(137c) Development and Optimization of Pressure/Temperature Swing Adsorption for Post-Combustion Carbon Capture 

 

K.T. Leperi,¹Â F. You,²Â R.Q. Snurr¹

¹Northwestern University, Evanston, IL, USA

² Cornell University, Ithaca, NY, 14850

With fossil fuels expected to be a significant portion of the worldâ??s energy mix for the near future, it is important to minimize CO₂ emissions from current power plants through carbon capture and sequestration (CCS). In post-combustion CCS, the CO₂ is separated from the power plant flue gas emissions, which contain mainly N₂ and CO₂. Among the more promising technologies for accomplishing this separation with minimal energy are adsorption based processes. Only a few studies have focused on temperature swing adsorption (TSA) compared with pressure/vacuum swing adsorption (P/VSA) for separation of CO₂ from N₂. This has been primarily due to long cycle times associated with the heating and cooling of the bed for TSA. However, potential benefits of TSA over PSA are larger adsorbent working capacities for temperature differences compared to pressure differences and the lower cost of using thermal energy to regenerate the bed compared to using electricity for compressors and vacuum pumps. Therefore, it is important to determine not only the optimal regeneration method for CO₂ capture, but also the optimal cycle utilizing these regeneration methods.

In this work, various PSA, TSA and Pressure/Temperature Swing Adsorption (P/TSA) processes are simulated utilizing our previously developed model.² This 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. This system of PDAEs is solved by discretizing the spatial dimension utilizing the finite volume method coupled with the weighted essential non-oscillatory (WENO) scheme to generate a system of ODEs, which is solved in MATLAB. The non-dominated sorting genetic algorithm (NSGA-II) is then used to determine the optimal operating parameters for capturing the CO₂ from the flue gas at the lowest cost while maintaining the desired CO₂ purity and recovery. The objective of this work is to compare the different methods for regenerating the adsorbent and identify the ideal cycle for minimizing the cost of capturing CO₂ from flue gas. Each cycle is investigated with zeolites 13X and 5A along with Ni-MOF-74 in order to determine potential influences the adsorbent has on the determination of the ideal cycle and regeneration method.

1. MIT. The Future of Coal; 2007. http://web.mit.edu/coal/.

2. Leperi KT, Snurr RQ, You F. Optimization of Two-Stage Pressure/Vacuum Swing Adsorption with Variable Dehydration Level for Postcombustion Carbon Capture. Ind. Eng. Chem. Res. 2016;55:3338-3350.