The work described in this Thesis is concerned with the preparation, characterisation and catalysis of a range of metal loaded Molecular Sieves and, in particular, gallium containing Zeolite and Zeotype materials. Commercially, the CYCLAR process transforms LPG to aromatics using a catalyst based on gallium and Zeolite ZSM-5. Methods for preparing both this catalyst and related materials employing alternative zeolite structures have been explored and the resulting catalysts studied for their activity in propane conversion. A range of zeolite molecular sieves and their gallium analogues, with the EUO and MFI framework structures, have been prepared. Attempts to prepare EUO materials with increased metal content yielded the intergrowth material NU-85. The basic physical properties of these materials have been characterised by a variety of techniques including X-ray powder diffraction (XRPD), thermal gravimetric analysis (tga), scanning electron microscopy (SEM), X-ray fluorescence (XRF), neutron activation analysis (NAA) and acidity determinations by ammonia temperature programmed desorption (TPD). X-ray photoelectron spectroscopy (XPS) has shown the isomorphous substitution of gallium into framework sites in these molecular sieves is not homogeneous, with the zeotype crystals having a gallium rich crust and a siliceous core. This technique has also shown the presence of partially reduced gallium species in discharged catalysts. In catalysis studies all materials exhibited hydrogenolysis, dehydrogenation, oligomerisation activity to varying degrees in addition to the aforementioned CYCLAR aromatisation. Although the commercial preparation displayed the highest activity for aromatisation several of the gallosilicate and gallium doped EU-1 catalysts showed a potentially useful high selectivity for propane dehydrogenation, albeit at low conversion.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:648978 |
| Date | January 1994 |
| Creators | Cruickshank, Graeme Duncan |
| Publisher | University of Edinburgh |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://hdl.handle.net/1842/13504 |
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