Polymer Metal-Organic Framework Composite Structure for CO₂ Capture Applications

POLYMER METAL-ORGANIC FRAMEWORK COMPOSITE STRUCTURE FOR CO2 CAPTURE APPLICATIONS
Ke Xie, Qiang Fu, Greg Qiao, Paul Webley

Metal-organic frameworks (MOF) are good candidates for gas separation due to their molecular sieving properties and high thermal stability. MOFs are cast into membranes (MOF membranes) or blended with polymer matrix to produce mixed matrix membranes (MMM). Neither of these techniques is optimal as the resultant membranes can have poor mechanical strength, defect-prone features and processing difficulties. In this study, the amino-functionalised MOF (NH₂- UiO-66) and the bromide functionalised MOF (Br@MOF) nanometric crystals (30~50 nm) were successfully prepared and characterised by XPS, XRD, TGA, SEM and TEM. Br@MOF was used to initiate the polymerisation of polyethylene glycol acrylate (PEGA) via atom transfer radical polymerisation (ATRP), resulting in a polymer grafted MOF composite (P@MOF). P@MOF was firstly applied as the catalyst carrier by loading Pd nanoparticles. Owing to its absolute water dispersity and pH-sensitive aggregation-deaggregation nature, Pd loaded P@MOF integrated the advantage of both high homogeneous (high activity) and heterogeneous (good recyclability) catalysts. Furthermore, the unique core-shell structure of P@MOF implies its potential for gas separation MMM. Currently, CO₂ separation measurements (over light gases like CH4 or N₂) are being performed to reveal the CO₂ capture capability of the membranes.