Amine-Functionalized MIL-53 Metal–Organic Framework in Polyimide Mixed Matrix Membranes for CO₂/CH₄ Separation

Flexible crystalline metal–organic framework (MOF) of nanosize particles (Al-MIL-53) and 6FDA-ODA polyimides were used to produce mixed matrix membranes (MMM). These MMM display excellent CO 2 /CH 4 separation properties even without any compatibilization (amine grafting). The ideal selectivity and separation factor were found to increase with increasing MOF loading. Furthermore, these materials have an improved CO 2 /CH 4 separation factor with increasing pressure, in contrast to traditional polymer membranes.