Application of Probe EPR Spectroscopy to the Studies of the Acidic Properties of Oxide Systems B2O3в€’Al2O3
V. L. YURPALOV1, V. A. DROZDOV1,2, E. D. FEDOROVA1, A. V. LAVRENOV1
1Institute of Hydrocarbons Processing, Siberian Branch of the Russian Academy of Sciences, Ul. Neftezаvodskаya 54, Omsk 644040 (Russia)
2Omsk Scientific Centre, Siberian Branch of the Russian Academy of Sciences, Prospekt Karla Marksa 15, Omsk 644024 (Russia)
Keywords: боратсодержащий оксид алюминия, зондовая ЭПР-спектроскопия, ЯМР твердого тела, бренстедовские кислотные центры, льюисовские кислотные центры, borate-containing aluminium oxide, probe EPR spectroscopy, NMR of solids, BrГёnsted acidic centres, Lewis acidic centres
Abstract
Acidity of a series of the samples of borate-containing aluminium oxide with B2O3 content 0.9 to 27.5 mass % used as a support for the catalysts of hydrocarbon hydroisomerization was studied by means of probe EPR spectroscopy. On the basis of the data on the interaction of probe molecule TEMPO with acidic centres, it was established that Lewis acidity decreases with an increase in B2O3 content from 0.9 to 13.9 mass %, while for the samples with 17.3 and 27.5 mass % B2O3 exclusively Brønsted acidity is manifested. It is demonstrated that the number of Brønsted acidic centres of medium strength, determined with the help of anthracene molecule as an EPR probe, increases with an increase in B2O3 content for the whole series of the studied oxide systems.
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