Synthesis, characterisation and analysis of metal-organic frameworks for sustainable catalysis applications

A range of metal-organic frameworks (MOFs) have been synthesised and characterised by a variety of techniques, primarily including powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), UV-Vis and Scanning Electron Microscopy (SEM). Some of these MOFs have been investigated for applications related to CO2 capture and catalysis. A mixed-metal MOF, MUV-10, comprised of titanium in combination with Ca or Mn, is thoroughly investigated with the aim of making modifications, including the substitution of some Ti for Sn. Synchrotron X-ray absorption spectroscopy confirmed the successful incorporation of Sn(IV) into the mixed-metal MOFs. Gas adsorption studies were also completed and a brief investigation into the modification of the organic linker used in the material, with effects on the band gap of the material discussed. The modified MUV-10 MOFs have been extensively analysed and their activity tested in the photoreduction of carbon dioxide, the reduction of carbon dioxide to cyclic carbonates using epoxides and in the conversion of glucose to 5-hydroxymethylfurfural (5-HMF). For the formation of cyclic carbonates using epoxides and carbon dioxide, MUV-10 offered excellent conversion, recyclability, and stability. For the conversion of glucose, when small quantities of HCl were used, MUV-10 demonstrated a greater production of 5-HMF compared to the UiO-66 reference material, with enhanced performance for MUV-10 substituted with Sn. The synthesis of novel Ti MOFs has been attempted, and although none were produced in a form for structure solution, some promising materials were identified for future study. Similar studies on the synthesis of Sn(IV) MOFs, not yet known in the literature, also proved not to form large enough crystals for structure solution, although a new anionic Sn(II) coordination polymer based on the chelidamate ligand was crystallised.