The possibility of increasing the yield of target products and para-selectivity of toluene disproportionation on modified zeolites by optimization of their microporous structure was studied.Benzene and xylenes (especially p-xylene) are widely used in industry. The main method of the synthesis of the above compounds is alkene dehydrocyclization. In the process, benzene (BZ) and xylenes (XLs) are formed together with large amounts of toluene (TL). Disproportionation of TL allows an increase in the production of BZ and XLs.The TL disproportionation (TD) is an acid-type reaction and is catalyzed by H forms of zeolites [1,2]. A study of TD on Y and M type zeolites and on pentasils showed that TD proceeds with the highest efficiency but with low selectivity on HY and on catalysts based on Y, with rapid deactivation of the catalysts. The catalysts based on mordenite are less active but more selective and stable than Y-based catalysts. The pentasil-based catalysts (ZSM-5) are less active but very selective and stable. They are also characterized by high selectivity for p-xylene (p-XL).Thus, development of new zeolite catalysts of TD should involve either Y-and M-based zeolite catalysts or enhancing the activity of ZSM-5. Taking into account that mordenite catalysts are highly active, selective [335], have commercial application [6], and are more stable with respect to modification than Y, we believe that the synthesis of more selective and active M-based catalysts for TD is possible.In this study, we examined the effects of modifying synthetic mordenite on the selectivity of TD and p-XL yield.EXPERIMENTAL Na-exchanged zeolites Y (Y), synthetic mordenite M (M), ZSM-5, and natural mordenite (NM) from Chananab deposit (Azerbaijan) were initial materials for the catalyst synthesis. The samples were synthesized by decationization of the initial zeolites by ion exchange with 2 M NH 4 Cl followed by calcinations at 823 K and dealumination with 2.5 M HCl [7]. After these procedures, the SiO 2 /Al 2 O 3 ratio for M was determined by the method suggested in [8]. Then, the zeolites obtained were modified with a rare-earth element (REE) (Gd) by the ion-exchange procedure (0.5 mol % Gd 2 O 3 ) and with a transition metal (Co) by ion-exchange impregnation (2.5 wt %). The modified zeolites were molded with a binding agent, alumina gel, taken in the amount of 25 g of Al 2 O 3 per 100 g of dry catalyst.The catalytic conversion of TL was studied at atmospheric pressure in a flow-type catalytic apparatus equipped with an adiabatic reactor. Experiments were performed within the 6733748 K range at the space velocity of 1 h !1 and H 2 /toluene ratio of 3.The products of TL conversion were analyzed chromatographically on a capillary column (50 0 0.25 mm) coated with liquid-crystalline phase, methoxyethoxyazobenzene (T = 360 K; carrier gas argon).Adsorption properties of the catalysts were studied gravimetrically on a vacuum device equipped with a McBain quartz balance. Benzene was used as an adsorbate. Experiments were performed at 293 K withi...
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