1315 ISSN 1070-4272, Russian Journal of Applied Chemistry, 2017, Vol. 90, No. 8, pp. 1315−1319. © Pleiades Publishing, Ltd., 2017. VARIOUS TECHNOLOGICAL PROCESSES Comparison of Catalytic Performance of Synthesized EU-1 Zeolite with Dealuminated EU-1 Zeolite for m-Xylene Isomerization Reaction 1 Zahra Vosoughi Rahbari a *, Mehrji Khosravan a , and Ali Nemati Kharat b a Department of Chemistry, Faculty of Science, Shahid Bahonar University of Kerman, Kerman, Iran b Department of Chemistry, Faculty of Science, University of Tehran, Tehran, Iran *e-mail: zahravosoughi@yahoo.com, vosoughi.z@sci.uk.ac.ir Received August 26, 2017 Abstract—EU-1 zeolite was synthesized with high purity by a hydrothermal method and under optimum con- ditions: synthesis time 72 h, temperature 200°C, and aging time 12 h. Then, the synthesized EU-1 zeolite was modified by dealumination with nitric acid and the changes of the properties such as surface area, pore volume, and Si/Al ratio were investigated. The catalytic performance of these two catalysts was studied and com- pared with a commercial mordenite catalyst for meta-xylene isomerization reaction in a fixed bed reactor. The results showed that the modification of catalyst with acid increases Si/Al ratio from 25 to 50 due to the removal of a number of aluminium atoms from the framework of zeolite. Also the catalyst surface area increased from 300.237 m 2 g ‒1 for EU-1 to 333.639 m 2 g ‒1 for modified EU-1. According to results, the modified Eu-1 had higher para/ortho ratio, meta-xylene conversion, and para-xylene yield than EU-1 and commercial mordenite in the meta-xylene isomerization reaction. DOI: 10.1134/S1070427217080201 1 The text was submitted by the authors in English. INTRODUCTION Para-xylene (p-xylene) is the feed for pure terephthalic acid (PTA) production which has the largest commercial market as compared to its isomers, meta -xylene (m-xylene) and ortho-xylene (o-xylene) [1]. In general, p-xylene is produced in the petrochemical industry by the following methods: (1) Isolation of p-xylene from isomers, (2) Conversion of ortho and meta to para through xylene isomerization [2]. In the recent years, numerous catalysts have been proposed for the xylene isomerization process, most of which were related to the use of zeolites in this reaction. Zeolites are regular microporous aluminosilicates that are formed from TO 4 tetrahedral units (T = Si, Al, ...). These units are connected to each other by oxygen in the tetrahedron vertices and form the three dimensional structural frameworks. Charge, size, and position of cations in the zeolites frameworks affect the structure of zeolites. This is especially important in connection with the use of zeolites as catalysts. Specific dimensions, shape selectivity, continuity of cavities, and empty spaces are the characteristics zeolites [3]. The high surface area of the zeolites has made them suitable for use as the catalysts. Due to the size of their cavities, these compounds can act as highly selective in entering and leaving various compounds. The pore size of zeolites can be adjusted by performing various operations, such as ion exchange [4]. Most of the previous studies are related to the isomeri- zation of xylene mixtures, and a limited number is about m-xylene isomerization [5]. m-Xylene conversion was performed on acidic zeolites with 10 or 12 membered rings such as: OFF, MOR, FAU, ZSM-48, ZSM-5, ZSM- 12. These zeolites have a different crystalline structure with different shapes and crystalline dimensions. Usually para/ortho selectivity over 10 membered rings zeolites with crystals larger than 1 μm are always high in m-xylene isomerization [6].