Using and finding applications from biomass is and will continue to be an important subject forresearch, and biomass from trees, has shown several outstanding aspects other than just for the pulpand paper applications. It is now, more than ever, time to find efficient uses for all the woodcomponents, in particular, the hemicelluloses. The hemicelluloses account for approximately onethirdof a dry composition of lignocellulosic wood biomasses. Of these hemicelluloses, xylan is themost abundant in many plants, particularly in hardwood. As for the Swedish forestry, xylan frombirch is considered as one of the most promising resources for the future.This thesis investigates the impact of acetylation of xylan on some properties such as solubility,thermal stability and film formation. Films were prepared using the non- and acetylated xylan withaddition of different plasticizers (glycerol, sorbitol and xylitol).Alkali-soluble birch xylan (ASX), obtained by ethanol/toluene extraction and sodium chloritedelignification of the wood sawdust followed by potassium hydroxide extraction of the obtainedholocellulose, and commercial xylan (CX) were acetylated to different degree of substitution withacetyl groups (DSAc), using acetic anhydride in dimethyl sulfoxide (DMSO) and 1-methylimidazole(NMI). Films were prepared by suspending non-acetylated xylan in water (H2O) and adding differentpercentages of plasticizers (20 and 40%) or by suspending acetylated xylan in chloroform (CHCl3).Characterizations of the non- and acetylated polymer (AcASX and AcCX) and films were conducted inorder to determine thermal and mechanical properties.CX and ASX presented different reactivity leading to different behaviour during acetylation and sodifferent DSAc. The thermal stability has been improved for both ASX and CX following the increase ofthe DSAc. Concerning film formation, ASX showed a great ability to form films through casting with orwithout plasticizers while it was impossible to obtain any films using only CX. For AcASX and AcCX thefilm formation using chloroform was depending on the DSAc and the dispersability in the solvent. Allthe films obtained have been mechanically and thermally tested. Best results for the mechanicaltests were obtained with 40% plasticizers with creation of a plastic behaviour and improvement ofthe flexibility. Thermally speaking, the thermal stability gained through acetylation of the samples islost by film casting, and use of plasticizers reduced the thermal stability as a new component wasadded to the composition. / Att använda och hitta tillämpningar från biomassa är och kommer att fortsätta att vara ett viktigtämne för forskning, och biomassa från träd har visat flera goda aspekter annat än bara för massaochpappersapplikationer. Det är hög tid att hitta effektiva användningar för alla träkomponenter, isynnerhet hemicelluloserna. Hemicelluloserna står för ungefär en tredjedel av en torrsammansättning av lignocellulosa. Av dessa hemicellulosor är xylan den vanligaste i många växter,särskilt i lövträ. När det gäller det svenska skogsbruket anses xylan från björk vara en av de mestlovande resurserna för framtiden.Denna avhandling undersöker effekterna av acetylering av xylan på vissa egenskaper, såsomlöslighet, termisk stabilitet och filmbildning. Filmer framställdes med användning av den icke-ochacetylerade xylanen med tillsats av olika mjukningsmedel (glycerol, sorbitol och xylitol).Alkalöslöslig björkxylan (ASX), erhållen genom etanol / toluenutvinning och natriumkloritfördelningav träsågspån följt av kaliumhydroxidutvinning av erhållen holocellulosa och kommersiell xylan (CX)acetylerades till olika grad av substitution med acetylgrupper (DSAc), med användning avättiksyraanhydrid i dimetylsulfoxid (DMSO) och 1-metylimidazol (NMI). Filmer framställdes genom attsuspendera icke-acetylerad xylan i vatten (H2O) och tillsätta olika procentdelar mjukningsmedel (20och 40%) eller genom att suspendera acetylerad xylan i kloroform (CHCI3). Karakteriseringar av denicke-och acetylerade polymeren (AcASX och AcCX) och filmer utfördes för bestämning av te rmiskaoch mekaniska egenskaper.CX och ASX presenterade olika reaktivitet vilket ledde till olika beteenden under acetylering och såolika DSAc. Den termiska stabiliteten har förbättrats för både ASX och CX efter ökningen av DSAc. Närdet gäller filmbildning uppvisade ASX en stor förmåga att bilda filmer genom gjutning med eller utanmjukningsmedel medan det var omöjligt att erhålla några filmer med endast CX. För AcASX och AcCXvar filmbildningen med användning av kloroform beroende av DSAc och dispergerbarheten ilösningsmedlet. Alla filmer som erhållits har testats mekaniskt och termiskt. Bästa resultat för demekaniska testerna erhölls med 40% mjukningsmedel med skapandet av ett plastiskt beteende ochförbättring av flexibiliteten. Termiskt sett förloras den termiska stabiliteten som erhållits genomacetylering av proverna genom filmgjutning, och användning av mjukningsmedel reducerade dentermiska stabiliteten som en ny komponent tillsattes till kompositionen.

The cleaning technology for exhaust air is an area under constant development. In collaboration with Ozone Tech Systems the project resulted in a lab scale test rig for air cleaning units. The test rig was designed primarily to investigate the mechanisms of an UV reactor as well as the life times of a hydrogen sulphide absorption bed and an activated carbon bed. The thesis consisted in the design of the system, the acquisition of units and the construction of the system followed by the modelling of the pollutant elimination in the UV reactor. Fluid dynamics of the process flow is neglected, while the light distribution is numerically calculated. Two separate pollutants were considered, one being volatile organic compounds represented by acetaldehyde, and the other being hydrogen sulphide, chosen due to their prevalence in exhausts. An experimental plan is developed to validate the model, find model parameters and finally to investigate process parameters in the UV reactor. / Luftföroreningar är ett mycket aktuellt problem, och tekniken för att rena luftströmmar är under ständig utveckling. I samarbete med Ozone Tech Systems designades och byggdes en testrigg för att undersöka olika luftreningsenheter. De primära målen var att undersöka mekanismerna i en UV reaktor samt livslängden för två lika packade bäddar; en absorptionsbädd för divätesulfid samt en adsorptionsbädd av aktiverat kol. Examensarbetet bestod av designmomentet, införskaffande av rätt enheter och konstruktionen av systemet. Även numerisk modellering av UV-reaktorn ingick i projektet, och denna gjordes med störst avseende på UV-ljusets fördelning i reaktorn medan flödesdynamiken försummades.Två olika föroreningar valdes p. g. a. deras frekventa förekomst i luftströmmar som ska renas; divätesulfid och flyktiga organiska ämnen (representerade här av acetaldehyd). Rapporten presenterar även en experimentell plan för att validera modellen, hitta modellens semiempiriska parametrar, samt till slut för att med hjälp av faktoriell design undersöka interaktionen mellan olika faktorer i UV-reaktorn.

As the mission to the decrease global warming and phase out highly pollutingenvironmental practices globally, regulations including Euro 6 and policies generated by theUnited Nations Framework Convention on Climate Change (UNFCCC) are pushing companiesto be more innovative when it comes to their energy sources. These regulations involve manyfactors related to the cleanliness of the fuel and produced emissions, for example, propertiesof the fuels such as sulfur content, ash content, water content, and resulting emission valuesof Carbon dioxide (CO2) and Nitrogen Oxides (NOx). Furthermore, Sweden has set achallenging target of a fossil-fuel-independent vehicle fleet by 2030 and no net greenhousegasemissions by 2050.One way to cut down on the polluting properties in the fuel, as well as weakening thedependence on fossil fuel based fuel includes utilizing higher blending ratios of biofuels in thetransport sector. This transition to biofuels comes with many challenges to the transportindustry due to higher concentrations of these new fuels leads to clogging of the filters in theengine, as well as, internal diesel injector deposits (IDIDs) that produce injector fouling. Thisclogging of the filters leads to lower performance by the engines which leads to higher repairtimes (uptime) and less time on the road to transport goods. The formation of these softparticles at the root of the clogging issue is a pivotal issue because the precise mechanismsbehind their formation are highly unknown. Scania, a leader in the Swedish automotiveindustry, is very interested in figuring out what mechanisms are the most influential in theformation of these particles in the engine. Understanding the key mechanisms would allowScania to make appropriate adjustments to the fuel or the engines to ensure more time onthe road and less maintenance.There are many conditions known to be possible causes of the formation of softparticles in engines such as water content, ash content, and temperature. After generatingsoft particles using a modified accelerated method, particles were analyzed using infraredtechnology (RTX-FTIR) and a Scanning Electric Microscope (SEM-EDX). Many differentexperiments were performed to be able to make a conclusion as to which mechanisms weremost influential including temperature, time, water, air, and oil. The combination of agingbiofuels (B100, B10, HVO) with metals, and water produced the largest amount of particlesfollowed by aging the biofuels with aged oil, metals, and water. Aging the fuels with aged oilincreased particles, meanwhile the addition of water prevented particle production possiblydue to additives. B100 produced the highest amount of particles when aged with Copper, B10with Brass, and HVO with Iron.

No description available.

The annual increase in waste car tires in addition to the enormous amount at present poses a major waste management problem as well as an environmental hazard. However, pyrolysis is emerging as a solution for waste tire management and a viable technology for material recycling and energy recovery that produces high energy liquid and gas products as well as char. The pyrolysis oil that is produced from this technology has the potential to be used as vehicle fuel but contains exceeding levels of sulfur and other impurities. This study investigates the upgrading and desulfurization of waste tire pyrolysis oil by reactive adsorption using a molybdenum modified zeolite and its desilicated form. The experiments were performed at 320 °C and a LHSV of 45-50 h-1 for approximately 45 min, and revealed that both desilication and Mo-modification resulted in the cracking of both gaseous and liquids compounds, reduction of TAN, denitrogenation, and deoxygenation. Desilication increased desulfurization while Mo-modification increased the EHI. The treatment was the most effective in the removal of oxygen, followed by nitrogen and sulfur. In conclusion, the treatment process is promising as a method for direct liquid upgrading but requires further research.

The study has been conducted in collaboration with Swestep AB, a Swedish company that specializes in the conversion of waste to valuable products via the KDV technology. The study explores the possibility of using cassava chips and cassava pulp as a potential feedstock in the production of synthetic diesel and compares the KDV method with fermentation, a conventional method of using cassava chips and cassava pulp in Thailand. To obtain the carbon yield, amount of product and system efficiency, a mass and energy balances were first performed on wood feedstock data provided by the company. The balances were thereafter used as a basis for a simulation analysis of the cassava feedstock. The diesel product yield is produced through a KDV 150 plant using 551kg/h of the different feedstock; wood, cassava chips and cassava pulp resulting in different amounts of diesel product 150 L/h, 116.79 L/h and 121.31 L/h, respectively. For cassava, the C yield in diesel is 0.41 while the C yield of ethanol production is 0.14, since C in the ethanol production is converted into other matters. Besides, the system efficiency of the KDV plant with different types of feedstock is around 0.84 because some parts of the KDV plant is self-supplied whereas the ethanol production plant (55% of system efficiency) is not. Economical evaluations of the KDV 5000 and ethanol production plant were performed. The KDV 5000 with cassava pulp as feedstock produces 31 ML/year and is feasible for investment in Thailand due to the low price of the feedstock which is driving the operation cost (15.167 baht/L or 0.46 USD/L). This is lower than the selling price (21.329 baht/L or 0.65 USD/L) whereas the KDV 5000 plant with cassava chips is not feasible. The KDV plant with cassava pulp as a feedstock will reach the breakeven point after running for 7 years. The ethanol production process with cassava chip as feedstock produces 49 M liter/year and has an operation cost of 19.693 baht/liter (0.6 USD/L) which is higher than the KDV plant due to the feedstock price. The selling price of ethanol is 23.11 baht/l (0.705 USD/L) which resulted in the process reaching the breakeven point after 14 years.

Sveriges riksdag har tagit fram 16 miljömål där ett av dem ämnar att minska övergödningen isvenska sjöar och vattendrag. Övergödning är bland annat ett resultat från näringsämnen somläckt från jordbruk. En lösning på övergödningsproblemet skulle kunna vara att samla upp deläckta näringsämnena och återföra dem till åkern. Detta skulle kunna göras med hjälp av biokolsom adsorbent och syftet med detta projekt är att undersöka dessa möjligheter samt biokoletsstruktur. Definitionen på biokol är att det är en heterogen kolliknande substans från hållbart framtagenbiomassa. Den ska även ha ett högt kolinnehåll och användas på ett sådant sätt att den binderupp kolet under en längre tid. Biokol framställs genom pyrolys eller förgasning under högtemperatur och syrefattiga förhållanden. Syftet med användande av biokol som adsorbent ärmöjligheten att kunna skapa ett kretslopp. Biokolet ska först verka som filter i avrinningsdikenvid åkermark för att sedan återföras, mättad med näringsämnen, tillbaka till åkermarken. Vid experimenten användes tre olika kol. Ett grillkol och två olika biokol. Strukturen på deolika kolen undersöktes med en BET-analys. Analysen av grillkolen gav ett orimligt svar menför de två biokolen gavs resultat som ansågs rimliga. Denna analys ger inte ett direkt värde påadsorptionsförmåga hos kolen utan behöver verifieras med ett experimentellt framtagetsamband mellan struktur och adsorptionsförmåga. Ett alternativ till BET-analysen är att göraen jodnummeranalys, som ger värden på adsorptionsförmåga för det undersökta ämnet. Denna analys utfördes inte praktiskt. Två lösningar med olika koncentrationer av Na3PO4 förbereddes och blandades underomrörning med de olika kolen. Två olika omrörningstider användes för att kunna undersökauppehållstidens betydelse. Efter omrörning filtrerades proverna för att få bort kol och de olikafiltraten genomgick en ICP-analys för undersökning av fosforinnehåll. Resultatet som framkomav denna analys var att filtraten hade en högre fosforhalt än vad de initiala lösningarna hade.Förklaringen till detta antas vara att biokolet redan innehöll fosforföreningar som Na3PO4 ut. Problemet med ICP-analysen var att den inte kunde detektera i vilken form fosforn var.Det gick heller inte att detektera kväve i ICP-analysen då luften runt omkringinstrumentet innehåller kväve vilken kontaminerar provet och detekteras i analysen. Enalternativ metod till ICP är att använda spektroskopi som dels kan detektera kväve men ävenolika former av fosfor- och kväveföreningar. Slutsatsen var att analys av biokols adsorptionsförmåga är att den är komplex. BET-analys ären bra metod för att visa struktur på kolen men jodnummer kan vara ett bättre alternativ för attdirekt hitta ett värde på kolets adsorptionsförmåga. För analys av lösningar fungerar ICP enbartför fosfor och därför skulle spektroskopi kunna vara ett bättre alternativ då det kan detekterakväve samt olika former av föreningar. / The aim of this project is to create a deeper understanding of biochar’s ability to adsorbnutrients. In the long run the aim is to find a way to use the most suitable structures of biocharfor a maximum adsorption of different kinds of nutrients. The objective of this project is tofind, through case studies and practical experiments, an effective method to examine andanalyze the structure of biochars and their ability to adsorb nitrates and phosphates. The conclusion of the project was that analysis of the biochar’s ability to adsorb is a complexmatter. The BET-analysis is a good method to find the structure of the biochar. However, iodinenumber analysis could be a better alternative to directly find a value on the biochar’s ability toadsorb. The ICP-analysis of the solutions only works for phosphor, therefore spectroscopywould be a better alternative since it also can detect nitrogen and the different compounds.

Transition metal phosphide materials have found themselves at the forefront of research revolving around energy applications. Due to the vast range of properties possessed by marginally different phase compositions, binary and ternary metal phosphides are utilized as catalysts, semi-conductors and magnetocaloric materials along with many others. These attractive properties, which are highly phase dependent, call for a versatile and cost effective synthesis route for various phosphide materials without sacrificing properties important at the nanoscale such as particle size and morphology. The primary focus outlined in the work of this dissertation pertains to a versatile wet chemical synthesis capable of producing multiple phases of binary and ternary phosphides containing one or more of the transition metals cobalt, iron and nickel. These metals were of particular interest due to the proven catalytic activity of iron, cobalt or nickel binary phases and the lack of research conducted on the corresponding ternary phases. The challenge presented by wet chemical synthesis methods is the ability to separate different crystal phases of metal phosphide in a short amount of time, with less toxic and lower cost chemicals, and a simple synthetic process with the ability to produce products on a larger scale. Oleylamine was used as a solvent, capping agent and reducing agent along with trioctylphosphine or triphenylphosphine as a phosphorus source. Many binary phosphide phases were synthesized with the same method and purity of phase was controlled primarily with temperature or phosphorus to metal ratio (P:M). At lower temperatures (290-320°C) or lower P:M (4:1) Ni3P,Ni2P, Fe2P, and Co2P were synthesized while higher temperatures (330-360°C) or higher P:M (22:1) produced Ni5P4, Ni12P5, FeP and CoP. Ternary phosphides FeCoP and CoNiP were also successfully synthesized at temperatures of 300-330°C with small excesses of phosphorus (2-5 molar excess). Preliminary catalytic studies for the evolution of hydrogen gas were conducted to test the efficacy of phosphide materials produced via the simplistic oleylamine method. Ni2P was found to have the highest activity toward hydrogen evolution with an overpotential of 320 mV which is comparable and in some cases better than other unsupported phosphide catalysts of the same phase. The ability to control phase composition using a simple, cost effective wet chemical synthesis is promising for the future production of active metal phosphide materials.

Nitrogenase, EC: 1.18.6.1 is the enzyme that catalyzes the reduction of dinitrogen to ammonia; this is known as biological nitrogen fixation. Nitrogen fixation is so important to our daily lives, that we utilize approximately 2% of the annual energy produced worldwide to fix nitrogen industrially via the Haber-Bosch process. The industrial process requires a high input of energy in the form of heat (>450°C) and pressure (>200 atm>), while the enzymatic system is performed under ambient conditions. Research invested into understanding the mechanism of this biological catalyst could eventually lead to understanding how nature performs difficult chemical reductions, which could allow researchers to develop catalysts that mimic this enzyme to perform many important reactions, such as nitrogen fixation, much more efficiently than today. Electron transfer in the nitrogenase is only partially understood, and is one of the key elements of understanding the mechanism of nitrogenase. Nitrogenase is composed of two proteins, the Fe protein delivers electrons to the MoFe protein, where N2 binds and is subsequently reduced. The conformational changes that take place upon Fe protein binding were investigated in order to better understand electron transfer within the enzyme. Further, studies were performed which probed the P-cluster, an iron sulfur cluster in the MoFe protein that acts as an intermediate in the electron transfer event, and successfully identified the biologically relevant redox state of the P-cluster, P+1. Other studies were performed which identified several variants of the MoFe protein which were able to accept electrons from a chemical reductant. These variants are the first examples of nitrogenase enzymes able to accept electrons from any source other than Fe protein and shown substrate reduction. These variants pinpoint where nitrogenase is likely to undergo conformational changes to allow electron transfer to the active site of the enzyme. Finally, studies were done on the isolated active site of the protein, the iron molybdenum cofactor to better understand how the active site of nitrogenase works The goal of this thesis is to better understand how electrons travel through nitrogenase, and how they are utilized at the active site, FeMo-cofactor, when they arrive.

Photosynthesis is a fundamental biological process that sustains life on earth. Chlorophyll is the pigment that captures sunlight and converts it to chemical energy through photosynthesis. These essential light-harvesting compounds are found in photosynthetic plants, cyanobacteria, green algae, angiosperms and gymnosperms. In the chlorophyll biosynthetic pathway, protochlorophyllide (Pchlide) serves as the precursor molecule for chlorophyll. Protochlorophyllide oxidoreductases are a class of enzymes that catalyze the conversion of Pchlide to chlorophyllide a (Chlide), which subsequently is reduced and modified to form chlorophyll. A light-dependent protochlorophyllide oxidoreductase (LPOR) is found in flowering plants (angiosperms), and as the name suggests, requires the energy from light to catalyze the conversion. An unrelated dark- operative light-independent version (DPOR - dark-operative protochlorophyllide oxidoreductase) is found in cyanobacteria, photosynthetic bacteria, green algae and gymnosperms. DPOR functions in the absence of light, or low-light conditions and in the absence of oxygen. DPOR is a multi-subunit complex consisting of the BchL, BchN and BchB proteins which share striking structural similarities to the Nif proteins in the nitrogenase complex. ATP binding and hydrolysis is an essential aspect of DPOR catalysis, though it still remains mysterious as to how the energy from ATP is used to drive substrate reduction. The role of ATP in the conversion of Pchlide to Chlide has been examined kinetically to establish when ATP is hydrolyzed in the catalytic mechanism. Additionally, variants of the BchL protein have been developed to include a functional linked BchL homodimer, as well as Walker A mutated forms on one, or both ATPase sites of the protein. The data suggest a dynamic mechanism in which the binding and hydrolysis of both ATP are required for normal function.