Barman Samir, Garcia Nestor, Jaseer E A, Elanany Mohamed, Khawaji Motaz, Alasiri Hassan, Peedikakkal Abdul Malik P, Akhtar Muhammad Naseem, Theravalappil Rajesh
Center for Refining and Advanced Chemicals, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia.
Fuels and Chemicals Division Aramco Research Center at KAUST, Thuwal 23955, Saudi Arabia.
ACS Omega. 2023 Jul 14;8(29):26437-26443. doi: 10.1021/acsomega.3c03029. eCollection 2023 Jul 25.
Novel -aryl-functionalized PNP ligands () bearing -alkyloxy/-silyloxy substituents were prepared and evaluated for chromium-catalyzed ethylene oligomerization using MMAO-3A as an activator. The selected Cr/PNP system under optimized condition exhibited high 1-octene-selective (up to 70 wt %) ethylene tetramerization at a remarkable rate (over 3000 kg gCr h). More importantly, the undesirable polyethylene selectivity was restricted to a minimum level of ∼1-2 wt % for pre-catalysts derived with ligands and . Employing chlorobenzene as a reaction medium yielded best productivity in conjunction to the total α-olefin (1-C + 1-C) selectivity (∼88 wt %). -aryl PNP ligands ( and ) incorporating -silyloxy substituents in the phenyl ring exhibited relatively poorer tetramerization performance while yielding higher PE fraction as compared to their -alkyloxy derivatives. A detailed molecular structure of the best-performing pre-catalyst -Cr was established by single-crystal X-ray diffraction analysis. The stability of /Cr-based catalyst system was investigated for a reaction time of up to 2 h under optimized condition.
制备了带有 - 烷氧基/- 甲硅烷氧基取代基的新型 - 芳基官能化PNP配体（），并使用MMAO - 3A作为活化剂对其在铬催化乙烯齐聚反应中的性能进行了评估。在优化条件下，所选的Cr/PNP体系在显著的速率（超过3000 kg gCr h）下表现出高1 - 辛烯选择性（高达70 wt%）的乙烯四聚反应。更重要的是，对于由配体 和 衍生的预催化剂，不需要的聚乙烯选择性被限制在约1 - 2 wt%的最低水平。使用氯苯作为反应介质，结合总α - 烯烃（1 - C + 1 - C）选择性（约88 wt%）可产生最佳的生产率。在苯环中含有 - 甲硅烷氧基取代基的 - 芳基PNP配体（ 和 ）表现出相对较差的四聚反应性能，同时与它们的 - 烷氧基衍生物相比产生更高的PE分数。通过单晶X射线衍射分析确定了性能最佳的预催化剂 -Cr的详细分子结构。在优化条件下，研究了基于 /Cr的催化剂体系在长达2小时的反应时间内的稳定性。
