Application of GA in Optimization of Modified Benzene Alkylation Process

Document Type : Research Paper


1 Department of Chemical and Petroleum Engineering, Sharif University of Technology

2 Petroleum Research Technology Laboratory, Department of Applied Chemistry & Chemical Engineering, University of Tabriz


A genetic algorithm is used to optimize the modified benzene alkylation process. Based on the previous studies, the modified process increases ethylbenzene selectivity and decreases energy consumption at the same time. The inlet ethylene flow rate of each alkylation reactor is optimized in order to reduce the chance of transalkylation reactions but increase ethylbenzene selectivity. The byproduct trans-ethylbenzene concentration is used as the fitness variable in the optimization process to confine undesired reactions throughout the process. The obtained optimal values of ethylene flow rate for the adiabatic reactors are 3.50, 2.94, 2.58, and 0.36 m3/hr. The ethylbenzene selectivity has been increased by applying the optimized values indicating the current unit is not operating under optimal conditions. Temperature profile within the alkylation reactors and temperature and concentration profiles through the towers of the fraction unit under the optimized conditions of the modified process are also presented.



[1]. Thomas F. Degnan Jr., C. Morris Smith and Chaya R. Venkat, “Alkylation of aromatics with ethylene and propylene: recent developments in commercial processes”, Applied Catalysis A: General 221 pp. 283–294, 2001.
[2]. Sun L., Guo X., Liu M. and Wang X., “Ethylation
of coking benzene over nano scale HZSM-5 zeolites: effect of hydrothermal treatment
”, calcinations and La2O2 modification, Appl. Catal. A: Gen. 355, pp. 184–191, 2009.
[3]. Barman S., Pradhan N.C. and Basu J.K., Kinetics of alkylation of benzene with ethyl alcohol catalyzed by Ce-exchanged NaX zeolite, Indian Chem. Eng. A 48 (1 Jan.–Mar., 2006.
[4]. Abu I.I., et al., “Studies on platinum-promoted sulfated zirconia alumina: effects of pretreatment environment and carrier gas on n-butane isomerization and benzene alkylation activities”, Journal of Colloid and Interface Science, 267, pp. 382–390, 2003.
[5]. Yongxin Li and Yantao Yang B.X., “Synthesis of ethylbenzene by alkylation of benzene with diethyl oxalate over HZSM-5. Fuel Processing Technology 90”, pp. 1220-1225, 2009.
[6]. Fonseca J.D.L., Faro A.D., Grau J.M and Rangel M.D., “Ethylbenzene production over platinum catalysts supported on modified KY zeolites”, Applied Catalysis A: General, 386, pp. 201-210, 2010.
[7]. G.C. Laredo, Castillo J. and Armendariz-Herrera H., “Benzene reduction in gasoline by alkylation with olefins: Effect of the experimental conditions on the product selectivity”, Applied Catalysis A: General, 384, pp. 115-121, 2010.
[8]. Craciun I., et al., “Effects of acid properties of Y zeolites on the liquid-phase alkylation of benzene with 1-octene: A reaction path analysis”, Journal of Molecular Catalysis A: Chemical, 277, pp. 1–14, 2007.
[9]. Cavani F., Bencini E. and Goffredi G., “Liquid-phase transalkylation of diethylbenzenes with benzene over ß-zeolite: effect of operating parameters”, 226, pp. 31-40, 2002.
[10]. Sharanappa N. and Bokade V.V., “Selective alkylation and disproportionation of ethylbenzene in the presence of other aromatics”, Journal of Molecular Catalysis A: Chemical, 217, pp. 185-191, 2004.
[11]. Longya Xu J.L., Wang Q., Liu S., Xin W. and Xu Y., “Coking kinetics on the catalyst during alkylation of FCC off-gas with benzene to ethylbenzene”, Applied Catalysis A: General. 258, pp. 47–53, 2004.
[12]. Al-Kinany M.C., Al-Khowaiter S.H., Al-Dosari M.A., Al-Megren H.A., Al-Zahrani S.M. and Al-Humaizi K.I., “Low temperature transalkylation of o-diethylbenzene with benzene to ethylbenzene using triflic acid as a catalyst, Chemical Engineering and Processing, 44 () 841-846, 2005.
[13]. Ebrahimi A.N., Sharak A.Z., Mousavi S.A., Aghazadeh F. and Soltani A., “Modification and optimization of benzene alkylation process for production of ethylbenzene”, Chemical Engineering and Processing 50 pp. 31–36, 2011.
[14]. Odedairo T. and Al-Khattaf S., “Kinetic analysis of benzene ethylation over ZSM-5 based catalyst in a fluidized-bed reactor”, Chemical Engineering Journal 157, pp. 204–215, 2010.
[15]. Namuangruk S., Pantu P. and Limtrakul J., “Alkylation
of benzene with ethylene over faujasite zeolite investigated by the ONIOM method
”, Journal of Catalysis 225 ,pp. 523–530, 2004.
[16]. Perego C. and Ingallina P., “Corrigendum to “Recent advances in the industrial alkylation of aromatics: new catalysts and new processes”, Catalysis Today 73, pp. 3-22, 2002.
[17]. Namuangruk S., Pantu P., and Limtrakul J., “Alkylation of benzene with ethylene over faujasite zeolite investigated by the ONIOM method”, Journal of Catalysis 225, pp. 523–530, 2004.
[18]. Jamshidi S., Boozarjomehry R.B., and Pishvaie M.R., “Application of GA in optimization of pore network models generated by multi-cellular growth algorithms Advances in Water Resources”, 32, pp. 1543–1553, 2009.
[19]. Sivanandam S.N. and Deepa S.N., Introduction to Genetic Algorithms., New York: Springer Berlin Heidelberg, 2008.
[20]. Katare S., Bhan A. and Caruthers J.M., “A hybrid genetic algorithm for efficient parameter estimation of large kinetic models Computers and Chemical Engineering”, 28, pp. 2569-2581, 2004.