Studies on electrochemical reforming of aqueous ethanol using proton exchange membrane for pure hydrogen production
Date of Issue2014
School of Mechanical and Aerospace Engineering
This study concerns with three major purposes: 1) To perform a study to explore an alternative and eco-friendly way to reform ethanol for onboard production of hydrogen, which can be used for fuel cells. 2) Investigation of the effects of operating parameters on the performance of miniature model of a PEM ethanol electrolyzer cell. 3) Based on the results obtained from the miniature model, a scaled up ethanol electrolyzer cell was designed, fabricated and tested for understanding the operational difficulties and performance output as well. Based on the works conducted in previous studies, it was found that the electrochemical activity of an electrolyzer cell depends on the combination of parameters such as voltage, temperature, concentration of fuel, catalysts, catalyst loading and thickness of polymer electrolyte membrane. Experiments were designed by taking all the above parameters into account. The initial experiments were aimed at studying the electrochemical activity of ethanol over different catalysts such as Pt!C, PtRu/C and PtSn/C. Hence cyclic voltammetry studies were carried out and the faradic current profiles were plotted against voltage applied to understand the insights of the potentiodynamic ethanol oxidation. With the aid of cyclic voltarnmetry experiments, the potential window for the single cell experiments were fixed for each catalyst based on the oxidation peaks obtained. Subsequently, preparations were made for the experiments with a mixture of novel methods and previous research work as well. The cell with an active area of 6.25 cm2 was opted for conducting the experiments. Though the results obtained were not commendable m reference to the other conventional sources of hydrogen production, we decided to set up a scaled up electrolyzer cell with an active area of nearly 56.25cm2 , in order to understand about the achievable outputs during size transition. Since several issues such as selection of materials for end plates, catalyst coating thickness on MEA, type of flow field patterns and thickness of gas diffusion layer were addressed during the miniature cell experiments, we had to only take care of few difficulties such as conditions required while sintering gas diffusion layers, operating conditions during hot pressing of MEA and the water circulation system for exchange of heat. Finally, the scaled up cell was built and tested with the help ofthe results extracted from the smaller cell. These results threw light on understanding the performance, efficiency and energy losses of the PEM ethanol electrolyzer cell under different operating parameters. Also the purity of the hydrogen produced by the scaled up cell was tested using a NOVA gas analyzer.