Degree Type

Dissertation

Date of Award

2015

Degree Name

Doctor of Philosophy

Department

Materials Science and Engineering

First Advisor

Vitalij K. Pecharsky

Abstract

Over the last few decades, interest in hydrogen-storage materials as an alternative high-efficiency and safe, green energy carriers is steadily increasing. Among numerous hydrides scrutinized for the purpose over the past 10-15 years, aluminum- and magnesium-based systems attract continued attention, mainly because of their high gravimetric capacity and low cost. However, difficulties associated with facile synthesis and hence the reversibility, relatively high desorption temperatures, and sluggish kinetics in many of these systems are still of great concern and hold them back from broad, large-scale applications, e.g. in automotive industry.

Our research was devoted to studies of mechanochemical activation and synthesis of nanostructured hydride systems of aluminum and magnesium by solid-state mechanical milling techniques. The structural and desorption properties of milled powders were examined by powder X-ray diffraction (XRD), solid-state nuclear magnetic resonance (NMR) spectroscopy and desorption analysis in a Sieverts-type apparatus.

The primary focus of this study was to investigate a number of aluminum-based hydride systems to develop advanced synthesis procedures for AlH3 (alane) using solvent-free solid-state mechanical milling under moderate hydrogen pressures at room temperature. The findings reported in this dissertation, may provide the much needed basic scientific insight necessary for the development of an approach for direct mechanochemical hydrogenation of metallic aluminum which still remains elusive despite numerous efforts worldwide. Here, we have demonstrated a mechanochemical approach for synthesis of alane via metathesis reactions between hydride sources and aluminum halides. Reaction pathways and parameters controlling the reactions were investigated. Additionally, the possibility of mechanochemical hydrogenation of magnesium boride (MgB2) was also studied.

Copyright Owner

Ihor Z. Hlova

Language

en

File Format

application/pdf

File Size

132 pages

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