Chemical and Biological Engineering MS Thesis Defense by Fatma Pelin Kınık








Title: Tuning Gas Adsorption and Separation Performances of ZIF-8 by [BMIM][PF6] Incorporation and Elucidation of the Interactions Between Ionic Liquid and Metal Organic Framework


Speaker: Fatma Pelin Kınık


Time: July 25, 2017, 11:30


Place: ENG-208

Koç University

Rumeli Feneri Yolu

Sariyer, Istanbul

Thesis Committee Members:

Assoc. Prof. Seda Keskin Avcı (Advisor, Koc University)

Asst. Prof. Alper Uzun (Advisor, Koc University)

Prof. A. Levent Demirel (Koc University)
Assoc. Prof. Uğur Ünal (Koc University)
Prof. Ramazan Yıldırım (Bogazici University)

Abstract: Natural gas which is mainly composed of CH4 is a cleaner energy source with higher H/C ratio compared to fossil fuels. It includes some impurities such as CO2 and N2 which may cause corrosion and low energy density. For an efficient gas storage and separation process, high capacity adsorbent materials have been used. Metal organic frameworks (MOFs) have drawn attention as porous adsorbent materials as a result of their remarkable structural characteristics, such as high surface area, high porosity, and low density as well good thermal and mechanical stability. To improve gas adsorption and separation performances of MOFs, incorporation of ionic liquid (IL) into their structure has been suggested as a new approach. In this study, first an imidazolium-based IL ([BMIM][PF6]) was incorporated into a MOF (ZIF-8) to investigate the effect of an IL incorporation on the gas adsorption and separation performance of a pure MOF. Gas adsorption measurements for CO2, CH4, and N2 were performed in combination with atomically-detailed simulations and density functional theory (DFT) calculations. Results suggest that IL-MOF interactions strongly affect the gas affinity of materials at low pressure. Direct interactions between IL and MOF lead to at least a doubling of CO2/CH4 and CO2/N2 selectivities of ZIF-8. Then, five different phosphonium-based ILs ([P4444][TOS], [P4441][MeSO4], [P(14)666][TMPP], [P(14)666][Br], and [P(14)666][DCA]) were incorporated into ZIF-8 and [P(14)666][DCA] was incorporated into CuBTC. The aim was to investigate the effect of different families of ILs and MOFs on the gas uptake and selectivity and extend the knowledge on IL/MOF composites. Results show that while phosphonium-based ILs could improve the gas capture performances of MOFs, none of them could increase selectivity of MOFs remarkably. The results show that incorporation of IL into MOF structure is a promising way to improve the gas adsorption and separation performances of pure MOFs. With the help of the results obtained in this thesis study, it is possible to extend the number of IL/MOF composites prepared by using different kinds of ILs and MOFs, and they can be investigated for different gas separation applications.