![]() The exceptional performance of Ca-A was maintained in CO2 breakthrough simulations.ĭelicate modification of the silica contents and porous structures within RHO zeolites was readily realized by adopting a variety of alkali metal-crown ether (AMCE) complexes as the templates. Significantly, Ca-A exhibited a higher volumetric CO2 uptake and CO2/N2 selectivity than Mg2(dobdc) (dobdc4- = 1,4-dioxido-2,5-benzenedicarboxylate Mg-MOF-74, CPO-27-Mg), one of the best performing adsorbents. A detailed study of CO2 adsorption kinetics further shows that the performance of Ca-A is not limited by slow CO2 diffusion within the pores. Neutron and x-ray powder diffraction studies reveal the precise location of the adsorption sites for CO2 in Ca-A and Mg-A. The large initial isosteric heat of adsorption of -58 kJ mol-1 indicates strong interactions between CO2 and the Ca-A framework. Among the zeolites tested, Ca-A exhibits the highest CO2 uptake (3.72 mmol g-1 and 5.63 mmol cm-3) together with an excellent CO2 selectivity over N2 under conditions relevant to capture from the dry flue gas stream of a coal-fired power plant. Zeolite adsorbents were evaluated for potential application in post-combustion CO2 capture using a new high-throughput gas adsorption instrument capable of measuring 28 samples in parallel. (9) In recent years, two-dimensional (2D) materials have attracted much attention for CO 2 capture because of their extremely high surface area–volume ratio and large reaction sites for capture and permeation. (6−8) Amine-functionalized carbon nanotubes have also held great potential because of their high stability and high adsorption capacity. Metal organic frameworks (MOFs) and zeolites, a subfamily of MOFs, have stood out because of their strong sensitivity, tunability, and broad applicability. Nanomaterials possess a naturally active surface and the ability to be functionalized with other materials, which are favorable properties for gas capture. Within the past few decades, there has been a proliferation of interest in using nanomaterials. (5) Still, they have not been widely implemented because of their higher price and lower solubility of CO 2 compared to other solvents. A proposed alternative to the amine process has been to use ionic liquids because they are nonvolatile, stable at high temperatures, and can be tuned to react with CO 2. ![]()
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