Carbon capture, from air or point sources, is among the key component of many proposed climate portfolios to reach carbon neutrality by 2050. Metal organic frameworks (MOFs), synthesized using organic linker molecules and metal joints, are promising solid adsorbents for CO2 capture applications. Post-synthesis modifications to MOFs have been reported in the literature to address some of the challenges with MOFs such as low CO2 selectivity and the use of toxic chemicals during synthesis. γ-cyclodextrin MOFs are eco-friendly MOFs with potential for use in CO2 capture applications if their large pore size was reduced to enable van der Waals attraction forces between MOFs and the CO2 molecules. The objective of the current study was to functionalize γ-cyclodextrin with polyethylenimine (PEI), linear and branched, to determine the optimal PEI type and loading that enhances the sorption capacity and selectively for CO2. The research hypothesis was that incorporation of PEI into the pores of γ-cyclodextrin MOFs would: 1) introduce Lewis basic amine groups to enhance sorption of CO2 molecules and 2) narrow the pores of the γ-cyclodextrin to an optimal size that enables physical attraction between the CO2 molecules and the surfaces of the MOFs. γ-cyclodextrin MOFs were synthesizing and functionalized with linear PEI and branched PEI with molecular weights of 600, 1,200 and 10,000. A quartz crystal microbalance (QCM) assembly was used for quantifying the CO2 sorption capacity of the γ-cyclodextrin MOFs at CO2 pressures ranging from 0.35 – 1.0 atm. Modifications of the 600 g/mole branched PEI achieved the best CO2 sorption capacity of 0.9 mmole CO2 at 1 atm. The poster will also present the characteristics of the control and the modified γ-cyclodextrin MOFs as well as guest-host interactions between the MOFs and PEI molecules.
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