Research Information System
Thesis Type: Doctorate
Institution Of The Thesis: Gazi University, Fen Bilimleri Enstitüsü, Turkey
Approval Date: 2023
Thesis Language: Turkish
Student: Özgü YÖRÜK
Principal Supervisor (For Co-Supervisor Theses): Özkan Murat Doğan
Co-Supervisor: Duygu Uysal
Abstract:
In the thesis study, the most reliable and well-known method in terms of obtaining 100% pure hydrogen, electrolysis, was integrated with coal, our national resource, and hydrogen production was carried out by coal electrolysis, which is an innovative method. In this context, firstly, different coal/carbon-containing sources were studied in order to examine the effect of different functional groups in the structure of coal, whose deficiency was noticed in similar processes in the literature, on hydrogen production. In the study, different parameters were studied with three different electrolysis systems and the most suitable conditions for hydrogen production were determined. First of all, parameter studies were carried out with raw materials selected according to their functional group structures in the two-electrode electrolysis cell to examine their electrolysis behavior and to determine the appropriate electrolysis environment. Hydrogen formation with the two-electrode electrolysis cell was investigated based on observation, and current density values under different operating conditions were recorded. The effects of different parameters such as temperature, stirring rate, coal particle size, electrolyte type, catalytic additives, electrode type on hydrogen formation and current density were investigated. In the two-electrode electrolysis cell, the highest current densities were obtained in the presence of catalytically effective Fe2+/3+ ion additive, at a stirring rate of 480 rpm, with a particle size of less than 0.25 mm, in the presence of a Zn/Zn electrode pair with activation pretreatment, 0.04 M H2SO4 medium, at a coal concentration of 0.03 g•mL-1 and at a temperature of 50oC, at electrode distances of 3 cm and closer, where intracellular resistances can be minimized. After the two-electrode cell experiments, experiments were carried out with Nafion XL membrane in a two-compartment electrolysis cell in order to examine the electrolysis behavior of different coal/carbon-containing materials in a different system, to analyze the gas products, and to determine the appropriate electrolysis environment for cubic cell studies involving the use of membrane-electrode assembly (MEA). In the experiments performed with Çan lignite, Tunçbilek lignite and leonardite, the highest current density values were obtained with Tunçbilek lignite. In the gas product analyses carried out, it was observed that 100% pure H2 was obtained from the cathode compartment. In the studies with the cubic electrolysis cell,f the highest current density values with MEA, which was prepared as 0.5 mg Zn/cm2 at the anode and 0.5 mg Pt/cm2 at the cathode, were reached in Tunçbilek lignite with a circular current collector in the presence of V5+/3+ catalytically effective additive.
Key Words : Hydrogen, electrolysis, coal