Rapid deactivation by coke deposition is the main obstacle of ethane aromatization over Zn/ZSM-5. In this work, using the prepared nanosized Zn/HZSM-5, an almost threefold product yield and significantly improved stability were achieved in comparison with those of the microsized catalyst. XRD and XPS analyses indicated that a higher percentage of reactive [ZnOZn]²⁺ species was maintained during ethane aromatization over nano-Zn/HZSM-5 than micro-Zn/HZSM-5. In addition, the evolution of carbon deposits over nanosized and microsized Zn/ZSM-5 was investigated during prolonged ethane aromatization reaction using Raman spectroscopy and thermogravimetry measurements. Compared to the microsized catalyst, the nanosized zeolite facilitated the faster escape of light aromatics and the precursors of carbon deposits from the zeolite pores, thus suppressing the accumulation of coke deposits and improving the catalyst stability. Based on the nanosized Zn/HZSM-5, a protocol of isothermal reaction followed by regeneration was developed by periodically removing carbonaceous deposits, and an ∼25–35% product yield was achieved after 10 reaction–regeneration cycles.

中文翻译：

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乙烷芳构化和纳米和微米尺寸Zn / ZSM-5催化剂上碳沉积的演变

焦炭沉积导致的快速失活是乙烷在Zn / ZSM-5上芳构化的主要障碍。在这项工作中，使用制备的纳米级Zn / HZSM-5，与微尺寸催化剂相比，获得了几乎三倍的产品收率和显着提高的稳定性。XRD和XPS分析表明，较高比例的反应性[ZnOZn] ²⁺在乙烷芳香化过程中，在纳米Zn / HZSM-5上比在微型Zn / HZSM-5上可以保留这些物种。此外，在长时间的乙烷芳构化反应过程中，使用拉曼光谱和热重测量法研究了纳米和微米尺寸Zn / ZSM-5上碳沉积物的演变。与微米尺寸的催化剂相比，纳米尺寸的沸石有助于轻质芳烃和碳沉积物的前体从沸石孔中更快地逸出，从而抑制了焦炭沉积物的积累并提高了催化剂的稳定性。基于纳米尺寸的Zn / HZSM-5，通过定期清除碳质沉积物，开发了等温反应后进行再生的方案，经过10个反应-再生循环，可达到约25-35％的产品收率。