Kinetics and Mechanism of Benzene, Toluene, and Xylene Methylation over H-MFI
Kinetics and Mechanism of Benzene, Toluene, and Xylene Methylation over H-MFI
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DOI：
10.1021/cs400377b
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发表时间：
2013-08
期刊：
影响因子：
12.9
通讯作者：
Ian M. Hill;A. Malek;A. Bhan
中科院分区：
文献类型：
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作者：
Ian M. Hill;A. Malek;A. Bhan
苯、甲苯、对二甲苯和邻二甲苯在MFI结构的H-ZSM-5和介孔自柱撑pentasil（H-SPP）上与二甲醚（DME）在低转化率（30：1）下的甲基化反应显示出苯和甲苯的甲基化速率对芳族压力的线性依赖性和对DME压力的零依赖性。这些结果与针对烯烃甲基化进行的研究一致，并且表明沸石表面被DME衍生的物质覆盖，所述DME衍生的物质在速率确定步骤中与苯或甲苯反应。在二甲苯压力依赖性实验中观察到反应速率的饱和（在473 K，<5 kPa二甲苯下）;然而，当比较101 μm微晶H-ZSM-5和2-7 nm介孔H-SPP时，没有观察到反应速率的增强，表明二甲苯甲基化在没有扩散限制的情况下进行。同时零级速率依赖于二甲苯和DME的压力所描述的二甲苯吸附到一个表面上的基础上的模型…
The methylation of benzene, toluene, para-xylene, and ortho-xylene over MFI structured H-ZSM-5 and mesoporous self-pillared pentasil (H-SPP) with dimethyl ether (DME) at low conversions ( 30:1) showed linear rate dependencies on aromatic pressure and zero dependence on DME pressure for benzene and toluene. These results are consistent with studies performed for olefin methylation, and are indicative of a zeolite surface covered in DME-derived species reacting with benzene or toluene in the rate-determining step. Saturation in the reaction rate was observed in xylene pressure dependence experiments (at 473 K, <5 kPa xylene); however, enhancement in the reaction rate was not observed when comparing ∼1 μm crystallite H-ZSM-5 and 2–7 nm mesopore H-SPP, indicating that xylene methylation proceeds in the absence of diffusion limitations. Simultaneous zero-order rate dependencies on xylene and DME pressures are described by a model based on adsorption of xylene onto a surface...