A sustainable solution for meeting the energy demands at our planet is by utilizing wind-, solar-, wave-, thermal-, biomass- and hydroelectric power. These renewable and CO2 emission-free energy sources are highly variable in terms of spatial and temporal availability over the Earth, introducing the need for an appropriate method of storing and carrying energy. Hydrogen has gained significant attention as an energy storage- and carrier media because of the high energy density that is exploited within the ‘power-to-gas’ process chain. A robust way of producing sustainable hydrogen is via electrochemical water splitting. In this work the search for new heterogeneous catalyst materials with the aim of increasing energy efficiency in water splitting has involved methods of both electrochemical water splitting and chemical water oxidation. Some 21 compounds including metal- oxides, oxofluorides, oxochlorides, hydroxide and metals have been evaluated as catalysts. Two of these were synthesized directly onto conductive backbones by hydrothermal methods. Dedicated electrochemical cells were constructed for appropriate analysis of reactions, with one cell simulating an upscale unit accounting for realistic large scale applications; in this cell gaseous products are quantified by use of mass spectrometry. Parameters such as real time faradaic efficiency, production of H2 and O2 in relation to power input or overpotentials, Tafel slopes, exchange current density and electrochemical active surface area as well as turnover numbers and turnover frequencies have been evaluated. Solubility, possible side reactions, the role of the oxidation state of catalytically active elements and the nature of the outermost active surface layer of the catalyst are discussed. It was concluded that metal oxides are less efficient than metal based catalysts, both in terms of energy efficiency and in terms of electrode preparation methods intended for long time operation. The most efficient material was Ni-Fe hydroxide electrodeposited onto Ni metal foam as conductive backbone. Among the other catalysts, Co3Sb4O6F6 was of particular interest because the compound incorporate a metalloid (Sb) and redox inert F and yet show pronounced catalytic performance. In addition, performance of materials in water splitting catalysis has been discussed on the basis of results from electron microscopy, solubility experiments and X-ray diffraction data.

<p>The major part of the present work, deals with the reduction kinetics of Cu₂O powder and a Cu₂O-WO₃ powder mixture by hydrogen gas, studied by ThermoGravimetric Analysis (TGA). The reduction experiments were carried out both isothermally and non-isothermally on thin powder beds over different temperature intervals. During the experiments, the reductant gas flow rate was kept just above the starvation rate for the reaction to ensure that chemical reaction was the rate-controlling step. The activation energy for the reactions was evaluated from isothermal as well as non-isothermal reduction experiments.</p><p>In the case of the reduction of Cu₂O, the impact of the stability of the copper oxide on the activation energy for hydrogen reduction under identical experimental conditions is discussed. A closer investigation of additions of Ni or NiO to Cu₂O did not have a perceptible effect on the kinetics of reduction.</p><p>In the case of the reduction of the Cu₂O-WO₃mixture, the reaction mechanism was found to be affected in the temperature range 923-973 K, which is attributed to the reaction/transformation in the starting oxide mixture. At lower temperatures, Cu₂O was found to be preferentially reduced in the early stages, followed by the reduction of the tungsten oxide. At higher temperatures, the reduction kinetics was strongly affected by the formation of a complex oxide from the starting materials. It was found that the Cu₂O-WO₃mixture underwent a reaction/transformation which could explain the observed kinetic behavior.</p><p>The composition and microstructures of both the starting material and the reaction products were analyzed by X-ray diffraction (XRD) as well as by microprobe analysis. vi Kinetic studies of reduction indicated that, the mechanism changes significantly at 923 K and the product formed had unusual properties. The structural studies performed by XRD indicated that, at 923 K, Cu dissolved in W forming a metastable solid solution, in amorphous/nanocrystalline state. The samples produced at higher as well as lower temperatures, on the other hand, showed the presence two phases, pure W and pure Cu. The SEM results were in conformity with the XRD analysis and confirmed the formation of W/Cu alloy. TEM analysis results confirmed the above observations and showed that the particle sizes was about 20 nm.</p><p>The structure of the W/Cu alloy produced in the present work was compared with those for pure copper produced from Cu2O produced by hydrogen reduction under similar conditions. It indicated that the presence of W hinders the coalescence of Cu particles and the alloy retains its nano-grain structure. The present results open up an interesting process route towards the production of intermetallic phases and composite materials under optimized conditions.</p>

The major part of the present work, deals with the reduction kinetics of Cu2O powder and a Cu2O-WO3 powder mixture by hydrogen gas, studied by ThermoGravimetric Analysis (TGA). The reduction experiments were carried out both isothermally and non-isothermally on thin powder beds over different temperature intervals. During the experiments, the reductant gas flow rate was kept just above the starvation rate for the reaction to ensure that chemical reaction was the rate-controlling step. The activation energy for the reactions was evaluated from isothermal as well as non-isothermal reduction experiments. In the case of the reduction of Cu2O, the impact of the stability of the copper oxide on the activation energy for hydrogen reduction under identical experimental conditions is discussed. A closer investigation of additions of Ni or NiO to Cu2O did not have a perceptible effect on the kinetics of reduction. In the case of the reduction of the Cu2O-WO3 mixture, the reaction mechanism was found to be affected in the temperature range 923-973 K, which is attributed to the reaction/transformation in the starting oxide mixture. At lower temperatures, Cu2O was found to be preferentially reduced in the early stages, followed by the reduction of the tungsten oxide. At higher temperatures, the reduction kinetics was strongly affected by the formation of a complex oxide from the starting materials. It was found that the Cu2O-WO3 mixture underwent a reaction/transformation which could explain the observed kinetic behavior. The composition and microstructures of both the starting material and the reaction products were analyzed by X-ray diffraction (XRD) as well as by microprobe analysis. vi Kinetic studies of reduction indicated that, the mechanism changes significantly at 923 K and the product formed had unusual properties. The structural studies performed by XRD indicated that, at 923 K, Cu dissolved in W forming a metastable solid solution, in amorphous/nanocrystalline state. The samples produced at higher as well as lower temperatures, on the other hand, showed the presence two phases, pure W and pure Cu. The SEM results were in conformity with the XRD analysis and confirmed the formation of W/Cu alloy. TEM analysis results confirmed the above observations and showed that the particle sizes was about 20 nm. The structure of the W/Cu alloy produced in the present work was compared with those for pure copper produced from Cu2O produced by hydrogen reduction under similar conditions. It indicated that the presence of W hinders the coalescence of Cu particles and the alloy retains its nano-grain structure. The present results open up an interesting process route towards the production of intermetallic phases and composite materials under optimized conditions. / QC 20101222

Transitioning from the conventional steel process to a direct hydrogen reduction process in the steel industry is a significant step towards reducing carbon dioxide emissions and achieving greater sustainability. The process involves using hydrogen gas as a reducing agent instead of carbon to remove oxygen from the iron ore. This study aimed to investigate the future capacity of the hydrogen-based steelmaking process in Sweden by 2050 while also examining the pathway for transitioning to hydrogen-based steelmaking in other European countries in comparison to the Swedish case. To achieve this goal, a systematic literature search was conducted using Scopus and Web of Science databases to identify relevant case studies and reviews that focused on green steel solutions and that discussed associated challenges and barriers. A aconsupteal model was designed by simplifying the process into three production steps, hydrogen storage, and hot briquette iron storage to calculate the energy consumption and material requirements for the hydrogen direct process in Sweden. Additionally, a survey providing insights regarding current practices and perspectives was administered to seven companies in Sweden and two in other European countries, namely the Netherlands and Germany. Furthermore, a comparative analysis of the literature review on life cycle assessment was conducted to compare the carbon emissions associated with two different steel production processes: the conventional process using the basic oxygen furnace and the emerging hydrogen-based steel production process.  An analysis of the energy consumption within the hydrogen-based steelmaking process reveals several components, including the electrolyze, direct reduction shaft furnace, electric arc furnace, and briquetted iron and hydrogen storage. The model results showed that electrolyzing alone accounts for 60% of the energy needed in the process. The model showed that hydrogen direct reduction steelmaking needs 3.66 MWH of electricity per ton of liquid steel produced in Sweden.  Only a few of the Swedish companies have adopted innovative approaches while the remaining steel mills primarily rely on scrap-based methods. While they may obtain hydrogen-reduced iron as a raw material in the future, emissions reduction is not their primary focus. These mills contribute to emissions through fuel usage, and efforts are underway to transition from fossil fuels to electricity, bio -based gas, or hydrogen. Hydrogen-based steel production produces significantly lower greenhouse gas emissions than conventional steel productio, by up to 90 percent, depending on the specific process and energy used, as stated in the life cycle analysis reviews.  This thesis shows key factors for the success of hydrogen-based steel production methods; low -emission electricity and flexibility to store hydrogen. All three countries have expressed interest in and invested in hydrogen-based steelmaking. the share of renewable energy produced and consumed in hydrogen-based steel production in Sweden is expected to make up a share of 2.3% of the total renewable energy production in the country, while Germany and the Netherlands are projected to contribute a modest 1.5% and 1.3% respectively. However, the search for ways to lower carbon dioxide emissions is costly in terms of the amount of electricity required. There are practical reasons for the restricted usage of this steelmaking process in Europe, including the availability of steel scrap, electricity demand, and the low likelihood of scrap generation and recycling scrap availability on the EU  market. Because of this, it is challenging to predict capacity and carbon dioxide reduction by 2050.

We are facing an important challenge, to reduce the greenhouse gas emissions to make sure that we limit global warming to 2 °C, preferably 1.5 °C. Drastic changes and developing new methods may be our only chance to keep global warming under 1.5 °C. The steel production in Sweden today accounts for 10% of the CO2 emission. The joint venture HYBRIT (Hydrogen Breakthrough Ironmaking Technology), between SSAB, LKAB and Vattenfall, aims to reduce the CO2 emission by developing a method that reduces iron ore pellets with hydrogen gas, leaving only water as off-gas. From simple thermodynamic calculations, it is evident that the reduction of iron ore using hydrogen gas is an endothermic reaction, requiring heat. Based on the calculated energy requirement, the temperature at the center of the pellet should not be the same as the temperature at the surface of the pellet but instead, decrease as the reduction reaction takes place. This report presents the temperature profile at the surface and in the center of a hematite pellet during hydrogen reduction at temperatures of 600 °C, 700 °C, 800 °C and 900 °C. Ideally, the results can be implemented in a model to better simulate the reduction reaction taking place inside a hematite pellet. The experiment consists of three sub-experiments, the first measures the temperature profile of the unreduced iron ore pellet in an argon gas atmosphere, secondly, the temperature profile and mass loss are measured during reduction, lastly, the temperature profile is measured for the reduced pellet in a hydrogen atmosphere. The mass loss measured during hydrogen reduction is used to calculate the degree of reduction. The results show that the reaction rate increases with increasing temperature and concentration of H2. Additionally, a higher reduction temperature gives the largest temperature decrease inside the pellet during reduction. At 900 °C, the temperature decrease is equal to 39 °C and at 600 °C, it is equal to 3 °C. The results prove that after a certain initial stage, gas diffusion and heat conduction through the product layers play important roles in controlling the reaction rate. There is even a period where a plateau of the reduction is observed, the reaction is mostly controlled by heat transfer. / Idag står vi inför en viktig utmaning, att minska utsläppen av växthusgaser och se till så att vi inte överskrider 2 °C uppvärmning, helst inte 1.5 °C. För att klara detta krävs drastiska förändringar och utvecklingar av nya metoder kan vara vår enda chans att uppnå 1.5-gradersmålet. Ståltillverkningen i Sverige idag står för 10% av CO2 utsläppen och för att bidra till att minska utsläppen av CO2 har företaget HYBRIT, vilket står för Hydrogen Brakethrough Ironmaking Technology, skapats. HYBRIT är en joint venture mellan SSAB, LKAB och Vattenfall som tillsammans vill skapa stål på ett mer miljövänligt sätt. Processen går ut på att reducera järnmalmspellets med hjälp av vätgas för att producera järnsvamp och ge ifrån sig vatten som avgas. Från enkla termodynamiska beräkningar är det lätt att inse att reduktionen med hjälp av vätgas är en endoterm process, som kräver energi. Det är genom denna kunskap som en kan föreställa sig att reduktionen av järnmalmspellets med hjälp av vätgas kommer bidra till en temperaturminskning. I denna rapport har temperaturprofilen inne i och på ytan av en hematitpellet mätts under tiden som den blivit reducerad med vätgas. Idealt kan resultaten implementeras i en modell för att bättre simulera reduktionsreaktionen som äger rum i en hematitpellets. Fyra olika reduktionstemperaturer har undersökts: 600 °C, 700 °C, 800 °C och 900 °C. Experimenten består av tre del-experiment, först mäts temperaturprofilen av den oreducerad hematitpelletsen i en argonatmosfär, sedan mäts viktminskningen och temperaturprofilen av pelleten medan den reduceras i en vätgasatmosfär, slutligen mäts temperaturprofilen av den reducerade pelleten i en argonatmosfär. Viktminskningen under reduktionen används för att beräkna reduktionsgraden under reduktionsförloppet. Resultaten visade att reduktionshastigheten ökade med ökande temperatur och koncentration av H2. Ökad temperatur gav även den största temperaturminskningen inne i pelleten då den reducerats med vätgas. Vid 900 °C uppmätes en temperaturminskning på 39 °C, varav reduktion vid 600 °C gav en temperaturminskning på 3 °C. Resultaten visar att efter en viss tids reduktion, spelar gasdiffusionen och värmeledningen genom produktlagret en viktig roll och är det som begränsar reduktions-hastigheten. Fortsatt, då hematitpelleten reducerades uppstod en platå där temperaturen var konstant och reaktionen till största delen var begränsad av värmeledningen genom produktlagret.

Nano-scaled carbons were produced by thermal treatment of pine wood chips and bio-char. The influence of temperature, heating rate, pyrolysis time, and type and flow rate of purge gas on the production of nano-carbons was investigated. Using TEM and SEM, different carbon-based nanomaterials were observed in the prepared samples. The effect of metal ion doping on the bio-char was also investigated. Highly functionalized nano carbonaceous materials were synthesized by low temperature hydrothermal carbonization (HTC) using glucose, sucrose, xylose, and cellulose. Carbon-encapsulated iron (Fe@C) core-shell particles were also synthesized by the HTC method and used as catalyst for Fischer-Tropsch synthesis to produce liquid hydrocarbons from syngas; it showed excellent activity. Nano-structured Co-Mo carbides over several nano-sized carbon materials were prepared using the carbothermal reduction and carbothermal hydrogen reduction methods. Nano-structured Co-Mo carbides derived from Vulcan® XC-72 were used as the catalyst to produce higher alcohols.

In this work, an approach for copper atomic layer deposition (ALD) via reduction of CuxO films was investigated regarding applications in ULSI interconnects, like Cu seed layers directly grown on diffusion barriers (e. g. TaN) or possible liner materials (e. g. Ru or Ni) as well as non-ferromagnetic spacer layers between ferromagnetic films in GMR sensor elements, like Ni or Co. The thermal CuxO ALD process is based on the Cu (I) β-diketonate precursor [(nBu3P)2Cu(acac)] and a mixture of water vapor and oxygen ("wet O2") as co-reactant at temperatures between 100 and 130 °C. Highly efficient conversions of the CuxO to metallic Cu films are realized by a vapor phase treatment with formic acid (HCOOH), especially on Ru substrates. Electrochemical deposition (ECD) experiments on Cu ALD seed / Ru liner stacks in typical interconnect patterns are showing nearly perfectly filling behavior. For improving the HCOOH reduction on arbitrary substrates, a catalytic amount of Ru was successful introduced into the CuxO films during the ALD with a precursor mixture of the Cu (I) β-diketonate and an organometallic Ru precursor. Furthermore, molecular and atomic hydrogen were studied as promising alternative reducing agents.