(128g) Combined Molecular- and Process-Level Modeling to Evaluate Metal-Organic Frameworks for Post-Combustion CO2 Capture

In order to reduce global greenhouse gas emissions in the near-term, it is imperative to develop economically promising carbon capture and sequestration (CCS) technologies. Post-combustion CCS, where CO₂ is separated from N₂ and other gases in the flue gas, has attracted much interest recently since the costs of retrofitting it to current power plants is cheaper than other methods. Of the technologies currently available for post-combustion CCS, pressure swing adsorption (PSA) is one of the more promising options due to low energy requirements and short cycle times compared to other adsorption based technologies. One attractive group of adsorbents for CCS applications are metal-organic frameworks (MOFs) due to their tuneable pore structure and chemical functionality. Because of these features, thousands of MOFs have been synthesized in recent years, with various proposed applications, including post-combustion CCS. Many authors measure CO₂ isotherms for MOFs and suggest that the materials are potentially promising for CCS, but metrics for rigorously comparing materials are limited. The objective of this work is to use a combination of molecular modeling, database screening, and process-level modeling to investigate promising MOFs that have been reported in the literature and calculate their process-level and economic performance.

We assessed the process performance of selected MOFs using a 5-step Skarstrom cycle with a heavy reflux step. We also determined the productivity and the energy requirements of the MOFs to determine their economic feasibility. Our PSA model consists of a system of partial differential algebraic equations incorporating mass and energy balances, pressure drop across the column, competitive multi-site Langmuir isotherms and the linear driving force model.² The MOFs investigated include Ni- and Mg-MOF-74, UTSA-16, and SIFSIX-2-Cu-i. In addition, we also evaluated two MOFs from the Computational-Ready Experimental (CoRE) MOF database³ identified as top candidates during our previous investigations.

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2. Leperi KT, Snurr RQ, You F. Optimization of Two-Stage Pressure/Vacuum Swing Adsorption with Variable Dehydration Level for Postcombustion Carbon Capture. Eng. Chem. Res. 2016;55:3338-3350.
3. Chung YG, Camp J, Haranczyk M, Sikora BJ, Bury W, Krungleviciute V, Yildirim T, Farha OK, Sholl DS, Snurr RQ. Computation-Ready, Experimental Metal–Organic Frameworks: A Tool To Enable High-Throughput Screening of Nanoporous Crystals. Mater. 2014;26:6185–6192.