Bryukhanov Ilya A, Rybakov Andrey A, Larin Alexander V
Institute of Mechanics , Lomonosov Moscow State University , Moscow 119192 , Russia.
Mechanical Engineering Research Institute of the RAS , Moscow 119334 , Russia.
J Phys Chem Lett. 2019 May 2;10(9):2191-2195. doi: 10.1021/acs.jpclett.9b00519. Epub 2019 Apr 19.
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 diffusion through 8R increases. For the first time, correlations between cationic and HCO/CO positions are demonstrated in favor of their significant interaction leading to the cationic drift from 8R windows. This phenomenon explains a nonzero CO 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.
利用PBE-D2/PAW水平的从头算分子动力学（AIMD）分析了由于阳离子漂移导致的沸石中小尺寸（8R，D8R）孔的解阻塞效应。证明了碳酸盐和碳酸氢盐物种对NaKA沸石中二氧化碳吸收的影响。结果表明，碳酸氢根或碳酸根阴离子可与K阳离子形成强络合物，并将其从8R窗口中移出，从而增加了CO通过8R扩散的概率。首次证明了阳离子与HCO/CO位置之间的相关性，有利于它们之间的显著相互作用，导致阳离子从8R窗口漂移。这种现象解释了高Na/K交换后窄孔沸石中CO的非零吸附。在气体混合物中，由于两种组分都可能通过部分打开的8R窗口平面，这种解阻塞效应会降低分离因子。
