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Title: Synthesis and characterisation of layered hydroxy anion exchange materials
Author: McIntyre, Laura J.
ISNI:       0000 0004 2700 2153
Awarding Body: University of Liverpool
Current Institution: University of Liverpool
Date of Award: 2009
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This thesis concerns the synthesis and characterisation of layered hydroxy anion exchange materials. The incorporation of rare-earth cations into these materials offers the potential to combine the optical, magnetic and catalytic properties of the lanthanides with the flexibility of intercalation hosts. A review of the literature surrounding intercalation chemistry and materials is presented in Chapter 1. Here the synthesis, structure and anion exchange reactions of layered hydroxides and their applications in the fields of catalysis, separation science, polymer additives and biological storage and delivery are discussed. Chapter 2 describes the hydrothermal synthesis and anion exchange capacity of new anion exchange host lattices containing the smaller lanthanide cations, with the composition Ln2(OH)5NO3•1.5H2O (Ln = Y, Gd - Lu), with Gd marking a limiting cation radius. Anion exchange reactions are facile with a wide range of organic carboxylates and sulfonates and investigations into their selectivity and optical properties have been carried out. This family has also been expanded to include Ln2(OH)5X•1.5H2O (X = Cl, Br; Ln = Y, Dy, Er, Yb) and crystal structures for orthorhombic and monoclinic Yb2(OH)5Cl•1.5H2O are reported. The findings of a time-resolved in situ X-ray powder diffraction study form the basis of Chapter 3. Three different phases with the layer composition [Yb2(OH)5]+; Yb2(OH)5NO3•1.5H2O d = 9.2 Å (1), Yb2(OH)5NO3•2H2O d = 9.4 Å (2) and Yb2(OH)5NO3•H2O d = 8.5 Å (3) were observed and shown to ultimately transform to a 3D structure Yb4O(OH)9NO3 d = 8.0 Å (4). Single crystal structures are given for phases 2 and 3, and the structure of 4 has been refined. The effects of temperature and metal concentration on phase formation have been investigated and compared with ex situ results. A full kinetic analysis is presented including the activation energy for the formation of phase 2. The values extracted indicate that the mechanism of crystallisation is phase boundary controlled. In Chapter 4 the room temperature precipitation synthesis of a related family of anion exchange host lattices with the composition, Ln2(OH)5NO3•H2O (Ln = Y, Eu–Er) and MgAl layered double hydroxides incorporating the precious metals Ru and Pd are discussed. Details of synthetic routes to the novel materials described and the methods of characterisation used are given in Chapter 5.
Supervisor: Fogg, Andrew M. ; Claridge, John Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
Keywords: Q Science (General) ; QD Chemistry