Proceedings of the 8 th Serbian-Croatian-Slovenian Symposium on Zeolites 81 THE INFLUENCE OF THE PREPARATION METHOD ON THE RATIO OF HETEROATOMS IN THE ZEOLITE BETA STRUCTURE Ivana Landripet 1 , Andreas Puškarić 1 , Josip Bronić 1 , Nataša Zabukovec Logar 2 , Matjaž Mazaj 2 ,Massimo Migliori 3 , Girolamo Giordano 3 1 Ruđer Bošković Institute, Bijenička 54, 10000 Zagreb, Croatia 2 National Institute of Chemistry, Hajdrihova 19, 1001 Ljubljana, Slovenia 3 Department of Environmental and Chemical Engineering, University of Calabria, Via Pietro Bucci, 87036 - Arcavacata di Rende (CS), Italy E-mail: ivana.landripet@irb.hr ABSTRACT Beta zeolite is microporous, aluminosilicate characterized by big 12-ring channel systems. It is commonly used as commercial adsorbent and catalyst. Although the pores are exceptionally large there are limitations which decrease efficiency of the catalysts. Such limitations should be avoided by creating mesoporous voids (channels and holes) during catalyst synthesis or by post synthesis treatment of classically prepared microcrystals. Another important issue in catalysis efficiency is the number of active sites (i.e. Lewis and Brønsted acid sites). It´s number can be increased with number of hetero T-atoms within framework by postsynthesis treatment. Keywords: mesoporous beta, wet impregnation, mechanochemistry, fluoride postsynthesis treatment. INTRODUCTION The BEA framework topology attracts much attention because of the three-dimensional large-pore channel system, large available micropore volume, and the presence of active sites in different concentrations that are useful in a number of acid-catalyzed reactions. Intracrystalline diffusion of the reactants and products within zeolite crystals is limited, and can be avoided reducing the size of the crystals or by introducing mesoporous voids. Efficiency of the catalytic process can be improved by increasing the number of active sites (i.e. Lewis and Brønsted acid sites) and by controlling crystallite size and morphology. EXPERIMENTAL Oxide form of the chemical composition of the starting mixture was: 2 Na 2 O × 30 (TEA) 2 O × Al 2 O 3 × 165 SiO 2 × 1980 H 2 O (1) Zeolite beta was prepared by classical hydrothermal synthesis (receipt adopted from ref. 1). The synthesis was made in Teflon-lined autoclaves as one pot synthesis on following way; After addition of aqueous solution of NaOH, redistilled water, 35 wt% aqueous solution of tetraethylammonium hydroxide (TEAOH) and Al(i-OPr) 3 , mixture was stirred using magnetic stirrer until complete hydrolysis (about 30 min). Then comes addition of colloidal silica (Ludox HS-40) and stirring for 24 h followed by heating for 5 days at 100 °C and 24 h at 150 °C [1]. Obtained product was washed, dried and slowly calcined at 600 °C in the stream of air. H-form of the samples was obtained by ion-exchange (0.8 M NH 4 NO 3 ) and heating. Postsynthesis treatment to obtain mesoporous (hierarchical structure) was made by dealumination/desilication using 5 M NH 4 F solution. Direct synthesis of hierarchical structure was made using similar procedure. Oxide form of the chemical composition of the starting mixture was: