ИСТИНА

The bulk and Young moduli have been calculated at the DFT level (РВЕ, PBE-D3) using VASP for cationic zeolite forms upon water addition [1] and the formation of carbonates during CO2 adsorption [2,3]. A qualitative agreement of the calculated elastic moduli of zeolites with the corresponding experimental data has been found. Upon the addition of water, the monovalent alkali ion and divalent alkaline earth ion exchanged zeolites presented opposite trends in the elastic modulus. The main contribution to a decrease of elastic modulus of alkali exchanged forms is assigned to cationic shift from framework oxygen atoms upon water addition while cationic coordination number often remains the same. An opposite increase of elastic modulus in divalent (alkaline earth) exchanged forms is conditioned by cation stabilization possibly due to its higher coordination which cannot be achieved within rigid zeolite framework without water. A similar mechanism of the decrease of the elastic constants has been found during the formation of carbonates in the same zeolites, leading to a substantial migration of alkali cations, which actually shield the carbonate or bicarbonate anion from the negatively charged framework of the zeolite. The authors thank the Russian Foundation of Basic Researches within the grant 17-53-18026-Bolg_а. The research is carried out using the equipment of the shared research facilities of HPC computing resources at Lomonosov Moscow State University [4]. 1. Bryukhanov I.A. et al. The role of water in the elastic properties of aluminosilicate zeolites: DFT investigation // J. Mol. Model. 2017. Vol. 23, № 3. P. 68. 2. Bryukhanov I.A. et al. Influence of carbonate species on elastic properties of NaX and NaKX zeolites // Microporous Mesoporous Mater. Elsevier Inc., 2014. Vol. 195. P. 276–283. 3. Bryukhanov I.A. et al. Chemical reduction of the elastic properties of zeolites: a comparison of the formation of carbonate species versus dealumination. // Dalton Trans. 2015. Vol. 44, № 6. P. 2703–2711. 4. Sadovnichy V. et al. “Lomonosov”: Supercomputing at Moscow State University // Contemporary High Performance Computing: From Petascale toward Exascale / ed. Vetter J.S. Boca Raton, USA: CRC Press, 2013. P. 283–307.