Synthesis of a Zeolite-Containing Catalyst for Gas-Phase Alkylation of Benzene with Ethylene
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hesis of a Zeolite-Containing Catalyst for Gas-Phase Alkylation of Benzene with Ethylene D. A. Shavaleeva, *, M. L. Pavlovb, R. A. Basimovab, and E. R. Naranovc, ** a
OOO Eurasia Commerce, Moscow, 125047 Russia and Technology Center, OOO Gazprom Neftekhim Salavat, Salavat, 453256 Russia c Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Moscow, 119991 Russia *e-mail: [email protected] **e-mail: [email protected] bScience
Received February 20, 2020; revised May 29, 2020; accepted June 11, 2020
Abstract—A multistage synthesis of the catalyst for the gas-phase alkylation of benzene with ethylene is implemented. A highly active catalyst is synthesized from zeolite ZSM-5 using thermal-vapor treatment. The obtained catalyst possesses an optimal acidity, which makes it possible to achieve a higher yield of ethylbenzene compared to the commercial catalyst based on ZSM-5 (88 and 62.7 wt %, respectively), an approximately equal ethylbenzene selectivity, and an almost three times lower concentration of the undesirable xylene impurity in an alkylate (0.004 and 0.011 wt %, respectively) in the gas-phase benzene alkylation with ethylene. Keywords: ZSM-5, zeolite, solid acid catalyst, alkylation, ethylbenzene DOI: 10.1134/S0965544120100114
Zeolites are porous crystalline materials with controlled acidity. They are widely used in oil refining due to their unique structural properties: high specific surface area, developed pore structure, and stability in comparison with amorphous materials [1]. Zeolite ZSM-5 with the MFI type structure is in common use as an alkylation catalyst due to its high acidity, rapid synthesis, easy separation from reaction products, and the absence of problems associated with disposal of the spent catalyst [2]. The size of zeolite crystals has a great influence on the catalytic activity and selectivity; particularly, nanocrystalline zeolite ZSM-5, in comparison with the usual commercial zeolite ZSM-5, is characterized by a large space of intercrystalline voids, a large pore volume, and more accessible external surface acid sites; therefore, it exhibits higher activity and better stability and is less prone to coking [3–5]. The alkylation of benzene with the simplest olefins over zeolite-containing catalysts, as well as the transalkylation of byproducts (alkylbenzenes), are well-studied processes [5]. At present, the main regularities of these reactions proceeding over zeolite-containing alkylation catalysts are known [6–12]. Ethylbenzene, the most important product of petrochemical synthesis, is obtained by the alkylation of benzene with ethylene. Until the 1980s, ethylbenzene production units mainly operated using aluminum chloride as a catalyst with a promoter [11]. Most of the modern developments focusing on the improvement of benzene
alkylation with ethylene are associated with the creation and use of heterogeneous, zeolite or zeolite-containing catalysts, among which a catalyst based on zeolite ZSM-5 (the MFI structural type) is in most common use [13–17]. The c
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