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  • 1. Dahlquist, Erik
    et al.
    Mirmoshtaghi, Guilnaz
    Larsson, Eva K.
    Thorin, Eva
    Yan, Jinyue
    Engvall, Klas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Liliedahl, Truls
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Dong, C.
    Hu, X.
    Lu, Q.
    Modelling and simulation of biomass conversion processes2015In: 2013 8TH EUROSIM CONGRESS ON MODELLING AND SIMULATION (EUROSIM), 2015, p. 506-512Conference paper (Refereed)
    Abstract [en]

    By utilizing biomass gasification, the energy content of the biomass can be utilized to produce gas to be used for cogeneration of heat and power as well as other energy carriers such as fuels for vehicles. The concept is suitable for application to existing CHP plants as well as for utilizing spent liqour in small scale pulp and paper mills. The introduction would enable flexible energy utilization, use of problematic fuels as well as protects the environment by e.g. avoiding the release of toxic substances. In this paper, the possibilities to develop this concept is discussed. In this paper we compare different gasification processes with respect to what gas quality we get, and how the gasification can be modelled using different modelling approaches, and how these can be combined. Results from simulations are compared to experimental results from pilot plant operations in different scales and with different processes like CFB and BFB Technologies, athmospheric and pressurized, and using steam, air and oxygen as oxidizing media.

  • 2.
    Evangelopoulos, Panagiotis
    et al.
    KTH, School of Industrial Engineering and Management (ITM).
    Arvelakis, Stylianos
    National Technical University of Athens.
    Kantarelis, Efthymios
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Experimental investigation of low temperature pyrolysis of printed circuit boards (PCBs) and printed circuit board components (PCB sockets)Manuscript (preprint) (Other academic)
    Abstract [en]

    Printed circuit boards (PCBs) are the heart of all electronics due to their compact size and the broad spectrum of applications but very challenging when their life ends. Recycling of these components is problematic since they consist of different metallic parts packed on plastic compressed cover. The present study focuses on low temperature pyrolysis of PCBs since this process can separate the organic fraction from the inorganics. The latter, enables further separation and purification of the metals which are not oxidized during mild treatment. The low Br content of the resultant char after treatment at 320 oC for 30 min indicates that it could be used as solid fuel if efficient separation from the inorganic part would be performed. Moreover, the liquids obtained by this process can be used for feedstock recycling since the results indicates that toxic bromine containing on the organic compounds has been decreased both by increasing the residence time of pyrolysis process or by increasing the temperature conditions.

  • 3. Evangelopoulos, Panagiotis
    et al.
    Persson, Henry
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Kantarelis, Efthymios
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology. KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Pyrolysis of waste electrical and electronic equipment (WEEE) on a single screw reactor for bromine free oil productionManuscript (preprint) (Other academic)
    Abstract [en]

    This study focuses on pyrolysis on waste electrical and electronic equipment or WEEE as it is usually referred in the literature. A new auger reactor has been designed and tested with WEEE material. The performance of the reactor as well as the fate of the bromine has been investigated and evaluated in order to be used for designing of industrial process. The mass balance calculations performed for the tested cases of 400, 500 and 600 °C, showed a high gas yield (44%) at the temperature of 600 °C, which can be used to fulfil the process energy needs. At the low temperature of 400 °C the oil production reach its maximum yield, while the bromine content of the oil has also a maximum percentage of 0.5% wt. Several valuable compounds have been detected in the oil composition, which can be used either as fuels or for feedstock recycling.

  • 4.
    Granestrand, Jonas
    et al.
    KTH.
    Dahlin, Sandra
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Immele, O.
    Germany.
    Schmalhorst, L.
    Germany.
    Lantto, C.
    Nilsson, M.
    París, R. S.
    Regali, F.
    Pettersson, L. J.
    Catalytic aftertreatment systems for trucks fueled by biofuels - Aspects on the impact of fuel quality on catalyst deactivation2018In: Catalysis:: Volume 30, Royal Society of Chemistry, 2018, p. 64-145Chapter in book (Refereed)
    Abstract [en]

    The issue of sustainable energy supply is a global problem for pursuing future endeavours in the energy area. In countries such as China and India there is a tremendous growth at the moment, which is envisaged by an ever growing demand for vehicles. Hence, one of the grand challenges of society is to meet the demands for sustainable and environmentally-friendly technologies in the transport sector. One way to tackle the problem of growing concentrations of carbon dioxide, which is believed to contribute to global warming, is the use of biofuels. It is becoming more and more evident that global warming is partly due to increasing anthropogenic carbon dioxide emissions. An important contribution to these emissions is the use of fossil fuels in the transport sector. Hence, more efficient engines and an increased use of biofuels would be a step in the right direction. Although new propulsion systems are emerging, such as hybrid power-trains and fuel cell systems, analysis shows that combustion systems with excess oxygen, such as the diesel engine, will be the most important engine concept for the next 20 years. In this paper we will identify the specific challenges related to the production and use of biofuels in heavy-duty trucks and how they influence the catalytic units in the emission after-treatment system in the truck. Biofuels, such as biodiesel, contain potential poisons for the vehicle exhaust after-treatment, such as potassium, sodium, magnesium, phosphorus, zinc, sulfur and other compounds.

  • 5.
    Harding, Daniel
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Bongers, Marian David
    Wagner, Stefan
    Hahn, Hinrich
    Neugebohren, Jannis
    Kitsopoulos, T. N.
    Wodtke, Alec M.
    Pundt, Astrid
    Probing the Effect of Surface Strain on CO Binding to Pd Thin Films2019In: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 123, no 19, p. 12255-12260Article in journal (Refereed)
    Abstract [en]

    We report measurements to investigate the effects of mechanical strain on the binding energy of carbon monoxide (CO) on the (111) surface of a 16 nm thin film of palladium (Pd) grown on rutile titanium dioxide (r-TiO2). The lattice mismatch between Pd and the r-TiO2 leads to a tensile mechanical in-plane stress in the Pd layer of approximately 0.38 GPa. We observe an increase of (40 +/- 10) kJ mol(-1) in the CO binding energy for the 16 nm sample compared to a bulk Pd(111) crystal, which is in qualitative agreement with expectations based on the d-band model.

  • 6.
    Kiros, Yohannes
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Shimamune, Takayuki
    Gas diffusion electrode2012Patent (Other (popular science, discussion, etc.))
    Abstract [en]

    A method of preparing a gas diffusion electrode comprising a diffusion layer, and a reaction layer arranged to eachother, wherein the diffusion layer is prepared by i) admixing a) sacrificial material, b) polymer and c) a metal - based material and d)optional further components, wherein the sacrificial material has a release temperature below about 275 °C and is added in anamount from about 1 to about 25 wt% based on the total weight of components a) -d) admixed; ii) forming a diffusion layer from theadmixture of step i); iii) heating the forming diffusion layer to a temperature lower than about 275 °C so as to release at least a partof said sacrificial material from the diffusion layer. A gas diffusion electrode comprising a diffusion layer and a reaction layer ar -ranged to one another, wherein the diffusion layer has a porosity ranging from about 60 to about 95 %, and an electrolytic cell comprising the electrode. An electrolytic cell, a fuel cell comprising the gas diffusion electrode and a metal-air battery comprising thegas diffusion electrode.

  • 7.
    Marks, Kess
    et al.
    Stockholm Univ, Fysikum, Dept Phys, S-10691 Stockholm, Sweden..
    Ghadami Yazdi, Milad
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Piskorz, Witold
    Jagiellonian Univ Krakow, Fac Chem, Gronostajowa 2, PL-31387 Krakow, Poland..
    Simonov, Konstantin
    Uppsala Univ, Dept Phys & Astron, S-75120 Uppsala, Sweden..
    Stefanuik, Robert
    Uppsala Univ, Dept Phys & Astron, S-75120 Uppsala, Sweden..
    Sostina, Daria
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Guarnaccio, Ambra
    CNR, ISM, Tito Scalo Unit, I-85050 Potenza, Italy..
    Ovsyannikov, Ruslan
    Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, ISRR, D-12489 Berlin, Germany..
    Giangrisostomi, Erika
    Helmholtz Zentrum Berlin Mat & Energie, Inst Methods & Instrumentat Synchrotron Radiat Re, ISRR, D-12489 Berlin, Germany..
    Sassa, Yasmine
    Chalmers Univ Technol, Dept Phys, SE-41296 Gothenburg, Sweden..
    Bachellier, Nicolas
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Muntwiler, Matthias
    Paul Scherrer Inst, CH-5232 Villigen, Switzerland..
    Johansson, Fredrik O. L.
    Uppsala Univ, Dept Phys & Astron, S-75120 Uppsala, Sweden..
    Lindblad, Andreas
    Uppsala Univ, Dept Phys & Astron, S-75120 Uppsala, Sweden..
    Hansson, Tony
    Stockholm Univ, Fysikum, Dept Phys, S-10691 Stockholm, Sweden..
    Kotarba, Andrzej
    Jagiellonian Univ Krakow, Fac Chem, Gronostajowa 2, PL-31387 Krakow, Poland..
    Engvall, Klas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Göthelid, Mats
    KTH, School of Engineering Sciences (SCI), Applied Physics, Materials and Nanophysics.
    Harding, Dan J.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Ostrom, Henrik
    Stockholm Univ, Fysikum, Dept Phys, S-10691 Stockholm, Sweden..
    Investigation of the surface species during temperature dependent dehydrogenation of naphthalene on Ni(111)2019In: Journal of Chemical Physics, ISSN 0021-9606, E-ISSN 1089-7690, Vol. 150, no 24, article id 244704Article in journal (Refereed)
    Abstract [en]

    The temperature dependent dehydrogenation of naphthalene on Ni(111) has been investigated using vibrational sum-frequency generation spectroscopy, X-ray photoelectron spectroscopy, scanning tunneling microscopy, and density functional theory with the aim of discerning the reaction mechanism and the intermediates on the surface. At 110 K, multiple layers of naphthalene adsorb on Ni(111); the first layer is a flat lying chemisorbed monolayer, whereas the next layer(s) consist of physisorbed naphthalene. The aromaticity of the carbon rings in the first layer is reduced due to bonding to the surface Ni-atoms. Heating at 200 K causes desorption of the multilayers. At 360 K, the chemisorbed naphthalene monolayer starts dehydrogenating and the geometry of the molecules changes as the dehydrogenated carbon atoms coordinate to the nickel surface; thus, the molecule tilts with respect to the surface, recovering some of its original aromaticity. This effect peaks at 400 K and coincides with hydrogen desorption. Increasing the temperature leads to further dehydrogenation and production of H-2 gas, as well as the formation of carbidic and graphitic surface carbon. 

  • 8.
    Menya, E.
    et al.
    Makerere Univ, Coll Engn Design Art & Technol, Dept Mech Engn, POB 7062, Kampala, Uganda.;Gulu Univ, Dept Biosyst Engn, POB 166, Gulu, Uganda..
    Olupot, P. W.
    Makerere Univ, Coll Engn Design Art & Technol, Dept Mech Engn, POB 7062, Kampala, Uganda..
    Storz, H.
    Thuenen Inst Agr Technol, Bundesallee 47, D-38116 Braunschweig, Germany..
    Lubwama, M.
    Makerere Univ, Coll Engn Design Art & Technol, Dept Mech Engn, POB 7062, Kampala, Uganda..
    Kiros, Yohannes
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Characterization and alkaline pretreatment of rice husk varieties in Uganda for potential utilization as precursors in the production of activated carbon and other value-added products2018In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 81, p. 104-116Article in journal (Refereed)
    Abstract [en]

    In this study, 13 rice husk (RH) varieties from 4 agro-ecological zones in Uganda were characterized, NaOH-pretreated, and evaluated for their potential utilization as precursors for production of bio-oil, ash, char, and activated carbon for selected applications. RH varieties were characterized through particle size analysis, bulk density, proximate and ultimate analyses, specific surface area, pore volume, as well as lignocellulosic and inorganic compositions. Selected RH varieties were subsequently pretreated at NaOH concentrations of 1-4%w/v, using pretreatment ratios of 5 g RH: 40 mL NaOH. Properties varied among RH varieties, suiting them as feedstocks for different applications. Upland rice husk varieties are more suited precursors for production of bio-oil, and activated carbon due to their relatively lower ash content, higher specific surface area, as well as higher volatile matter and fixed carbon contents. Upland rice husks could as well be employed in the preparation of electrodes for electrochemical devices, due to their relatively higher specific surface area. A high ash content (21-32% dry basis) of lowland rice husks presents good prospects for their calcination, since larger amounts of rice husk ash could be obtained, and employed in different applications. Lowland rice husk varieties could also be more suited precursors for production of char for soil amendment, due to their relatively higher ash content, which subsequently increases their char yields. However, alkaline pretreatment of rice husks using 2-4%w/v NaOH can reduce the ash content by as much as 74-93%, depending on the rice husk variety, which paves way for utilizing rice husks with a high ash content in different applications. Aside from ash reduction, the enhanced specific surface area (1.2-1.7 m(2) g(-1)), volatile matter (68-79%db) and fixed carbon (19-24%db) contents of NaOH-pretreated rice husks suggests they are more suited feedstocks than when employed in their raw form, for production of bio-oil, as well as activated carbon.

  • 9. Mesfun, S.
    et al.
    Lundgren, J.
    Toffolo, A.
    Lindbergh, Göran
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Lagergren, Carina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Engvall, Klas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Integration of an electrolysis unit for producer gas conditioning in a bio-synthetic natural gas plant2019In: Journal of energy resources technology, ISSN 0195-0738, E-ISSN 1528-8994, Vol. 141, no 1, article id 012002Article in journal (Refereed)
    Abstract [en]

    Producer gas from biomass gasification contains impurities like tars, particles, alkali salts, and sulfur/nitrogen compounds. As a result, a number of process steps are required to condition the producer gas before utilization as a syngas and further upgrading to final chemicals and fuels. Here, we study the concept of using molten carbonate electrolysis cells (MCEC) both to clean and to condition the composition of a raw syngas stream, from biomass gasification, for further upgrading into synthetic natural gas (SNG). A mathematical MCEC model is used to analyze the impact of operational parameters, such as current density, pressure and temperature, on the quality and amount of syngas produced. Internal rate of return (IRR) is evaluated as an economic indicator of the processes considered. Results indicate that, depending on process configuration, the production of SNG can be boosted by approximately 50-60% without the need of an additional carbon source, i.e., for the same biomass input as in standalone operation of the GoBi-Gas plant.

  • 10. Mesfun, Sennai
    et al.
    Lundgren, Joakim
    Toffolo, Andrea
    Lindbergh, Göran
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Lagergren, Carina
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Applied Electrochemistry.
    Engvall, Klas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Integration of an electrolysis unit for producer gas conditioning in a bio-SNG plant2017In: 30th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2017, 2017Conference paper (Refereed)
    Abstract [en]

    Producer gas from biomass gasification contains impurities like tars, particles, alkali salts and sulfur/nitrogen compounds. As a result a number of process steps are required to condition the producer gas before utilization as a syngas and further upgrading to final chemicals and fuels. Here, we study the concept of using molten carbonate electrolysis cells (MCEC) both to clean and to condition the composition of a raw syngas stream, from biomass gasification, for further upgrading into SNG. A mathematical MCEC model is used to analyze the impact of operational parameters, such as current density, pressure and temperature, on the quality and amount of tailored syngas produced. Investment opportunity is evaluated as an economic indicator of the processes considered. Results indicate that the production of SNG can be boosted by approximately 50% without the need of an additional carbon source, i.e. for the same biomass input as in standalone operation of the GoBiGas plant.

  • 11.
    Montecchio, Francesco
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Fluid dynamics model development for scaling-up UV reactors in VOC abatement applicationsManuscript (preprint) (Other academic)
    Abstract [en]

    The present work focuses on the treatment of VOC emissions from industrial processes, since they represent a very severe environmental hazard. For removing the VOC, an AOP (Advanced Oxidation Process) stage based on UV light and ozone was considered, analyzing the methods for the unit scale-up. An innovative CFD (Computational Fluid Dynamics) model, combining UV irradiation, reaction kinetics and fluid dynamics, describing the behavior of UV reactors in the laboratory scale, was developed. This model was verified against experimental results, displaying good agreement. Therefore, we concluded the CFD model could adequately describe relevant features regarding the performance of UV reactors. After analyzing the laboratory reactors, two designed and scaled up prototypes, were simulated using the CFD model. While the first prototype has a standard lamps configuration, the second presents an innovative lamps distribution. As for the laboratory cases, the most relevant features in terms of irradiation and reaction were described for the prototypes, comparing their performance. We evaluated both the overall VOC conversion and VOC conversion per UV lamp, analyzing the energy efficiency of each configuration with adequately accuracy. Therefore, we conclude the CFD model to be an important tool for reactor scale-up as a result of the good prediction of experimental results and the accurate description of the governing phenomena. By using the developed model, the scale-up process of UV reactors can be quickly improved, by screening various configurations with the simulator before testing them, saving significant time and effort in the development of full-scale reactors.

  • 12.
    Montecchio, Francesco
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Process Optimization of UV-Based Advanced Oxidation Processes in VOC Removal Applications2018Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Air pollution is a major concern in developed countries due to its hazardous health effects. Recent studies by the WHO (World Health Organization) estimate that urban air pollution causes a number of diseases of the respiratory tract and is associated with 150,000 deaths each year. Volatile organic compounds (VOCs) are among the major pollutants affecting the outdoor air quality. Given that industrial processes are the main source of atmospheric VOC emissions, national and international authorities have issued regulations to limit such emissions. However, traditional removal technologies such as incineration, have low energy efficiency and high investment costs. AOPs (advanced oxidation processes) offer a promising alternative in which very reactive conditions can be achieved at room temperature, thus greatly increasing energy efficiency. However, this is still not a mature technology due to challenges that limit the range of applications.

    This thesis focuses on two types of UV-based AOP: photocatalysis and UV-ozone. The goal is to improve VOC conversion and achieve a process that is competitive with traditional technologies. The research on photocatalysis presents an innovative UV reactor design that is closer to industrial conditions and has the ability to effectively screen different samples. Effort was put into finding a metallic support for the photocatalyst without using additional adhesives. Several electrochemical treatments were performed on metals to restructure the surface. One treatment proved to be superior when it came to stabilizing the TiO2 coating, especially when compared with the traditional ceramic support.

    Research on UV-ozone AOPs focused on reactor modelling, developing a numerical and a fluid dynamics model. The goal was to gain a deep understanding of the governing phenomena of UV-ozone reactors so as to optimize the reactor configuration. The numerical model created described the UV irradiation and the reaction kinetics accurately, while a computational fluid dynamics (CFD) simulator modelled the fluid a larger scale, simulating two prototypes. The work resulted in general guidelines for the design of UV-ozone UV reactors as well as for full-scale units. 

  • 13.
    Montecchio, Francesco
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering. KTH, Dept Chem Engn, SE-10044 Stockholm, Sweden..
    Altimira, Mireia
    KTH, School of Engineering Sciences (SCI), Mechanics.
    Andersson, Anna
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Engvall, Klas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Fluid dynamics modelling of UV reactors in advanced oxidation processes for VOC abatement applications2019In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 369, p. 280-291Article in journal (Refereed)
    Abstract [en]

    The present work focuses on the treatment of VOC emissions from industrial processes, since they represent a very severe environmental hazard. For removing the VOC, an AOP (Advanced Oxidation Process) stage based on UV light and ozone was considered, analyzing the methods for the unit scale-up. An innovative CFD (Computational Fluid Dynamics) model, combining UV irradiation, reaction kinetics and fluid dynamics, describing the behavior of UV reactors in the laboratory scale, was developed. This model was verified against experimental results, displaying good agreement. Therefore, we concluded the CFD model could adequately describe relevant features regarding the performance of UV reactors. After analyzing the laboratory reactors, two designed and scaled up prototypes, were simulated using the CFD model. While the first prototype has a standard lamps configuration, the second presents an innovative lamps distribution. As for the laboratory cases, the most relevant features in terms of irradiation and reaction were described for the prototypes, comparing their performance. We evaluated both the overall VOC conversion and VOC conversion per UV lamp, analyzing the energy efficiency of each configuration with adequately accuracy. Therefore, we conclude the developed CFD model to be an important tool for reactor scale-up as a result of the good prediction of experimental results and the accurate description of the governing phenomena. By using the developed model, the scale-up process of UV reactors can be quickly improved, by screening various configurations with the simulator before testing them, saving significant time and effort in the development of full-scale reactors.

  • 14.
    Moud, Pouya H.
    et al.
    KTH, School of Biotechnology (BIO), Theoretical Chemistry and Biology.
    Andersson, Klas
    Haldor Topsoe Res Labs, Lyngby, Denmark..
    Engvall, Klas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Biomass-derived gas-phase alkali as a tar reforming catalyst promoter in sulfur-laden biomass gasification gas2016In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 251Article in journal (Other academic)
  • 15.
    Moud, Pouya H.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Granestrand, Jonas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Dahlin, Sandra
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Nilsson, Marita
    Scania CV AB, Mat Technol Engine Performance & Emiss, Sodertalje, Sweden..
    Andersson, Klas
    Haldor Topsoe Res Labs, Lyngby, Denmark..
    Pettersson, Lars J.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Engvall, Klas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Role of alkali in heterogeneous catalysis for gas cleaning in stationary and mobile applications2015In: Abstracts of Papers of the American Chemical Society, ISSN 0065-7727, Vol. 249Article in journal (Other academic)
  • 16.
    Musavi, Zari
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Kusar, Henrik
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Andersson, R.
    Engvall, Klas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Modelling and optimization of a small diesel burner for mobile applications2018In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 11, no 11, article id 2904Article in journal (Refereed)
    Abstract [en]

    While extensive research has been done on improving diesel engines, much less has been done on auxiliary heaters, which have their own design challenges. The study analyzes how to optimize the combustion performance of an auxiliary heater, a 6 kW diesel burner, by investigating key parameters affecting diesel combustion and their properties. A model of a small diesel heater, including a simulation of fuel injection and combustion process, was developed step-wise and verified against experimental results that can be used for scaling up to 25 kW heaters. The model was successfully applied to the burner, predicting the burner performance in comparison with experimental results. Three main variables were identified as important for the design. First, it was concluded that the distance from the ring cone to the nozzle is essential for the fluid dynamics and flame location, and that the ring cone should be moved closer to the nozzle for optimal performance. Second, the design of the swirl co-flow is important, and the swirl number of the inlet air should be kept above 0.6 to stabilize the flame location for the present burner design. Finally, the importance of the nozzle diameter to avoid divergent particle vaporization was pointed out.

  • 17. Neugebohren, J.
    et al.
    Borodin, D.
    Hahn, H. W.
    Altschäffel, J.
    Kandratsenka, A.
    Auerbach, D. J.
    Campbell, C. T.
    Schwarzer, D.
    Harding, Dan J.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology. University of Goettingen, Göttingen, German.
    Wodtke, A. M.
    Kitsopoulos, T. N.
    Velocity-resolved kinetics of site-specific carbon monoxide oxidation on platinum surfaces2018In: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 558, no 7709, p. 280-283Article in journal (Refereed)
    Abstract [en]

    Catalysts are widely used to increase reaction rates. They function by stabilizing the transition state of the reaction at their active site, where the atomic arrangement ensures favourable interactions 1. However, mechanistic understanding is often limited when catalysts possess multiple active sites - such as sites associated with either the step edges or the close-packed terraces of inorganic nanoparticles 2-4 - with distinct activities that cannot be measured simultaneously. An example is the oxidation of carbon monoxide over platinum surfaces, one of the oldest and best studied heterogeneous reactions. In 1824, this reaction was recognized to be crucial for the function of the Davy safety lamp, and today it is used to optimize combustion, hydrogen production and fuel-cell operation 5,6. The carbon dioxide products are formed in a bimodal kinetic energy distribution 7-13 ; however, despite extensive study 5, it remains unclear whether this reflects the involvement of more than one reaction mechanism occurring at multiple active sites 12,13. Here we show that the reaction rates at different active sites can be measured simultaneously, using molecular beams to controllably introduce reactants and slice ion imaging 14,15 to map the velocity vectors of the product molecules, which reflect the symmetry and the orientation of the active site 16. We use this velocity-resolved kinetics approach to map the oxidation rates of carbon monoxide at step edges and terrace sites on platinum surfaces, and find that the reaction proceeds through two distinct channels 11-13 : it is dominated at low temperatures by the more active step sites, and at high temperatures by the more abundant terrace sites. We expect our approach to be applicable to a wide range of heterogeneous reactions and to provide improved mechanistic understanding of the contribution of different active sites, which should be useful in the design of improved catalysts.

  • 18.
    Paulraj, Alagar R.
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Kiros, Yohannes
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    La0.1Ca0.9MnO3/Co3O4 for oxygen reduction and evolution reactions (ORER) in alkaline electrolyte2018In: Journal of Solid State Electrochemistry, ISSN 1432-8488, E-ISSN 1433-0768, p. 1-14Article in journal (Refereed)
    Abstract [en]

    Non-precious metal bifunctional catalysts are of great interest for metal–air batteries, electrolysis, and regenerative fuel cell systems due to their performance and cost benefits compared to the Pt group metals (PGM). In this work, metal oxides of La0.1Ca0.9MnO3 and nano Co3O47 catalyst as bifunctional catalysts were used in oxygen reduction and evolution reactions (ORER). The catalysts were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and N2 adsorption isotherms. The electrocatalytic activity of the perovskite-type La0.1Ca0.9MnO3 and Co3O4 catalysts both as single and mixtures of both were assessed in alkaline solutions at room temperature. Electrocatalyst activity, stability, and electrode kinetics were studied using cyclic voltammetry (CV) and rotating disk electrode (RDE). This study shows that the bifunctional performance of the mixed La0.1Ca0.9MnO3 and nano Co3O4 was superior in comparison to either La0.1Ca0.9MnO3 or nano Co3O4 alone for ORER. The improved activity is due to the synergistic effect between the La0.1Ca0.9MnO3 and nano Co3O4 structural and surface properties. This work illustrates that hybridization between these two metal oxides results in the excellent bifunctional oxygen redox activity, stability, and cyclability, leading to a cost-effective application in energy conversion and storage, albeit to the cost of higher catalyst loadings.

  • 19.
    Paulraj, Alagar Raj
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Studies on Rechargeable Fe-air electrodes in Alkaline electrolyte2019Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Energy storage system is an important component in the energy system based on variable renewable energy sources into the grid. Energy storage system could contribute to decarbonization, energy security, offset the demand and supply of the electricity sector, especially for the electric grid. These can be either mechanical, electrochemical, chemical, electromagnetic or thermal devices. The most important functional characteristics of an energy storage system are capital cost, roundtrip efficiency, energy and power rating, response times and cycle life. Electrochemical energy storage systems (EES) have the following edge over the other systems: fast response time, relatively short duration of storage, size, high efficiency, a decentralized installation which is closer to generation or consumption site.

    The focus of this thesis is on the development of cost-effective iron anode materials and electrocatalytic air electrodes for Fe-air batteries that potentially could become as an energy storage system. Iron-based systems are attractive due to their safety, cheapness, non-toxicity and ubiquitous availability of materials. However, both the anode and cathode parts have numerous drawbacks that need to be addressed. The anode exhibits poor charge efficiency, rate capability and low capacity utilization while the cathode has sluggish kinetics, poor activity, structural stability and the numbers of active non-noble metal catalysts are limited.

    This work utilized Cu and Sn-doped iron nanomaterials and different additives (Bi2S3, CNT, LiOH) to enhance the performance of the iron electrode. The performance of the electrodes were evaluated using the charge/discharge cycling, rate capability, cyclic voltammetry (CV), galvanostatic and potentiodynamic polarization measurements, in operando charging measurements combined with mass spectrometry. The fresh and cycled electrodes and powders were characterized by ex-situ XRD, BET, SEM, TEM , XPS and Raman spectroscopy. The most striking results are the prevention of nanoparticle agglomeration, increased charging efficiency (80-91%), effect of Cu and Sn dopants on specific capacity (367-603 mAh g-1) and improved performance of the electrodes at high charge current densities.

    In the subsequent air electrode part, non-precious metal La-doped CaMnOx, nano Co3O4 and NiFeOX electrocatalysts were synthesized using co-precipitation and hydrothermal methods. Both the single and mixed catalysts were used as bi-functional catalysts for oxygen reduction and evolution reactions (ORER). The catalysts were characterized by XRD, SEM, TEM, BET, Raman and XPS. The electrocatalytic activity and stability were assessed in alkaline solutions on gas diffusion electrodes and glassy carbon electrode by linear sweep voltammetry (LSV), CV and rotating disk electrode (RDE). Furthermore, the mixed catalyst and NiFeOX showed excellent bifunctional performance such as high activity and stability achieved by the hybridization of the two catalysts and the effect of catalyst loading on the electrocatalytic performance. These findings can help to develop a cost-effective material for Fe-air batteries.

  • 20.
    Paulraj, Alagar Raj
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Kiros, Yohannes
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Chamoun, Mylad
    Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden.
    Svengren, Henrik
    Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden.
    Noréus, Dag
    Department of Materials and Environmental Chemistry, Stockholm University, SE-106 91 Stockholm, Sweden.
    Göthelid, Mats
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Skårman, Björn
    Höganäs AB, SE-263 83 Höganäs, Sweden.
    Vidarsson, Hilmar
    Höganäs AB, SE-263 83 Höganäs, Sweden.
    Johansson, Malin B
    Division of Physical Chemistry, Department of Chemistry, The Ångström Laboratory, Uppsala University, P.O. Box 523, SE-75120 Uppsala, Sweden.
    Electrochemical Performance and in Operando Charge Efficiency Measurements of Cu/Sn-Doped Nano Iron Electrodes2019In: Batteries, E-ISSN 2313-0105, no 1Article in journal (Other academic)
    Abstract [en]

    Fe-air or Ni-Fe cells can offer low-cost and large-scale sustainable energy storage. At present, they are limited by low coulombic efficiency, low active material use, and poor rate capability. To overcome these challenges, two types of nanostructured doped iron materials were investigated: (1) copper and tin doped iron (CuSn); and (2) tin doped iron (Sn). Single-wall carbon nanotube (SWCNT) was added to the electrode and LiOH to the electrolyte. In the 2 wt. % Cu + 2 wt. % Sn sample, the addition of SWCNT increased the discharge capacity from 430 to 475 mAh g−1, and charge efficiency increased from 83% to 93.5%. With the addition of both SWCNT and LiOH, the charge efficiency and discharge capacity improved to 91% and 603 mAh g−1, respectively. Meanwhile, the 4 wt. % Sn substituted sample performance is not on par with the 2 wt. % Cu + 2 wt. % Sn sample. The dopant elements (Cu and Sn) and additives (SWCNT and LiOH) have a major impact on the electrode performance. To understand the relation between hydrogen evolution and charge current density, we have used in operando charging measurements combined with mass spectrometry to quantify the evolved hydrogen. The electrodes that were subjected to prolonged overcharge upon hydrogen evolution failed rapidly. This insight could help in the development of better charging schemes for the iron electrodes.

  • 21. Ruivo, L.
    et al.
    Yaremchenko, A.
    Engvall, Klas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Kantarelis, Efthymios
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Frade, J.
    Tarelho, L.
    Catalytic upgrading of biomass-derived raw gas in fluidized bed gasifiers2019In: European Biomass Conference and Exhibition Proceedings, ETA-Florence Renewable Energies , 2019, p. 551-558Conference paper (Refereed)
    Abstract [en]

    Natural ilmenite has been proposed as potential low-cost catalyst for biomass gasification due to its mechanical stability and thermochemical properties at high temperature. Previously works demonstrated that ilmenite showed high activity in water-gas shift reactions, but its limited catalytic activity in tar conversion requires improved performance. Therefore, the present work is focused on synthesis of synthetic catalyst based on Fe-Ti-Ni-O system, testing of their catalytic activity, and detailed studies of relevant factors such as structural and microstructural features and redox behavior under gasification conditions. Thermodynamic predictions were performed to assess expected thermochemical conditions required for the synthesis of catalyst, and the corresponding stability windows in prospective catalytic operation. A simple approach based on microwave irradiation was applied in the preparation of the catalyst, revealing a high potential for reducing production costs. Preliminary catalytic testing using model tar compounds demonstrated that the synthesized catalyst shows enhanced performance for conversion of tar impurities through steam reforming reaction.

  • 22.
    Solis Valdivia, Jerry Luis
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Conversion processes for biofuel production2019Doctoral thesis, monograph (Other academic)
    Abstract [en]

    Despite the global positive impacts of soybean-, maize- and sugarcane-based (first-generation) liquid biofuels, several drawbacks pertaining to increased use of agricultural land, causing deforestation in some countries and extensive practice of fertilizers have been observed. As a result, developing advanced (second- and third-generation) liquid biofuels have been identified as better alternatives and are considered to be of great importance in the future. These alternative biofuels will help to meet the energy demand by transition to ameliorate and fulfil the energy demand, especially in the transport sector.The actual energy demand for fossil fuels in Bolivia is unsustainable due to its continuous increase. Bolivia has its own fossil fuel resources, but these still fall short of demand, forcing the government to budget for yearly fuel imports. This situation has prompted attempts to achieve energy independence through the production of biofuels. However, it is important that Bolivian energy independence endeavours include a sustainable vision. Bolivia has great potential for local first- and second-generation liquid biofuel production. However, the intensification of liquid biofuel production should focus on second- and third-generation biofuel production to minimize direct and indirect undesired impacts.This thesis considers the development of suitable technology and procedures to produce second-generation liquid biofuels, which can be divided into biodiesel and ethanol production. The proposed biodiesel production includes the development of heterogeneous catalysts that enable the production of biodiesel from edible and non-edible oils (i.e. rapeseed, babassu, and Ricinus oils). These heterogeneous catalysts are based on gel-based mayenite and alumina supports with the co-precipitation of metal oxides of calcium, lithium, magnesium and tin. The synthesized catalysts were characterized using, N2 physisorption, X-ray powder diffraction, scanning electron microscopy, and thermogravimetric analysis (TGA). The experimental design and optimum results indicate that heterogeneous biodiesel production is feasible, being able to produce biodiesel yields ranging from 85% to 100%. Ethanol production was studied using the residues of Schinus molle seeds after the essential oil extraction process, which is available in excess in Bolivia. The biomass was characterized to elucidate its properties using high-performance liquid chromatography and TGA. The biomass was pre-treated with chemical, physical, andVIenzymatic hydrolysis to increase the fermentation yield. To obtain the highest ethanol production, two native yeast strains were isolated and characterized. By using native yeast strains, a high content of ethanol per gram of biomass was achieved. The proposed implementation of the fermentation process could result in a significant global warming potential reduction. The implementation of heterogeneous catalysts to produce biodiesel and residual lignocellulosic biomass to produce ethanol represent a great potential to supply the Bolivian fuel demand. High biodiesel and ethanol yields from second-generation feedstocks are feasible and could help reduce pollution levels and import dependency.

  • 23.
    Soroka, Inna
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Bjervås, Jens
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Ceder, J.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Wallnerström, G.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Connan, Mallory
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH).
    Tarakina, N. V.
    Maier, Annika Carolin
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemistry, Applied Physical Chemistry.
    Kiros, Yohannes
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Particle size effect of Ag-nanocatalysts deposited on carbon as prepared by γ-radiation induced synthesis2019In: Radiation Physics and Chemistry, ISSN 0969-806X, E-ISSN 1879-0895, article id 108370Article in journal (Refereed)
    Abstract [en]

    The effect of silver particle sizes on the catalytic performance of Ag/C electrodes for oxygen reduction reaction (ORR) was studied. The Ag particles were precipitated from AgNO3 solutions on Vulcan XC-72 carbon as support by γ-radiation induced synthesis method. The structural and morphological characterizations of the electrode materials were done by X-ray diffraction (XRD) and transmission electron microscopy (TEM). It was found that particles with smaller diameters, 11 ± 6 nm, possess higher catalytic activity for ORR (50 mA/cm2 at 0.3 V) as compared to those with larger diameters, 41 ± 5 nm, ORR activity is 25 mA/cm2 at 0.3 V. The observed effect may be explained by an increased amount of low coordinated atoms in smaller particles as compared to the larger ones.

  • 24.
    Wan, Wei
    et al.
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Engvall, Klas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Weihong, Yang
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Novel Model for the Release and Condensation of Inorganics for a Pressurized Fluidized-Bed Gasification Process: Effects of Gasification Temperature2018In: ACS OMEGA, ISSN 2470-1343, Vol. 3, no 6, p. 6321-6329Article in journal (Refereed)
    Abstract [en]

    A model is established to investigate the release and condensation of inorganics for a wood steam/oxygen-blown fluidized-bed gasification process. In the established model, fates of major elements (C, H, O, N, S, and Cl) and minor elements (Al, Ca, Fe, K, Mg, Mn, Na, P, Si, Ti, and Zn) are modeled separately. The composition of gaseous species involving major elements is predicted using Aspen Plus based on a semiempirical model. The release of minor elements and the condensation of inorganics are predicted using software SimuSage. The combination of Aspen Plus with SimuSage is achieved by manually inputting the stream parameters calculated from Aspen Plus into SimuSage. On the basis of this developed model, effects of gasification temperature on the condensation of Na-, K-, and Cl-containing species during gas cooling are studied. Results show that the process model established by combining Aspen Plus and SimuSage is valid and can be used to investigate the release of inorganics during gasification and condensation of inorganics during gas cooling. Under the investigated gasification conditions, regardless of the bed material, there are two temperature ranges within which no salt melt is formed during gas cooling. As the gasification temperature increases, the high-temperature range without salt melt formation becomes successively wider.

  • 25.
    Wan, Wei
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Engvall, Klas
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering, Process Technology.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Möller, Bjorn Fredriksson
    EON Gas Sverige AB, SE-20509 Malmo, Sweden..
    Experimental and modelling studies on condensation of inorganic species during cooling of product gas from pressurized biomass fluidized bed gasification2018In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 153, p. 35-44Article in journal (Refereed)
    Abstract [en]

    In a biomass gasification process, condensation of inorganic species can cause problems such as corrosion and deposition on the downstream equipment. In this work, in order to investigate the condensation of inorganics during the gas cooling step of the biomass gasification system, both experimental and modelling studies were conducted. Experiments were performed on a pilot-scale steam/oxygen blown fluidized bed gasification facility. A CO2 cooled probe was located at the head of a filter to condense inorganic species. Five thermocouples were used to monitor the probe temperature profile. Deposits on the probe were characterized using scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS) to analyze the elemental composition of deposits. A process model based on the local chemical and phase equilibriums was developed using software SimuSage to predict both release and condensation of inorganics. A customized thermodynamic database extracted from the FactSage 7.1 was used during model calculations. Two cases including with and without addition of bed material were calculated. Results show that the identified elemental compositions of deposit under different gas cooling temperatures reasonably agree with the elemental compositions predicted by model calculations. This demonstrates that the established model and the customized thermodynamic data are valid. A large amount of carbon is identified in the deposit of low temperature probe sections, which may come from the condensed tar. Additionally, a temperature window is found, where melts are formed during gas cooling.

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