Synthesıs of sodıum borohydrıde from sodıum amıde by mechanochemıcal process, ıts catalytıc dehydrogenatıon and usage ın fuel cells


Thesis Type: Postgraduate

Institution Of The Thesis: Gazi Üniversitesi, Fen Bilimleri Enstitüsü, Turkey

Approval Date: 2011

Student: ÖZGE USTA

Co-Consultant: İRFAN AR, METİN GÜRÜ

Abstract:

Because of the growing world population and development of technology, the growing population's desire to achieve better living conditions is rising day by day. Correspondingly, there is more consumption and the amount of energy to meet the needs of production is increasing. Increasing energy demand causes the exhaustion of fosil fuels and also enforces to investigate for new and renewable energy sources' development. Although hydrogen energy is a clean energy there are storage, transportation and safely usage problems. Sodium borohydride is synthesized to overcome these problems. At the same time, controlled hydrogen release during dehydrogenation and its safe usage is become more important. Studies have been continued under the different reaction conditions to reach the best hydrogen yield in optimum conditions using various catalysts in this subject. In this study sodium borohydride which can store high amount of hydrogen was synthesized from mechanochemical reaction of sodium amide, magnesium hydride and boronoxide in spex type miller. Ethylene diamine was used to purify the raw product. FT-IR, XRD, TGA/DTA, particle size analysis and iodimetric analysis were done to characterize the synthesized product. Hydrogen was produced from the catalytic dehydrogenation of sodium borohydride to get energy. Catalysts' used in dehydrogenation reaction were synthesized in economical ways. Kinetic properties of dehydrogenation reactions were developed from the datum of experiments. SEM+EDS and BET analysis were done to investigate the surface properties and elemental compositions of catalysts. Pre-studies were done to improve the usage of produced hydrogen in PEM fuel cell. Required entegrated system conditions were determined with performance measurement of PEM fuel cell. As a result of experimental studies, the highest efficiency was obtained by using 30% excess MgH2 in spex type mill with a 500 min mechanochemical reaction time. Purification of product by using ethylene diamine results 84% yield. Prepared catalyst could achieve hydrogen liberation for 2171 cycle, which equals 212 days uninterruptedly