EPR Study of Dealuminated HY Zeolite and Silica Containing Cu-Mn-Zn Spinels: The Effect of Support
P. Decyk a, A.B. Więckowskib,c, L. Najder-Kozdrowska b, I. Bilkova a and M. Ziółek a
aAdam Mickiewicz University, Faculty of Chemistry, Umultowska 89b, 61-614 Poznań, Poland
bUniversity of Zielona Góra, Faculty of Physics and Astronomy, Institute of Physics, Z. Szafrana 4a, 65-516 Zielona Góra, Poland
cInstitute of Molecular Physics, Polish Academy of Sciences, Division of Physics of Dielectrics and Molecular Spectroscopy, M. Smoluchowskiego 17, 60-179 Poznań, Poland
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A mixture of antiferromagnetic Cu1.4Mn1.6O4 and Cu0.5Zn0.5Mn2O4 or/and ZnMn2O4 spinels was prepared. Dealuminated HY zeolite and silica were doped by these Cu-Mn-Zn spinels. The materials were investigated by X-ray diffraction, the Fourier transform: infrared spectroscopy and EPR spectroscopy. Additionally, all the samples were tested for their activity for isopropyl alcohol dehydration/dehydrogenation. Three EPR signals were observed for Cu-Mn-Zn/dealuminated HY and Cu-Mn-Zn/SiO2 samples at 293 K. In contrast to the spectra recorded at 293 K, only one broad line attributed to Cu-Mn-Zn spinels was visible at 77 K. The EPR signal from pure Cu-Mn-Zn spinels consists only of a single broad line when recorded at 293 K, whereas at 77 K the line is narrower. For all samples subjected to evacuation at high vacuum up to 573 K, the Cu-Mn-Zn spinels were stable. The evacuation at 673 K resulted in a rapid lowering of the intensity of EPR spectrum.

DOI: 10.12693/APhysPolA.132.38
PACS numbers: 68.43.-h, 76.30.-v, 76.30.Fc, 82.75.Vx