Download Determining the state of copper ions in the zeolite matrix by electron

Main field of study: 010900 Applied Mathematics and Physics
Area of specialization: Quantum Radiophysics
Department of Nuclear-Physics Research Methods
Scientific advisor: Assoc. Prof. Shelyapina M.G.
Reviewer: Vorontcova A.A.
Determining the state of copper ions in the zeolite matrix by electron
paramagnetic resonance and computer simulation data
Kovalev A.N.
Copper-containing zeolites are very promising catalytically active materials for the NOx
reduction. The catalytic properties of these materials are determined by both the state and
localization of copper ions in the zeolite matrix. The difficulty in determining the positions of
copper ions is that they do not occupy certain crystallographic positions.
The aim of this work was to determine the state of the copper ions in the mordenite matrix
and their coordination by water molecules, and also to test one of the possible localizations of
these complexes in the mordenite matrix, namely, in the small channel. To solve the problem the
following methods were used: thermal analysis, electron paramagnetic resonance (EPR) and
density functional theory.
We studied two samples of the protonated mordenite HMOR10: pure and with partial
substitution of H+ ions by copper ions (CuMOR10). As it follows from the thermal analysis the
water outlet is faster in CuMOR10. This behavior may be due to the symmetry breaking of the
zeolite framework in the HMOR10 sample, as evidenced by NMR studies. Substitution copper
ions for H+ leads to the zeolite framework recovering.
Based on the analysis of the EPR spectra of the CuMOR10 sample one can conclude that
the copper ions are in the 2+ state, and Cu2+ cations form two types of centers with axial
symmetry with weight ratio 2:1. Using the density functional theory method the following free
complexes were calculated: (Cu2+)nH2O (n = 4, 5, 6). It was found that for all considered
complexes the g-tensor parameters are in good agreement with experiment, but the calculated
parameters of the hyperfine interaction tensor noticeably differ from the experimental data.
For the (Cu2+)6H2O complex the effect of the mordenite framework on the calculated EPR
parameters was considered. The complex was placed in the small channel of mordenite. From a
comparison of the calculated and experimental data it was concluded that this complex can not
be realized in practice.
The list of the publications
1. Kovalev A.N., Shelyapina M.G., Petranovskii V.P., Materials of 10th Winter youth SchoolConference Spinus. Magnetic resonance and its applications, 119-121, 2013.
2. Kovalev A.N., Shelyapina M.G., Petranovskii V.P., Book of abstracts IV Russian-Mexican
workshop on Nanoparticles, Nanomaterials and Nanoprocessing, 73-75, 2014.
3. Zhukov Y.M., Kultaeva A.Y., Kovalyov A.N., Shelyapina M.G., Petranovskii V.P., Book of
abstracts IV Russian-Mexican workshop on Nanoparticles, Nanomaterials and Nanoprocessing,
38-39, 2014