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- Title
Synthesis and study of superacid ZrO<sub>2</sub>-SiO<sub>2</sub>-Al<sub>2</sub>O<sub>3</sub> mixed oxide.
- Authors
Inshina, Olena; Korduban, Alexander; Tel'biz, German; Brei, Volodymyr
- Abstract
Strongly acidic ZrO2-SiO2-Al2O3 mixed oxide with different Zr:Si:Al ratios have been synthesized by sol-gel method. It was found that superacid (H0 = -14.52) sites are formed at 12 ≤ Zr4+ ≤ 39, 48 ≤ Si4+ ≤ 72, 3 ≤ Al3+ ≤ 31 at.%. According to the infrared spectra of adsorbed pyridine and acetonitrile-D3, acidic B- and strong L-sites are present on ZrO2-SiO2-Al2O3 surface. Observed high-energy shift of Zr 3d5/2 peak in the X-ray photoelectron spectrum and low-field shift of 29Si nuclear magnetic resonance signal of superacid Zr35Si53Al12 oxide indicate that the electron density transfers from zirconium to silicon atom. The generation of superacidity in ZrO2-SiO2-Al2O3 matrix could be explained by formation of coordinatively unsaturated Zr4+ ions which are strong L-sites. It was shown that superacid ZrO2-SiO2-Al2O3 efficiently catalyzes polymerization of tetrahydrofuran in the presence of acetic anhydride at 40°C with 68% yield of polytetramethyleneoxide acetate.
- Subjects
ZIRCONIUM compounds synthesis; SOL-gel processes; UNSATURATED compounds; MAGNETIC resonance; ADSORPTION (Chemistry)
- Publication
Adsorption Science & Technology, 2017, Vol 35, Issue 5/6, p439
- ISSN
0263-6174
- Publication type
Article
- DOI
10.1177/0263617417694887