Hydrogen transfer reaction (HTR) is the pivotal side reaction in the catalytic cracking process of low carbon olefins. The intricate reaction pathways and product diversity of HTR directly impact the selective formation of ethylene and propylene. Therefore, elucidating the key HTR in various reaction pathways and defining the hydrogen transfer index (HTI) as a criterion lay a scientific foundation for precisely regulating HTR during olefin catalytic cracking process. Herein, the influence of the acid strength of ZSM-5 zeolites on the HTR degree was analyzed in butene catalytic cracking. Results showed that isobutane was the predominant component of HTR products, mainly derived from HTR during the dimerization-cracking of pentene (butene primary cracking product). Subsequent pentene catalytic cracking experiments validated this conclusion. Thus, the HTI in butene or pentene cracking process was defined as follows: for butene cracking process, HTI = S/S; for pentene cracking process, HTI = S/S. The HTI accurately reflected the extent of HTR with respect to the acid properties of the catalysts. Moreover, the reaction network of butene catalytic cracking process was optimized, providing a comprehensive explanation for the intriguing phenomenon of decreasing butene conversion with increasing reaction temperature when the acid strength of ZSM-5 was weak. Finally, a high-performance butene catalytic cracking catalyst, De-TS-1-0.25%P, was developed, exhibiting high olefin selectivity (92.33 %) and outstanding stability (307 h) in the conversion of butene.

中文翻译：

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ZSM-5丁烯催化裂化氢转移反应

氢转移反应（HTR）是低碳烯烃催化裂化过程中关键的副反应。 HTR复杂的反应途径和产物多样性直接影响乙烯和丙烯的选择性形成。因此，阐明各个反应途径中的关键高温TR，并定义氢转移指数（HTI）作为判断标准，为烯烃催化裂化过程中精确调控高温TR奠定科学基础。本文分析了丁烯催化裂化中ZSM-5沸石的酸强度对高温TR度的影响。结果表明，异丁烷是高温热解产物的主要成分，主要来源于戊烯二聚裂解过程中的高温热解（丁烯初级裂解产物）。随后的戊烯催化裂化实验验证了这一结论。因此，丁烯或戊烯裂解过程中的HTI定义如下：对于丁烯裂解过程，HTI=S/S；对于戊烯裂解工艺，HTI = S/S。 HTI 准确地反映了 HTR 相对于催化剂酸性质的程度。此外，还对丁烯催化裂化过程的反应网络进行了优化，为ZSM-5酸强度弱时丁烯转化率随反应温度升高而降低的有趣现象提供了全面的解释。最终开发出高性能丁烯催化裂化催化剂De-TS-1-0.25%P，在丁烯转化过程中表现出高烯烃选择性（92.33%）和出色的稳定性（307 h）。