818 ISSN 1070-4272, Russian Journal of Applied Chemistry, 2017, Vol. 90, No. 5, pp. 818−825. © Pleiades Publishing, Ltd., 2017. VARIOUS TECHNOLOGICAL PROCESSES Effect of Synthesis Parameters on the Crystallinity of EU-1 Zeolite for the 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 *e-mail: vosoughi.z@sci.uk.ac.ir b Department of Chemistry, Faculty of Science, University of Tehran, Tehran, Iran Received April 24, 2017 Abstract—The EU-1 zeolite with Si/Al = 25 was synthesized by hexamethonium bromide as a template. The ef- fects of crystallization time, synthesis temperature, and the pH of the synthesis gel on the structure and crystallinity of EU-1 zeolite were investigated. The synthesized EU-1 zeolite was characterized by X-ray powder diffraction, BET, Fourier transforms infrared spectroscopy, scanning electron microscope, and inductively coupled plasma. The most effective conditions for synthesis of EU-1 were identified as follow: synthesis time 72 h, temperature 200°C, pH of gel – ~ 13, and aging time of 12 h. The catalytic performance of this catalyst was investigated for meta-xylene isomerization reaction in a fixed bed reactor under the following conditions: pressure of 10 bars, the temperature of 380°C, feed space velocity of 3.35 h –1 and 4 g of the EU-1 catalyst. In comparison to other reported catalysts our synthetic EU-1 showed good m-xylene conversion and high PX/OX ratio. DOI: 10.1134/S107042721705024X 1 The text was submitted by the authors in English. INTRODUCTION Mixed xylenes are a mixture of ethylbenzene and three xylene isomers. Xylene and ethylbenzene (EB) are C 8 H 10 aromatic isomers [1]. Xylenes contain three isomers: ortho, meta, and para. They have many applications in the industry as solvents or intermediates for many derivatives. Mixed xylenes and ethylbenzene are commercially available from pyrolysis of gasoline, catalytic reformate, toluene disproportionation product and coke over light oil [2]. Isomerization of xylenes has been widely used in petroleum refining industries for production of important petrochemicals [3]. Particularly para-xylene which may be derived from a mixture of C 8 aromatic isomers is a valuable chemical feedstock and has the largest commercial market [4]. Para-xylene is the main feedstock for production of pure terephthalic acid (PTA), which is used in synthesis of polyesters, resins, and films. Since there is a great demand for PTA; it is desired to convert other xylene isomers, ortho and meta, to para form [5]. The xylenes distributions in aromatic cuts are as follows: 25% of para-isomer, 50% of meta isomer, and 25% of ortho isomer [6]. Zeolites are porous crystalline framework materials containing molecular pores. Conventional zeolite can be negatively charged by substituting some of Si atoms present in the framework with Al and some Si atoms present in the pore structure with a cations such as Na or alkaline metals. These changes in structure lead to important features and ion exchange properties [7]. In recent years, there has certainly been a noticeable increase in interest in research on zeolite membranes due to their well-defined microporous structure, good structural and their thermal stability [8, 9]. Numerous catalysts have been proposed for use in xylene isomerization processes such as: ZSM-5, mordenite and so on [1, 10, 11]. ZSM-5 is preferred when performing ethylbenzene dealkylation. Mordenite-based catalyst, undergo a number of secondary acidic reactions such as: disproportionation, transalkylation, dealkylation, and cracking [12].