Reversibility of dealumination-realumination process of BEA zeolite

The reversibility of dealumination-realumination process of BEA zeolite by pH control was investigated by means of nitrogen adsorption, XRD, Al-27 MAS NMR and FT-IR. Aluminum species in the solution, which were eliminated from the framework of BEA zeolite by HCl treatment, were easily reinserted into the framework by controlling the pH value of the suspension below 7. The amount of reinserted framework aluminum increased with an increase in the pH value. The realumination efficiency was also studied by evaluating the change in the cracking activity of cumene. The activity of the BEA zeolite realuminated at pH 5.1 was comparable to that of parent BEA zeolite. (C) 2001 Elsevier Science BN. All rights reserved.