Electro-oxidation of ethanol on smooth platinum surfaces was studied in thetemperature range 21C to 140C for 0.2 M ethanol in 0.5 M sulphuric acid.This was done by use of cyclic voltammetry and electrochemical impedancespectroscopy. In addition cyclic voltammetry with different ethanol concentrationsfrom 0.1 M to 1 M, in 0.5 M sulphuric acid was done at room temperature.Cyclic voltammetry with different ethanol concentrations showed a shift to morepositive potentials for the first oxidation peak in positive going scan as the ethanolconcentration increased. A shift to more positive potentials was also observed forthe oxidation peak in the negative scan as the concentration increased from 0.1M to 1 M. This indicates that the optimum surface condition is reached at higherpotentials for higher ethanol concentrations. This can be because ethanol andadsorbed ethanol derivatives take up more active sites at the surface, thus leavingless active sites available for adsorbed water derivatives which is necessary for theoxidation of ethanol to acetic acid and CO2.Cyclic voltammetry was done for increasing temperatures from 21C up to 140Cfor 0.2 M ethanol in 0.5 M sulphuric acid. These results showed an increasein oxidation current for all oxidation peaks as the temperature increased. Adecrease in peak potential for the first oxidation peak was observed for increasingtemperatures. This indicates that the optimum surface condition for ethanoloxidation is reached at lower potentials at higher temperatures. There was alsoseen an decrease in the apparent onset potential of the first oxidation peak as thetemperature increases. These effects can come from increased thermal activity forwater adsorption at higher temperatures. The peak potential for the oxidationpeak in negative going scan increased with increasing temperatures. This cancome from an easier reduction of platinum oxide at higher temperatures.Dynamic electrochemical impedance spectroscopy measurements was done atdifferent temperatures from 21C up to 140C for 0.2 M ethanol in 0.5 Msulphuric acid solution. The results from the measurements at 60C was fittedto electrochemical equivalent circuits. This gave indications of one kineticallysignificant surface adsorbed species in most potential regions with a notableoxidation current. This in combination with literature suggesting that acetic acidand acetaldehyde is the major products from ethanol electro-oxidation suggestthat the adsorbed intermediate is something other than CO(ads). Results fromthis work together with existing literature on ethanol oxidation was used to givea suggested simplified reaction mechanism for ethanol electro-oxidation.

Hindering the degradation of amines in the CO2-capturing process is important both for economical purposes when it comes to loss of solvent and impacts on the process, and to prevent emissions of volatile degradation compounds such as ammonia, nitrosamines and formaldehyde. To prevent the absorbent from degrading, either a non-degrading absorbent can be developed or a degradation inhibitor can be added to minimize the degradation. The degradation inhibitors tested in this thesis are meant to inhibit the oxidative degradation that mainly occurs in the absorber. The carbamate polymerization degradation due to CO2 and temperature has to be addressed on its own. The inhibitor screening apparatus was new, and a part of the assignment was testing this setup. The first experiment conducted on the inhibitor screening apparatus used a gas blend of 6% O2/2 % CO2 (N2 balance). This did not give enough degradation, which caused the need for rebuilding the rig. In the other experiments on the screening apparatus, a gas composition of 98 % O2/2 % CO2 was used to get sufficient amount of degradation for inhibitor screening. Inhibitor screening experiments were done using 150 mL of a 30 weight% (wt%) 2-aminoethanol (MEA) solution loaded with 0,4 mol CO2/mol MEA, at 55 °C with a gas flow of 10 mL/min. To test the stability of the inhibitors at higher temperature, thermal experiments with inhibitors were conducted. 7 mL solution was filled in stainless steel cylinders and heated at 135 °C, for a period of five weeks. The solution was 30 wt% MEA loaded with 0,5 mol CO2/mol MEA. Hydrazine was screened for inhibitory effect using a circulative closed loop apparatus because of the hazards related to this compound. The experiment was run with air, using a 30 wt% MEA solution loaded with 0,4 mol CO2/mol MEA, at 55 °C. Since experiments with both 6 % and 98 % oxygen were conducted, it was natural to compare the impact of oxygen concentration on the degradation products. Results indicated that 2-oxazolidinone (OZD) was preferred at the conditions with high oxygen, while N-(2-hydroxyethyl) glycine (HeGly) concentrations increased with decreasing oxygen content. The effect of metals on product composition was also investigated. The degradation compound N-(2-hydroxyethyl) imidazole (HEI) seems to be dependent on the metal concentrations, increasing in the presence of metals. For the inhibitors screened, the inhibition ranged from 23,59-67,81 %. Two compounds gave an increase in degradation. 1-hydroxyethane 1,1-diphosphonic acid (HEDP) was the only chelating agent stable at thermal conditions. The inhibitors did not appear to have a substantial effect on the carbamate polymerization. Quantification of degradation compounds in the samples was done using liquid chromatography-mass spectrometry (LC-MS) and anion chromatography-electrochemical detector (IC-EC). Amine loss and CO2-loading were determined using titration methods. Metal concentrations were determined using inductively coupled plasma-mass spectrometry (ICP-MS). Some analyses were done gravimetrically while others were done volumetrically. For comparison purposes, simple density measurements were done, and the data converted according to the amine loss in the sample.The initial intention was to use gas chromatography - mass spectrometry (GC-MS) to analyze the samples from the thermal experiments. The system was however not operable during the time available. ICP-MS analysis was not done in time for the last experiment. Ammonia analyses were not conducted in time for this thesis.

In this project the main goal was to establish a routine for making a microfluidic flow cell (MFFC) using soft lithography methods, and test the flow cell with different electrolytes, sulphuric acid and a ruthenium red-ox couple, and eventually use the established routine to make a microfluidic fuel cell and test it. A routine was established using the negative photoresist ma-N405. The photoresist was overdeveloped to make sure an undercut profile was reached, which proved to be necessary for the subsequent metal lift-off. Titanium (10 nm) and platinum (25 nm) were vapor deposited on the glass chips, and the lift-off process was completed in a couple of days. Flow channels of two different heights (about 15 and 100 µm) were made by making an impression in PDMS. A low flow channel, height of 15 µm, showed a significant electrolyte resistance in the experimental electrochemical work, and none of the experiments gave the expected results. The electrolyte resistance was measured by electrochemical impedance spectroscopy and taken to be the value corresponding to the high frequency intersection of the real axis. In addition, this resistance was estimated from cyclic voltammetry and taken to be the reciprocal of the slope of the curve, and was found to vary between 104-107 Ω. The results from EIS and CV were compared, and they overlapped quite well. An MFFC with a channel height of 100 µm and 500 µm electrodes, resulted in a significant decrease in measured electrolyte resistance and gave improved electrochemical results. The electrolyte resistance was measured from EIS and was reduced a lot to about 300 - 10000 Ω. These results were not compared with linear regression of the linear hydrogen area since the hydrogen area was no longer linear. The cell was tested with a ruthenium red-ox couple (hexaammineruthenium(II)chloride and hexaammineruthenium(III)chloride), and an external hydrogen reference electrode placed in the outlet was found to be simpler to control than an internal reference electrode. The potential limits were -0.3 and 0.3 V vs. an external hydrogen electrode in the same electrolyte. The effect of flow rate, sweep rate and oxygen content in the electrolyte was investigated.

The goal of this work was the synthesis of a carotenoid cationic lipid for the research of carriers of nucleic acids into defective cells via transfection therapy. In the course of this project a precursor for the carotenoid cationic lipid was successfully obtained, but because of the limited time the synthesis of the carotenoid cationic lipid itself was not performed.

A procedure for texturing of lead-free piezoelectric ceramics based on sodium potassium niobate (KNN) was investigated with respect to texturing procedure and choice of materials.Material compositions that were considered include KNN with and without addition of 0.5 mol% MnO, and KNN modified with Li and Ta (KNNLT), and Mn substituted into the A or B site of the perovskite structure. The two compositions KNN-Mn and KNNLT-Mn(A) compositions were further investigated as candidate materials for texturing.Textured samples of the two materials were made by tape casting and templated grain growth, using needle-shaped KNN particles as templates, while non-textured reference samples were made by conventional sintering of powders. Both textured and non-textured dense materials were characterized with respect to density, degree of texture and piezoelectric and dielectric properties. The non-textured materials sintered to high relative densities of 93.9 % for KNN-Mn and 96.7 % for KNNLT-Mn(A). A converse piezoelectric coefficient of over 250 pm/V was measured for non-textured KNNLT-Mn(A), and around 200 pm/V for KNN-Mn.Texturing led to a lower relative density of both compositions, 89.1 % for KNN-Mn and 92.1 % for KNNLT-Mn(A). The piezoelectric performance of KNN-Mn was not significantly affected by the texturing procedure, while the piezoelectric performance of KNNLT-Mn(A) became significantly poorer. This is due to the formation of a secondary phase in KNNLT-Mn(A) during sintering, which is probably caused by the compositional mismatch between the templates and the fine-grained matrix powder.Based on the results, and a theoretical consideration of the texturing procedure, a different choice of template particles is suggested for further work on texturing of KNN-based materials.

Through this study it has been observed that in contrast to propargyl esters which give cyclopropyl products, the high reactivity of propargyl acetals allows a new tandem cyclization to take place, resulting in bicyclic products. It has also been found that steric effects may cause propargyl acetals to react by unexpected pathways. NMR studies confirmed a particularly high reactivity of propargyl acetal compared to propargyl ester. These results show how molecular diversity can easily be achieved by varying the substrates in gold(I) catalysis.

Reaksjoner med vinylderivater i nærvær av gull(I)katalysator. Sykloaddisjoner og dimeriseringsreaksjoner er studert.

A study of the influence of artificial ageing temperature on the precipitation behaviour in three distinct direct chill casted and extruded Al-Mg-Si alloys has been carried out. The total amount of alloying elements is approximately the same in these alloys, but the difference is the ratio between these elements. The master thesis is a continuation of the work reported in Characterization of precipitates at maximum hardness in Al-Mg-Si alloys which was written in connection to the course TMT4500 Materials Technology, Specialization Project. The primary objective of this work was to identify the value of maximum hardness, and at what time it is obtained for these alloys after they have been artificially aged, one set at 200 °C and another at 250 °C, i.e. six cases in total. The aim in the master thesis has been to investigate which type and relative amount of needle shaped precipitates that are present, and what size, number density and volume fraction that is responsible for these conditions by using transmission electron microscopy (TEM). In addition, all three alloys have been shown to obtain a local hardness maximum at overaged conditions in the 200 °C case. These conditions have also been analysed by comparing with an overaged condition for KK5 for an ageing time shorter than the one were the local maximum appears. Therefore, ten different conditions have been investigated in total.One sample has been selected from each case based on the hardness curves in the project work, and prepared for analysis in two different TEM instruments. A number of general trends between alloy composition, heat treatment, and the resulting microstructure and hardness that already have been reported, have been verified during the master thesis. The maximum hardness conditions after artificial ageing at 200 °C have been found to be quite different for KK5, KK6 and KK7 in terms of type and relative amount of precipitates, and precipitate size and number density. Artificial ageing at 250 °C has been observed to give very similar values of maximum hardness for the three alloys primarily due to the size and number density of the precipitates. The local maximum hardness peaks observed at overaged conditions after artificial ageing at 200 °C have been seen to be purely due to precipitate size and number density, but the reason for their appearance has not been clarified. The observed differences between the three alloys in each condition and the differences between the conditions themselves for each alloy have been seen to be reflected in both type and relative amount of precipitates, and precipitate size and number density.

Silicon quantum dots were synthesised wet-chemically by three different methods based on reduction of silicon tetrachloride with the reduction agents potassium naphthalide, sodium cyclopentadiene and the alkalide of potassium. The purpose of these quantum dots was to deposit them on a substrate in order to use them as down converters on top of photovoltaic solar cells for enhanced solar cell efficiency. One possible method for the formation of down converting layers is to incorporate quantum dots into silica thin films by deposition of quantum dots in an ethanol based silica sol, followed by spin coating. It is believed that when the quantum dots are water dispersible, this will make it easier to bind them to the silica network, and a good dispersion in the film is facilitated. The different hydrophilic functionalisations investigated were pentenoxy capping, oxidised pentenoxy capping, oxidised acrylic acid capping and ethanolamine capping. Challenges were encountered during the synthesis of water dispersible quantum dots, the most important were related to agglomeration and purification of the quantum dots. This was believed to be due to the tendency of hydrophilic surface groups to attract each other, interaction with the polar solvent and similar solubility characteristics of the quantum dots and the byproduct salts.Si quantum dots with hydrophobic octoxy capping were also synthesised. Dispersions of these quantum dots were deposited onto solid substrates followed by solvent evaporation. This was done to see whether it was possible to deposit the synthesised quantum dots by this simple approach, to investigate the fundamentals upon evaporation, the degree of agglomeration and the byproducts present in the quantum dot dispersions. It was found that agglomeration was very pronounced after the solvent had evaporated and that quite large amounts of byproducts were present in the final quantum dot dispersions. The most important reasons to this were believed to be too weak steric repulsive forces between the particles, too fast evaporation of the solvent and an insufficient purification procedure. For the use of Si quantum dots synthesised wet-chemically as down converters in solar cells, improvements of the particles are needed.

This work explores the hydrothermal synthesis of LaFeO3 (LFO) nanorods with a high aspect ratio. Synthesis of rod shaped LFO is a stepping stone to the synthesis of strontium doped LFO (LSF) nanorods with high aspect ratio. These LSF rods can be used to structure and increase the area of dense LSF oxygen permeable membranes, which can be applied in the partial oxidation of methane for the production of synthesis gas. Obtaining a larger surface area can increase the oxygen transport through the membrane when the transport is limited by surface exchange reactions. Increasing the oxygen transport is the objective of the work. LFO was attempted synthesised by a direct and a two-step synthesis. Product morphology and phase composition have been explored by the use of SEM and XRD. In the direct synthesis the effect of potassium hydroxide concentration, molar ratio of iron to lanthanum and synthesis duration were varied to investigate the effect of these parameters. LFO was not produced in the direct synthesis; the products consisted of La(OH)3 and Fe2O3. Since LFO was not obtained, a calculation exploring the temperature where LFO become more stable than La(OH)3 and Fe2O3 was performed. The calculations show that the transition temperature where LFO is thermodynamically favoured is close to the operating synthesis temperature. The small driving force for formation of LFO at a temperature close to the transition temperature is the reason why LFO have not formed in the direct syntheses.The two-step method consists of hydrothermal synthesis of La(OH)3 nanorods, which were covered by iron nitrate solution and attempted converted into LFO by a topochemical reaction. In the study performed, the rod structure is lost when the product is calcined at 400 ºC. LFO is not observed formed at this temperature, and LFO nanorods were therefore not obtained in the two-step synthesis.