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Title: Optimisation of mechanical activation of aluminium for an economical on-demand hydrogen production
Author: Siddiqui, E. M.
ISNI:       0000 0004 7229 1855
Awarding Body: London South Bank University
Current Institution: London South Bank University
Date of Award: 2017
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Hydrogen gas, H2 is generated when aluminium metal is reacted with water. Due to the protective oxide layer, the reaction does not take place at ambient conditions. Different activation schemes are possible however most are either expensive or not very practical for H2 generation. This work attempted to address this issue of activation of aluminium particles by means of a reactive ball milling technique. A number of studies based on the activation (preparing it to react with water without the aid of any external heat or catalyst) of aluminium Al, by this method, was reported previously where the energy investment was substantial. This gap in knowledge motivated us to perform milling with a different approach. Milling protocols were identified and devised and presented a milling programme which aided in reducing the energy investment considerably. The motivation behind this work is to use the Al powder prepared by milling in a hydrogen generator connected to fuel cells for in situ generation. Due to the sensitive nature of fuel cell, it was necessary to produce hydrogen gas at a steady rate. It was found that the powder made up of a mixture of metal oxides and salt prepared in-house, provided an excellent base to achieve this. It was also seen that milling of the Al particles to 40 μm proved to perform the best for hydrogen production with yield reaching 85 % in 3 hrs reaction time using only 0.3 g of activated aluminium at ambient conditions. Reaction time can be improved by increasing milling time it would not be economically attractive. After reactive milling and reactions were examined/ inspected using SEM, EDX and XRD techniques for in-depth analysis of Al particle crystalline structure, morphology and size. Milling modifies the surface of the aluminium particles promoting hydrogen gas production. It was also noted that this reaction does not require any heat and that it can generate hydrogen gas at the ambient conditions. It was noticed that when the initial temperature of the solution is increased the reaction rate first improves up to 32 oC than it declines at 45 oC and beyond when larger Al particles are used. This work revealed that reaction requires agitation throughout the process in order to maintain a high yield of hydrogen. While this presented work used deionised water, it should be mentioned that other solvents (aqueous solutions) may be used for hydrogen production as shown in the research. However, the highest amount of yield was produced when deionised water and urea solution was used at 25 oC. “If we had a hydrogen economy worldwide, every nation on earth could create its own energy source to support its economy and the threat of war over diminishing resources would just evaporate” - Dennis Weaver.
Supervisor: Zhou, John ; Zhao, Donglin Sponsor: iHOD USA
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral