In this project, we have successfully developed metal organic framework/polymer mixed matrix membranes (MOF-MMM). We studied a range of systems but NOTT-300(Al)/6FDA-TMP/DABA was found to be especially effective for the separation of CO2/CH4 gas mixtures. The study of the morphology of this membrane by scanning electron microscope confirms the homogeneous distribution of MOF particles within the polymer matrix without the presence of macro-voids. The interaction between the CO2 gas molecules and the NOTT-300(Al) in the 6FDA-TMP/DABA polymer matrix was investigated by Fourier Transform Infrared Spectroscopy and Diamond Light Source, UK. It has been found that when CO2 is adsorbed into the bare polymer, there is no notable host-guest binding interaction. However, on inclusion of NOTT-300(Al) into the polymer, there is a highly selective interaction between the CO2 and MOF particles as indicated by the observed shift of the ν(µ2-OH) band in the MOF. Thus, the NOTT-300(Al) particles have created homogeneous selective pathways within the MMM to accelerate the permeation of CO2, but also to partially block the permeation of CH4 due to its poor binding interaction and adsorption. This results in a significant simultaneous increase in CO2 permeability (911 Barrer at 303 K) and ideal selectivity of CO2/CH4 (32 at 303 K), which moves this MOF-MMM well above the 2008 Robeson upper bound. With further investigation and optimisation, the NOTT-300(Al)/6FDA-TMP/DABA membrane can produce a more efficient separation media which will utilise less energy and perform their targeted function more efficiently in industrial gas separations. Theses membranes will potentially bring economic benefits to end users by reducing their costs by replacing expensive existing technologies, whilst in parallel also facilitating new markets to emerge which will exploit our MMMs for the separation of gas and substrate mixtures. The application of our MOF-MMMs can potentially address some of the key social challenges of the 21st Century around climate change, environmental sustainability and the provision of clean drinking water.
