Kinetics of toluene alkylation with methanol catalyzed by pure and hybridized HZSM-5 catalysts
Kinetics of toluene alkylation with methanol catalyzed by pure and hybridized HZSM-5 catalysts
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DOI：
10.1016/j.cej.2012.04.100
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发表时间：
2012-07-01
影响因子：
15.1
通讯作者：
Al-Khattaf, Sulaiman
中科院分区：
文献类型：
--
作者：
Alabi, Wahab;Atanda, Luqman;Al-Khattaf, Sulaiman
在纯HZSM-5、丝光沸石/ZSM-5(丝光沸石和HZSM-5的杂化)和ZM13(HZSM-5和MCM-41的混合物)上进行了甲苯与甲醇的烷基化反应动力学研究。采用间歇沸腾床反应器，在300℃、350℃和400℃，反应时间为3、5、7、10、13、15和20 S的条件下，考察了甲苯甲基化和甲苯歧化反应在三种催化剂(甲苯烷基化通常伴随甲苯歧化的酸性催化剂)上的反应速率。在此基础上，建立了一个由三个反应组成的简化的幂定律动力学模型，用于同时估算甲苯甲基化和歧化反应的活化能。用反应时间和反应物转化率衰减函数计算了催化剂上的结焦情况。所有参数都是基于准稳态近似估计的。估算的动力学参数与实验结果吻合较好。催化剂的烷基化能力顺序为ZM13>；HZSM-5>；丝光沸石/ZSM-5；甲苯歧化能力相反(丝光沸石/ZSM-5>；HZSM-5>；ZM13)。因此，在ZM13催化剂上，甲苯的烷基化反应是最有利的，这是由于合成路线和酸含量引起的介孔效应共同作用的结果。甲苯与甲醇的摩尔比为1：1最适合甲苯烷基化反应。(C)2012爱思唯尔B.V.保留所有权利。
A kinetic study of toluene alkylation with methanol was performed over pure HZSM-5, mordenite/ZSM-5 (hybrid of mordenite and HZSM-5), and ZM13 (composite mixture of HZSM-5 and MCM-41 at pH 13). Experimental runs were conducted using a batch fluidized bed reactor at temperatures of 300, 350 and 400 degrees C and reaction times of 3, 5, 7, 10, 13, 15 and 20 s. The rate of toluene methylation and toluene disproportionation were studied on the three catalysts (toluene alkylation is usually accompanied by toluene disproportionation on acid catalyst). Based on the results obtained, a simplified power law kinetic model consisting of three reactions was developed to estimate the activation energies of toluene methylation and disproportionation simultaneously. Coke formation on catalysts was accounted for using both reaction time and reactant conversion decay functions. All parameters were estimated based on quasi-steady state approximation. Estimated kinetic parameters were in good agreement with experimental results. The order of alkylation ability of the catalysts was found to be ZM13 > HZSM-5 > mordenite/ZSM-5, while the reverse is for toluene disproportionation (mordenite/ZSM-5 > HZSM-5 > ZM13). Thus, alkylation of toluene is most favorable on ZM13 due to combined effect of mesoporosity induced through its synthetic route and acid content. Toluene/MeOH molar ratio of 1:1 was most suitable for toluene alkylation reaction. (c) 2012 Elsevier B.V. All rights reserved.