The thermal stability of α-diimine nickel catalysts has always been a hot research topic, and its thermal deactivation mechanism has not been determined for the time being. In this work, three model α-diimine nickel catalysts with simple backbone structures and only one or two –CH3 differences were synthesized to catalyze ethylene polymerization at different temperatures. For the first time, the focus of catalyst thermal stability was related to the internal essence (active centers) from the external manifestation (thermal stability of catalyst structure, catalytic activity), and the quenching method of thiophene-2-carbonyl chloride (TPCC) was adopted to further elucidate the essence of catalyst thermal stability from the perspectives of the quantity (quantity of active centers at low/high temperature) and quality (insertion rate constant) of active centers. In this study, it is proposed that the thermal stability of catalysts is a result of the combined effect of the quantity and quality of active centers, while increasing the steric effect by means of increasing –CH3, etc., essentially affects the balance between the quantity and the quality of active centers. Designing suitable steric effects and finding the optimum point between the above influencing factors is one of the effective ways to improve the thermal stability of catalysts.

中文翻译：

---

α-二亚胺镍催化剂及活性中心热稳定性微观机制研究


α-二亚胺镍催化剂的热稳定性一直是研究热点，其热失活机理暂时尚未确定。在这项工作中，合成了三种主链结构简单、只有一个或两个-CH3差异的模型α-二亚胺镍催化剂，用于在不同温度下催化乙烯聚合。首次从外在表现（催化剂结构热稳定性、催化活性）关注催化剂热稳定性的关注点，涉及到内在本质（活性中心），以及噻吩-2-碳酰氯（TPCC）的猝灭方法从活性中心的数量（低温/高温下活性中心的数量）和质量（插入速率常数）的角度进一步阐明催化剂热稳定性的本质。本研究提出催化剂的热稳定性是活性中心的数量和质量共同作用的结果，而通过增加-CH3等手段增加空间效应，本质上是影响活性中心之间的平衡。活跃中心的数量和质量。设计合适的空间效应并找到上述影响因素之间的最佳点是提高催化剂热稳定性的有效途径之一。