The design of zeolite-based catalysts with reduced diffusion limitation has attracted much attention for the enhanced activity and stability in light alkane aromatization. Here we employed three types of zeolite-based catalysts including micron zeolite, solid nano zeolite, and hollow zeolite with nano size to investigate the effects of diffusion length and pore structure of zeolites on their mass transport efficiency and catalytic performance during ethane aromatization. It was indicated that the shortened diffusion length and increased mesoporosity of Zn/hollow-HZSM-5 endow it with substantial improvement in mass transport, leading to enhanced accessibility to active acid sites and rapid escape of formed lighter aromatics rather than further polymerization to form coke. Contrarily, the solid micron zeolites with long diffusion path experience strong diffusion limitation, which extends the contact time of reactants and products with the active acid sites within zeolites thus resulting in severe coke deactivation. After being subjected to ethane aromatization for 400 min, the aromatics selectivity toward Zn/hollow-HZSM-5 catalyst retained 50%, which is almost threefold with respect to that of the solid Zn/micro-HZSM-5 and Zn/nano-HZSM-5. Based on the Thiele modulus, it can be suggested that shortening diffusion length and introducing mesopores into zeolites can effectively alleviate diffusion resistance, then enhance their catalytic activity and stability toward ethane aromatization.

具有降低的扩散限制的沸石基催化剂的设计因其在轻烷烃芳构化中增强的活性和稳定性而引起了人们的广泛关注。在这里，我们使用三种类型的沸石催化剂，包括微米级沸石，固体纳米沸石和具有纳米尺寸的中空沸石，研究了沸石的扩散长度和孔结构对其在乙烷芳构化过程中的传质效率和催化性能的影响。结果表明，Zn /空心-HZSM-5的扩散长度缩短，介孔率提高，使传质有了实质性的改善，导致活性酸位点的可及性增强，并且形成的轻质芳烃迅速逸出，而不是进一步聚合形成焦炭。相反，具有长扩散路径的固体微米沸石经历强的扩散限制，这延长了反应物和产物与沸石内活性酸位的接触时间，从而导致严重的焦炭失活。进行乙烷芳香化400分钟后，对Zn /空心HZSM-5催化剂的芳烃选择性保持50％，几乎是固态Zn / micro-HZSM-5和Zn / nano-HZSM的三倍。 -5。根据Thiele模量，可以认为缩短扩散长度并在沸石中引入中孔可以有效地降低扩散阻力，