SYNTHESIS AND APPLICATIONS OF MONOLITHIC CAO@UIO-66

Abstract

This dissertation reports experiments pertaining to the synthesis of CaO@monoUiO-66, in which CaO nanoparticles (NPs) are encapsulated by a monolith of metal-organic framework (MOF) UiO-66. CaO NPs have garnered attention in catalysis owning to their potential biodiesel synthesis applications, specifically by promoting the transesterification of triglycerides. Whilst promising biodiesel production, these NPs suffer from poor recovery, can change morphology, and can potentially contaminate the product. Immobilisation in highly porous but robust monolithic MOFs promises a new avenue in catalyst capacities. Chapter 1 introduces the theoretical grounding for the work and presents the ideas which were used to inform the direction of the study. It introduces MOFs and the advent of monolithic forms of these materials. It then assess the literature on these and NP-containing monolithic MOFs before briefly summarizing the role of catalysts in biodiesel production. Chapter 2 describes the experimental and analytical procedures employed in the synthesis and characterization of the materials studied in this work. It presents the synthesis of monolithic UiO-66 and explains how manipulation of the reaction washing procedure was performed to modulate the percentage of CaO taken up by the evolving monolith. Chapter 3 describes the analytical tests used to probe the structure, composition, and morphology of catalytic CaO@monoUiO-66 composites. Some control is shown over levels of CaO doping and results establish that washing the intermediate UiO-66 gel prior to CaO introduction allows higher doping levels. Porosity data establishes that incorporating CaO does not disrupt the formation of highly porous, crystalline MOF monoliths. Preliminary testing of composites in the transesterification of triglycerides at 70 °C shows modest biodiesel yields using 120 minute reactions. The monolithic composites resist mechanical destruction during tests. Conclusions are summarized in Chapter 4 and future work efforts are outlined. Further experimental details may be found in the Appendix.