Thesis (Ph. D.)--University of Texas at Austin, 2005. / Supervisor: S. Joe Qin. Vita. Includes bibliographical references.

Thesis (M.S.)--University of Wisconsin--Madison, 1983. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 116-117).

Thesis (Ph.D.) - University of Queensland, 2006. / Includes bibliography.

Thesis (Ph. D.)--University of Washington, 1986. / Vita. Bibliography: leaves [164]-168.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references. Also available via the Internet.

No description available.

Copper is one of the most important metals globally, due to its wide application range and excellent chemical properties. Today it is commonly produced from chalcopyrite concentrates by the pyrometallurgical route with high emissions of greenhouse gasses. Tougher restrictions from authorities and governments on the industry give rise to research on other production routes for metals. Research has proven that copper production from chalcopyrite concentrates by the electrochemical route is possible. The project purposes were to produce copper from a chalcopyrite concentrate by removing sulfur during molten salt electrolysis and determine how the trace elements arsenic and antimony distributed. The chalcopyrite concentrate used in the trials was clean with low amount of impurities, therefore a dirty pyrite concentrate with higher content of impurities was used for determining the distribution of As and Sb. The electrolysis would roughly process 80 g of raw concentrate. The experimental set-up consisted of a pit-furnace with a stainless-steel crucible filled with 43.9 wt% NaCl and 56.1 wt% KCl.. The working electrode was composed of baskets made of molybdenum mesh containing either 2 or 4 briquettes of 20 g. The counter electrode was composed of a graphite block and the atmosphere was kept inert with nitrogen gas. The equimolar salt mixture was heated to 770 ° and a constant cell voltage at 2.5 V was applied until the current had decreased and stabilized.   It was concluded that the time-current curve for reduction of chalcopyrite followed a similar trend to that reported in the literature. The up-scaling of electrolysis of sulfuric concentrates was proven to be successful. Iron was captured on the inside of the sample holder and copper from the outside, separating the two elements into two fractions. This indicated that the separation of copper and iron occurred spontaneously, probably due to the magnetization of the reduced iron particles under the influence of the electromagnetic field induced by the electrolysis current.  Analyses by XRD, SEM, LECO and XRF proved that sulfur was reduced to < 0.2 wt% in the two product fractions. Most of the sulfuric compounds in the raw concentrates ended up as pure elements (As, Sb, Pd and Zn) in the copper product followed by the loss of the corresponding metallic elements in the exhaust gas due to evaporation of these elements.  Much knowledge of electrolysis of chalcopyrite was gained. To reach the original objectives further trials with an improved basket holder functioning as the cathode must be made. The results indicated that the electrochemical approach is suitable for copper production from chalcopyrite concentrates and further studies are recommended.

A method originally developed at the division of Chemical Technology, Luleå University of Technology was tailored for the preparation of well-defined ZSM-5 films and zoned MFI films on supports suitable for catalysis and adsorption applications. Films were grown on monoliths, ceramic foams, alumina beads, soda glass beads and quartz glass. The supports were seeded with silicalite-1 crystals and hydrothermally treated in a single or several steps. The materials were evaluated by scanning electron microscopy, x-ray diffraction, N2 and NO2 sorption, x-ray photoelectron spectroscopy, ICP-AES, p-xylene isomerization and cracking of 1,3,5-tri-isopropylbenzene. The thickness of the continuous films could be controlled from 110 nm to 9 µm. Zoned MFI films were prepared from precursor ZSM-5 films by overgrowth with silicalite-1. A multi-step synthesis protocol was used to prevent excessive bulk crystallization. Ultrasound treatment was beneficial for removal of loosely attached crystals on top of the zeolite films. Defects such as cracks and open grain boundaries were observed by SEM and in concert, mesopores were observed by N2 sorption. Model parameters were fitted to experimental data from catalytic test reactions and these parameters indicated that thicker films contained more defects, probably in the form of open grain boundaries and cracks (mesopores) as observed by SEM and N2 sorption. Films supported on quartz were more catalytically active than films on alumina and soda glass. This was attributed to partial poisoning of the acid sites in the films on the latter two substrates, probably due to solid-state ion exchange of impurities such as alkali metals from the alumina and soda glass support to the film. As expected, thicker films possessed higher diffusion resistance than thin films. Surprisingly, a higher external activity was observed after zoning. This was attributed to formation of mesopores, migration of aluminum from the precursor ZSM-5 film to the external surface, and increased surface roughness upon zoning. ZSM-5 films supported on monoliths were successfully tested for NO2 sorption. As expected, the adsorption capacity per g zeolite was independent of film thickness. Formation of NO was observed as a result of NO2 adsorption on strong sites. Thicker films resulted in higher diffusion resistance as expected. The present work has resulted in substantial and valuable new fundamental understanding of the performance of thin molecular sieve film catalysts and adsorbents. These findings may facilitate development of novel materials for industrial applications. / Godkänd; 2005; 20061004 (ysko)

Global warming is believed to be caused by the extensive emission of greenhouse gases, for example carbon dioxide, into the atmosphere by combustion of fossil fuels, such as coal, oil and natural gas. To reduce the emission of carbon dioxide and hence avoid global warming, alternative fuels derived from renewable resources are desired. Another reason for the worldwide interest in finding alternative fuels is that the reserves of the fossil fuels are limited and the oil and gas sources will eventually run out. Biogas and biobutanol are renewable biofuels which are interesting alternatives to fossil fuels. Biogas is produced during degradation of organic material forming a mixture of mainly methane and carbon dioxide with water as a common trace component. Biobutanol is produced from ABE (acetone, butanol and ethanol) fermentation of biomass. Purification of biogas and biobutanol is essential to increase the heat value of the fuels. Traditional purification processes are energy demanding and expensive. Therefore, other separation processes are currently sought for. Zeolites are promising alternatives due to their great potential both as selective adsorbents and as membranes. Due to the unique pore structure, zeolites are capable of separating components based on their adsorption properties. In the present work, single component adsorption of biogas components such as methane, carbon dioxide and water in zeolite ZSM-5 was studied as well as adsorption of water and butanol in silicalite-1 using in-situ ATR-FTIR spectroscopy. The method was successfully further used to study multicomponent adsorption. For single gas adsorption experiments, recorded infrared spectra of adsorbed methane, carbon dioxide and water showed characteristic, well separated, bands for each gas. Adsorbed concentrations were determined from the recorded infrared spectra. The Langmuir model was fitted to the adsorption isotherms and the model matched the experimental data very well. The fitted Langmuir parameters obtained in the present work was in agreement with values reported in the literature. For multicomponent adsorption experiments, the Ideal Adsorbed Solution Theory (IAST) was used to predict the adsorbed concentrations of methane, carbon dioxide and water using the single component adsorption isotherm parameters as input. In general, the IAST was shown to be a fairly good model for predicting the adsorbed concentrations of methane and carbon dioxide from binary mixtures. For the amount of adsorbed methane from mixtures including water, the IAST predicted the values fairly well. However, for mixtures containing water and carbon dioxide, the IAST could not fully describe the adsorption behavior of the two components. The CO2/CH4 adsorption selectivity was determined for various gas compositions and temperatures showing a general increase in the selectivity with decreasing temperature. This indicates that the separation of carbon dioxide from biogas should be more efficient at lower temperatures. Compared to the literature, the selectivity observed in the present work is relatively high indicating that Na-ZSM-5 may be an effective membrane material for upgrading biogas. Moreover, butanol was preferentially adsorbed over water in silicalite-1, indicating that silicalite-1 may be a promising material for recovery of butanol from dilute water solutions. / Godkänd; 2015; 20150325 (linohl); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Lindsay Ohlin Ämne: Kemisk Teknologi /Chemical Technology Avhandling: An in-situ ATR-FTIR Spectroscopy Study of Adsorption in MFI Zeolites Opponent: Professor Niklas Hedin, Avd för materialkemi, Stockholms universitet, Stockholm Ordförande: Biträdande professor Mattias Grahn, Avd för kemiteknik, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet, Luleå Tid: Fredag 29 maj kl 10.15 Plats: C305, Luleå tekniska universitet

To deal with the increasing demand of renewable fuels, more efficient processes for the production of biofuels are needed. Zeolite membranes have the potential to improve many existing processes that could be used for production of biofuels. Methanol is a potential biofuel that may be produced from synthesis gas in an equilibrium limited reaction. The production of methanol from synthesis gas could be improved by use of a membrane reactor, which could increase the conversion of synthesis gas to methanol per pass in the reactor. Methanol and several other biofuels can be prepared by first gasifying biomass to synthesis gas. Synthesis gas produced from biomass usually contains significantamounts of carbon dioxide that must be removed before methanol synthesis. However, commercial processes for carbon dioxide removal are very energy intense, and a membrane process could also improve this process and offer lower energy costs and less complicated and more compact equipment.In the present work, silicalite-1 and ZSM-5 membranes (NaZSM-5 and BaZSM-5) were successfully prepared on graded α-aluminasupports and evaluated for removal of carbon dioxide and hydrogen sulfide from synthesis gas. Both synthesis gas prepared from pure gas from gas cylinders and synthesis gas obtained from a black liquor pilot plant gasifier were used. The separations were performed at industrial relevant conditions, i.e. high pressures. It was found that the carbon dioxide fluxes were very high for carbon dioxide separation from synthesis gas free from water and hydrogen sulfide prepared from gas cylinders. Carbon dioxide fluxes up to 657 kg m-2 h-1 were observedfor a binary mixture of carbon dioxide and hydrogen. The high flux was a result of a thin membrane film, an open graded support, and ahigh pressure gradient over the membrane. A CO2/H2separation factor of 32.1 was observed at 2 ˚C and the selectivity was controlled by carbon dioxide adsorption, blocking the transport of hydrogen. The differences in carbon dioxide separation performance, observed for the different evaluated membranes, were likely due to differences in the carbon dioxide adsorption isotherms. The silicalite-1 membrane had a more favourable adsorption isotherm compared to the ZSM-5 membranes at these conditions, which resulted in larger difference in fractional surface loading between feed and permeate side of the membrane. It was also found that the carbon dioxide flux and separation factor decreased substantially when carbon dioxide and hydrogen sulfide was separated from synthesis gas derived from black liquor also containing water and hydrogen sulfide. This was probably an effect of competitive adsorption of hydrogen sulfide and water, which are probably blocking carbon dioxide molecules from permeating through the membrane. Furthermore, all-zeolite membranes (membranes consisting of both zeolite film and zeolite support) were prepared and evaluated for removal of carbon dioxide from synthesis gas in the present work. The membranes were carbon dioxide selective, but quite brittle, which made testing difficult. The zeolite supports used for all-zeolite membranes were prepared by collaborating researchers as an attempt to reduce crack formation in zeolite membranes, since the thermal expansion mismatch between the zeolite film and the membrane support will be minimized using this approach. Mathematical models of a traditional methanol synthesis process and two alternative membrane processes were also developed in the present work. Recorded experimental permeation data for a ZSM-5membrane was used as input to the models. The estimated performance of the traditional process was compared with a membrane reactor process (MRP) and a membrane module process (MMP). The mathematical model indicated that the MRP is the best alternative, since it enabled one pass operation, due to the highest conversion per pass. The MMP is however better from a practical point of view compared to the MRP since membrane and catalyst is separated and the membrane and reactor can be operated at their optimal respective temperatures and the membrane and catalyst can be replaced independently. By adding more membrane modules, the performance of the MMP will approach that of the MRP, to the price of higher complexity of the process. / <p>Godkänd; 2014; 20141007 (sjoeri); Nedanstående person kommer att disputera för avläggande av teknologie doktorsexamen. Namn: Erik Sjöberg Ämne: Kemisk teknologi/Chemical Technology Avhandling: Zeolite Membranes for Production of Biofuels Opponent: Professor Joaquin Coronas, Chem. &amp; Environ, Eng. University of Zaragoza, Spanien Ordförande: Professor Jonas Hedlund, Institutionen för samhällsbyggnad och naturresurser, Luleå tekniska universitet Tid: Torsdag den 4 december 2014, kl 10.00 Plats: C305, Luleå tekniska universitet</p>