Superacid L-Sites on the Surface of Ternary ZrO2-SiO2-Al2O3 and ZrO2-SiO2-SnO2 Oxides

Abstract

Superacid (H₀ ≥ –14.52) ternary Zr₃₅Si₅₃Al₁₂ and Zr₂₁Si₆₇Sn₁₁ oxides have been studied by X-ray photoelectron spectroscopy. The high-energy shifts of Zr3d levels indicate the electron density shift from zirconium to silicon atoms, which is facilitated by the presence of tetrahedrally coordinated Al³⁺ and Sn⁴⁺ ions in Zr⁴⁺ environment. Models of the superacid L-sites that include coordinatively unsaturated zirconium ions are proposed.