Are we missing something when evaluating adsorbents for CO2 capture at system level?
Adsorption with porous solid materials is gaining attention as a promising CO2 capture technology due to potential improvement in energy efficiency and cost reductions. This study investigates for the first time the potential performance of MOFs Cu-BTC, Mg-MOF-74, and UTSA-16 for CO2 capture at commercial large-scale using multiscale modeling; a selected activated carbon was also included for comparative purposes, while zeolite 13X was used as the benchmark. We have developed a multiscale model that integrates molecular simulations results with process model of Pressure/Vacuum Swing Adsorption (P/VSA) process. The model was first validated at pilot-scale and then used to assess the performance of the above-mentioned adsorbents and processes attached to a 550 MW coal plant, in order to achieve USA Department of Energy 90% recovery and 95% purity targets. The optimal design, scheduling and operating conditions of these adsorbents was obtained while minimizing total cost and improving non-monetized Key Performance Indicators (KPIs) such as productivity, selectivity, working capacity, energy consumption and modified Adsorption Figure of Merit (AFM) obtained in global sensitivity analyses. A key finding from this study is that the recently proposed UTSA-16 can be as good as traditional zeolite 13X for industrial scale post-combustion capture and compression, at a cost of < $45∙tCO2-1 and energy consumption of < 550 kWhe∙tCO2-1. It is also shown that sometimes using specific KPIs for the evaluation of adsorbents can guide to misleading results as the overall performance depends on dynamics operating conditions at cyclic steady state, material cost, scheduling and column geometry. This study underlines the importance of utilizing detailed multiscale model and system-level analysis for the reliable assessment of different adsorbents at industrial-scale carbon capture.