Effect of Treatment with NaAlO2 Solution on the Surface Acid Properties of Zeolite β

The influence of treatment with an NaAlO2 aqueous solution of NaAlO2 on the surface acid properties of zeolite β was studied as a method to increase the number of both Brønsted and Lewis acid sites. The Hβ samples, prepared by treating with an aqueous solution of NaAlO2, were characterized by XRD, NH3-TPD, pyridine-IR, 29Si MAS NMR, and 27Al MAS NMR. The surface properties of the Hβ zeolite changed after treatment with the aqueous NaAlO2 solution: the number of strong and weak acid sites, the total amount of acid, and the Brønsted and Lewis acid sites increased. The treatment of zeolite β with an aqueous solution of NaAlO2 may realuminate an Si(0Al)A site by the isomorphous substitution of Al(OH)4− anions.