Development of solid sodium borohydride hydrogen gas generator for portable pem fuel cell applications

2018
Boran, Aslı
Hydrogen is considered as a promising candidate to replace fossil fuels. For implementing a hydrogen based infrastructure, hydrogen storage is the mainobstacle that is needed to be overcome. Being boron based compound, sodium borohydride, NaBH4, is a convenient hydrogen storage material for applications like unmanned air vehicles. There are several issues behind commercialization of NaBH4 hydrolysis systems. This doctorate thesis aims to be solution of NaBH4 hydrolysis system by highlighting three main contributions. First, the usage of solid state NaBH4 enables to increase the gravimetric H2 storage capacity of the system in order to meet international targets. Second, solid NaBH4 usage decreases the system’s weight since it does not require a separate fuel storage tank, which is very important for practical applications. Finally, by using accessible and effective catalysts like FeCl3 and CoCl2 it decreases the system’s cost. In this study catalyst was added by following two methodologies. In the Case 1, solid catalyst was placed in a glass reactor with solid NaBH4 and water added to initiate the hydrolysis reaction. The water amount is found to be a critical parameter that should be optimized. The maximum hydrogen generation rate was obtained for Case 1 is 1.88L/min with an efficiency of 63.5% when 5g of NaBH4, 0.5 g FeCl3 and 33.3g water was used. In Case 2, solid NaBH4 was placed in a glass reactor. Solid catalyst was dissolved in desired amount of water to obtain catalyst solution. This catalyst solution was added into the reactor to generate hydrogen. The maximum hydrogen generation rate was obtained for Case 2 is 2.6L/min when 10g NaBH4, 1g FeCl3 was dissolved in 66.6g water with an efficiency of 76.28%. This condition is used in the integrated developed solid NaBH4 system with PEMFC. This is the first time that solid state sodium borohydride hydrolysis system was tested for PEM fuel cell performance.

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Citation Formats
A. Boran, “Development of solid sodium borohydride hydrogen gas generator for portable pem fuel cell applications,” Ph.D. - Doctoral Program, Middle East Technical University, 2018.