Synthesis and characterization of [NaO3SOCH2CH2OSO3Na] and its anchored form:: Surface-grafted acid groups on zirconium hydroxide

A disodium 1,2-ethanediol bis(hydrogen sulfate) salt, [NaO3SOCH2CH2OSO3Na], has been synthesized and anchored onto zirconium hydroxide to produce a high concentration of solid dual acid sites. The reaction of HCON(CH3)(2)-SO3, (CH2OH)(2), and NaOH produced a stable [NaO3SOCH2CH2OSO3Na] precursor in 40% yield. The [NaO3SOCH2CH2OSO3Na] salt was exchanged with NH4+ using an NH4-R resin followed by impregnation of a zirconium hydroxide slurry, yielding [-O3SOCH2CH2OSO3-](2-) anchored on Zr(OH)(4). The characterization of the samples included high-resolution X-ray photoelectron, near-infrared diffuse reflectance, H-1 NMR, and C-13 magic angle spinning NMR spectroscopies. The results provided evidence of a mu (2)-CH2CH2- ligand bridged between two -OSO3- groups in the precursor and the anchored precursor. The ethyl bridge was removed upon calcination at 500 degreesC to yield surface-grafted acid groups on zirconia. This material had a surface area of 97 m(2) g(-1) and an acid-exchange capacity of 0.70 mequiv of H+/g, corresponding to 7.2 mu mol acid sites/m(2), which was about 50% higher than that of sulfated zirconia prepared by standard methods of impregnation by sulfuric acid or ammonium sulfate.