Paraxylene (PX) is essential for producing polyethylene terephthalate fibers. We conduct particle-resolved CFD simulations, coupled with our reaction kinetics, on a fixed bed reactor randomly filled with catalyst shapes including sphere, cylinder, trilobe and quadrilobe to enlarge PX productivity in the catalytic isomerization of C aromatics. Our findings reveal the effects of catalyst shapes on velocity, concentration, temperature fields, and pressure drop. Although all catalyst shapes present particle utilization above 70 %, trilobes and quadrilobes show superior PX yield and ethylbenzene conversion due to their larger surface area and reduced mass transfer distance. Yet, among these catalysts, trilobes have twice the pressure drop of the others for complex geometric surface. Therefore, quadrilobes are more practical as their higher bed voidage, smaller pressure drop, better reactivity for desired reactions, and lower adiabatic temperature rise. This work provides guidance for catalyst design and process optimization to enhance PX productivity in aromatic isomerization.

中文翻译：

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采用粒子分辨 CFD 方法模拟固定床反应器中受催化剂形状影响的 C8 芳烃气固相异构化


对二甲苯 (PX) 对于生产聚对苯二甲酸乙二醇酯纤维至关重要。我们在随机填充球形、圆柱形、三叶形和四叶形等催化剂形状的固定床反应器上进行颗粒解析 CFD 模拟，结合反应动力学，以提高 C 芳烃催化异构化中的 PX 生产率。我们的研究结果揭示了催化剂形状对速度、浓度、温度场和压降的影响。尽管所有催化剂形状的颗粒利用率均高于 70%，但三叶形和四叶形催化剂由于其较大的表面积和较短的传质距离而显示出优异的 PX 产率和乙苯转化率。然而，在这些催化剂中，对于复杂的几何表面，三叶催化剂的压降是其他催化剂的两倍。因此，四叶体更实用，因为它们具有更高的床层空隙率、更小的压降、更好的所需反应反应性以及更低的绝热温升。这项工作为催化剂设计和工艺优化提供了指导，以提高芳烃异构化中的 PX 生产率。