Systematic evaluation of materials for post-combustion CO₂ capture in a Temperature Swing Adsorption process

Carbon dioxide separation from nitrogen and impurities in a Temperature Swing Adsorption (TSA) process is a topic of increasing interest for both, academia and industry; however, there is still work needed to find the most suitable material for this separation. For this purpose, we present here a systematic computational comparison of several representative types of MOFs vs. zeolites and other materials currently used for gas storage and CO₂ purification. The work focuses on the behavior of the materials at the industrial conditions. A first screen was done based on adsorption isotherms, Henry's constants and isosteric heats of adsorption calculated from Grand Canonical Monte Carlo simulations. Predicted selectivities were evaluated and complemented with breakthrough curves and working capacities for a TSA process among the different frameworks, with and without water traces. This is the first study in which the effect of water as an impurity is explicitly considered in a throughout comparison of different materials at process conditions. Taking into account that an ideal adsorbent for a post-combustion stream should exhibit a high selectivity for CO₂ over the other flue gas components, high adsorption capacities under the operating conditions and minimal energy penalty for regeneration, results show that among the 11 studied adsorbents, Mg-MOF-74 shows a great potential to become a material to be used for this separation under the TSA operating conditions, with even better performance than the most traditionally used zeolite 13X (NaX). This is a step forward in moving Mg-MOF-74 to industrial applications in an advantageous manner vs. current used materials.