Department of Chemical Engineering

Zeolit imidazolat kafes katkılı polimerik gaz ayırma membranlarının hesaplamalı yöntemler kullanılarak taranması

Metal organic frameworks (MOFs) are nanoporous inorganic-organic hybrid materials. Zeolitic imidazolate frameworks (ZIFs), composed of transition metal ions and imidazolate type organic linkers, are a subclass of MOFs. Many MOFs have been synthesized to date since these materials have been reported to be highly promising in gas separation applications. They are alternatives to traditional nanoporous materials which are used as adsorbents and membranes in gas separation processes. In this thesis, two structurally similar ZIFs, ZIF-11 and ZIF-12, which have not been examined as gas separation adsorbents and membranes yet, were studied for separation of H2/CH4, H2/CO2 and CO2/CH4 mixtures using atomically detailed simulations. Results showed that ZIF-11 and ZIF-12 outperform many nanoporous membranes and adsorbents for separation of CO2 from CH4 and H2. Although MOFs are promising membranes, fabrication of defect free thin film MOF membranes is challenging. Mixed matrix membranes (MMMs) combine high selectivity and permeability of MOFs with processability of polymers. Gas permeability and selectivity of MOF-based MMMs for H2/CH4, H2/CO2, CO2/CH4 and CO2/N2 separations were examined combining atomically detailed simulations and theoretical permeation models. The results were compared with the available experimental data to test the accuracy of the calculation methods. After showing the good agreement between the predictions of theoretical methods and experiments, gas separation performances of 750 new MMMs composed of various polymers and MOFs were estimated. It was observed that MOF-based MMMs generally have higher gas permeabilities and selectivities compared to pure polymer membranes. Performances of MMMs containing two different types of fillers were also predicted using a new methodology introduced in this thesis. Effects of filler flexibility, filler loading and operation conditions on separation performance of MOF-based MMMs were also investigated.