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  • 1.
    Evangelopoulos, Panagiotis
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Arato, Samantha
    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.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Reduction of brominated flame retardants (BFRs) in plastics from waste electrical and electronic equipment (WEEE) by solvent extraction and the influence on their thermal decompositionIn: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456Article in journal (Refereed)
    Abstract [en]

    Consumption of electronics increases due to modern society’s growing needs, which leads to increasing generation of waste electrical and electronic equipment (WEEE). Recycling of WEEE has been a global concern during the last few decades because of the toxic compounds that are produced during recycling. Different recycling techniques have been adapted on a commercial scale in order to overcome this issue, but the recycling of WEEE still lacks the technology to treat different kinds of feedstocks and to maximise the recycling rates. Pyrolysis is an alternative that has not been commercialised yet. One of the challenges for the implementation of this technology is the toxic brominated organic compounds that can be found in the pyrolysis oils.

    In this study, tetrabromobisphenol A (TBBPA), one of the major flame retardants, is reduced in three different WEEE fractions through solvent extraction as a treatment prior to pyrolysis. Two solvents have been experimentally investigated: isopropanol and toluene, the latter of which can be derived from pyrolysis oil. The results indicate that TBBPA was extracted during pre-treatment. Moreover, the total bromine content of WEEE material was reduced after the treatment with a maximum reduction of 36.5%. The pyrolysis experiments indicate that reduction of several brominated organic compounds was achieved in almost all the tested cases, and two brominated compounds (2,4,6-tribromophenol and 2,5-Dibromobenzo(b)thiophene) reached complete removal. Also, the thermal decomposition behaviour of the raw samples and the treated was investigated, showing that the reduction of TBBPA influences the decomposition by shifting the starting decomposition temperature.

  • 2. 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.

  • 3.
    Han, Tong
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Sophonrat, Nanta
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Evangelopoulos, Panagiotis
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Persson, Henry
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Weihong, Yang
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Evolution of sulfur during fast pyrolysis of sulfonated Kraft lignin2018In: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 33, p. 162-168Article in journal (Refereed)
    Abstract [en]

    Sulfonated Kraft lignin, the most available commercial lignin of today, has high sulfur content due to the extraction and the subsequent sulfonation processes. In this work, the evolution of sulfur during fast pyrolysis of sulfonated Kraft lignin has been studied. Fast Pyrolysis experiments have been done using Py-GC/MS. It is found that main sulfur-containing products in the pyrolytic vapors are present as the following small molecular compounds: H2S, SO2, CH3SH, CH3SCH3, and CH3SSCH3. This indicates that sulfur-containing radicals preferentially combine with the other small radicals such as H and CH3 during fast pyrolysis process. Sulfur is suggested to be mainly present as sulfite (SO3) and sulfide (S) in the sulfonated Kraft lignin. Sulfite that is incorporated into lignin during the sulfonation process mainly result in the formation of SO2. The nature of the sulfur links created during the Kraft pulping process is difficult to determine, but they are supposed to mainly exist in form of sulfide (S) bonds, which lead to the formation of H2S, CH3SH, CH3SCH3 and CH3SSCH3.

  • 4.
    Montecchio, Francesco
    et al.
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Persson, Henry
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Engvall, Klas
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology, Chemical Technology.
    Delin, Jack
    Scandinavian Centriair AB, Sweden.
    Lanza, Roberto
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Development of a stagnation point flow system to screen and test TiO2-based photocatalysts in air purification applications2016In: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 306, p. 734-744Article in journal (Refereed)
    Abstract [en]

    An innovative system suitable for the abatement of VOCs (Volatile Organic Compounds), using photo catalysis under UV light, was designed and built. The design of the reactor is based on the stagnation point flow geometry and the fluid dynamics of the system was carefully investigated in order to avoid mass transfer limitations. The proportions of the elements in the reactor were adjusted in order to homogenize the UV irradiation on the catalyst surface. The supports used for the coating of the catalysts were aluminum plates in order to accurately reproduce industrial conditions. After each test, the catalytic plate was examined to evaluate the mechanical strength of the bonding between the catalyst powder and the metallic support. The coating proved to be sufficiently stable for tests in the designed set up. The potential scale-up of the features of the system was considered throughout the design and especially the power of the UV lamps was decided in order to be representative of the industrial cases. In order to evaluate the suitability of the system for catalysis investigations, various photocatalysts, both synthesized and commercial, were screened. Analyzing the activity results, using acetyl aldehyde as a model VOC, it was possible to evaluate clear differences between the samples and P90 proved to be the most active sample. All the aspects investigated in this work demonstrate that the design of the reactor is in accordance with the expectations and that the system is suitable for screening and testing of photocatalysts for VOCs removal applications.

  • 5.
    Persson, Henry
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Duman, Isa
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Wang, Shule
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Pettersson, Lars
    KTH, School of Engineering Sciences in Chemistry, Biotechnology and Health (CBH), Chemical Engineering.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Catalytic pyrolysis over transition metal-modified zeolites: a comparative study between catalyst activity and deactivation2019In: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 138, p. 54-61Article in journal (Refereed)
    Abstract [en]

    The utilization of metal-doped zeolites in catalytic pyrolysis of biomass is a well-known approach to promote the formation of certain compounds. One major technical issue of using zeolites in biomass pyrolysis processes is their rapid deactivation due to coke formation. However, little is known about how metal-doping influences the characteristics of coking, such as coking rate and its composition.

    In this study, four different materials were experimentally evaluated based on their catalytic activity and coking characteristics: HZSM-5, Fe/ZSM-5, Ni/ZSM-5 and FeNi/ZSM-5. The materials were prepared and characterized followed by screening in a bench-scale setup for in-situ catalytic pyrolysis. The mass balance and composition of pyrolysis products including catalyst coke were analyzed.

    It was found that metal-doping increases the concentration of aromatic hydrocarbons in the liquid product from 59.0 to 82.8 % of GC/MS peak area, especially monoaromatic hydrocarbons (MAHs) and naphthalenes. Fe mainly promotes MAHs whereas Ni additionally promotes naphthalenes. FeNi/ZSM-5 enhances the production of both compound groups as well as further reducing the total acid number (TAN). Regarding the catalyst coke, metal-doped catalysts present an increased concentration of aromatic hydrocarbons in terms of MAHs, naphthalenes and polyaromatic hydrocarbons. For each catalyst, the chemical composition of catalyst coke reflects the catalyst’s activity seen in vapor upgrading. A reaction pathway based on the observed catalyst activities of metal-doped ZSM-5 and HZSM-5 is proposed.

    The results also show that metal-doping of catalysts increases the formation of catalyst coke, mainly due to a higher concentration of strong acid sites. Also, the rate of coking is dependent on the strength of acid sites, where the strength correlates with the severity of coking. The coke yield was seen to increase from 3.5 wt% in the case of HZSM-5 to maximum 7.2 wt% over Fe/ZSM-5. However, the metal-doping of catalysts reduces the temperature of catalyst regeneration and catalyzes the oxidation of coke. Overall, this work presents a comparative study between catalyst activity and deactivation during thermochemical conversion of biomass.

  • 6.
    Persson, Henry
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Evangelopoulos, Panagiotis
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Svanberg, Rikard
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Weihong, Yang
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Two-step pyrolysis of biomass to enhance the chemical stability of pyrolytic liquids2017In: European Biomass Conference and Exhibition Proceedings 2017, ETA-Florence Renewable Energies , 2017, Vol. 7, no 25thEUBCE, p. 1186-1189Conference paper (Refereed)
    Abstract [en]

    Aging of pyrolytic liquid during storage changes its chemical and physical properties. The reason for aging is the chemical instability of the liquid, which is not at thermodynamic equilibrium when quenched after pyrolysis. Compounds active in these reactions mainly derivatives from hemicellulose (e.g. acids and carbonyls). In this work, a two-step pyrolysis concept was investigated to separate these compounds in a lower temperature treatment step upstream a conventional pyrolyzer. Different temperatures of the lower temperature treatment was investigated with constant conditions of the conventional treatment. The total liquid yield derived did not vary from pyrolysis in one step. Results show that the two-step pyrolysis process significantly reduces the concentration of organic acids and carbonyls in the liquid product from the second pyrolyzer, which instead are found in the liquid from the lower temperature treatment. Also, the concentration of sugar derivatives from the second step treatment is increased with the temperature of the first step. However, a complete separation of aging active compounds is not possible without sacrificing partial fractions of others (lignin derivatives were found in the low-temperature treatment). By varying the temperature of the first step one can control the concentrations and the liquid yield from each step.

  • 7.
    Persson, Henry
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Gulshan, Samina
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Svanberg, Rikard
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Production of renewable aromatic hydrocarbons by ex-situ catalytic fast pyrolysis of biomass in a combined fluidized bed and fixed bed reactor systemManuscript (preprint) (Other academic)
    Abstract [en]

    An ex-situ catalytic fast pyrolysis lab-scale setup consisting of a fluidized bed pyrolyzer and a fixed bed catalytic reactor was experimentally evaluated. The effect of weight hourly space velocity was investigated in the range of 0.35-0.77 h-1 during 260 min of operation. A lower biomass feed rate over a fixed amount of catalyst results in a higher degree of vapor deoxygenation (from 71 to 79.5 wt%) as well as higher concentrations of aromatic hydrocarbons. The carbon conversion from biomass to upgraded liquids is negatively correlated with the aromatic concentrations. Online gas analysis present no significant changes in the catalytic performance during the operational time. The results of this study indicate that the difference in liquid deoxygenation observed when varying the biomass feed rate is dependent on the vapor concentration in the gas stream over the catalytic bed rather than being significantly affected by catalyst deactivation during operation.

  • 8.
    Persson, Henry
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Han, Tong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Xia, Wei
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Evangelopoulos, Panagiotis
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Weihong, Yang
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Fractionation of liquid products from pyrolysis of lignocellulosic biomass by stepwise thermal treatment2018In: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 154, p. 346-351Article in journal (Refereed)
    Abstract [en]

    The thermal properties of cellulose, hemicellulose and lignin can be utilized to improve the characteristics of pyrolysis liquids. In this study, a concept of stepwise pyrolysis to fractionate the liquid based on the thermal properties of the biomass constituents was investigated. Lignocellulosic biomass was thermally treated in two steps: 200–300 °C followed by 550 °C. Derived liquids were studied for GC/MS analysis, water content, acid concentration and a solvent extraction method. Pyrolytic liquid derived from 550 °C after treatment at lower temperatures have a higher relative composition of phenolic compounds compared to one-step pyrolysis (increased from 58 to 90% of GC/MS peak area). Also, compounds known to promote aging, such as acids and carbonyl compounds, are derived at lower temperatures which may suppress aging in the liquid derived downstream at 550 °C. For liquids derived at 550 °C, the total acid number was reduced from 125 in one-step treatment to 14 in two-step treatment. Overall, no significant difference in the total liquid yield (sum of the liquids derived in separated treatments) nor any variations in their collective composition compared to one-step treatment at 550 °C was observed, i.e. stepwise pyrolysis can be utilized for direct fractionation of pyrolytic vapors.

  • 9.
    Persson, Henry
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Kantarelis, Efthymios
    KTH, School of Chemical Science and Engineering (CHE), Chemical Engineering and Technology.
    Evangelopoulos, Panagiotis
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Wood-derived acid leaching of biomass for enhanced production of sugars and sugar derivatives during pyrolysis: Influence of acidity and treatment time2017In: Journal of Analytical and Applied Pyrolysis, ISSN 0165-2370, E-ISSN 1873-250X, Vol. 127, p. 329-334Article in journal (Refereed)
    Abstract [en]

    Inorganic matter in biomass (especially alkali and alkaline earth metals) acts like intrinsic catalysts during pyrolysis and influences the composition of derived liquids. In this work, the influence of acidity and time on leaching of inorganics with wood pyrolysis-derived acids was investigated in order to understand their effect on the biomass characteristics and the composition of pyrolysis products, as well as to study the mechanism of leaching of different inorganic elements. Aqueous solutions of 5 and 10. wt% acetic acid (main acid in pyrolysis products and in similar concentrations) were used for demineralizing softwood at 85. °C for 30-90. min. Biomass characteristics, composition of intrinsic inorganics and primary pyrolytic vapors from different pretreatment cases are presented. Results show that removal of inorganics was in all cases enhanced by higher acidity; time of treatment was only seen to have a positive effect at lower acidity. The volatile matter of biomass was not affected by the pretreatment, confirming the conditions investigated being relatively mild. Results from Py-GC/MS of leached biomass show an increased selectivity towards sugars and sugar derivatives and simultaneous suppression of the relative composition of carbonyls and phenolic compounds in derived vapors. Sugars and sugar derivatives was enhanced by increasing the leaching time at higher acidity, without seeing a clear correlation to removal of alkali and alkaline earth metals. It is therefore suggested that other factors might influence the pathway of formation of primary pyrolysis products than what has previously been suggested by others. Because of the enhanced production of sugars and sugar derivatives from pyrolysis of leached biomass, this procedure might serve as a pathway to be enable the utilization of pyrolytic liquids as feedstock for existing fermentation-based biorefineries.

  • 10.
    Persson, Henry
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Yang, Weihong
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering.
    Catalytic pyrolysis of demineralized lignocellulosic biomass2019In: Fuel, ISSN 0016-2361, E-ISSN 1873-7153, Vol. 252, p. 200-209Article in journal (Refereed)
    Abstract [en]

    The effect of ash removal pre-treatment of lignocellulosic biomass prior to catalytic pyrolysis for producingbiofuels was investigated. Non-catalytic and catalytic pyrolysis of demineralized and raw biomass was performedin Py-GC/MS and bench-scale experiments to study the performance of in-bed and ex-bed upgrading. Pretreatedbiomass shows a significant increase in the organic liquid yield in experiments performed at 600 °C: from31 to 42 wt% compared to raw biomass, as well as a significant reduction of char yield. The performance of inbedcatalytic pyrolysis of pre-treated biomass over HZSM-5 is limited compared to the corresponding raw material.However, ex-bed catalytic pyrolysis of pre-treated biomass at 600 °C results in an overall increased yield ofBTX compounds. Pyrolysis vapors from pre-treated biomass present a suitable composition for catalytic upgradingafter secondary vapor-phase reactions. Additionally, demineralization reduces the total acid number ofderived liquids in catalytic and non-catalytic pyrolysis.

  • 11.
    Wang, Shule
    et al.
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Persson, Henry
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Weihong, Yang
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Jönsson, Pär
    KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
    Effect of H2 as Pyrolytic Agent on the Product Distribution during Catalytic Fast Pyrolysis of Biomass Using Zeolites2018In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029Article in journal (Refereed)
    Abstract [en]

    Bio-oil generated from catalytic fast pyrolysis or hydrotreating processes represents one of the most promising alternatives to liquid fossil fuels. The use of H2 as carrier gas in the pyrolysis of biomass requires further research to study the catalytic fast pyrolysis reactions in the case of using reactive atmosphere. In this work, pyrolysis experiments with lignocellulosic biomass have been performed in a fixed bed reactor in H2 and N2 atmospheres with/without HZSM-5 additions to investigate the influence of the pyrolytic agents during fast pyrolysis of biomass and upgrading of pyrolytic vapors over a zeolitic catalyst. It was found that in a H2 atmosphere, H2 was consumed in both noncatalytic and catalytic pyrolysis processes, respectively. Higher yields of nonaqueous liquids and permanent gases are obtained in a H2 atmosphere compared to a N2 atmosphere. A catalytic pyrolysis process using HZSM-5 in a H2 atmosphere increased the production of polymer aromatic hydrocarbons and suppressed the production of monomer aromatic hydrocarbons compared to similar tests performed in a N2 atmosphere. The results show an overall increased activity of HZSM-5 in the reactive H2 atmosphere compared to a N2 atmosphere.

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