II-P-21 - Study on the acidity of modified H Y zeolites prepared by combination of chemical dealumination and h y d r o t h e r m a l treatment M. Han, L.-P. Zhou, X.-W. Li and L.-Q. She* College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, [email protected]
, chem.pku, edu. cn, China Acidity of modified HY zeolites prepared by combination of chemical dealumination and hydrothermal treatment have been characterized by IR, MAS NMR and n-butylamine titration. The results showed that by increasing the level of dealumination, the total amount of acid sites decreased while the strongest acid sites (H0 < -8.2) increased. The strength population profile of acid sites revealed that only the aluminum atoms associated with the stronger acid sites (-8.2 < H0 < -5.6) were extracted from the framework during the dealumination steps. These results were correlated with the population of Si(nA1) groupings obtained from the spectra of 29Si MAS NMR. The acidity changes at each step of preparation procedure are discussed.
11-P-22 - Modification of Beta-zeolite by dealumination and realumination J.Y. Zhang, L.-P. Zhou and X.-W. Li
Department of Chemistry, Peking University, Beijing 100871, China [email protected]
, chem.pku, edu. cn The dealumination and realumination of low sodium [3-zeolite have been studied by IR spectroscopy and powder X-Ray diffraction. The calcination-dealuminated HI3 was easily realuminated by direct treatment with aluminate sodium solution. After transformation into protonic HI3, the framework Bronsted sites (IR band at 3610 cm ~) were restored and the acidity was the same as in the original HI3. The realumination of acid dealuminated HI3 was difficult, but could be achieved with aluminate sodium solution by hydrothermal treatment in autoclave. This incorporation of A1 into zeolite framework increased the number of acid sites, in particular that of weak acid sites which in comparison with parent HI3.
11-P-23 - Ultrastable zeolites Y (USY) modified with p h o s p h o r u s and boron A.V. Abramova a, Y.V. Slivinsky a, L.Y. Kitaev b, A.A. Kubasov b, H. Lechert c, W.D. Basler c, V.V. Yushchenko b and Z.M. Matieva a
a A. V. Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Leninsky prospect, 29, 117912, Moscow, B-71, Russia, e-mail." [email protected]
b Moscow 34. V. Lomonosov State University, Moscow, Russia r Institute of Physical Chemistry, University of Hamburg, Hamburg, Germany USY zeolite has been modified by an acid treatment with H3PO4 and H3BO3. The properties of the modified samples have been investigated by various methods. After loading with platinum the catalytic properties with respect to n-hexane isomerisation have been studied. The modification changes significantly the adsorption properties. The modified catalysts are more active in n-hexane isomerization than USY.