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  • 301.
    Golets, Mikhail
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Samikannu, Ajaikumar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Blomberg, D.
    Processum Biorefinery Initiative AB, Örnsköldsvik, Sweden.
    Grundberg, H.
    Aditya Birla Domsjö Fabriker AB, Örnsköldsvik, Sweden.
    Wärnå, J.
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Salmi, T.
    Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Mikkola, Jyri-Pekka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Laboratory of Industrial Chemistry and Reaction Engineering, Process Chemistry Centre, Åbo Akademi University, Åbo-Turku, Finland.
    Liquid phase acetoxylation of α-pinene2012Inngår i: NWBC 2012: the 4th Nordic Wood Biorefinery Conference, VTT , 2012, s. 339-341Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Chemical pulping and bio-refining results in many fractions such as. tall oil and turpentine that contain substantial amounts of α-pinene and other terpenes. Today these fractions are usually burned in the recovery boilers. However, the northern forest industry, primarily utilizing the boreal forests, faces serious challenges from developing markets (South America, Asia), because of lower cost of raw material resources and labor. At the same time, there is a growing concern about emissions of greenhouse gases and security of supply connected to the use of fossil oil for transportation and as a feedstock for the chemical industry. The mentioned fact renders the substitution of petrochemical-related raw materials an important field of research.

    The flavor and fragrance industry is one of the main users of terpene esters. From those esters, α-terpinyl and bornyl acetates are produced from α-pinene and commonly used for bath products and perfumes. Due to the imperfection of conventional two-stage production method of the mentioned esters, which lays in the equipment corrosion, environmental pollution, large load and nonrecyclability of a catalyst, the novel one-stage catalytic process is always of high priority.

    The possibility of α-pinene liquid phase catalytic acetoxylation is introduced in the present study. The complex product distribution and reaction network analysis, influent reaction and catalytic factors optimization, combined with the reaction kinetic modeling were the main aims of research. The ion-exchange resin catalyst Amberlyst 70 was characterized as the catalyst used in the studied reaction and compared with the solvent-catalyzed mode. Valuable combinations of acetates were obtained for both studied modes. A wide range of process factors were studied in the batch (Parr) reactor used. The mentioned type of reactor is suitable for the consequent industrial operations scale-up calculations.

  • 302.
    González Guisasola, Carlos
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Temperature dependence of the electro-oxidation of D-glucose and D-sorbitol in a PEMFC2011Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The influence of temperature on the electro-oxidation of glucose and sorbitol has been studied in this work. The oxidation reaction was carried out on the anode of a direct sugar fuel cell with the help of a porous carbon supported Pt-RuO2 electrode. Temperature showed to increase cathodic current densities in the measurements of cyclic voltammetry. The direct glucose fuel cell constructed in the laboratory with Pt on carbon as cathode and PtRu/C as anode gave 8.6 mW/cm2 peak power density in 1M glucose at 800 C. In the case of sorbitol; 5.8 mW/cm2 were obtained. When compared with measurements in the literature, the results obtained in this study were ten times better, when normalized to the amount of Pt in the electrodes. Deactivation of catalyst was observed when using glucose and sorbitol. Activation procedures were tested on the membrane-electrode assembly to reverse catalyst poisoning.

  • 303.
    Goralski, Alma
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH).
    Removal of pharmaceutical residues from wastewater2019Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    Today, pharmaceutical residues are widely found in nature as a cause of the extensive use of human and veterinary medicine. The pharmaceutical residues have shown to have a damaging impact on flora and fauna. Wastewater Treatment Plants (WWTPs), today, are not designed for pharmaceutical removal, which calls for new methods and the implementation of these to avoid increased concentrations of pharmaceutical residues in nature.

    This thesis addresses three main areas. Firstly, a pre-study regarding the prevalence of pharmaceutical residues at different parts of a WWTP and in the nearby river, secondly, an evaluation of removal of pharmaceutical residues using ozone and, thirdly, the construction of a pilot plant scale Activated Carbon (AC) unit and an evaluation of its capacity for pharmaceutical and ozone removal. This work was done in order to verify the quality of a future full-scale unit including the advanced techniques ozone and AC that will be implemented at a WWTP for pharmaceutical removal.

    The pre-study shows that the total concentration of the Active Pharmaceutical Ingredients (APIs) was largest at the inlet (93.8 mg/L) and decreased throughout the process steps to be the lowest at the outlet (5.6 mg/L). Paracetamol was found in the highest concentration (86.5 mg/L) at the inlet but could not be detected in the outlet. In the recipient none of the APIs could be found. However, caffeine was detected in the recipient.

    The pilot plant studies were performed in a batch process, one at high ozone generation and one at low ozone generation. The pilot test at high ozone generation showed that all of the measured APIs were below their Limit of Quantification (LOQ) after 2 minutes. The pilot test at low ozone generation showed a total API-removal of 44% after 7 minutes, 78% after 13 minutes, 97% after 20 minutes and more than 99% after 60 minutes. All of the APIs were below their LOQ after 180 min.

    The AC-filter construction mirrored the conditions within a full-scale unit as closely as possible and was scaled by the superficial velocity. The AC-filter showed an ozone removal of approximately 99% and removed all pharmaceutical residues apart from Ranitidine which was decreased by 76%.

    Fulltekst (pdf)
    fulltext
  • 304.
    Gorski, Dmitri
    et al.
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för tillämpad naturvetenskap och design.
    Hill, Jan
    QualTech AB (Previously Norske Skog ASA), SE-282 21, Tyringe, Sweden.
    Improved quality of SC magazine paper through enhanced fibre development using the ATMP process2012Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, nr 1, s. 35-41Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A pilot scale refining trial was conducted using the ATMP (Advanced Thermomechanical Pulp) refining concept with White spruce as raw material. Low-intensity TMP and high-intensity TMP with mechanical pre-treatment of chips were compared to ATMP (Mg+P), where development of fibres was enhanced using hydrogen peroxide and magnesium hydroxide. The main goal of the trial was to evaluate the potential of using ATMP process for production of SC (supercalendered) magazine paper. SC paper is especially demanding when it comes to the paper surface structure which is strongly influenced by the development of fibre properties.

    Improvement in individual fibre properties such as flexibility, fibre split index and fibre surface area index achieved using ATMP process was found to translate into decreased surface roughness and air permeability of calendered laboratory sheets. Both the refining process configuration and the addition of process chemicals were found to have significant impacts though the process configuration had major role. The influence of process chemicals on PPS was mainly pronounced after second stage refining. The magnitude of surface roughening (fibre rising) was found to be influenced mainly by the process configuration.

    Fulltekst (pdf)
    Gorski_SC_magazine_paper
  • 305.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Development of a novel experimental technique for studying zeolites: combining zeolite coated ATR elements and FTIR spectroscopy2006Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Thin zeolite films have great potential in several novel application areas such as structured catalysts, membranes and sensors. To fully exploit the advantages of these films it is of great importance to determine the adsorption properties of the films. A powerful technique for studies of phenomena at surfaces or in thin films is FTIR/ATR-spectroscopy (Fourier Transform Infra Red / Attenuated Total Reflection). In this work, MFI zeolite films were prepared on ATR elements using two methods. One method produced 200 nm thick films with small crystals (<200nm). The other method was used for preparing b-oriented ZSM-5 films. These films were discontinuous and ca 420 nm thick and consisted of well intergrown, and substantially larger crystals, ca 1.1 ìm in diameter. Silicalite-1 coated elements were evaluated as gas sensors and the sensitivity for a hydrocarbon for zeolite-coated elements was compared with a standard 10 cm gas cell. The sensitivity was approximately 85 times higher for the coated elements at low hydrocarbon concentration. The response time was investigated by exposing the coated element to a step increase of an analyte and recording the response as a function of time. The response was relatively fast, equilibrium was achieved after approximately 250 s, but already after a few seconds, a strong signal could be detected. The coated elements were also used for determining single gas adsorption isotherms. The studied systems were n-hexane/silicalite-1, p-xylene/silicalite-1 and p-xylene/ZSM-5. The observed isotherms for temperatures between 323 and 423 K were typical for microporous materials with a fast increase of the amount adsorbed at low partial pressures. p-Xylene isotherms of type I were observed as opposed to the type IV isotherms reported in literature for powders. This difference was assigned to strain in the films and/or to reduced flexibility of the MFI framework when attached to a support. Further, some capillary condensation occurred at higher pressures in the films consisting of smaller crystals, which was assigned to condensation in open grain boundaries. Henry's constants and heats of adsorption determined from low-pressure data agreed well with previous reports. Measurements with polarized radiation revealed that p- xylene molecules are mainly oriented with their long axis in the b- direction of the crystals and it was also observed that some kind of rearrangement of n-hexane occurs with increasing loading, both of these findings were in agreement with previously reported results.

    Fulltekst (pdf)
    FULLTEXT01
  • 306.
    Grahn, Mattias
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Development of a novel zeolite coated ATR-FTIR sensor2004Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Thin zeolite films have great potential in several novel application areas such as: structured catalysts, membranes and sensors. To fully exploit the advantages of these films it is of great importance to determine the properties of the films. A powerful technique for studies of phenomena at surfaces or in thin films is FTIR/ATR-spectroscopy (Fourier Transform Infra Red / Attenuated Total Reflection). Furthermore, thin zeolite films may be utilized for enhanced selectivity and sensitivity for this technique. In this work films with a thickness of 200 nm of the zeolites ZSM-5 and silicalite-1 were grown on ZnSe, ZnS, ZrO2, Si and Ge ATR elements using a method that had been developed previously. The coated elements were evaluated in a gas sensor application by comparing the sensitivity for a hydrocarbon of zeolite-coated elements versus a standard 10 cm gas cell. The sensitivity was approximately 85 times higher for the coated elements compared to the gas cell at low hydrocarbon concentration. The response time was investigated by exposing the coated element to a step increase of an analyte and recording the response as a function of time. The response was relatively fast, equilibrium was achieved after approximately 250 s, but already after a few seconds a strong signal could be detected. The coated elements were also used to determine single gas adsorption isotherms. The systems studied were n-hexane/silicalite-1 and p-xylene/silicalite-1. Adsorption isotherms determined at varying temperatures were typical for microporous materials. Capillary condensation was observed at higher concentration of the adsorbent. Henry constants and heats of adsorption determined from low-pressure data agreed well with previously reported data in the literature.

    Fulltekst (pdf)
    FULLTEXT01
  • 307. Grahn, Mattias
    et al.
    Agarwal, Shilpa
    Luleå tekniska universitet.
    Holmgren, Allan
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    In-situ ATR-FTIR spectroscopy of structured zeolite H-ZSM-5 catalysts2010Konferansepaper (Annet vitenskapelig)
  • 308.
    Grahn, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Faisal, Abrar
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. Department of Chemical Engineering, COMSATS University Islamabad, Lahore Campus, Lahore, Pakistan.
    Öhrman, Olov G.W
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik. RISE ETC - Energy Technology Center, SE-941 28 Piteå, Sweden.
    Zhou, Ming
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Signorile, Matteo
    Department of Chemistry, NIS and INSTM Reference Centre, Università di Torino, Torino, Italy.
    Crocellà, Valentina
    Department of Chemistry, NIS and INSTM Reference Centre, Università di Torino, Torino, Italy.
    Nabavi, Mohammad Sadegh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Small ZSM-5 crystals with low defect density as an effective catalyst for conversion of methanol to hydrocarbons2020Inngår i: Catalysis Today, ISSN 0920-5861, E-ISSN 1873-4308, Vol. 345, s. 136-146Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This work presents the synthesis of nearly defect-free ZSM-5 nanosized crystals, prepared in fluoride medium by seeding with silicalite-1. This material was carefully characterized and its catalytic performances in the methanol to hydrocarbons (MTH) reaction were assessed. Such fluoride-based material was compared to a reference ZSM-5, produced through a conventional alkaline synthesis but from the same seeding. Despite both the materials show closely identical morphology and they have a comparable acid site population, the catalyst prepared using the fluoride route showed significantly longer lifetime in MTH compared to the catalyst prepared using conventional synthesis at high pH. The slower deactivation for the samples prepared using the fluoride route was ascribed, thanks to a thorough in situ IR spectroscopy study, to its lower density of internal defects. According to the UV-Raman characterization of coke on the spent catalyst, the fluoride-based ZSM-5 catalyst produces less molecular coke species, most probably because of the absence of enlarged cavities/channels as due to the presence of internal defects. On the basis of these observations, the deactivation mechanism in the ZSM-5 synthesized by fluoride medium could be mostly related to the deposition of an external layer of bulk coke, whereas in the alkali-synthesized catalyst an additional effect from molecular coke accumulating within the porous network accelerates the deactivation process.

  • 309.
    Grahn, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Kemiteknik.
    Maxwell-Stefan modelling of High flux tubular silicalite-1 membranes for CO2 removal from CO2/H2 gas mixtures2014Inngår i: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 471, s. 328-337Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, a Maxwell-Stefan model for high flux tubular silicalite-1 membranes for separation of CO2 from a CO2/H2 mixture was developed. The model concerns tubular membranes operating in a counter flow module and includes transport through flow-through defects in the silicalite-1 film and pressure drop over the graded alumina support. Adsorption and diffusion parameters for perfect silicalite-1 crystals were taken from literature. The flux and selectivity predicted by the model were in reasonably good agreement with experimentally observed data for a ZSM-5 membrane without any fitting of the model. However, the CO2 flux and selectivity measured experimentally for the ZSM-5 membrane were higher than that predicted by the model for a silicalite-1 membrane.The model was used to investigate a case with a 20 000 Nm3/d feed comprised of a 50/50 mixture of CO2/H2 at pressure of 25 bar and a membrane temperature of 296 K. The permeate pressure was 1 bar and 90% of the CO2 permeated the membrane. In this case, the membrane permselectivity and CO2 flux varied along the length of the tubes between 20–26 and 950–396 kg/(m2 h), respectively. Further, both defects and pressure drop over the support were shown to have an adverse effect on the selectivity, which indicates that membrane selectivity can be improved by reducing the flow-through defects and/or by preparing supports with less flow resistance. For a one-stage process, the required membrane area is as small as ca 0.85 m2 and the hydrogen loss through the membrane was 12.4%. For a two-stage process the required membrane area almost doubled to 1.6 m2, however the hydrogen loss through the second membrane is reduced to as little as 2.5%. In summary, this work shows that high flux zeolite membranes may be an interesting option for CO2 removal from synthesis gas.

  • 310.
    Grahn, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Holmgren, Allan
    Hedlund, Jonas
    Adsorption of n-hexane and p-xylene in thin silicalite-1 films studied by FTIR/ATR spectroscopy2008Inngår i: The Journal of Physical Chemistry C, ISSN 1932-7447, E-ISSN 1932-7455, Vol. 112, nr 20, s. 7717-7724Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Adsorption isotherms for p-xylene and n-hexane in silicalite-1 films with a thickness of 200 nm were determined at 323, 343, 368, 393, and 423 K using Fourier transform infrared/attenuated total reflection (FTIR/ATR) spectroscopy. For both adsorbates, the low-pressure data agreed with literature data for MFI powder and the estimated Henry's constant and adsorption enthalpy were close to previously reported results. The upper region of the n-hexane isotherm (p > 2 kPa at 323 K) was likely influenced by micropores in open grain boundaries, as expected for a polycrystalline film of small (<200 nm) crystals. As for n-hexane, the first part (0 ≤ p ≤ 65 Pa at 323 K) of the p-xylene isotherm agreed with data for powder. However, the saturation capacity was only about half of that previously reported for powders, which indicates that p-xylene molecules do not adsorb in the sinusoidal channels in the film. We speculate that the small crystals used in the present work may behave differently from the larger crystals in previous works. Another explanation for the lower saturation capacity may be the bonding of crystals to the supports, which are known to induce strain in the attached crystals.

  • 311.
    Grahn, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Lobanova, Antonia
    Luleå tekniska universitet.
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    A novel experimental technique for estimation of molecular orientation in zeolite2007Inngår i: Studies in Surface Science and Catalysis, ISSN 0167-2991, Vol. 170, s. 724-731Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    FTIR spectroscopy in combination with polarized light and an ATR probe coated with a b-oriented ZSM-5 film was for the first time used to determine the orientation of adsorbed molecules in the ZSM-5 structure. Two adsorbates were studied, n-hexane and p-xylene and the results agreed with previously reported results obtained by other experimental techniques.

  • 312.
    Grahn, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Lobanova, Antonina
    Luleå tekniska universitet.
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Hedlund, Jonas
    Luleå tekniska universitet.
    Orientational analysis of adsorbates in molecular sieves by FTIR/ATR spectroscopy2008Inngår i: Chemistry of Materials, ISSN 0897-4756, E-ISSN 1520-5002, Vol. 20, nr 19, s. 6270-6276Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    ZnS ATR elements were coated with well-defined b-oriented ZSM-5 films by in situ growth. Both adsorption isotherms, as well as molecular orientation of p-xylene adsorbed in the films, were measured at 323 and 373 K by FTIR/ATR spectroscopy. The observed isotherms for the b-oriented ZSM-5 films in the present work were very similar to previously reported isotherms of supported MFI films, albeit the crystals in the latter films were aluminum free (silicalite-1) and orientated differently relative to the support surface than the crystals in the films studied in the present work. The novel technique facilitated, for the first time, the examination of how the tilt angle varies with loading and temperature. The data obtained in the present work showed that the p-xylene molecules were mainly oriented with their long axis parallel to the b-direction of the MFI crystals in concert with previously reported results based on FTIR microscopy, Monte Carlo simulations, NMR, and XRD data. At high concentrations, the tilt angle was in good agreement with observations by FTIR microscopy. It was also found that the orientation of the molecules changed with loading, this might be due to different adsorption geometries in the channel intersection as reported previously. The observed tilt angles may also be influenced from competitive adsorption on silanol groups, as was also indicated in the spectra. The results also indicate that the adsorption properties of zeolite films and powders may differ. Hence, adsorption parameters determined for zeolite powders may not necessarily be applicable to films.

  • 313.
    Grahn, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik. SKF Engineering & Research Center, Nieuwegein, The Netherlands.
    Suarez, Aldara Naveira
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement. SKF Engineering & Research Center, Nieuwegein, The Netherlands.
    Pasaribu, Rihard
    SKF Engineering & Research Center, Nieuwegein, The Netherlands.
    Effect of ZDDP on friction and wear in fretting contacts2010Inngår i: 14th Nordic Symposium on Tribology: NORDTRIB 2010 : Storforsen, Sweden, June 8-11, 2010, Luleå: Luleå tekniska universitet, 2010Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The effect of ZDDP on fretting wear was investigated in a ball on flat machine. The results confirm previous work that anti-wear agents may reduce friction and wear in fretting contacts. It was further found that temperature, adsorption time and base oil polarity were all important parameters affecting the ability of ZDDP to protect the surfaces against fretting wear.

    Fulltekst (pdf)
    fulltext
  • 314.
    Grahn, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Suarez, Aldara Naveira
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Maskinelement.
    Pasaribu, Rihard
    SKF Engineering & Research Center, Nieuwegein.
    Effect of ZDDP on friction in fretting contacts2011Inngår i: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 273, nr 1, s. 70-74Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The effect of ZDDP on fretting wear was investigated in a ball on flat machine. The results confirm previous work that anti-wear agents may reduce friction and wear in fretting contacts. It was further found that temperature, adsorption time, base oil polarity as well as the presence of other surface active additives in the oil were all important parameters affecting the ability of ZDDP to protect the surfaces against fretting wear.

  • 315.
    Grahn, Mattias
    et al.
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Wang, Zheng
    Luleå tekniska universitet.
    Lidström-Larsson, Margareta
    Luleå tekniska universitet.
    Holmgren, Allan
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Hedlund, Jonas
    Luleå tekniska universitet.
    Sterte, Johan
    Luleå tekniska universitet.
    Silicalite-1 coated ATR elements as sensitive chemical sensor probes2005Inngår i: Microporous and Mesoporous Materials, ISSN 1387-1811, E-ISSN 1873-3093, Vol. 81, nr 1-3, s. 357-363Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A novel sensitive chemical sensor probe has been fabricated. The sensor principle is based on silicalite-1 coated ATR (attenuated total reflection) elements and FTIR spectroscopy. The microporous silicalite-1 film enriches the analyte to the probe surface, thus increasing the sensitivity. At a relative pressure of n-hexane in helium of 6 × 10−5 the sensitivity of the probe is approximately 85 times higher for the silicalite-1 coated element compared to a 10 cm transmission gas cell and ca. 180 times higher compared to an uncoated element. The performance of the probe is illustrated by determination of an adsorption isotherm for n-hexane in silicalite-1.

  • 316.
    Granberg, Hjalmar
    et al.
    RISE., Innventia.
    Gustafsson Coppel, Ludovic
    RISE., Innventia.
    Eita, Mohamed
    RISE., Innventia.
    De Mayolo, Eduardo Antunez
    RISE., Innventia.
    Arwin, Hans
    RISE., Innventia.
    Wågberg, Lars Göran
    RISE., Innventia.
    Dynamics of moisture interaction with polyelectrolyte multilayers containing nanofibrillated cellulose2012Inngår i: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, nr 2, s. 496-499Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Recent findings have shown that it is possible to use the Layer-by-Layer technique to create nanofibrillated cellulose / polyethyleneimine interference films whose colour change with relative humidity. This study uses different optical models to describe spectral ellipsometry measurements data of interference films and how the film properties alter in dry and humid environments. The results indicate that water condensation initially is filling the surface pores within seconds whereas relaxation of the film to adjust to the added water is a slower process that reaches a steady state after ~20 min. The maximum swelling ratio of the LbL films is almost independent of the number of layers within the film, but decreases considerably by crosslinking via heat treatment. The films show a distinct birefringence with optical axis perpendicular to the surface. Analysis of the moisture response with different optical models indicates that the films swell uniformly in the thickness direction with no separate water film on top. The results provide important understanding for the design of NFC based LbL films for visual moisture sensors and interactive security paper.

  • 317.
    Granestrand, Jonas
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Kemisk teknologi.
    Paris, Rodrigo Suarez
    Scania CV, Mat Technol, S-15187 Södertälje, Sweden..
    Nilsson, Marita
    Scania CV, Mat Technol, S-15187 Södertälje, Sweden..
    Regali, Francesco
    Scania CV, Mat Technol, S-15187 Södertälje, Sweden..
    Pettersson, Lars J.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Kemisk teknologi.
    Assessment of the Impact of Trace Elements in FAME Biodiesel on Diesel Oxidation Catalyst Activity after Full Lifetime of Operation in A Heavy-Duty Truck2020Inngår i: Catalysts, E-ISSN 2073-4344, Vol. 10, nr 12, artikkel-id 1439Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fatty acid methyl ester (FAME) biodiesel contains some trace amounts of Na, K, P, Ca, and Mg. Our objective was to investigate whether the presence of such elements can poison a diesel oxidation catalyst that has been used for an entire regulatory lifetime in a heavy-duty truck fueled by FAME biodiesel. The investigated vehicle-aged catalyst contained high loadings of S, P, and Na, as well as a visible layer of soot. Activity in the NO oxidation reaction was severely decreased compared to a fresh catalyst of the same type, while the CO and C3H6 oxidation reactions were less affected. Subsequent selective trace element removal procedures, followed by activity tests, were used to decouple the effect of different poisons. Sintering was observed to be the main cause of catalyst deactivation. Of the trace elements present on the catalyst, P had the greatest effect on catalyst activity, while the other trace elements had little effect.

  • 318.
    Granestrand, Jonas
    et al.
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik.
    Suárez París, Rodrigo
    Scania CV, Materials Technology, SE-1518, Sweden.
    Nilsson, Marita
    Scania CV, Materials Technology, SE-1518, Sweden.
    Regali, Francesco
    Scania CV, Materials Technology, SE-1518, Sweden.
    Pettersson, Lars
    KTH, Skolan för kemi, bioteknologi och hälsa (CBH), Kemiteknik, Processteknologi.
    Assessment of the impact of trace elements in FAME biodiesel on diesel oxidation catalyst activity after full lifetime of operation in a heavy-duty truckInngår i: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    FAME biodiesel contains some trace amounts of Na, K, P, Ca and Mg. A diesel oxidation catalyst that had been used for an entire regulatory lifetime in a heavy-duty truck was studied, to investigate whether the presence of such trace elements poisons the catalyst. The vehicle-aged catalyst contained high loadings of S, P and Na, as well as a visible layer of soot. Activity in the NO oxidation reaction was severely decreased compared to a fresh catalyst of the same type, while the CO and C3H6 oxidation reactions were less affected. Activity testing after subsequent selective trace element removal procedures was used to decouple the effect of different poisons. Sintering was observed to be the main cause of catalyst deactivation. Of the trace elements present on the catalyst, P had the largest effect on catalyst activity, while the other trace elements had little effect.

  • 319.
    Granlund, Moa Z.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Görke, Oliver
    Pfeifer, Peter
    Pettersson, Lars J.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Comparison between a micro reactor with multiple air inlets and a monolith reactor for oxidative steam reforming of diesel2014Inngår i: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 39, nr 31, s. 18037-18045Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Abstract In order to lower the emission from idling heavy-duty trucks auxiliary power units can be implemented. Due to limited space available on-board the truck the units needs to be both efficient and compact. One alternative for these units is a fuel cell supplied with hydrogen from a fuel reformer. Today, mostly monolithic reactors are used in the field of oxidative steam reforming of fuels, which has some challenges that need to be addressed before a possible breakthrough occurs on the market. One is the temperature gradient developed over the length of the monolith as a consequence of the sequential reactions. This could be improved by using a metallic micro reactor with better heat integration between the reaction zones and further improving the integration with multiple air inlets along the catalytic bed. The aim with this study was to compare a conventional monolith reactor for oxidative steam reforming of fuel with a novel micro reactor design where air was dosed at four different positions along the reactor channels. The experiments were not necessarily conducted autothermal, i.e. a heating jacket was applied for operation.

  • 320.
    Granlund, Moa Z.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Jansson, Kjell
    Stockholm University, Arrhenius Laboratory, Department of Materials and Environmental Chemistry.
    Nilsson, Marita
    Scania CV AB, Materials Technology, Engine Performance and Emissions.
    Dawody, Jazaer
    Volvo Group Trucks Technology, Advanced Technology & Research, Energy Efficiency & Environmen.
    Pettersson, Lars. J.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Evaluation of Co, La, and Mn promoted Rh catalysts for autothermal reforming of commercial diesel2014Inngår i: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 154, s. 386-394Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The objective of this paper was to study the influence three promoters (Co, La, Mn) had on the catalytic activity of Rh-based catalysts for autothermal reforming of diesel. The catalysts were supported on CeO2ZrO2 and the loading was 1 wt.% Rh and 6 wt.% promoter. The catalytic activity was evaluated in a monolith bench scale reactor with Swedish Environmental diesel, MK1. The process parameters employed at the ATR experiments were; O-2/C similar to 0.45, H2O/C similar to 2.5 and GHSV similar to 50,000h(-1), meanwhile the reactor temperature was ramped from 700 degrees C to 950 degrees C. The catalysts were compared based on their fuel conversion, H-2 yield and the selectivity of different short-chain hydrocarbons. The results showed that all three catalysts had both high fuel conversion and H-2 yield in the optimal ATR operation temperatures. The H-2 yield and fuel conversion were increasing in the order Rh/Mn, Rh/La, Rh/Co. To get further insight in the difference between the materials the fresh and aged catalytic materials were characterized. The characterization methods used were H-2-temperature programmed reduction (H-2-TPR), powder X-ray diffraction (XRD), and BET surface measurements. The BET surface measurements showed that promotion with La gave improved thermal stability of the material. The XRD showed a high dispersion of all metals except Co, which was present as crystals in the size range of the particles of the support.

  • 321.
    Granlund, Moa Z.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Jansson, Kjell
    Stockholm University.
    Nilsson, Marita
    Dawody, Jazaer
    Pettersson, Lars J.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Evaluation of Co, La, and Mn promoted Rh catalysts for autothermal reforming of commercial diesel: Aging and characterization2015Inngår i: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 172, s. 145-153Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this study three bimetallic catalysts are evaluated for autothermal reforming (ATR) of fuels (1 wt.% Rh and 6 wt.% X (X = Co, La or Mn) supported on high-surface area CeO2-ZrO2). The catalysts are aged for approximately 35 h and carefully characterized both as fresh and aged materials. The objective is to illuminate the changes in material properties after time on stream as well as the differences among the materials. The changes in material properties are evaluated by H2-TPR, BET surface area analysis, TEM, SEM and STEM. The material’s tendency to coke is investigated by TPO analysis.

    The three materials exhibit promising initial activity. However, the Co-promoted sample decreases sharply in activity after 25 h of operation. Meanwhile, the other two materials display a more stable activity throughout the evaluated time. The deactivation of the Co-promoted material could be linked to the high amount of coke deposited during operation. Based on the results from the activity evaluation and characterization, the material promoted with lanthanum displays the most promising results. The addition of lanthanum resulted in a catalyst that was both stable and had high activity, even though a low rhodium loading is used. The material also shows superior thermal resistance compared to the other two materials. In addition, the tendency to coke is significantly lower compered to the other materials, which is especially beneficial when dealing with ATR of complex fuels. 

  • 322.
    Granlund, Moa Z.
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Zacherl, Sabina
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Pettersson, Lars J.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi. Univ Stellenbosch, South Africa.
    Comparison between ceria-zirconia and alumina as supports for oxidative steam reforming of biodiesel2015Inngår i: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 58, nr 14-17, s. 933-938Artikkel i tidsskrift (Annet vitenskapelig)
    Abstract [en]

    The objective of the study is to illustrate the advantages with using ceria–zirconia instead of promoted alumina as support for rhodium-based catalysts in oxidative steam reforming of biodiesel. The evaluation is based on long-term oxidative steam reforming experiments where the stability and durability of the catalysts are evaluated. The durability and fuel conversion of the two catalysts were comparable. However, the H2 yield of the ceria–zirconia supported catalyst was 10 % higher than for the catalyst supported on promoted alumina after 65 h on stream. Included are also measurements of the acidity of the catalysts, where it was concluded that the promoted alumina catalyst was significantly more acidic. The acidity of the materials could then be related to the amount of coke deposited, where the amount of coke on the alumina catalyst was almost five times higher after 50 h of operation compared to the ceria–zirconia catalyst.

  • 323.
    Gren Vikander, Lukas
    KTH, Skolan för kemivetenskap (CHE).
    Purification oflignin-based oil2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    The combustion of petroleum-based fuels in the transportation sector is a major contributor to the carbon footprint humans make on the Earth. There is a big need for innovative solutions replacing today’s crude oil based fuels. RenFuel has come up with a pioneering solution to enable co-processing of lignin with crude oil fractions at refineries. This thesis is focused on proof of concept for liquid-liquid extraction purification of lignin-based oil, which will enable further processing to diesel and gasoline additives.

    Liquid-liquid extraction has been considered as the method of purification and was prove meet the separation criteria. Later laboratory trials was carried out to find design parameters for the full-scale purification procedure, which has led to a process route that has been suggested. The proposed process route meets the criteria for the separation. On a second thought, the process route will not be recommended for RenFuel´s pilot plant, the main reason for this is that it limits the plant's flexibility. Propositions for alternative purification methods and future research have been presented.

  • 324.
    Grimler, Henrik
    KTH, Skolan för kemivetenskap (CHE).
    Investigating Urea Vaporization in a Controlled Environment Using Infrared Thermography2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    As the emission legislation becomes more stringent, higher demands are put on the aftertreatment system in trucks. For dealing with nitrous oxides, AdBlue® (urea–water solution) is injected into the exhausts which evaporates and reduces nitrous oxides to nitrogen. At low exhaust temperatures, it is more difficult to evaporate the injected AdBlue® as the exhausts contain less energy. The injected solution may instead form a wall film. In this wall film, side reactions can occur which leads to the formation of deposits.

    This thesis aims at understanding how and when wall films and deposits are formed. To achieve this, a test rig that allowed visual and infrared observations of the process and variation of governing properties was designed and built.

    The results show that thicker plates can sustain higher dosages than thinner plates since the temperature drop and film area are smaller for the thicker plate. It was also observed that at plate temperatures >340 °C, the water in the impacting spray evaporated, leaving a urea dust in the gas phase.

    It is also clear that deposits form faster at higher gas temperatures (> 350 °C) compared to at lower temperatures (200–250 °C). The deposits form at the edge of the wall film in a region with a temperature higher than in the middle of the wall film. At lower temperatures, a wall film that spreads out over a very large area is formed and after a longer time period, deposits form at obstacles and at the wall film edge. Experiments for 2 h at lower temperatures left approximately the same amount of deposits as experiments for 30 min at higher temperatures.

    Fulltekst (pdf)
    fulltext
  • 325.
    Gruvnäs, Filip
    KTH, Skolan för kemivetenskap (CHE).
    Modellering av åldring av dieseloxidationskatalysatorer2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    A conventional exhaust gas after treatment system (EATS) for the Euro VI legislation contains four different catalyst. The first two (particulate filter system) remove particulates and the last two (SCR system) remove nitrogen oxides (NOx). The particulate filter system also optimizes the gas composition with respect to nitrogen monoxide (NO) and nitrogen dioxide (NO2). The performance of the SCR system has a strong dependency on the NO:NO2 ratio as the so called selective catalytic reduction (SCR) reaction is kinetically favored at a NO:NO2 ratio of 1:1.

    The diesel oxidation catalyst (DOC) is placed first in the EATS. Due to this placement, the DOC is subjected to a rough environment, e.g. high temperatures and oil/fuel impurities that with time will affect its performance, i.e. the catalyst ages.

    In this master thesis, the aging of the DOC has been empirically correlated to thermal load and sulfur exposure. The study shows that it is possible to predict how the NO oxidation performance decays as a function of thermal and sulfur exposure. The empirical relation was fitted against two aging cycles and validated against an additional four. The results show that the loss of catalytic activity can to a large extent be explained by the cycle it has been used on.

    Fulltekst (pdf)
    fulltext
  • 326.
    Grönkvist, Stefan
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Bryngelsson, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Westermark, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Oxygen efficiency with regard to carbon capture2006Inngår i: Energy, ISSN 0360-5442, E-ISSN 1873-6785, Vol. 31, nr 15, s. 3220-3226Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Carbon capture is often discussed in the literature with the sole focus on power processes, despite the fact that carbon dioxide emissions from other sources are just as relevant for the impact on the atmosphere. Furthermore, some carbon capture methods are relatively inefficient when applied to power production processes. Carbon capture should preferably be performed where the cost is as low as possible, i.e. not necessarily from power production processes. As an example, carbon capture using combustion with pure oxygen is far more energy efficient if it is used together with lime kilns or cement kilns than together with power production processes. A new concept termed "oxygen efficiency" is introduced in this paper. It describes the amount of carbon dioxide that can potentially be captured per unit of oxygen. As such, the oxygen efficiency quantifies the value of a certain unit of oxygen for carbon capture reasons. The base concept is that the energy penalty for the production of one part of oxygen is the same no matter where it is produced; hence, if this unit of oxygen can be used to capture more carbon dioxide, it is more efficient. Typically, the oxygen efficiency would be five times greater for carbon capture when utilising pure oxygen together with cement kilns rather than together with methane-fired power plants. Furthermore, the concept of oxygen efficiency illustrates the importance of considering how carbon capture methods can be utilised in the most efficient way, in addition to evaluating which carbon capture method is the most suitable for a particular technology.

  • 327.
    Gualtieri, Magdalena
    Luleå tekniska universitet.
    Synthesis and characterization of zeolite films and membranes2006Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    In this work, a seeding technique was used to synthesize films and membranes of FAU, LTA and MFI type zeolites. In the first part, hydrothermal growth was performed without organic template molecules, which resulted in template-free zeolite films and membranes. The samples were characterized by Scanning Electron Microscopy, X-ray Powder Diffraction and permeation measurements with gaseous probe molecules. Thin films of FAU-type zeolite were prepared on polished single crystals. The thickness and morphology of the films could be controlled by varying the synthesis conditions. Preparation of LTA-type membranes was also attempted. However, the membranes cracked during drying at temperatures above room temperature. Template free MFI membranes with higher quality could be prepared. These membranes had a maximum separation factor alpha of 17.8 at 220°C for a n-butane/i-butane mixture. Cracks formed at temperatures higher than 250°C. Crack formation in zeolite membranes at high temperatures has also been reported by several other groups. Since no model for the crack formation process has been established in the literature, the second part of this work was devoted to study crack formation and to develop a model. Relatively thick (ca 1800 nm) alpha-alumina supported MFI films, prepared using organic template molecules (TPA+), were selected for the study since data on crack formation in the form of SEM images and permeation measurements for these membranes had been obtained in earlier work by the group. These membranes were further studied by in-situ High Temperature X-ray Powder Diffraction experiments in the present work. In addition, MFI powder and a blank alpha-alumina support were also investigated. Data were collected with the aid of a Synchrotron radiation facility as well as with a conventional laboratory instrument for the temperature cycle 25-500-25°C. The Rietveld method was used to determine the unit cell parameters of MFI and alpha-alumina as well as the TPA+ occupancy of MFI. The out-of- plane strain (i.e. strain in the direction perpendicular to the film surface) in the film and the support was calculated. In addition, the microstructure of the support was investigated by pattern decomposition and Williamson-Hall plots. In agreement with previous reports in the literature, it was found that the TPA-MFI structure contracts as a consequence of template removal and possibly also a structure intrinsic mechanism and the alpha-alumina support expands. Hence, a large thermal expansion mismatch occurs in the membranes during heating. An overall out- of-plane compressive strain was observed for the MFI film during heating, which indicates an in-plane tensile stress (i.e. in the direction parallel to the film surface) in the film. This result was explained by the larger expansion of the support, compared to the film. The alpha-alumina support was also found to be under an overall out-of-plane compressive strain at non-ambient temperatures, presumably due to zeolite in the pores of the support. The microstrain for the MFI coated alpha-alumina support increased during heating, and remained during cooling, which indicate the formation of structural defects in the support. Based on these results and results from earlier work, a model for crack formation was proposed: In the thick films (ca 1800 nm) studied in the present work, the crystals are well intergrown. During heating, the MFI crystals contracts and the alpha- alumina support expands. Consequently, a thermal stress develops in the composite which eventually leads to formation of cracks. In addition, part of the stress is also released via formation of structural defects in the alpha-alumina support. In thinner films (ca 500 nm), the crystals are less well intergrown and the thermal expansion mismatch between the crystals in the film and the support leads to opening of grain boundaries in the film rather than cracks.

    Fulltekst (pdf)
    FULLTEXT01
  • 328.
    Gualtieri, Magdalena Lassinantti
    et al.
    Luleå tekniska universitet.
    Andersson, Charlotte
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser.
    Jareman, Fredrik
    Luleå tekniska universitet.
    Hedlund, Jonas
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Industriell miljö- och processteknik.
    Gualtieri, Alessandro F.
    Dipartimento di Scienze della Terra, Università di Modena e Reggio Emilia, Modena, Italy.
    Leoni, Matteo
    Dipartimento di Ingegneria dei Materiali, Università di Trento, Mesiano, Italy.
    Meneghini, Carlo
    Dipartimento di Fisica ‘E. Amaldi’ Università di Roma Tre, Roma, Italy.
    Crack formation in α-alumina supported MFI zeolite membranes studied by in situ high temperature synchrotron powder diffraction2007Inngår i: Journal of Membrane Science, ISSN 0376-7388, E-ISSN 1873-3123, Vol. 290, nr 1-2, s. 95-104Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cracks are frequently formed in α-alumina supported MFI membranes during calcination. To better understand crack formation, in situ powder diffraction data were collected during calcination of a type of MFI membrane (ca. 1800 nm thick) which is known to crack reproducibly. In addition, data for MFI powder and a blank support were also collected. Both a synchrotron radiation facility and an in-house instrument were used. The unit cell parameters were determined with the Rietveld method, and the strain in the direction perpendicular to the film surface was calculated for the film as well as for the support. The microstrain in the support was also estimated. Based on the results obtained here, a model for crack formation in this type of MFI membrane was proposed. The lack of cracks in other types of MFI membranes (ca. 500 nm) prepared in our laboratory is also explained by the model. In thicker MFI films, the crystals are well intergrown. During heating, the MFI crystals contract and the α-alumina support expands. Consequently, a thermal stress develops in the composite which eventually leads to formation of cracks in the film and structural defects in the support. In thinner films, the crystals are less well intergrown and the thermal expansion mismatch leads to opening of grain boundaries rather than cracks.

  • 329.
    Guan, Tingting
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Biomass-fuelled PEM FuelCell systems for small andmedium-sized enterprises2015Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Biomass-fuelled proton exchange membrane fuel cells (PEMFCs) offer asolution for replacing fossil fuel for hydrogen production. Through using thebiomass-derived hydrogen as fuel, PEMFCs may become an efficient andsustainable energy system for small and medium-sized enterprises. The aim ofthis thesis is to evaluate the performance and potential applications of biomassfuelledPEMFC systems which are designed to convert biomass to electricity andheat. Biomass-fuelled PEMFC systems are simulated by Aspen plus based ondata collected from experiments and literature.The impact of the quality of the hydrogen-rich gas, anode stoichiometry, CH4content in the biogas and CH4 conversion rate on the performance of the PEMFCis investigated. Also, pinch technology is used to optimize the heat exchangernetwork to improve the power generation and thermal efficiency.For liquid and solid biomass, anaerobic digestion (AD) and gasification (GF),respectively, are relatively viable and developed conversion technologies. ForAD-PEMFC, a steam reformer is also needed to convert biogas to hydrogen-richgas. For 100 kWe generation, the GF-PEMFC system yields a good technicalperformance with 20 % electrical efficiency and 57 % thermal efficiency,whereas the AD-PEMFC system only has 9 % electrical efficiency and 13 %thermal efficiency. This low efficiency is due to the low efficiency of theanaerobic digester (AD) and the high internal heat consumption of the AD andthe steam reformer (SR). For the environmental aspects, the GF-PEMFC systemhas a high CO2 emissions offset factor and the AD-PEMFC system has anefficient land-use.The applications of the biomass-fuelled PEMFC systems are investigated on adairy farm and an olive oil plant. For the dairy farm, manure is used as feedstockto generate biogas through anaerobic digestion. A PEMFC qualified for 40 %electrical efficiency may generate 360 MWh electricity and 680 MWh heat peryear to make a dairy farm with 300 milked cows self-sufficient in a sustainableway. A PEMFC-CHP system designed for an olive oil plant generating annual 50000 m3 solid olive mill waste (SOMW) and 9 000 m3 olive mill waste water(OMW) is simulated based on experimental data from the Biogas2PEM-FCproject1. After the optimization of the heat exchanger network, the PEMFC-CHP 

    system can generate 194 kW electricity which corresponds to 62 % of the totalelectricity demand of the olive oil plant.The economic performance of the PEMFC and biogas-fuelled PEMFC areassessed roughly including capital, operation & maintenance (O&M) costs of thebiogas plant and the PEMFC-CHP, the cost of heat and electricity, and the valueof the digestate as fertilizer.

    Fulltekst (pdf)
    Thesis
  • 330.
    Guan, Tingting
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Alvfors, Per
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    An overview of biomass-fuelled proton exchange membrane fuel cell (PEMFC) systems2015Inngår i: CLEAN, EFFICIENT AND AFFORDABLE ENERGY FOR A SUSTAINABLE FUTURE, Elsevier, 2015, s. 2003-2008Konferansepaper (Fagfellevurdert)
    Abstract [en]

    PEMFC fuelled by biomass-derived hydrogen is an efficient and sustainable energy system for small-scale residential applications. Gasification and anaerobic digestion combined with steam reforming are seen as the most suitable conversion processes for hydrogen production. Since the biomass-derived hydrogen contains many kinds of contaminants including CO, CO2, H2S, NH3 and N-2, extensive work has been done on the mechanism and mitigation methods for their poisoning the PEMFC. Although the biomass-fuelled PEMFC systems have been tested in several experiments and checked through simulation work for different perspectives, further research and demonstration work are required to improve the system efficiency and reliability. (C) 2015 The Authors. Published by Elsevier Ltd.

  • 331.
    Guan, Tingting
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Alvfors, Per
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Cogeneration PEM fuel cell system fuelled by olive mill wastes for its application in an olive oil plantManuskript (preprint) (Annet vitenskapelig)
  • 332.
    Gunarathne, Duleeka
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Advanced Gasification of Biomass/Waste for Substitution of Fossil Fuels in Steel Industry Heat Treatment Furnaces2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    With the current trend of CO2 mitigation in process industries, the primary goal of this thesis is to promote biomass as an energy and reduction agent source to substitute fossil sources in the steel industry. The criteria for this substitution are that the steel process retains the same function and the integrated energy efficiency is as high as possible.

    This work focuses on advanced gasification of biomass and waste for substitution of fossil fuels in steel industry heat treatment furnaces. To achieve this, two approaches are included in this work. The first investigates the gasification performance of pretreated biomass and waste experimentally using thermogravimetric analysis (TGA) and a pilot plant gasifier. The second assesses the integration of the advanced gasification system with a steel heat treatment furnace.

    First, the pyrolysis and char gasification characteristics of several pretreated biomass and waste types (unpretreated biomass, steam-exploded biomass, and hydrothermal carbonized biomass) were analyzed with TGA. The important aspects of pyrolysis and char gasification of pretreated biomass were identified.

    Then, with the objective of studying the gasification performance of pretreated biomass, unpretreated biomass pellets (gray pellets), steam-exploded biomass pellets (black pellets), and two types of hydrothermal carbonized biomass pellets (spent grain biocoal and horse manure biocoal) were gasified in a fixed bed updraft gasifier with high-temperature air/steam as the gasifying agent. The gasification performance was analyzed in terms of syngas composition, lower heating value (LHV), gas yield, cold gas efficiency (CGE), tar content and composition, and particle content and size distribution. Moreover, the effects on the reactions occurring in the gasifier were identified with the aid of temperature profiles and gas ratios.

    Further, the interaction between fuel residence time in the bed (bed height), conversion, conversion rate/specific gasification rate, and superficial velocity (hearth load) was revealed. Due to the effect of bed height on the gasification performance, the bed pressure drop is an important parameter related to the operation of a fixed bed gasifier. Considering the limited studies on this relationship, an available pressure drop prediction correlation for turbulent flow in a bed with cylindrical pellets was extended to a gasifier bed with shrinking cylindrical pellets under any flow condition. Moreover, simplified graphical representations based on the developed correlation, which could be used as an effective guide for selecting a suitable pellet size and designing a grate, were introduced.

    Then, with the identified positive effects of pretreated biomass on the gasification performance, the possibility of fuel switching in a steel industry heat treatment furnace was evaluated by effective integration with a multi-stage gasification system. The performance was evaluated in terms of gasifier system efficiency, furnace efficiency, and overall system efficiency with various heat integration options. The heat integration performance was identified based on pinch analysis. Finally, the efficiency of the co-production of bio-coke and bio-H2 was analyzed to increase the added value of the whole process.

    It was found that 1) the steam gasification of pretreated biomass is more beneficial in terms of the energy value of the syngas, 2) diluting the gasifying agent and/or lowering the agent temperature compensates for the ash slagging problem in biocoal gasification, 3) the furnace efficiency can be improved by switching the fuel from natural gas (NG) to syngas, 4) the gasifier system efficiency can be improved by recovering the furnace flue gas heat for the pretreatment, and 5) the co-production of bio-coke and bio-H2 significantly improves the system efficiency.

    Fulltekst (pdf)
    fulltext
  • 333.
    Gunnarsson, Rickard
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Plasma och beläggningsfysik. Linköpings universitet, Tekniska fakulteten.
    Titanium oxide nanoparticle production using high power pulsed plasmas2016Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    This thesis covers fundamental aspects of process control when growing titanium oxide nanoparticles in a reactive sputtering process. It covers the influence of oxygen containing gas on the oxidation state of the cathode from which the growth material is ejected, as well as its influence on the particles oxidation state and their nucleation. It was found that a low degree of reactive gases was necessary for nanoparticles of titanium to nucleate. When the oxygen gas was slightly increased, the nanoparticle yield and particle oxygen content increased. A further increase caused a decrease in particle yield which was attributed to a slight oxidation of the cathode. By varying the oxygen flow to the process, it was possible to control the oxygen content of the nanoparticles without fully oxidizing the cathode. Because oxygen containing gases such as residual water vapour has a profound influence on nanoparticle yield and composition, the deposition source was re-engineered to allow for cleaner and thus more stable synthesis conditions.

    The size of the nanoparticles has been controlled by two means. The first is to change electrical potentials around the growth zone, which allows for nanoparticle size control in the order of 25-75 nm. This size control does not influence the oxygen content of the nanoparticles. The second means of size control investigated was by increasing the pressure. By doing this, the particle size can be increased from 50 – 250 nm, however the oxygen content also increases with pressure. Different particle morphologies were found by changing the pressure. At low pressures, mostly spherical particles with weak facets were produced. As the pressure increased, the particles got a cubic shape. At higher pressures the cubic particles started to get a fractured surface. At the highest pressure investigated, the fractured surface became poly-crystalline, giving a cauliflower shaped morphology.

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  • 334.
    Görling, Martin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Larsson, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Alvfors, Per
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Bio-methane via fast pyrolysis of biomass2013Inngår i: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 112, nr SI, s. 440-447Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bio-methane, a renewable vehicle fuel, is today produced by anaerobic digestion and a 2nd generation production route via gasification is under development. This paper proposes a poly-generation plant that produces bio-methane, bio-char and heat via fast pyrolysis of biomass. The energy and material flows for the fuel synthesis are calculated by process simulation in Aspen Plus®. The production of bio-methane and bio-char amounts to 15.5. MW and 3.7. MW, when the total inputs are 23. MW raw biomass and 1.39. MW electricity respectively (HHV basis). The results indicate an overall efficiency of 84% including high-temperature heat and the biomass to bio-methane yield amounts to 83% after allocation of the biomass input to the final products (HHV basis). The overall energy efficiency is higher for the suggested plant than for the gasification production route and is therefore a competitive route for bio-methane production.

  • 335.
    Görling, Martin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Westermark, Mats
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Energiprocesser.
    Integration Feasibilities for Combined Cycles in Biofuel Production2011Inngår i: Proceedings of the 24th International Conference on Efficiency, Cost, Optimization, Simulation and Environmental Impact of Energy Systems, ECOS 2011, Nis University , 2011, s. 3498-3508Konferansepaper (Fagfellevurdert)
    Abstract [en]

    The aim of this paper is to evaluate the opportunities for gas turbine integration into biofuel production. When producing biofuels via gasification, a significant amount of the input of chemical energy is converted to reaction heat. A steam cycle is therefore used to recover the heat to useful power, but despite that, the plant often remains net users of electricity. To further enhance the production several studies suggest integration of gas turbines, often fired with offgas from the fuel synthesis. The excess of low level heat in the gas turbine exhaust is successfully integrated in the steam cycle which creates integration synergies. Gasification of biomass for fuel synthesis generally implies that oxygen is used as gasification agent. Despite the synergies in the joint steam cycle, the positive effects are outweighed by the energy penalty from oxygen production. Conclusively, serial production of biofuel and power is not beneficial. More interesting is the integrating of a parallel, air-blown gasifier to produce syngas for the gas turbine. Also the natural gas fired gas turbines have successfully been integrated.

  • 336.
    H. Moud, Pouya
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Catalytic Conversion of Undesired Organic Compounds to Syngas in Biomass Gasification and Pyrolysis Applications2017Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    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.

    Fulltekst (pdf)
    Thesis summary_PouyaHMoud
  • 337.
    Haghighi Moud, Pouya
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Andersson, Klas J.
    Lanza, Roberto
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Engvall, Klas
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik, Kemisk teknologi.
    Equilibrium potassium coverage and its effect on a Ni tar reforming catalyst in alkali- and sulfur-laden biomass gasification gases2016Inngår i: Applied Catalysis B: Environmental, ISSN 0926-3373, E-ISSN 1873-3883, Vol. 190, s. 137-146Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    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.

  • 338.
    Haglund, Peter
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Spinnel, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    A modular approach to pressurized liquid extraction with in-cell clean-up2010Inngår i: LC GC Europe, ISSN 1471-6577, Vol. 23, nr 6, s. 292-301Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new concept for the extraction of solid samples has been developed. The popular pressurized liquid extraction (PLE) technique has been modified so that the extraction cell can be divided, which greatly increases the flexibility and versatility of this technique. The system uses simple adaptors to couple commercially available extraction cells, which may be loaded with either sample or adsorbent(s). These segmented extraction cells make it possible to selectively retain analytes or matrix to achieve simultaneous extraction and clean-up or fractionation. The ultimate aim is to perform simultaneous extraction and clean-up and obtain a purified extract that is ready for instrumental analysis, all in line with current trends in analytical chemistry to automate and streamline the analytical procedures to reduce the analysis costs, solvent consumption, manual labour and increase the quality of analysis. Selected modes of operations are presented and a few recent environmental applications of modular PLE are reviewed.

  • 339.
    Haglund, Peter
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Spinnel, Erik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    A modular approach to pressurized liquid extraction with in-cell clean-up2010Inngår i: LCGC Asia Pacific, ISSN 1754-2715, Vol. 13, nr 2, s. 6-12Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A new concept for the extraction of solid samples has been developed. The popular pressurized liquid extraction (PLE) technique has been modified so that the extraction cell can be divided, which greatly increases the flexibility and versatility of this technique. The system uses simple adaptors to couple commercially available extraction cells, which may be loaded with either sample or adsorbent(s). These segmented extraction cells make it possible to selectively retain analytes or matrix to achieve simultaneous extraction and clean-up or fractionation. The ultimate aim is to perform simultaneous extraction and clean-up and obtain a purified extract that is ready for instrumental analysis, all in line with current trends in analytical chemistry to automate and streamline the analytical procedures to reduce the analysis costs, solvent consumption, manual labour and increase the quality of analysis. Selected modes of operations are presented and a few recent environmental applications of modular PLE are reviewed.

  • 340.
    Hagman, Henrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik. Perstorp Specialty Chemicals AB.
    Co-firing animal waste, sludge, residue wood, peat and forest fuels in a 50MWth CFB boiler: ash transformation, availability and process improvements2014Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The direct variable costs for heat and electricity production based on solid biomass fuel combustion is approximately 3-5 times lower than the costs in a fossil fuel-oil based boiler in Sweden. In addition waste derived biomass fuels are typically much cheaper than biomass not classified as waste. The introduction of the waste derived fuels; wastewater treatment sludge, demolition wood, and animal waste in a 50MWth circulating fluidized bed (CFB) biomass boiler located in Perstorp, Sweden, led to rapid deposit buildup in superheaters, heavy ash accumulation in economizers and failing boiler tubes and vortex finders that forced frequent boiler shutdowns. This in turn increased the use of expensive oil (fossil fuel) in backup boilers and the CO2 footprint of the on-site energy conversion system. This work aims to increase the general mechanistic understanding of combustion systems using complex fuels, and includes: A mapping of the boiler failure and preventive maintenance statistics; elemental composition analysis of ash, deposits and fuel fractions; flue-gas composition measurements; chemical speciation analysis; an attempt to describe the overall ash transformation reactions and mass balance throughout the combustion process. Scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) was used to analyze the elemental composition of ash and deposits. The SEM-EDS results were used together with data from X-ray powder diffraction (XRD) analysis, thermodynamic phase data, and equilibrium calculations in an attempt to quantify the crystalline phases and the overall ash transformation of the process. Based on the findings concerning ash transformation and the failure statistics, it has been possible to identify generic key parameters regarding boiler design and process parameters, enabling major improvements of the CFB boiler availability, a lower overall energy conversion cost and a reduced CO2 footprint.

    Fulltekst (pdf)
    Co-firing animal waste, sludge, residue wood, peat and forest fuels in a 50MWth CFB boiler
  • 341.
    Hagman, Henrik
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för tillämpad fysik och elektronik.
    Co-firing complex biomass in a CFB boiler: ash transformation, corrosion control and materials selection2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The effects of greenhouse gas net emissions on global warming, stricter legislation on waste handling, and the pursuit of ever cheaper heat- and power production are all important factors driving the introduction of complex fuels in incineration plants. However - without fundamental knowledge regarding ash transformation, corrosion control, and materials selection – this introduction of potentially economically and environmentally beneficial fuels, might instead cause economic loss and environmentally adverse effects.

    The present work is a contribution to the transition from today's CO2 net generating energy conversion system, to a more environmentally friendly and cost-efficient one. This is done using scientific methods to generate knowledge concerning mechanisms of ash transformation, corrosion control, and materials selection, in a co-fired industrial scale circulating fluidized bed (CFB) boiler, using a novel and biomass-based fuel mix, rich in Na, K, Cl, N, S, P, Ca and Si. Fuel fractions, ashes, flue gas, deposits, and construction material samples have been collected and analyzed using various techniques, including scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), and X-ray Diffraction (XRD). The experimental results have been evaluated and interpreted using chemical equilibrium calculations.

    The results of this work include:

    1) An analysis of; the failure and preventive maintenance statistics of the industrial scale CFB boiler at hand; the elemental composition of boiler ashes and deposits, the flue gas composition and elemental composition of a multitude of fuel fractions; correlations between boiler design, operational parameters, elemental composition of deposits and boiler availability; a boiler elemental mass balance revealing details regarding deposit buildup mechanisms; properties of the fly ash relevant to flue gas filter design; and findings regarding the nitrogen chemistry of the novel and nitrogen-rich fuel mix.

    2) Speciation and description of the overall ash transformation and fireside alloy interaction, enabling the implementation of on-line corrosion control which significantly inhibits superheater and dew-point corrosion in the boiler; and, an equation describing the sulfation potential of the fuel mix, as a result of the direct and indirect interactions between all major ash-forming elements.

    3) A literature review relevant for the co-fired CFB cyclone vortex finder alloy selection and corrosion at 880 °C; An alloy selection study including long term exposures of several commercially available alloys identifying materials that are more than twice as cost-efficient as the often used alloy 253MA; a suggestion of novel methods for both systematic comparison of heavily degraded alloys, and for alloy service-life estimations; a detailed analysis of heavily degraded alloys 310S, 800H/HT and 600, identifying the driving corrosion mechanisms of the VF alloy degradation, including aspects of how the alloy internal mass transport and fireside surface interaction develops over time.

    The knowledge gained during this project has been used in the improvement work of the Perstorp 50 MWth CFB boiler, improving the boiler availability with 7 %, reducing the overall energy conversion costs with around 1.7 MEUR/year.

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  • 342. Hallinder, Samuel
    Reaction Conditions Data Mining: The application of Machine Learning towards predicting the future of process development2019Independent thesis Advanced level (professional degree), 20 poäng / 30 hpOppgave
    Abstract [en]

    In organic chemistry and especially process chemistry, there is a constant need to develop cost-effective ways to optimize different reaction conditions. With the increased development of Machine Learning (ML) combined with Data Mining (DM) new possibilities arise to reduce time and costs in the field of chemical science. In order to address the need for reduced time-/cost savings in process chemistry, the often-employed Suzuki-Miyaura reaction was studied by such ML and DM methods. A representative dataset containing molecular and structural properties of substrates and product were calculated with open-source toolkits Indigo, Chemistry Development Kit and RDKit available in KNIME. To predict any form of reaction outcomes, catalysts and reaction conditions were ranked based on several binary classification Machine Learning models designed with a Random Forest algorithm. On model lead to a binary classification model performing at a low computational cost. It showed an AUC of 98.5% predicting a reaction to a certain threshold of yield ( >=60% and<=40%). A second model encompassed six unique binary classification models and presented an average accuracy of 91.6% to predict a correct catalyst. These six different models were combined to later rank catalysts that are best suited for a new reaction and gave a probability result between 23.6% to 77.3%. The experimental validation was proven to highlight the uncertainty of the performance, were the least suitable (23.6%) catalyst demonstrated best performance. Overall, the models showed a promising correlation to support the synthesis optimization problem and with further adjustment there are great opportunities to obtain a model that can assist chemists in the future.

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    Reaction Conditions Data Mining
  • 343.
    Halvarsson, Alfred
    KTH, Skolan för kemivetenskap (CHE).
    Katalytisk omvandling av pyrolysgas i WoodRoll-processen för ökad processtillförlitlighet2015Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    This project was a cooperation between the division of Chemical Technology at KTH, Cortus Energy and Haldor Topsoe A/S. The goal was to build up a totally new setup for converting and deoxygenate pyrolysis bio-oil, in order to increase the performance of Cortus Energy’s WoodRoll process. Therefore an iron based catalyst from Haldor Topsoe was used.

    The building up of the new setup with all reactors and the control panel was a complicated and time-consuming work. This led to an only short time slot for performing experiments, which means that more work needs to be done to get more valuable results. The most important success of this project was to get all the knowledge about the system and to make everything (the whole experimental setup) running properly. However, the sampling system needs to be improved before making further experiments.

    The experiments which have been done show promising results and that the iron based catalyst was working well for converting the bio-oil. During the two hour long experiment there were not shown any indications of deactivation, when looking at the gas compositions, but the results from temperature programmed oxidation (TPO) show carbon deposition on the catalyst and the BET surface also shows a slight decrease in surface area.

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    fulltext
  • 344.
    Halvarsson, Sören
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap, teknik och matematik.
    Manufacture of straw MDF and fibreboards2010Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The purpose of this thesis was to develop an economical, sustainable, and environmentally friendly straw Medium Density Fibreboard (MDF) process, capable of full-scale manufacturing and to produce MDF of requested quality. The investigated straw was based on wheat (Triticum aestivum L.) and rice (Oryzae sativa L.). In this thesis three different methods were taken for manufacture of straw MDF; (A) wheat-straw fibre was blowline blended with melamine-modified urea-formaldehyde (MUF), (B) rice-straw fibre was mixed with methylene diphenyl diisocyanate (MDI) in a resin drum-blender, and (C) wheat-straw fibre was activated in the blowline by the addition of Fenton’s reagent (H2O2/Fe2+) for production of non-resin MDF panels.  The MUF/wheat straw MDF panels were approved according to the requirements of the EN standard for MDF (EN 622-5, 2006). The MDI/rice-straw MDF panels were approved according to requirements of the standard for MDF of the American National Standard Institute (ANSI A208.2-2002). The non-resin wheat-straw panels showed mediocre MDF panel properties and were not approved according to the requirements in the MDF standard. The dry process for wood-based MDF was modified for production of straw MDF. The straw MDF process was divided into seven main process steps.

    1. 1.       Size-reduction (hammer-milling) and screening of straw
    2. 2.       Wetting and heating of straw
    3. 3.       Defibration
    4. 4.       Resination of straw fibre
    5. 5.       Mat forming
    6. 6.       Pre-pressing
    7. 7.       Hot-pressing

     

     

     

    The primary results were that the straw MDF process was capable of providing satisfactory straw MDF panels based on different types of straw species and adhesives. Moreover, the straw MDF process was performed in pilot-plant scale and demonstrated as a suitable method for producing straw MDF from straw bales to finished straw MDF panels. In the environmental perspective the agricultural straw-waste is a suitable source for producing MDF to avoid open field burning and to capture carbon dioxide (CO2), the biological sink for extended time into MDF panels, instead of converting straw directly into bio energy or applying straw fibre a few times as recycled paper. Additionally, the straw MDF panels can be recycled or converted to energy after utilization.

    A relationship between water retention value (WRV) of resinated straw fibres, the thickness swelling of corresponding straw MDF panels, and the amount of applied adhesive was determined. WRV of the straw fibre increased and the TS of straw MDF declined as a function of the resin content. The empirical models developed were of acceptable significance and the R2 values were 0.69 (WRV) and 0.75 (TS), respectively. Reduced thickness swelling of MDF as the resin content is increased is well-known. The increase of WRV as a function of added polymers is not completely established within the science of fibre swelling. Fortunately, more fundamental research can be initiated and likely a simple method for prediction of thickness swelling of MDF by analysis of the dried and resinated MDF fibres is possible.

    Fulltekst (pdf)
    FULLTEXT02
  • 345.
    Hamidi, Amirhossein
    et al.
    School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran, Iran.
    Nazari, Pouria
    School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran, Iran.
    Shakibania, Sina
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi.
    Rashchi, Fereshteh
    School of Metallurgy and Materials Engineering, College of Engineering, University of Tehran, Tehran, Iran.
    Microwave irradiation for the recovery enhancement of fly ash components: Thermodynamic and kinetic aspects2023Inngår i: Chemical Engineering and Processing, ISSN 0255-2701, E-ISSN 1873-3204, Vol. 191, artikkel-id 109472Artikkel i tidsskrift (Fagfellevurdert)
  • 346.
    Han, Tong
    et al.
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Yang, Weihong
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Jönsson, Pär
    KTH, Skolan för industriell teknik och management (ITM), Materialvetenskap.
    Pyrolysis and subsequent steam gasification of metal dry impregnated lignin for the production of H2-rich syngas and magnetic activated carbon2020Inngår i: Chemical Engineering Journal, ISSN 1385-8947, E-ISSN 1873-3212, Vol. 394, artikkel-id 124902Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    An integrated process that includes the pyrolysis of FeSO4 dry impregnated lignin and subsequent steam gasification of the produced biochar has been performed to produce H2-rich syngas and magnetic activated carbon. The results show that gasification is more beneficial for hydrogen production than pyrolysis. Increasing the pyrolysis temperature from 550 °C to 800 °C and iron loading from 4% to 8% not only promotes the extension decomposition of lignin but also induces the production of char, which is more effective for gasification. As a result, the syngas yield and H2 volumetric percentage of both the pyrolysis and steam gasification processes are enhanced. The maximum overall H2 yield and exergy efficiency for producing H2 are estimated to be 42.73 mol/kg-lignin and 46.63%, respectively. Magnetic activated carbon materials produced from the proposed integrated process have a good porous property and high saturation magnetization value. Magnetic activated carbon that is produced from the same process that achieves a maximum H2 yield is obtained and exhibits an approximate 70% total phosphate and 20% ammonia and nitrogen removal efficiency for treating real domestic wastewater.

  • 347.
    Hannl, Thomas Karl
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Phosphorus recovery from sewage sludge fluidized bed gasification processes2020Licentiatavhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    One of the most sustainable pathways of sewage sludge treatment in recent years has been thermal conversion. The benefits of thermal treatment of sewage sludge are the recovery of energy or valuable chemical products, the destruction of harmful organic compounds, the separation of heavy metals from the P-rich coarse ash fraction, and the decreased and sanitized ash volume. The ashes created by these thermal conversion processes of sewage sludge are often rich in P that is mostly present in minerals with low plant-availability such as apatite. Due to the enrichment of P in the created ashes, a variety of post-processing steps have been developed to recover P from sewage sludge ashes. One proven way for the sus-tainable recovery of P from such ashes is thermal post-processing with alkaline salts, e.g., Na2SO4 or K2CO3, which was able to transform less plant-available phosphates in the sewage sludge into more plant-available alkali-bearing phos-phates. Based on these results, one could facilitate creating these phosphates with enhanced plant-availability by providing the chemical potential to form them already during the thermal conversion process of sewage sludge.  

    This thesis aims to increase the current knowledge about the ash transformation processes of P and to suggest suitable process parameters for the alteration of the phosphate speciation in sewage sludge ashes by co-conversion with alkaline-rich agricultural residues. More specifically, the possibility of incorporating K derived from agricultural residues in phosphate structures derived from sewage sludge was evaluated with respect to the influence of the process temperature, the conver-sion atmosphere, and the fuel mixture. The studied parameters were chosen to generate knowledge relevant for fluidized bed gasification processes, with a spe-cial focus on dual fluidized bed (DFB) gasification systems.

    The applicability of feldspar bed materials in fluidized bed gasification systems was investigated to enable the substitution of the commonly used olivine, which often contains heavy metals (potentially contaminating recovered ashes), and quartz, which is very reactive towards fuel-derived K and potentially leads to bed material fragmentation and bed agglomeration (Paper I & II). Subsequently, the thermodynamic potential for the alteration of the P-species in sewage sludge ash during co-combustion and co-gasification processes with agricultural residues was investigated (Paper III). Thereafter, an experimental evaluation of the ash transformation chemistry in thermal conversion processes of sewage sludge with different types of alkali-rich agricultural residues in temperatures relevant for flu-idized bed technology was conducted (Paper IV & V).

    The methodology employed was chosen with respect to the state of technology of the specific investigated process. Paper I & II applied SEM, EDS, XRD, and thermodynamic equilibrium modeling for bed material samples derived from an industrial indirect gasifier. Paper III applied thermodynamic equilibrium calcula-tions to theoretically evaluate ash compositions resulting from co-conversion of sewage sludge and agricultural residues. Paper IV & V employed SEM, EDS, ICP-AES/MS, XRD, and thermochemical modeling on ash samples derived from single pellet lab-scale experiments.

    The results obtained by analysis of bed material from indirect wood gasification showed the difference in interaction mechanism for K-feldspar and Na-feldspar, most notably the enhanced disintegration of Na-feldspar by K originating from the fuel (Paper I & II). Thermodynamic models employed for fuel mixtures of sewage sludge and agricultural residues showed the thermodynamic preference for the formation of the desired alkali-bearing phosphates (Paper III). Experi-ments conducted with these fuel mixtures (Paper IV & V) supported the theo-retical findings, and the influence of temperature and process conditions could be obtained. However, practical investigations also showed that attainment of the desired ash composition is subject to significant restrictions.

    Derived from the elaborated results and discussions, it was possible to assess the critical process and fuel parameters for the development of up-scaled gasification processes focusing on the conversion of sewage sludge with the aim of creating improved phosphate formation in the ash. The selection of a suitable bed material in fluidized bed conversion and the transformation mechanisms defining the ash chemistry were found to be of vital importance for future applications. The pur-suit of the predefined aims in reference to P-recovery from sewage sludge has led to a multitude of suggestions for suitable process parameters that must be ad-dressed in future bench- and pilot-scale experimental runs.

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    fulltext
  • 348. Hansson, Anders
    et al.
    Bryngelsson, Mårten
    KTH, Skolan för kemivetenskap (CHE), Kemiteknik.
    Attitudes regarding CO2 capture and storage from a Swedish perspective2005Inngår i: Proceedings of the Fourth Annual Conference on Carbon Capture and Sequestration, 2005, s. 1-16Konferansepaper (Fagfellevurdert)
    Abstract [en]

    This study examines the attitudes of Swedish politicians, scientists, NGOs and industry regarding CO2capture and storage (CCS), i.e. actors who possess knowledge about CCS today and will influence thepublic opinion of tomorrow. The study is unique since the phenomenological approach is seldom seenin this specific context. The empirical data is gathered through interviews and is structured andanalyzed in respect to expressed basic assumptions, systems view and a theoretical frameworkstemming from history of technology. From data, different ideal types are constructed - the CCSopponent, the CCS pragmatic and the CCS supporter. Results show a lot of skepticism and evenopposition to the technology among NGOs and politicians, while industry and scientists generally areproponents. The large group of pragmatics is especially interesting since it is presumed to take a standin the foreseeable future.Over time the energy politics in Sweden has been subject to intense controversies. Betweenthe 1960s and 1980s hydropower and nuclear power were heavily debated. With arguments stemmingfrom environmental protection the public opinion, represented by a wide array of strongorganizations, restricted the expansion of those power sources far below the originally plannedcapacity. Now this new technology, CCS, is about to enter the Swedish debate. It is a controversialtechnology with similar characteristics compared to its precedents regarding e.g. large-scale, risk, andlong-term storage, i.e. characteristics that led to the referendum deciding a nuclear power phase out.Unless a careful approach to implementing the technology, could CCS also be phased outprematurely? Will history repeat itself?The results should be seen from a Swedish point of view since Sweden has vast bio-fuel andhydropower resources, which together with an extensive amount of nuclear power makes CO2emissions per capita and GDP low, and the opposition against fossil fuels high.

  • 349.
    Harris, Kurt L.
    et al.
    University of Queensland, Australia.
    Thomson, Raine E. S.
    University of Queensland, Australia.
    Gumulya, Yosephine
    University of Queensland, Australia.
    Foley, Gabriel
    University of Queensland, Australia.
    Carrera-Pacheco, Saskya E.
    Universidad UTE, Ecuador.
    Syed, Parnayan
    University of Queensland, Australia.
    Janosik, Tomasz
    RISE Research Institutes of Sweden, Bioekonomi och hälsa, Kemiska processer och läkemedel.
    Sandinge, Ann-Sofie
    AstraZeneca, Sweden.
    Andersson, Shalini
    AstraZeneca, Sweden.
    Jurva, Ulrik
    AstraZeneca, Sweden.
    Bodén, Mikael
    University of Queensland, Australia.
    Gillam, Elizabeth M. J.
    University of Queensland, Australia.
    Ancestral Sequence Reconstruction of a Cytochrome P450 Family Involved in Chemical Defense Reveals the Functional Evolution of a Promiscuous, Xenobiotic-Metabolizing Enzyme in Vertebrates2022Inngår i: Molecular biology and evolution, ISSN 0737-4038, E-ISSN 1537-1719, Vol. 39, nr 6, artikkel-id msac116Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The cytochrome P450 family 1 enzymes (CYP1s) are a diverse family of hemoprotein monooxygenases, which metabolize many xenobiotics including numerous environmental carcinogens. However, their historical function and evolution remain largely unstudied. Here we investigate CYP1 evolution via the reconstruction and characterization of the vertebrate CYP1 ancestors. Younger ancestors and extant forms generally demonstrated higher activity toward typical CYP1 xenobiotic and steroid substrates than older ancestors, suggesting significant diversification away from the original CYP1 function. Caffeine metabolism appears to be a recently evolved trait of the CYP1A subfamily, observed in the mammalian CYP1A lineage, and may parallel the recent evolution of caffeine synthesis in multiple separate plant species. Likewise, the aryl hydrocarbon receptor agonist, 6-formylindolo[3,2-b]carbazole (FICZ) was metabolized to a greater extent by certain younger ancestors and extant forms, suggesting that activity toward FICZ increased in specific CYP1 evolutionary branches, a process that may have occurred in parallel to the exploitation of land where UV-exposure was higher than in aquatic environments. As observed with previous reconstructions of P450 enzymes, thermostability correlated with evolutionary age; the oldest ancestor was up to 35 °C more thermostable than the extant forms, with a 10T50 (temperature at which 50% of the hemoprotein remains intact after 10 min) of 71 °C. This robustness may have facilitated evolutionary diversification of the CYP1s by buffering the destabilizing effects of mutations that conferred novel functions, a phenomenon which may also be useful in exploiting the catalytic versatility of these ancestral enzymes for commercial application as biocatalysts.

  • 350.
    Hashemzehi, Mojgan
    et al.
    Ferdowsi University of Mashhad, IRN.
    Saghatoleslami, Naser
    Ferdowsi University of Mashhad, IRN.
    Nayebzadeh, Hamed
    Ferdowsi University of Mashhad, IRN.
    Microwave-Assisted Solution Combustion Synthesis of Spinel-Type Mixed Oxides for Esterification Reaction2017Inngår i: Chemical Engineering Communications, ISSN 0098-6445, E-ISSN 1563-5201, Vol. 204, nr 4, s. 415-423Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Environmentally benign production of biodiesel using heterogeneous catalysts is an important issue that requires the preparation of catalysts with high activity and reusability by a simple procedure. In this study, pure alumina and zinc oxide-and copper oxide-modified alumina were tested for the esterification of oleic acid to its methyl ester. The microwave-assisted solution combustion (MSC) method was used to prepare the catalyst samples that were characterized by X-ray diffraction (XRD), Fourier transform infra-red (FTIR), Brunauer-Emmett-Teller (BET) surface area measurement, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The spinel-type zinc aluminate was successfully synthesized, but CuO-modified alumina particles were clearly observed. Whereas in the alumina, much lower activity was observed than the doped alumina, zinc aluminate showed higher activity than copper oxide-alumina due to its smaller particle size, higher BET surface area, larger average pore size, and higher acidity. Finally, after the reaction conditions for the conversion of oleic acid were optimized for the case of spinel ZnAl2O4 as nanocatalyst, a yield of higher than 94% was obtained at 180 degrees C, 9 methanol/oleic acid molar ratio, 3 wt% of catalyst for 6 h. Furthermore, the catalyst deactivation was not observed after four reaction cycles at the optimal reaction conditions, indicating the feasibility of the proposed method for the preparation of industrial catalysts.

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