Journal of Catalysis, Vol.161, No.1, 186-193, 1996
The Acid Strength of Sulfated Zirconia Measured by 2 H-1-NMR Techniques in the Presence of Water - 4 K Broad-Line and 300 K High-Resolution MAS
The interaction of known concentrations of water molecules with sulfated zirconia has been studied by H-1 NMR : broad-line at 4 K and MAS at 300 K. The dependence of the ratio of H3O+ to SO4 groups (H3O+/SO4) on the ratio of adsorbed H2O to SO4 lads. H2O/SO4) has been determined; (H3O+/SO4) is equal to 1 when ads. H2O/SO4 = 2. The acidity of the sample is directly comparable to that of H2SO4, which means that, not being more acidic than H2SO4, it cannot really be described as a "superacid." On the basis of the experimental data, the sulfated zirconia sample has been ranked in a previously proposed scale of Bronsted acid strength for solids.
Keywords:DOPED ZRO2 CATALYSTS;SOLID SUPERACIDS;BRONSTED ACIDITY;LEWIS ACIDITY;N-BUTANE;SITES;ION;ISOMERIZATION;SURFACE;H-1-NMR