高密度聚乙烯形成中性Ni[N,N]催化剂的设计:关于催化剂失活的见解
Bence Szabó1, Lennox W Stewart1, Georgina M Rosair1
1Institute of Chemical Sciences, School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, U.K.
新的催化剂使乙烯聚合成为可能,产生高密度聚乙烯. 这些催化剂意外地经历C-H激活,形成循环金属化复合体,揭示了聚合催化剂的新型分解途径.
科学领域:
- 有机金属化学 有机金属化学
- 聚合物科学 聚合物科学
- 催化剂是一种催化剂.
背景情况:
- 复合物是乙烯聚合的关键催化剂.
- 现有的催化剂包括中性Ni-[N,O]和阴离子Ni-[N,N]类型.
- 开发具有定制性质的新催化剂对于聚合物合成至关重要.
研究的目的:
- 合成和描述新的中性Ni-[N,N]催化剂.
- 研究这些新复合物在乙烯聚合过程中的催化活性.
- 探索这些催化剂的稳定性和分解途径.
主要方法:
- 中性Ni-[N,N]复合物的合成与特定的配体 (L = 2-(arylamido)-5-methylcyclopent-2-en-1-arylimine或2-(arylamido) -cyclohex-2-en-1-arylimine).
- 使用B-(C6F5) 3作为激活剂的乙烯聚合实验.
- 聚乙烯产品根据点 (Tm) 的表征.
- 使用多核核核磁共振光谱和单晶X射线衍射,研究催化剂分解途径.
主要成果:
- 合成的中性Ni-[N,N]催化剂,尽管有固体质量,但产生高密度聚乙烯 (HDPE),Tm在0°C时高达140°C.
- 聚合所需的三二甲 (BC6F5) 3作为激活剂.
- 意想不到的是,催化剂在室温下经历了C-H激活,形成了循环金属化Ni-II) 复合物.
- 通过C-H激活的分解途径首次具有结构性特征.
结论:
- 新型中性Ni-[N,N]催化剂可以有效地生产HDPE.
- 这些催化剂表现出一种独特的分解机制,涉及C-H激活和循环金属化.
- 这些发现为基于的聚合催化剂的稳定性和反应性提供了新的见解.
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