Enhanced Trace Carbon Dioxide Capture on Heteroatom‐Substituted RHO Zeolites under Humid Conditions

Abstract Boron and copper heteroatoms were successfully incorporated into the frameworks of high‐silica RHO zeolite by adopting a bulky alkali‐metal–crown ether (AMCE) complex as the template. These heteroatom‐doped zeolites show both larger micropore surface areas and volumes than those of their aluminosilicate analogue. Proton‐type RHO zeolites were then applied for the separation of CO 2 /CH 4 /N 2 mixtures, as these zeolites have weaker electric fields and, thus, lower heats of adsorption. The adsorption results showed that a balance between working capacity and adsorption heat could be achieved for these heteroatom‐doped zeolites. Ideal adsorbed solution theory predictions indicate that these zeolites should have high selectivities even for remarkably dilute sources of CO 2 . Finally, the heteroatom‐substituted zeolites, especially the boron‐substituted one, could be thermally regenerated rapidly at 150 °C after full hydration and maintained high regenerability for up to 30 cycles; therefore, they are potential candidates for trace CO 2 removal under humid conditions.