| 1. |
- H. Moud, Pouya, et al.
(författare)
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Biomass pyrolysis gas conditioning over an iron-based catalyst for mild deoxygenation and hydrogen production
- 2017
-
Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 211, s. 149-158
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Bio-crude is a renewable source for production of valuable energy carriers. Prior to its utilization, a conditioning step of the raw pyrolysis gas can be beneficial before the bio-crude is converted via catalytic hydrodeoxygenation (HDO) into liquid hydrocarbon products, or via steam reforming (SR) to synthesis gas/hydrogen. An experimental small industrial scale study for the chemistry of atmospheric pressure pyrolysis gas conditioning resulting in bio-crude deoxygenation and a hydrogen-rich gas using an iron-based catalyst without addition of hydrogen or steam is presented and discussed. Following a short catalyst stabilization period with fluctuating bed temperatures, the catalyst operated near 450°C at a space velocity of 1100 h-1 for 8 hours under stable conditions during which no significant catalyst deactivation was observed. Experimental results indicate a 70-80% reduction of acetic acid, methoxy phenols, and catechol, and a 55-65% reduction in non-aromatic ketones, BTX, and heterocycles. Alkyl phenols and phenols were least affected, showing a 30-35% reduction. Conditioning of the pyrolysis gas resulted in a 56 % and a 18 wt% increase in water and permanent (dry) gas yield, respectively, and a 29 % loss of condensable carbon. A significant reduction of CO amount (-38 %), and production of H2 (+1063 %) and CO2 (+36 %) over the catalyst was achieved, while there was no or minimal change in light hydrocarbon content. Probing the catalyst after the test, the bulk phase of the catalyst was found to be magnetite (Fe3O4) and the catalyst exhibited significant water gas shift (WGS) reaction activity. The measured gas composition during the test was indicative of no or very limited Fischer-Tropsch (FT) CO /CO2 hydrogenation activity and this infers that also the active surface phase of the catalyst during the test was Fe-oxide, rather than Fe-carbide. The results show that iron-based materials are potential candidates for application in a pyrolysis gas pre-conditioning step before further treatment or use, and a way of generating a hydrogen-enriched gas without the need for bio-crude condensation.
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| 2. |
- H. Moud, Pouya
(författare)
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Catalytic Conversion of Undesired Organic Compounds to Syngas in Biomass Gasification and Pyrolysis Applications
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Reliable energy supply is a major concern and crucial for development of the global society. To address the dependency on fossil fuel and the negative effects of this reliance on climate, there is a need for a transition to cleaner sources. An attractive solution for replacing fossil-based products is renewable substitutes produced from biomass. Gasification and pyrolysis are two promising thermochemical conversion technologies, facing challenges before large-scale commercialization becomes viable. In case of biomass gasification, tar is often and undesired by-product. An attractive option to convert tar into syngas is nickel-based catalytic steam reforming (SR). For biomass pyrolysis, catalytic SR is in early stages of investigation as a feasible option for bio-crude conversion to syngas.The focus of the thesis is partly dedicated to describe research aimed at increasing the knowledge around tar reforming mechanisms and effect of biomass-derived impurities on Ni-based tar reforming catalyst downstream of gasifiers. The work focuses on better understanding of gas-phase alkali interaction with Ni-based catalyst surface under realistic conditions. A methodology was successfully developed to enable controlled investigation of the combined sulfur (S) and potassium (K) interaction with the catalyst. The most striking result was that K appears to lower the sulfur coverage and increases methane and tar reforming activity. Additionally, the results obtained in the atomistic investigations are discussed in terms of naphthalene adsorption, dehydrogenation and carbon passivation of nickel.Furthermore, the thesis describes research performed on pyrolysis gas pre-conditioning at a small-industrial scale, using an iron-based catalyst. Findings showed that Fe-based materials are potential candidates for application in a pyrolysis gas pre-conditioning step before further treatment or use, and a way for generating a hydrogen-enriched gas without the need for bio-crude condensation.
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| 3. |
- Haghighi Moud, Pouya, et al.
(författare)
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Equilibrium potassium coverage and its effect on a Ni tar reforming catalyst in alkali- and sulfur-laden biomass gasification gases
- 2016
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Ingår i: Applied Catalysis B. - : Elsevier. - 0926-3373 .- 1873-3883. ; 190, s. 137-146
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Tidskriftsartikel (refereegranskat)abstract
- Biomass conversion to syngas via gasification produces certain levels of gaseous by-products, such as tar and inorganic impurities (sulfur, potassium, phosphorus etc.). Nickel, a commonly used catalyst for hydrocarbqn steam reforming, suffers reduced reforming activity by small amounts of sulfur (S) or potassium (K), while resistance against deleterious carbon whisker formation increases. Nevertheless, the combined effect of biomass derived gas phase alkali at varying concentrations together with sulfur on tar reforming catalyst performance under realistic steady-state conditions is largely unknown. Prior to this study, a methodology to monitor these effects by precise K dosing as well as K co-dosing with S was successfully developed. A setup consisting of a 5 kW biomass fed atmospheric bubbling fluidized bed gasifier, a high temperature hot gas ceramic filter, and a catalytic reactor operating at 800 degrees C were used in the experiments. Within the current study, two test periods were conducted, including 30 h with 1 ppmv potassium chloride (KCl) dosing followed by 6 h without KCl dosing. Besides an essentially carbon-free operation, it can be concluded that although K, above a certain threshold surface concentration, is known to block active Ni sites and decrease activity in traditional steam reforming, it appears to lower the surface S coverage (theta(s)) at active Ni sites. This reduction in theta(s) increases the conversion of methane and aromatics in tar reforming application, which is most likely related to K-induced softening of the S-Ni bond. The K-modified support surface may also contribute to the significant increase in reactivity towards tar molecules. In addition, previously unknown relevant concentrations of K during realistic operating conditions on typical Ni-based reforming catalysts are extrapolated to lie below 100 mu K/m(2), a conclusion based on the 10-40 mu K/m(2) equilibrium coverages observed for the Ni/MgAl2O4 catalyst in the present study.
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| 4. |
- Hernandez, Asbel, et al.
(författare)
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Gas-Phase Potassium Effects and the Role of the Support on the Tar Reforming of Biomass-Derived Producer Gas Over Sulfur-Equilibrated Ni/MgAl2O4
- 2020
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Ingår i: Energy & Fuels. - : American Chemical Society. - 0887-0624 .- 1520-5029. ; 34:9, s. 11103-11111
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Tidskriftsartikel (refereegranskat)abstract
- Biomass gasification is a sustainable way to convert biomass residues into valuable fuels and chemicals via syngas production. However, several gas impurities need to be removed before the final synthesis. Understanding of the interactions and effects of biomass-derived producer gas contaminants (S and K) on the performance of reforming catalysts is of great importance when it comes to process reliability and development. In the present study, the steam reforming activity at 800 °C of a sulfur-equilibrated nickel catalyst during controlled exposure to alkali species (∼2 ppmv K) and in its absence was investigated using real producer gas from a 5 kWth O2-blown fluidized-bed gasifier. Conversions of CH4, C2H4, and C10H8 were used to evaluate the performance of the Ni/MgAl2O4 catalyst and MgAl2O4 support. A significant and positive effect on the catalyst activity is observed with addition of gas-phase KCl. This is assigned primarily to the observed K-induced reduction in sulfur coverage (θS) on Ni—an effect which is reversible. The catalytic contribution of the K-modified pure MgAl2O4 support was found to be significant in the conversion of naphthalene but not for light hydrocarbons. The product and catalyst analyses provided evidence to elucidate the preferential adsorption site for S and K on the catalyst as well as the role of the support. Whereas S, as expected, was found to preferentially adsorb on the surface of Ni particles, forming S-Ni sites, K was found to preferentially adsorb on the MgAl2O4 support. A low but still significant K adsorption on S–Ni sites, or an effect on only the fraction of exposed Ni surface area near the metal–support interface, can, however, not be excluded. The result suggests that an improved Ni/MgAl2O4 catalyst activity and an essentially carbon-free operation can be achieved in the presence of controlled amount of gas-phase potassium and high sulfur coverages on Ni. Based on the results, a mechanism of the possible K–S interactions is proposed.
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| 5. |
- Hernandez, Asbel, et al.
(författare)
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Preferential adsorption of K species and the role of support during reforming of biomass derived producer gas over sulfur passivated Ni/MgAl2O4
- 2020
-
Ingår i: Energy & Fuels. - 0887-0624 .- 1520-5029. ; 34:9, s. 11103-11111
-
Tidskriftsartikel (refereegranskat)abstract
- Biomass gasification is a sustainable way to convert biomass residues into valuable fuels and chemicals via syngasproduction. However, several gas impurities need to be removed before thefinal synthesis. Understanding of the interactions andeffects of biomass-derived producer gas contaminants (S and K) on the performance of reforming catalysts is of great importancewhen it comes to process reliability and development. In the present study, the steam reforming activity at 800°C of a sulfur-equilibrated nickel catalyst during controlled exposure to alkali species (∼2 ppmv K) and in its absence was investigated using realproducer gas from a 5 kWthO2-blownfluidized-bed gasifier. Conversions of CH4,C2H4, and C10H8were used to evaluate theperformance of the Ni/MgAl2O4catalyst and MgAl2O4support. A significant and positive effect on the catalyst activity is observedwith addition of gas-phase KCl. This is assigned primarily to the observed K-induced reduction in sulfur coverage (θS)onNianeffect which is reversible. The catalytic contribution of the K-modified pure MgAl2O4support was found to be significant in theconversion of naphthalene but not for light hydrocarbons. The product and catalyst analyses provided evidence to elucidate thepreferential adsorption site for S and K on the catalyst as well as the role of the support. Whereas S, as expected, was found topreferentially adsorb on the surface of Ni particles, forming S-Ni sites, K was found to preferentially adsorb on the MgAl2O4support.A low but still significant K adsorption on S−Ni sites, or an effect on only the fraction of exposed Ni surface area near the metal−support interface, can, however, not be excluded. The result suggests that an improved Ni/MgAl2O4catalyst activity and anessentially carbon-free operation can be achieved in the presence of controlled amount of gas-phase potassium and high sulfurcoverages on Ni. Based on the results, a mechanism of the possible K−S interactions is proposed
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| 6. |
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| 7. |
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| 8. |
- Ahmadi, Mozhgan, et al.
(författare)
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Application of Solid-Phase Microextraction (SPME) as a Tar Sampling Method
- 2013
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Ingår i: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 27:7, s. 3853-3860
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents the result of an investigation of the potential use of solid-phase microextraction (SPME) as a tar sampling method. The SPME stationary phase used was 50 mu m of polydimethylsiloxane (PDMS) coated on a fused silica fiber. Tar model compounds normally present in a producer gas from gasifiers, benzene, toluene, indane, indene, naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, fluoranthene, and pyrene, were used in the investigation. The adsorbed compounds were analyzed by injection into gas chromatography coupled to a flame ionization detector (GC- FID). The amount of adsorbed tar on the SPME fiber determined the detection and quantification limits for the method. The results showed that adsorption of tar model compounds on the SPME fiber increased with decreasing polarity. The adsorption of compounds increased with a decreasing temperature, enabling a possibility to tune the sensitivity of the method by changing the sampling temperature. Conclusively, SPME has a very high potential as a tar sampling method and, in combination with GC- FID trace analysis of tar, is a feasible application.
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| 9. |
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| 10. |
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| 11. |
- Ahmadi, Mozhgan, et al.
(författare)
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Development of an on-line tar measurement method based on photo ionization technique
- 2011
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Ingår i: Catalysis Today. - : Elsevier BV. - 0920-5861 .- 1873-4308. ; 176:1, s. 250-252
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents work in progress for development of an on-line method based on PID (Photo Ionization Detector) for quantitative measurement of tar from biomass gasification. To calibrate the method the PID signals are compared to quantitative data of individual tar compounds obtained by an established reference method. The measured response factors for the model tar compounds demonstrated very good linearity. The PID approach was tested on-line with real producer gases from an atmospheric fluidized bed gasifier operated at 800-900 °C. The results suggest that PID can be used for continuous on-line tar measurement of product gases from biomass gasification.
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| 12. |
- Ahmadi Svensson, Mozhgan
(författare)
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Sampling and Analysis of Tars by Means of Photo Ionization Detection and Solid Phase Micro Extraction
- 2013
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Gasification of biomass will likely play an important role in the production of energy and chemicals in a future sustainable society. However, during gasification impurities, such as tars, will be formed. Tars may cause fouling and blockages of equipment downstream the gasifier. It is therefore important to minimize the formation of tars, alternatively to remove the formed tars. These processes need to be monitored, which makes it necessary to develop tar analysis methods suitable for this task.This work describes the development of two tar analysis methods, an on-line method based on a photoionization detector (PID) and an off-line method based on solid phase microextraction (SPME). Both methods were successfully validated against the established solid phase adsorption (SPA) method.The method based on PID was shown to have a very fast response time. Furthermore, the PID method is selective towards tar, but only limited information will be obtained regarding the composition of the tar compounds. The PID method is suitable for applications where it is important to detect fast changes of the tar concentration, i.e. process monitoring.The SPME method was shown to be a very sensitive method for qualitative and quantitative tar analysis. The sampling temperature was shown to be crucial for obtaining analysis results with the wanted detection limit. The SPME method is suitable for applications where extremely low detection and quantification limits are needed, i.e. for syngas production.
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| 13. |
- Aminlashgari, Nina, 1986-
(författare)
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SALDI-MS Method Development for Analysis of Pharmaceuticals and Polymer Degradation Products
- 2012
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Surface assisted laser desorption ionization-mass spectrometry (SALDI-MS) was evaluated as a new tool for analysis of polymer degradation products. A SALDI method was developed enabling rapid analysis of low molecular mass polyesters and their degradation products. In addition, the possibility to utilize nanocomposite films as easy-to-handle surfaces for analysis of pharmaceutical compounds was investigated. Poly(ε-caprolactone) was used as a model compound for SALDI-MS method development. The signal-to-noise values obtained by SALDI-MS were 20 times higher compared to traditional matrix assisted laser desorption ionization-mass spectrometry (MALDI-MS) of the same samples with 2,5-dihydroxybenzoic acid as a matrix. Halloysite nanoclay and magnesium oxide showed best potential as surfaces and clean backgrounds in the low mass range were observed. The SALDI-MS method for the analysis of polyester degradation products was also verified by electrospray ionization-mass spectrometry (ESI-MS). An advantage over ESI-MS is the possibility to directly analyze degradation products in buffer solutions. Compared to gas chromatography-mass spectrometry (GC-MS) it is possible to analyze polar compounds and larger molecular mass ranges at the same time as complicated extraction steps are avoided. The possibility to use nanocomposite films as surfaces instead of free nanoparticles was evaluated by solution casting of poly(lactide) (PLA) films with eight inorganic nanoparticles. The S/N values of the pharmaceutical compounds, acebutolol, propranolol and carbamazepine, analyzed on the nanocomposite surfaces were higher than the values obtained on the surface of plain PLA showing that the nanoparticles participated in the ionization/desorption process even when they are immobilized. Beside the ease of handling, the risk for instrument contamination is reduced when nanocomposites are used instead of free nanoparticles. The signal intensities depended on the type of drug, type and concentration of nanoparticle. PLA with 10 % titanium oxide or 10 % silicon nitride functioned best as SALDI-MS surfaces.
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| 14. |
- Bäbler, Matthäus Ulrich, et al.
(författare)
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Modeling and pilot plant runs of slow biomass pyrolysis in a rotary kiln
- 2017
-
Ingår i: Applied Energy. - : Elsevier. - 0306-2619 .- 1872-9118. ; 207, s. 123-133
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Tidskriftsartikel (refereegranskat)abstract
- Pyrolysis of biomass in a rotary kiln finds application both as an intermediate step in multistage gasification as well as a process on its own for the production of biochar. In this work, a numerical model for pyrolysis of lignocellulosic biomass in a rotary kiln is developed. The model is based on a set of conservation equations for mass and energy, combined with independent submodels for the pyrolysis reaction, heat transfer, and granular flow inside the kiln. The pyrolysis reaction is described by a two-step mechanism where biomass decays into gas, char, and tar that subsequently undergo further reactions; the heat transfer model accounts for conduction, convection and radiation inside the kiln; and the granular flow model is described by the well known Saeman model. The model is compared to experimental data obtained from a pilot scale rotary kiln pyrolyzer. In total 9 pilot plant trials at different feed flow rate and different heat supply were run. For moderate heat supplies we found good agreement between the model and the experiments while deviations were seen at high heat supply. Using the model to simulate various operation conditions reveals a strong interplay between heat transfer and granular flow which both are controlled by the kiln rotation speed. Also, the model indicates the importance of heat losses and lays the foundation for scale up calculations and process optimization.
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| 15. |
- Chien, Tzu-En, 1991-
(författare)
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Near-ambient pressure velocity map imaging
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Catalytic reactions on solid surfaces have been studied under Ultra-high vacuum (UHV) conditions for decades. These studies provide crucial information for catalytic reactions, such as surface structures, adsorption sites, and reaction mechanisms. However, industrial catalysis operates under high gas pressure to increase the reaction rate, so the knowledge we learn from the previous UHV studies may not be able to directly transfer to the industry. This difference is referred to as the “pressure gap”, and it represents the difficulties that scientists encounter when attempting to investigate and comprehend catalytic reactions at high pressure. To address this issue, in situ/operando techniques and instruments have been developed to study reactions at pressures closer to real-world applications.The present thesis aims to showcase the new instrument, Near-Ambient Pressure Velocity Map Imaging (NAP-VMI), and its applications to molecular spectroscopy and surface science at near-ambient pressures. This instrument features a velocity map imaging (VMI) setup with redesigned ion optics and uses differential pumping to achieve a working pressure of 10−3 mabr. It allows time-resolved measurements at microsecond time scales using the pump-probe technique with a pulsed molecular beam and a pulsed laser. The performance is validated using N2O photodissociation and N2 surface scattering. CO oxidation on Pd(110) and Pd(100) surfaces is studied at elevated oxygen pressure (1×10−5 mbar) where the surfaces reconstruct.The results show the suppression of CO2 production in oxygen rich environments for both surfaces. The difference in kinetics and dynamics behavior between the two surfaces also suggests that surface structures and adsorption sites are important in the reaction mechanisms. These findings highlight the importance of surface structure in catalytic reactions and pave the way for more effective catalysts to be designed by tailoring surface properties and reaction conditions.
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| 16. |
- Cieślik, M., et al.
(författare)
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Engineering of bone fixation metal implants biointerface - Application of parylene C as versatile protective coating
- 2012
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Ingår i: Materials science & engineering. C, biomimetic materials, sensors and systems. - : Elsevier BV. - 0928-4931 .- 1873-0191. ; 32:8, s. 2431-2435
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Tidskriftsartikel (refereegranskat)abstract
- The tribological and protective properties of parylene C coatings (2-20 ÎŒm) on stainless steel 316L implant materials were investigated by means of electrochemical measurements and wear tests. The thickness and morphology of the CVD prepared coatings were characterized by scanning electron and laser confocal microscopy. The stability of the coatings was examined in contact with Hanks' solution and H 2O 2 (simulating the inflammatory response). It was concluded that silane-parylene C coating with the optimum thickness of 8 ÎŒm exhibits excellent wear resistance properties and limits the wear formation. The engineered versatile coating demonstrates sufficient elastomer properties, essential to sustain the implantation surgery strains and micromotions during long-term usage in the body.
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| 17. |
- Cieślik, M., et al.
(författare)
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Metal release and formation of surface precipitate at stainless steel grade 316 and Hanks solution interface : Inflammatory response and surface finishing effects
- 2009
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Ingår i: Corrosion Science. - : Elsevier BV. - 0010-938X .- 1879-0496. ; 51:5, s. 1157-1162
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Tidskriftsartikel (refereegranskat)abstract
- The influence of surface finishing (polishing and passivation) on the release of Cr, Fe, Ni from the stainless steel 316 implant materials to Hanks solution with or without H2O2 (simulating a body inflammatory response) was investigated. The surfaces were characterized by means of SEM EDXS, XPS and Kelvin Probe measurements before and after exposure to the synthetic body fluids. The total metal ions release rates are more than 10 times higher in the presence of H2O2, independently of the surface finishing. In the absence of H2O2, formation of a surface layer consisting mainly of Ca3(PO4)2 was observed, most likely it was responsible for the observed decrease of the release rates. © 2009 Elsevier Ltd. All rights reserved.
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| 18. |
- Cieślik, M., et al.
(författare)
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Parylene coatings on stainless steel 316L surface for medical applications : Mechanical and protective properties
- 2012
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Ingår i: Materials science & engineering. C, biomimetic materials, sensors and systems. - : Elsevier BV. - 0928-4931 .- 1873-0191. ; 32:1, s. 31-35
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Tidskriftsartikel (refereegranskat)abstract
- The mechanical and protective properties of parylene N and C coatings (2-20 μm) on stainless steel 316L implant materials were investigated. The coatings were characterized by scanning electron and confocal microscopes, microindentation and scratch tests, whereas their protective properties were evaluated in terms of quenching metal ion release from stainless steel to simulated body fluid (Hanks solution). The obtained results revealed that for parylene C coatings, the critical load for initial cracks is 3-5 times higher and the total metal ions release is reduced 3 times more efficiently compared to parylene N. It was thus concluded that parylene C exhibits superior mechanical and protective properties for application as a micrometer coating material for stainless steel implants. © 2011 Elsevier B.V. All rights reserved.
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| 19. |
- Cieslik, Monika, et al.
(författare)
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Silane-parylene coating for improving corrosion resistance of stainless steel 316L implant material
- 2011
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Ingår i: Corrosion Science. - : Elsevier. - 0010-938X .- 1879-0496. ; 53:1, s. 296-301
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Tidskriftsartikel (refereegranskat)abstract
- The corrosion resistance of a two-layer polymer (silane + parylene) coating on implant stainless steel was investigated by microscopic observations and electrochemical measurements Long term exposure tests in Hanks solution revealed that the coating of 2 mu m can be successfully used for corrosion protection However the addition of H2O2 simulating the inflammatory response of human body environment causes a dramatic destruction of the protective coating Analysis of the experimental data in terms of circuit models enables proposing a deterioration mechanism OH radicals formed at the metal surface attack the polymer thus the deterioration starts from the metal/polymer interface and progress towards the outward surface.
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| 20. |
- Dahlquist, Erik, 1951-, et al.
(författare)
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Biomass and black liquor gasification
- 2013. - 1
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Ingår i: Technologies for Converting Biomass to Useful Energy. - : CRC Press. - 9780415620888 ; , s. 175-216
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Bokkapitel (refereegranskat)abstract
- Officially the use of biomass for energy use globally is only 10-13 % of the total energy demand of 140 000 TWh/y. Still, the production of biomass annually is in the range of 270 000 TWh/y. Most of it obviously is not used very efficiently, although some is also used as food. There is thus a need for new methods for converting biomass into refined products like chemicals, fuels, wood and paper products, heat, cooling and electric power. The different type of conversion methods covered is biogas production, bio-ethanol production, torrefaction, pyrolysis, high temperature gasification and combustion. These methods are covered as well as principals for controlling the processes. The suitability for the different methods for different type of biomass as well as different versions of the methods is presented – both existing methods and those being developed for the future. System optimization using modeling methods and simulation is covered as well as analysis of advantages of different solutions. Many key-experts from all over the world are presenting the keys of their specialties to give us an up-to-date view of the situation all over the world. This book has the aim to give facts and inspiration to professionals like engineers and researchers, students as well as those working for different type of authorities or societal organizations.
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| 21. |
- Dahlquist, Erik, et al.
(författare)
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Modelling and Simulation of Biomass Conversion Processes
- 2015
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Ingår i: Proceedings - 8th EUROSIM Congress on Modelling and Simulation, EUROSIM 2013. - 9780769550732 ; , s. 506-512
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Konferensbidrag (refereegranskat)abstract
- By utilizing biomass gasification, the energy contentof the biomass can be utilized to produce gas to be used forcogeneration of heat and power as well as other energy carrierssuch as fuels for vehicles. The concept is suitable forapplication to existing CHP plants as well as for utilizing spentliqour in small scale pulp and paper mills. The introductionwould enable flexible energy utilization, use of problematicfuels as well as protects the environment by e.g. avoiding therelease of toxic substances. In this paper, the possibilities todevelop this concept is discussed. In this paper we comparedifferent gasification processes with respect to what gas qualitywe get, and how the gasification can be modelled usingdifferent modelling approaches, and how these can becombined. Results from simulations are compared toexperimental results from pilot plant operations in differentscales and with different processes like CFB and BFBTechnologies, athmospheric and pressurized, and using steam,air and oxygen as oxidizing media.
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| 22. |
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| 23. |
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| 24. |
- Ding, Saiman, et al.
(författare)
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Effects of Porous Structure Development and Ash on the Steam Gasification Reactivity of Biochar Residues from a Commercial Gasifier at Different Temperatures
- 2020
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Ingår i: Energies. - : MDPI AG. - 1996-1073. ; 13:18
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Tidskriftsartikel (refereegranskat)abstract
- The present study aims at investigating the effects of porous structure development and ash content on the observed reactivity during steam gasification of biochar residues from a commercial gasifier. The experiments were conducted at a temperature range of 700 to 800 °C using biochar, derived from entrained flow gasification of biomass, under isothermal conditions using a thermogravimetric analyzer. The pore size distribution, surface area and morphology of char samples were determined by N2 physiosorption and scanning electron microscopy (SEM). The results showed that the gasification temperature does not affect the porous structure development considerably. The total surface area of char exhibits a threefold increase, while the total pore volume increase ranges between 2.0 and 5.3 times, at all temperatures. Both properties are directly proportional to the observed reactivity, especially at conversions up to 70%. Catalytic effects of the mineral matter of the char (mainly potassium) become predominant at the later stages of conversion (conversion greater than 70%).
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| 25. |
- Ding, Saiman
(författare)
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Gasification of biochars: Evolution of pore structure, effects of alkalis and alkali release
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Renewable energy sources are indispensable to meet the rising demand of energy usage while reducing the negative environmental impact of utilising fossil fuels. Gasification is an efficient technology to convert biogenic waste into valuable gaseous products. The rate of conversion of char, produced in an intermediate step in the conversion, plays an essential role in the conversion of biogenic materials. The conversion of char is significantly affected by properties such as the structure of the char and its alkali content. This thesis presents findings related to the influence of char pore structure development and alkalis content on char gasification, as well as the alkali release during gasification and co-gasification. Experimental results show that the generation of micropores are directly proportional to the observed reactivity up to 70% of char conversion, after which the catalytic effects of potassium become the dominating factor. Furthermore, investigations of the effect of different intrinsic potassium contents on woody char reactivity demonstrate that no alkali surface saturation point is reached, as is the case for high-ash chars. Application of a modified random pore model enabled a successful capture of the later stages of char conversion in comparison to other kinetic models applied. Alkali release and sample mass changes were monitored simultaneously, using a thermogravimetric analyser together with a surface ionization detector (TGA-SID). The studies revealed a significant release of alkali as woody char conversion approaches completion during CO2 gasification. For straw char the release of alkali decreased continuously throughout the conversion process. Similar results were obtained for biochar gasification under steam conditions in a fixed bed reactor. However, in this case the process is more complex, including transfer of alkali between particles inside the fixed bed, which influences char conversion. Co-gasification of different types of biomass can substantially affect char conversion efficiency. In comparison to pure wood, mixing wood and straw had positive effects on the char conversion for rates below 90% of conversion, while exceeding this degree of conversion resulted in negative effects. The most significant positive effect was observed at a gasification temperature of 900 °C, particularly when using a wood-straw blend of 75 wt%:25 wt%. The above findings are important for the understanding of the mechanisms of char conversion and are valuable in the design of gasifiers. The research provides with a deeper understanding of char structure development, alkali release, and migration during gasification of biogenic materials.
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| 26. |
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| 27. |
- Ding, Saiman, et al.
(författare)
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Potassium-Induced Phenomena and Their Effects on the Intrinsic Reactivity of Biomass-Derived Char during Steam Gasification
- 2023
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Ingår i: ACS Omega. - : American Chemical Society (ACS). - 2470-1343. ; 8:32, s. 29131-29142
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Tidskriftsartikel (refereegranskat)abstract
- The mineral content of biomass plays an important role in the gasification rate of biomass-derived char. The understanding and quantification of mineral-related phenomena are thus of importance when considering gasification reactor design. In the present work, the potassium-induced catalytic phenomena during gasification of biomass-derived char have been studied. Char samples with similar structure and different intrinsic potassium content were gasified in a steam atmosphere at a temperature range of 700-800 °C. It was found that for all the samples, irrespective of the temperature and the initial potassium content, there is a critical K/C ratio (5 × 10-3), whereafter the catalytic phenomena prevail. The instantaneous conversion rate of the char is positively correlated with the potassium content and the progressively increasing conversion. The application of the modified random pore model was able to capture the later stages of conversion by the introduction of two additional parameters (c and p). It was found that these constants are not just fitting parameters but that there is an underlying physical significance with c being directly related to the intrinsic potassium content while being temperature independent and with p being temperature dependent.
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| 28. |
- Ding, Saiman, et al.
(författare)
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Secondary tar cracking in fixed bed using char residues from the wood gasification
- 2019
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Konferensbidrag (refereegranskat)abstract
- Biomass gasification is a promising technology for production of synthesis gas, hydrogen (H2) and carbon monoxide (CO), which can be subsequently converted into valuable end products. However, high tar content in the product gas during gasification is one of the major problems, limiting the further usage of the producer gas. Tar decomposition using char from the pyrolysis of biomass becomes more popular. Alternatively, using char residues, derived from the gasification process itself, could also be a measure to further reducing the tar content. Char and char-supported catalysts have been studied for the decomposition of model tar compounds, such as toluene, benzene, naphthalene as well as phenol.Moreover, there is no information about interactions or synergistic effects between light and heavy tar model compounds in mixtures of toluene and naphthalene. In this study, the catalytic effect of char samples derived from entrained flow gasification and high pressure carbonization process, on the tar model compounds decomposition was investigated using a fixed-bed reactor. The effects of differently produced char on the tar cracking efficiency was evaluated at 800 °C and 900 °C at a weight hourly space velocity (WHSV) 0.2 h-1 and a tar concentration of 5 g/Nm3.The effect of differently produced char on the efficiency of tar cracking is also evaluated. Preliminary results show that naphthalene and toluene conversion is increased over the char from the entrained flow with increased temperature. It verifies the catalytic effect of char on tar removal. However, conversions decreased over time most likely due to a decrease in specific surface area from 42 to 1.5 m2/g during the test at 900 °C. Comparation of catalytic tar cracking properties between different chars will be provided later on.
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| 29. |
- Ding, Saiman, et al.
(författare)
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Time-resolved alkali release during steam gasification of char in a fixed bed reactor
- 2024
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 356, s. 129528-
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Tidskriftsartikel (refereegranskat)abstract
- In this study time-resolved char conversion and alkali release under steam gasification conditions were investigated using a fixed bed reactor. The behaviour of an industrial char and chars produced from straw and furniture waste was investigated. For woody chars, an increase in gasification reactivity is observed together with a notable alkali release as the gasification approaches completion (degree of conversion > 0.8). In contrast, straw char exhibited a decrease in conversion rate and alkali release throughout the gasification process, attributed to the formation of catalytically inactive potassium silicates inhibiting the catalytic role of alkali. Aerosol particles in the 0.01–22 µm size range are emitted during the char conversion. A fraction is formed by nucleation of alkali compounds and other condensable gases. A wide particle distribution that extends over the whole size range is also observed, and the particles are likely to consist of solid char fragments. The study concludes on the importance of alkali release, illustrating the difference in alkali release pattern for high and low ash char.
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| 30. |
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| 31. |
- Ekström, Magnus Pär, et al.
(författare)
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The association of body mass index, weight gain and central obesity with activity-related breathlessness : the Swedish Cardiopulmonary Bioimage Study
- 2019
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Ingår i: Thorax. - : BMJ Publishing Group Ltd. - 0040-6376 .- 1468-3296. ; 74:10, s. 958-964
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Breathlessness is common in the population, especially in women and associated with adverse health outcomes. Obesity (body mass index (BMI) >30 kg/m(2)) is rapidly increasing globally and its impact on breathlessness is unclear.Methods: This population-based study aimed primarily to evaluate the association of current BMI and self-reported change in BMI since age 20 with breathlessness (modified Research Council score >= 1) in the middle-aged population. Secondary aims were to evaluate factors that contribute to breathlessness in obesity, including the interaction with spirometric lung volume and sex.Results: We included 13 437 individuals; mean age 57.5 years; 52.5% women; mean BMI 26.8 (SD 4.3); mean BMI increase since age 20 was 5.0 kg/m(2); and 1283 (9.6%) reported breathlessness. Obesity was strongly associated with increased breathlessness, OR 3.54 (95% CI, 3.03 to 4.13) independent of age, sex, smoking, airflow obstruction, exercise level and the presence of comorbidities. The association between BMI and breathlessness was modified by lung volume; the increase in breathlessness prevalence with higher BMI was steeper for individuals with lower forced vital capacity (FVC). The higher breathlessness prevalence in obese women than men (27.4% vs 12.5%; p<0.001) was related to their lower FVC. Irrespective of current BMI and confounders, individuals who had increased in BMI since age 20 had more breathlessness.Conclusion: Breathlessness is independently associated with obesity and with weight gain in adult life, and the association is stronger for individuals with lower lung volumes.
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| 32. |
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| 33. |
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| 34. |
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| 35. |
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| 36. |
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| 37. |
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| 38. |
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| 39. |
- Engvall, Klas, et al.
(författare)
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Upgrading of raw gas from biomass and waste gasification : Challenges and opportunities
- 2011
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Ingår i: Topics in catalysis. - : Springer-Verlag New York. - 1022-5528 .- 1572-9028. ; 54:13-15, s. 949-959
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Forskningsöversikt (refereegranskat)abstract
- The depletion of fossil fuel-based resources and concerns for increasing emissions of CO2 call for newways of producing environmentally- friendly substitutes for motor fuels and chemicals. Thermo-chemical conversion of biomass andwaste using gasification is a strong candidate tomeet these challenges. For efficient and cost-effective application of this technique, novel solutions for hot gas cleaning are needed. This review highlights some important areas for improvement of upgrading technologies for pressurised fluidised bed gasification systems using biomass as a fuel.
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| 40. |
- Farah, Elise, et al.
(författare)
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Controlling the Activity and Selectivity of HZSM-5 Catalysts in the Conversion of Biomass-Derived Oxygenates Using Hierarchical Structures : The Effect of Crystalline Size and Intracrystalline Pore Dimensions on Olefins Selectivity and Catalyst Deactivation
- 2023
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Ingår i: Topics in catalysis. - : Springer Nature. - 1022-5528 .- 1572-9028. ; 66:17-18, s. 1310-1328
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Tidskriftsartikel (refereegranskat)abstract
- The conversion of biomass-derived oxygenates over zeolite catalysts constitutes a challenge for the efficient production of bio-based chemicals and fuels due to difficulty in controlling the selectivity and high coke formation of such reactions. This is partly attributed to the microstructure of zeolite catalyst which affects the conversion and selectivity of products derived from biomass-derived oxygenates. In this study, the conversion and deactivation characteristics of three different model oxygenates found in biomass bio-oil (namely, acetol, furfural and guaiacol) over ZSM-5 zeolites of varying acidity, pore and crystal size prepared with bottom-up and top-down approaches were evaluated using a fixed bed microreactor at atmospheric pressure and a space velocity of 5 h−1 at a temperature range of 450–650 °C. Analysis of the experimental results indicates that the optimum temperature for such conversions is in the vicinity of 600 °C allowing for complete conversion of the compounds and high resistance to coking. The mechanisms of those conversions are discussed based on the obtained results. In general, crystal size and mesoporosity induce easier access to active sites improving mass transfer but also alter the location type, and strength of acid sites allowing for higher yields of primary and intermediate products such as olefins.
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| 41. |
- Ge, Yaxin, 1992, et al.
(författare)
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Effect of fresh bed materials on alkali release and thermogravimetric behavior during straw gasification
- 2023
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 336
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Tidskriftsartikel (refereegranskat)abstract
- Alkali-associated problems are key issues for the efficient use of straw that is available as a major renewable energy resource worldwide. The effects of six bed materials commonly used in fluidized bed reactors on straw pyrolysis and char gasification were evaluated using online monitoring of alkali release and thermogravimetric analysis. Scanning electron microscopy with energy dispersive spectroscopy was used to determine the elemental composition of the char surface. In the straw pyrolysis stage, alkali release is reduced by the addition of dolomite and silica due to alkali adsorption on the bed materials, and enhanced by the addition of alumina because of its high sodium content. In the char gasification stage, silica, sea sand, olivine, and ilmenite reduce the char reactivity and alkali release, which is attributed to transfer of Si and Ti from the bed materials to the char and reaction with alkali to form stable and catalytically inactive compounds. Alumina also reduces the char conversion rate by transfer of Al to the char and formation of K-Al-Si and Ca-Al-Si compounds, while alkali release from the straw and alumina blend remains high due to the high Na content in alumina. Dolomite initially appears to increase the char gasification reactivity, but the results are affected by conversion of volatile matter that deposited on the dolomite in the straw pyrolysis stage. Dolomite also significantly increases the alkali release, which is attributed to Ca reactions with aluminosilicate compounds that allow potassium to remain in volatile form. Fresh bed materials are concluded to have significant effects on straw conversion depending on their chemical composition, and the results can contribute to the understanding required for efficient use of straw in commercial applications of biomass thermochemical conversion.
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| 42. |
- Ge, Yaxin, et al.
(författare)
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Effects of used bed materials on char gasification : Investigating the role of element migration using online alkali measurements
- 2022
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Ingår i: Fuel processing technology. - : Elsevier. - 0378-3820 .- 1873-7188. ; 238
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Tidskriftsartikel (refereegranskat)abstract
- Online alkali measurements using surface ionization are employed to study alkali release during heating of used industrial fluidized bed materials and gasification of biomass-based char and bed material mixtures. The alkali release from the bed materials starts at 820 °C and increases with temperature, the time a bed material has experienced in an industrial process, and in the presence of CO2. Online alkali measurement during heating of char mixed with used bed material shows significant alkali uptake by the char. Complementary SEM-EDS studies confirm the alkali results and indicate that other important inorganic elements including Si, Mg, and Ca also migrate from the bed material to the char. The migration of elements initially enhances alkali release and char reactivity, but significantly reduces both during the final stage of the gasification. The observed effects on char gasification become more pronounced with increasing amount of bed material and increasing time the material experienced in an industrial process. The ash-layer on the used bed material is concluded to play an important role as a carrier of alkali and other active components. The char and bed material systems are closely connected under operational conditions, and their material exchange has important implications for the thermal conversion.
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| 43. |
- Ge, Yaxin, 1992, et al.
(författare)
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Impacts of fresh bed materials on alkali release and fuel conversion rate during wood pyrolysis and char gasification
- 2023
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 353
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Tidskriftsartikel (refereegranskat)abstract
- Bed materials provide efficient heat transfer and catalytic function in the thermochemical conversion of biomass, but their interactions with the fuel remain incompletely understood. In this study, the effects of bed materials on alkali release and fuel conversion during wood pyrolysis and CO2 gasification are investigated by online alkali detection combined with thermogravimetric analysis. The investigated bed materials include silica, sea sand, alumina and the natural ores olivine, ilmenite and dolomite. Only dolomite has a significant effect on fuel mass loss and alkali release during wood pyrolysis, while all bed materials influence char reactivity and alkali release during gasification. Sea sand, alumina and dolomite enhance the char gasification during the whole or most of the gasification process, which is related to alkali migration from the bed materials. All bed materials affect char reactivity and alkali release when the conversion approaches completion, and small amounts of some bed materials reduce the alkali release by an order of magnitude. The findings can be understood based on the chemical composition of the different materials. Silicon-rich materials reduce the levels of catalytically active alkali by formation of stable alkali silicates, and a similar explanation applies for ilmenite that captures alkali efficiently. Magnesium and calcium in contrast promote alkali release through their influence on alkali silicate chemistry. Analysis of char surfaces using scanning electron microscopy with energy dispersive spectroscopy indicates that low amounts of several elements are transferred from the bed material to the char where they may be directly involved in the char conversion process. The transferred elements are specific for each bed material and relates to their chemical composition. Mechanisms for material exchange between bed material and char are discussed.
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| 44. |
- Ge, Yaxin, 1992, et al.
(författare)
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Online monitoring of alkali release during co-pyrolysis/gasification of forest and agricultural waste: Element migration and synergistic effects
- 2023
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Ingår i: Biomass and Bioenergy. - : Elsevier BV. - 0961-9534 .- 1873-2909. ; 172, s. 106745-106745
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Tidskriftsartikel (refereegranskat)abstract
- Fuel blends may be used to meet several operational needs in thermal conversion of biomass waste, including optimization of ash properties and fuel conversion efficiency. In this study, online alkali measurements using surface ionization are employed to study synergistic effects produced by inorganic elements during co-pyrolysis/gasification of wood and straw waste. Synergistic effects on the fuel conversion behavior are not observed during co-pyrolysis, while alkali migration from straw to wood is clearly observed above 600 °C by online alkali monitoring. In contrast, synergistic effects on char conversion and alkali release are substantial during co-gasification. Positive effects on char reactivity during most of the gasification process are attributed to alkali migration from the straw to the wood char, and the most pronounced effect occurs at a gasification temperature of 900 °C and a straw content of 25%. Negative effects on char reactivity are observed at the final gasification stage, which is associated with a significantly reduced alkali release from fuel blends compared to pure wood char. The effect is attributed to the migration of silicon, phosphorus, and aluminum to the wood char, as revealed by scanning electron microscopy with energy dispersive spectroscopy, where the elements react with alkali to form catalytically inactive compounds. The mixing of biofuels is concluded to result in substantial effects on the fuel conversion efficiency, which should be taken into consideration in thermochemical conversion of biomass.
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| 45. |
- Ge, Yaxin, 1992, et al.
(författare)
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Real-time monitoring of alkali release during CO2 gasification of different types of biochar
- 2022
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Ingår i: Fuel. - : Elsevier BV. - 0016-2361 .- 1873-7153. ; 327
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Tidskriftsartikel (refereegranskat)abstract
- Potassium and sodium compounds play both positive and negative roles during biomass gasification, but the detailed behavior of alkali metal compounds remain incompletely understood. In this study, alkali release during CO2 gasification of biochar is characterized online with a surface ionization method in combination with thermogravimetric analysis of the char samples undergoing gasification. For wood chars, the alkali release rate follows a slowly decreasing trend as the char conversion proceeds, but increases by up to two orders of magnitude when the conversion approaches completion. In contrast, the alkali release from straw char is 40-50 times higher than observed for wood char and decreases continuously during the whole gasification process. A high temperature and a high CO2 concentration enhance both alkali release and char reactivity. The char preparation method also influences the alkali release from pine char, while the char reactivity is less affected. Alkali release and char reactivity are linked, but other factors including mineral content, surface area and char structure may play important roles for the observed reactivity. The results provide a basis for understanding of alkali behavior during gasification and may help optimize catalytic effects and reduce detrimental issues in biomass gasification.
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| 46. |
- Ghadami Yazdi, Milad, et al.
(författare)
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Naphthalene on Ni(111) : experimental and theoretical insights into adsorption, dehydrogenation and carbon passivation
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- An attractive solution to mitigate tars and also to decompose lighter hydrocarbons in biomass gasification is secondary catalytic reforming, converting hydrocarbons to useful permanent gases. Albeit in use for long time in fossil feedstock catalytic steam reforming, the understanding of the catalytic processes is still limited. Naphthalene is typically present in the biomass gasification gas and to further understand the elementary steps of naphthalene transformation, we investigated the temperature dependent naphthalene adsorption, dehydrogenation and passivation on Ni(111). TPD (temperature programmed desorption) and STM (scanning tunneling microscopy) in ultra-high vacuum environment from 110 K up to 780 K, combined with DFT (density functional theory) were used in the study. Room temperature adsorption results in a flat naphthalene monolayer. DFT favors the di-bridge[7] geometry but the potential energy surface is rather smooth. DFT also reveals a pronounced dearomatization and charge transfer from the adsorbed molecule into the nickel surface. Dehydrogenation occurs in two steps, with two desorption peaks at approximately 450 K and 600 K. The first step is due to partial dehydrogenation generating active hydrocarbon species that at higher temperatures migrates over the surface forming graphene. The graphene formation is accompanied by desorption of hydrogen in the high temperature TPD peak. The formation of graphene effectively passivates the surface both for hydrogen adsorption and naphthalene dissociation. In conclusion, the obtained results on the model naphthalene and Ni(111) system, provides insight into elementary steps of naphthalene adsorption, dehydrogenation and carbon passivation, which may serve as a good starting point for rational design, development and optimization of the Ni catalyst surface, as well as process conditions, for the aromatic hydrocarbon reforming process.
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| 47. |
- Ghadami Yazdi, M., et al.
(författare)
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Naphthalene on Ni(111) : Experimental and Theoretical Insights into Adsorption, Dehydrogenation, and Carbon Passivation
- 2017
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Ingår i: The Journal of Physical Chemistry C. - : American Chemical Society (ACS). - 1932-7447 .- 1932-7455. ; 121:40, s. 22199-22207
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Tidskriftsartikel (refereegranskat)abstract
- An attractive solution to mitigate tars and also to decompose lighter hydrocarbons in biomass gasification is secondary catalytic reforming, converting hydrocarbons to useful permanent gases. Albeit that it has been in use for a long time in fossil feedstock catalytic steam reforming, understanding of the catalytic processes is still limited. Naphthalene is typically present in the biomass gasification gas and to further understand the elementary steps of naphthalene transformation, we investigated the temperature dependent naphthalene adsorption, dehydrogenation and passivation on Ni(111). TPD (temperature-programmed desorption) and STM (scanning tunneling microscopy) in ultrahigh vacuum environment from 110 K up to 780 K, combined with DFT (density functional theory) were used in the study. Room temperature adsorption results in a flat naphthalene monolayer. DFT favors the dibridge[7] geometry but the potential energy surface is rather smooth and other adsorption geometries may coexist. DFT also reveals a pronounced dearomatization and charge transfer from the adsorbed molecule into the nickel surface. Dehydrogenation occurs in two steps, with two desorption peaks at approximately 450 and 600 K. The first step is due to partial dehydrogenation generating active hydrocarbon species that at higher temperatures migrates over the surface forming graphene. The graphene formation is accompanied by desorption of hydrogen in the high temperature TPD peak. The formation of graphene effectively passivates the surface both for hydrogen adsorption and naphthalene dissociation. In conclusion, the obtained results on the model naphthalene and Ni(111) system, provides insight into elementary steps of naphthalene adsorption, dehydrogenation, and carbon passivation, which may serve as a good starting point for rational design, development and optimization of the Ni catalyst surface, as well as process conditions, for the aromatic hydrocarbon reforming process.
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| 48. |
- Golda-Cepa, M., et al.
(författare)
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Development of crystalline-amorphous parylene C structure in micro-and nano-range towards enhanced biocompatibility : the importance of oxygen plasma treatment time
- 2015
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 5:60, s. 48816-48821
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Tidskriftsartikel (refereegranskat)abstract
- The crystalline-amorphous parylene C structure was fabricated by Chemical Vapour Deposited (CVD) and functionalised in the micro- and nano-range with the oxygen plasma treatment. The evolution of thermal stability, structure and surface biocompatibility of parylene C films as an effect of oxygen plasma treatment time were evaluated by means of thermogravimetric/differential thermal analysis (TG/DTA), X-Ray Diffraction (XRD) and cells adhesion tests (crystal violet assay, fluorescence microscopy). The results are epitomized by a crystalline-amorphous parylene C structural model. It was found that the time of oxygen plasma treatment is critical for adhesion of osteoblast cells with the optimum of 5-8 minutes.
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| 49. |
- Golda-Cepa, M., et al.
(författare)
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LDI-MS examination of oxygen plasma modified polymer for designing tailored implant biointerfaces
- 2014
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Ingår i: RSC Advances. - : Royal Society of Chemistry (RSC). - 2046-2069. ; 4:50, s. 26240-26243
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Tidskriftsartikel (refereegranskat)abstract
- A versatile polymer coating for biomaterials was fabricated by the mild oxygen plasma treatment of Chemical Vapour Deposited (CVD) parylene C. The surface properties were tailored while the excellent protective properties of the bulk were preserved. The species, formed due to the plasma functionalisation, were fingerprinted by a novel Laser Desorption/Ionisation-Mass Spectrometry (LDI-MS) method. Improved osteosarcoma cells (line MG-63) attachment and viability on a modified surface were demonstrated.
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| 50. |
- Golda-Cepa, M., et al.
(författare)
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Microbiological investigations of oxygen plasma treated parylene C surfaces for metal implant coating
- 2015
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Ingår i: Materials science & engineering. C, biomimetic materials, sensors and systems. - : Elsevier. - 0928-4931 .- 1873-0191. ; 52, s. 273-281
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Tidskriftsartikel (refereegranskat)abstract
- Parylene C surface was modified by the use of oxygen plasma treatment and characterized by microscopic and surface-sensitive techniques (E-SEM, AFM, XPS, LDI-TOF-MS, contact angle). The influence of the treatment on surface properties was investigated by calculations of surface free energy (Owens-Wendt method). Moreover, early adhesion (Culture Plate Method, Optical Microscopy Test) and biofilm formation ability (Cristal Violet Assay) on the parylene C surface was investigated. The bacteria strains which are common causative agents of medical device-associated infections (Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa - reference strains and clinical isolates) were used. It was concluded that chemical (oxygen insertion) and physical (nanotopography generation) changes, have a significant impact on the biocompatibility in terms of increased hydrophilicity (θw of unmodified sample = 88° ± 2°, θw of 60 min modified sample = 17.6° ± 0.8°) and surface free energy (SFE of unmodified sample = 42.4 mJ/m2, and for 60 min modified sample = 70.1 mJ/m2). At the same time, no statistical effect on biofilm production and bacteria attachment to the modified surface of any of the tested strains was observed.
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