Hammett Acidity Function for Mixed ZrO<sub>2</sub>–SiO<sub>2</sub> Oxide at Elevated Temperatures
The mixed ZrO2?SiO2 oxides with different 4 ? Zr/Si ? 0.25 atomic ratios have been prepared using a sol-gel method. It was shown that the concentration-strength acid site distributions on the surface of ZrO2?SiO2 are caused by Zr4+/Si4+ ratio. The ZrO2?SiO2 with Zr/Si = 0.5 is characterized by the h...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Chuiko Institute of Surface Chemistry of NAS of Ukraine
2012-11-01
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| Series: | Хімія, фізика та технологія поверхні |
| Online Access: | https://cpts.com.ua/index.php/cpts/article/view/187 |
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| Summary: | The mixed ZrO2?SiO2 oxides with different 4 ? Zr/Si ? 0.25 atomic ratios have been prepared using a sol-gel method. It was shown that the concentration-strength acid site distributions on the surface of ZrO2?SiO2 are caused by Zr4+/Si4+ ratio. The ZrO2?SiO2 with Zr/Si = 0.5 is characterized by the highest strength of acid sites (Н0 = –11.35). According to the IR-spectra of adsorbed pyridine, the B- and L-acid sites are present in the ZrO2?SiO2 samples with Zr/Si<1 whereas at Zr/Si>1 only L?sites are formed. Basing on the UV-Vis diffuse reflectance spectra of adsorbed indicators, the H0 values for ZrO2?2SiO2 have been determined at elevated temperatures. The Hammett acidity function reaches the superacid value of Н0 ? –14.5 at Т ? 85 °С. |
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| ISSN: | 2079-1704 2518-1238 |