Carbon Dioxide Adsorption and Catalytic Conversion in Porous Coordination Polymers

Abstract

This thesis reports an investigation into carbon dioxide capture and catalysis in several target metal-organic frameworks (MOFs) and porous organic polymers (POPs). In chapter 2, a series of Zr-MOFs were synthesised for potential applications in carbon capture and storage. In the first instance, a novel Zr-based MOF was constructed exclusively from the monocarboxylate ligand formate. Despite the low surface area, the new material exhibited a high affinity for CO2 over nitrogen at room temperature. In addition, the water-stable Zr–tricarboxylate series of frameworks, exhibited tunable porosity by virtue of systematic modulation of the chain length of the monocarboxylate ligand. Last but not least, defect concentrations and their compensating groups have been systematically tuned within UiO-66 frameworks by using modified microwave-assisted solvothermal methods. Both of these factors have a pronounce effect on CO2 and H2O adsorption at low and high pressure. Chapter 3 focuses on the development of a rapid and efficient microwave-assisted solvothermal method for a series of zirconium oxide based MOFs known as MIL-140s. Combined experimental and computational studies have revealed the interplay between the framework pore size and functionality on the CO2 adsorption performance of MIL-140 frameworks. The potential for CO2 photocatalysis in POPs was also explored in chapter 4. A POP with free 2,2’-bipyridyl sites was prepared via Sonogashira-Hagihara coupling and catalytically active moieties ([(α-diimine)Re(CO)3Cl]) were introduced using a post-synthesis metalation method. Thereafter, the Re-containing porous organic polymer was tested for the photocatalytic reduction of CO2. After an induction period, Re-POP produced CO at a stable rate, unless soluble [(bpy)Re(CO)3Cl] (bpy = 2,2´-bipyridine) was added. This provides some of most convincing evidence to date that [(α-diimine)Re(CO)3Cl] catalysts for photocatalytic CO2 reduction decompose via a bimetallic pathway.