A contribution towards the performance and structural understanding of copper and nickel salts as ammonia stores

Breternitz, Joachim (2016) A contribution towards the performance and structural understanding of copper and nickel salts as ammonia stores. PhD thesis, University of Glasgow.

Abstract

The ongoing depletion of fossil fuels and the severe consequences of the greenhouse effect make the development of alternative energy systems crucially important. While hydrogen is, in principle, a promising alternative, releasing nothing but energy and pure water. Hydrogen storage is complicated and no completely viable technique has been
proposed so far. This work is concerned with the study of one potential alternative to pure hydrogen: ammonia, and more specifically its storage in solids.

Ammonia, NH3, can be regarded as a chemical hydrogen carrier with the advantages of strongly reduced flammability and explosiveness as compared to hydrogen. Furthermore, ammine metal salts presented here as promising ammonia stores easily store up to 50 wt.-% ammonia, giving them a volumetric energy density comparable to natural gas. The model system NiX2–NH3 ( X = Cl, Br, I) is studied thoroughly with respect to ammine salt formation, thermal decomposition, air stability and structural effects. The system CuX2–NH3 ( X = Cl, Br) has an adverse thermal decomposition behaviour, making it impractical for use as an ammonia store. This system is, however, most interesting from a structural point of view and some work concerning the study of the structural behaviour of this system is presented. Finally, close chemical relatives to the metal ammine halides, the metal ammine nitrates are studied. They exhibit interesting anion arrangements, which is an impressive showcase for the combination of diffraction and spectroscopic information.

The characterisation techniques in this thesis range from powder diffraction over single crystal diffraction, spectroscopy, computational modelling, thermal analyses to gravimetric uptake experiments. Further highlights are the structure solutions and refinements from powder data of (NH4)2[NiCl4(H2O)(NH3)] and Ni(NH3)2(NO3)2, the combination of crystallographic and chemical information for the elucidation of the (NH4)2[NiCl4(H2O)(NH3)] formation reaction and the growth of single crystals under ammonia flow, a technique allowing the first documented successful growth and single crystal diffraction measurement for [Cu(NH3)6]Cl2.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Keywords: Chemistry, inorganic chemistry, materials, materials chemistry, solid state chemistry, energy, energy storage, gas storage, ammonia storage, crystallography, powder diffraction, single crystal diffraction, neutron diffraction, thermal analyses, spectroscopy.
• Subjects: Q Science > QD Chemistry
• Colleges/Schools: College of Science and Engineering; College of Science and Engineering > School of Chemistry
• Supervisor's Name: Gregory, Professor Duncan H.
• Date of Award: 2016
• Depositing User: Joachim Breternitz
• Unique ID: glathesis:2016-7552
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 02 Sep 2016 14:32
• Last Modified: 06 Oct 2016 12:13
• URI: https://theses.gla.ac.uk/id/eprint/7552