An effect of deblocking of small size (8R, D8R) pores in zeolites due to cation drift is analyzed by using ab initio molecular dynamics (AIMD) at the PBE-D2/ PAW level. The effect of carbonate and hydrocarbonate species on the carbon dioxide uptake in NaKA zeolite is demonstrated. It is shown that a hydrocarbonate or carbonate anion can form strong complexes with K + cation and withdraw it from the 8R window, so that the probability of CO 2 diffusion through 8R increases. For the first time, correlations between cationic and HCO 3 − /CO 3 2− positions are demonstrated in favor of their significant interaction leading to the cationic drift from 8R windows. This phenomenon explains a nonzero CO 2 adsorption in narrow pore zeolites upon high Na/K exchange. In a gas mixture, such deblocking effect reduces the separation factor because of the possible passage of both components through the plane of partly open 8R windows.
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