline and naphtha, indicating that bio-oil needs to be upgraded for further coprocessing in the FCC unit. Experimental results showed that different catalysts significantly affected the product composition and yield; Ni-based catalysts were strongly active tending to generate a high yield of gas, while Mo- and Pt-based catalysts seemed better for production of liquid with improved quality. The quality of FPBO was improved by reducing the formation of reactive oxygenates through the atmospheric CHP process. The composition of oil obtained from hydropyrolysis also showed that the yields of phenols and aromatic hydrocarbons were enhanced. © 2024 The Authors.
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