magistrsko delo
Mitja Kostelec (Author), Miran Gaberšček (Mentor), Igor Plazl (Thesis defence commission member), Marjan Marinšek (Thesis defence commission member)

Abstract

Gorivne celice s protonsko izmenjalno membrano (PEMFC) predstavljajo eno izmed rešitev okoljske krize iz vidika toplogrednih plinov. Srce gorivne celice predstavlja elektrokatalizator, katerega osnovna aktivna komponenta je platina. Slabost tega so velike izgube, katerih vzrok je počasna kinetika reakcije redukcije kisika (ORR) na katodi. Ker je platina zelo redka ter posledično zelo draga kovina, je bistvena optimizacija njenega izkoristka. Pri temu nam pomaga na eni strani uporaba platine v obliki nanodelcev, saj elektrokemijske reakcije, kot je ORR potekajo le na njeni površini. To hkrati pomeni, da je vsa platina, ki nahaja v središču nanodelcev slabo izkoriščena. Posledično se prav tako poslužujemo uporabe platinskih zlitin, s čimer prav tako platini povečamo njeno aktivnost za ORR na maso platine. Na Kemijskem inštitutu (Odsek za kemijo materialov) se je v ta namen razvila in patentirala metoda galvanske izmenjave z dvojno pasivacijo (DP) za elektrokatalizatorje na osnovi zlitin platine z bakrom. Nova metoda omogoča enakomerno razporeditev nanodelcev plemenite kovine po površini prevodnega nosilnega materiala. V tem delu je predstavljena ekstrapolacija te metode na zlitine platine s kobaltom ter optimizacija procesa njihove priprave. V prvem delu so bili preučeni kemijski parametri, v nadaljevanju pa še inženirski. Ko so bili mehanizmi le-teh poznani, se je s pomočjo računalniške dinamike tekočin (CFD) napovedala povečava proizvodnje oziroma prenos na manjši polšaržni pilotni reaktor z mehanskim mešalom. Osnovan je bil tudi pretočni reaktor ter omenjen proces prenešen tudi nanj. Nazadnje so bili dobljeni produkti eksperimentalno primerjani s komercialno najboljšimi katalizatorji, s čimer je bila pokazana konkurenčnost katalizatorjev, pripravljenih z metodo DP.

Keywords

elektrokatalizatorji;platina;gorivna celica s protonsko prevodno membrano;PEMFC;dvojna pasivacija;nanodelci;računalniška dinamika tekočin;CFD;povečana proizvodnja;magistrska dela;

Data

Language: Slovenian
Year of publishing:
Typology: 2.09 - Master's Thesis
Organization: UL FKKT - Faculty of Chemistry and Chemical Technology
Publisher: [M. Kostelec]
UDC: 621.355(043.2)
COBISS: 127165443 Link will open in a new window
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Downloads: 106
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Other data

Secondary language: English
Secondary title: Optimization of production of electrocatalysts based on platinum alloys and transfer to reactor systems
Secondary abstract: Proton exchange membrane fuel cells (PEMFCs) represent one of the solutions to the environmental crisis that is arising from the greenhouse gases. The electrocatalyst, whose primary active component is platinum, represents the heart of the fuel cell. Its disadvantage are, however, the high losses resulting from the sluggish kinetics of the oxygen reduction reaction (ORR) on the cathode. Since platinum is a very rare and consequently very expensive metal, optimizing its utilization is essential. In addition, since electrochemical reactions such as ORR take place only on platinum’s surface, we use it in the form of nanoparticles. This also means that all the platinum located in the core of the nanoparticles is poorly utilized. Consequently, we also resort to the use of platinum-alloys, which results in an additional increase of ORR activity per mass of platinum. For this purpose, the National Institute of Chemistry (Department of Materials Chemistry) developed and patented a method of galvanic exchange with double passivation (DP) for electrocatalysts based on platinum-copper alloys. The new method enables uniform distribution of precious metal nanoparticles on the surface of the conductive supporting material. In this work, the method is extrapolation of this method to platinum-cobalt alloys as well as the process optimization of their preparation are presented. Whereas the first part of this works covers the chemical parameters, the second part covers the studying of the engineering parameters. Upon understanding of their mechanisms, computational fluid dynamics (CFD) have been used to predict the scale up of the production as well as the transfer to a smaller half-batch mechanically stirred pilot reactor. In addition, a flow-type reactor has been established, and the aforementioned process transferred to it as well. Finally, the catalysts obtained by the DP method have been compared experimentally with the best commercially available catalysts, thereby demonstrating their competitiveness.
Secondary keywords: proton exchange membrane fuel cell;double passivation;nanoparticle;computational fluid dynamics;production scale up;Univerzitetna in visokošolska dela;
Type (COBISS): Master's thesis/paper
Study programme: 1000376
Embargo end date (OpenAIRE): 1970-01-01
Thesis comment: Univ. v Ljubljani, Fak. za kemijo in kemijsko tehnologijo, smer Kemijsko inženirstvo
Pages: 75 str.
ID: 16382217