The traditional aluminum production process (Hall-Héroult process) involves electrolyzing the alumina dissolved in the molten cryolite salt. This process is energy intensive and emits massive amounts of CO2 and other greenhouse gases. The market demand of aluminum and the environmental impact of the current aluminum production process justify research and development of alternative electrolytic processes for aluminum production that can both reduce the cost and eliminate adverse environment impacts. Solid oxide membrane (SOM) based electrolysis process is an innovative technology that has been demonstrated to successfully produce many energy-intensive metals directly from their oxides in an efficient, economical and environmentally sound way. During the SOM electrolysis process, an oxygen-ion-conducting SOM tube made of ytteria-stabilized zirconia (YSZ) separates the pre-selected molten flux with dissolved metal oxide from the inert anode assembly inside the YSZ tube. When the applied DC potential between the cathode and the anode exceeds the dissociation potential of desired metal oxide, the metal is reduced at the cathode while oxygen ions migrate through the YSZ membrane and are oxidized at the anode. Employing the inert anode allows the oxygen to be collected at the anode as a value added byproduct. In this work, a zero-direct-carbon-emission aluminum production process utilizing SOM electrolysis is presented. The molten flux used in the electrolysis process is optimized through careful measurements of its physio-chemical properties. The liquidus temperature, volatilization rate, alumina solubility, aluminum solubility, YSZ membrane degradation rate and electrical conductivity of various flux compositions were measured, and the flux chosen for SOM electrolysis was a eutectic MgF2-CaF2 system containing optimized amounts of YF3, CaO and Al2O3. Laboratory scale SOM electrolysis employing the inert anode were performed at 1100 ~ 1200oC to demonstrate the feasibility of producing and collecting aluminum while producing pure oxygen as a byproduct. The aluminum product was characterized by scanning electron microscopy (SEM) and energy dispersive x-ray spectroscopy (EDS). An equivalent circuit model for the electrolysis process was developed in order to identify the polarization losses in the SOM electrolysis cell. / 2016-12-21T00:00:00Z

Den högkvalitativa stenkolstjäran, som används som anodbindemedel inom aluminiumindustrin, innebär utmaningar när det gäller att möta kraven på kolanod. Dess produktion är beroende av ohållbara fossila bränslen, vilket bidrar till ökade koldioxidutsläpp. Följaktligen är det ett iögonfallande forskningsämne att finna ett hållbart alternativ. Produkten av biooljauppgradering, så kallat biobeck, kan anses vara en genomförbar utmanare. Detta biobeck undersöks som ett potentiellt substitut för stenkolstjärabeck på grund av dess liknande reologiska egenskaper. Det primära syftet med denna studie är att utsätta tre biooljor från samma källa för olika värmebehandlingsmetoder och screena en riktig bioolja för vidare arbete. Karakteriseringen av dessa biooljor och deras destillationsprodukter syftar till att öka deras lämplighet som potentiella substitut för stenkolstjärabeck. Olika destillationsförhållanden ger olika resultat från de tre biooljorna. Fysiska och kemiska egenskapstester utförs på både bioolja och biobeck, såsom vattenhalt, FTIR, TGA och viskositet. Genom att jämföra dessa värden med karakteriserade koltjärabeckdata från litteraturen kan lämpliga biooljekandidater identifieras, och distinktionerna mellan biobeck och stenkolstjärabeck kan undersökas. Denna utforskning ger förståelse för att tillhandahålla justeringar i destillationsprocessen. / The high-quality coal-tar-pitch, used as an anode binder within the aluminum industry, poses challenges in meeting requirements of carbon anode. Its production relies on unsustainable fossil fuels, contributing to heightened carbon dioxide emissions. Consequently, It is an eye-catching research topic to distinguish a sustainable alternative. The product of upgrading bio-oil, named bio-pitch, can be considered a doable contender. This bio-pitch is being explored as a potential substitute for coal-tar pitch because of its similar rheological properties. The primary objective of this study is to subject three bio-oils from the same source to distinct heat treatment methods and screen a proper bio-oil for further work. The characterization of these bio-oils and their distilling products aims to raise their suitability as potential substitutes for coal-tar-pitch. Different distillation conditions yield varied bio-pitch outcomes from the three bio-oils. Physical and chemical property tests are conducted on both the bio-oil and bio-pitch, such as water content, FTIR, TGA, and viscosity. By comparing these values to characterized coal-tar-pitch data from the literature, suitable bio-oil candidates can be identified, and the distinctions between bio-pitch and coal-tar-pitch can be investigated. This exploration provides understanding to furnish adjustments in the distillation process.