The role of Ir4 cluster in enhancing the adsorption of CO2 on selected zeolites – GCMC simulations

• We simulate adsorption of CO2 on EMT, SAO, SBT, SBS and IWS zeolites containing no, one and two Ir4 clusters per unit cell.
• Independently from zeolite framework, the interaction of CO2 with the Ir4 cluster is significantly stronger than with the zeolite, thus, the cluster is the most preferable adsorption site.
• The introduction of the cluster into zeolite framework increases the adsorption capacity. This effect, depending on the zeolite structure, either fades with the pressure or is preserved in the whole pressure range.
• The presence of the cluster distorts the main type of adsorption in its area, what has a direct correlation with the shape of adsorption isotherms.

We have investigated the adsorption of CO2 molecules inside the EMT, SAO, SBS, SBT and IWS zeolites with respect to the influence of the Ir4 clusters on the adsorption capabilities of these materials. We have determined that the capabilities of CO2 adsorption depend on the combined effect of the framework topology and the position of the Ir4 cluster. Adsorption intensifies despite the fact that a fraction of the pore volume is occupied by the Ir4 cluster, and thus, the adsorption is more intense than that on empty zeolite. The pore topology however is also playing a crucial role in the effect, as in certain cases it allows the CO2 molecules to order in such a way they fill the most pore space.

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