Tailoring the pore size of mesoporous sulfated zirconia

In the early 1990s aggregates of surfactant molecules were used as templates to make mesoporous silicate materials, the first of these being MCM-41. This method is called liquid-crystal templating (LCT). In the work reported here, the LCT method has been applied to zirconia in order to synthesize mesoporous sulfated zirconia. The materials have been characterized by X-ray diffraction, infrared spectroscopy and nitrogen-adsorption measurements. Zirconia treated with sulfuric acid exhibits extremely strong acidity and is capable of catalyzing the isomerization of n-butane at room temperature. The conventional preparations of this catalyst lead to microporous material of high catalytic activity for reactions of small molecules in the vapor phase; this material is less suited for liquid-phase reactions of larger molecules. By using the neutral templating method it is possible to synthesize mesoporous sulfated zirconia, and by changing synthetic parameters, such as surfactant concentration and cosolvent, it is possible to alter the size of the mesopores. Preliminary catalytic testing has shown that the diameter of the pores of the catalyst does affect the reaction rate for a specific large-molecule alkylation reaction in the liquid phase. (C) 2000 Elsevier Science B.V. All rights reserved.