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ABSTRACT:The IR and UV-vis diffuse reflectance spectra of mesoporous WO 3 /ZrO 2 are discussed and a scheme proposed for the acid site structure on the WO 3 /ZrO 2 surface. The high Brönsted acidity of WO 3 /ZrO 2 (H 0 ≤ −11.38) can be explained by the formation of large zirconium polytungstate species such as on the WO 3 /ZrO 2 surface.

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Superacid ternary ZrO2 SiO2 SnO2 oxide has been synthesized by the sol-gel method with a different atomic ratio Zr:Si:Sn. The highest strength of acid sites has been observed in the ranges of 20 ≤ Zr4+ ≤ 29, 60 ≤ Si4+ ≤ 67, 11 ≤ Sn4+ ≤ 20 at.%. According to the XPS spectra and 119Sn, 29Si MAS NMR spectra of ZrO2 SiO2 SnO2 a partial shift of electron density from zirconium to silicon ions was observed resulting in the formation of superacid Lewis sites. It was shown that superacid Zr29Si60Sn11 mixed oxide efficiently catalyzes acylation of toluene with acetic anhydride at 423 K in a flow reactor with 45% conversion of anhydride at 100% selectivity towards p-methylacetophenone.