Imine‐linked covalent organic frameworks coordinated with nickel for ethylene oligomerization

Abstract

The functionalized covalent organic framework materials play an important role in catalytic application. A convenient tactic is developed to design and synthesize an imine-linked covalent organic frameworks (COFs) material (COF-PD) with abundant nitrogen atoms, which can provide coordination active site and facilitate the incorporation of COFs with nickel ions. Nickelcoordinated COF-PD complex (COF-PD-Ni) is prepared and used in ethylene oligomerization. COF-PD-Ni displays the highest catalytic activity of 1.98 Â 10 5 g/(molÁNiÁh) in ethylene oligomerization with MAO as co-catalyst and cyclohexane as solvent. Various reaction parameters including reaction temperature, time, solvent, and the amount of cocatalyst are evaluated in detail, dramatically impacting the catalytic activities as well as the distribution of the products. What is more, the effect of COFs structure on the catalytic performance is also studied, suggesting more coordination sites were more important for high activity.

Ethylene Oligomerization Catalyzed by Different Homogeneous or Heterogeneous Catalysts

“…The Niloaded COFs were evaluated for ethylene oligomerization using MAO as a cocatalyst (Al/Ni = 500 to 700), and the best activity was found in toluene as a solvent at 25 • C with a productivity of 8.31 × 10 4 g mol −1 Ni h −1 and 1-butene selectivity of 59% using Ni@MABD-COF and a productivity of 15.68 × 10 4 g mol −1 Ni h −1 and 1-butene selectivity of 51% using Ni@MAPA-COF. Recently, another group [60] reported another nickelcoordinated imine-linked covalent organic frameworks material (COF-PD-Ni) for ethylene oligomerization with a productivity of 1.98 × 10 5 g mol −1 Ni h −1 . In the condition with the highest activity, the selectivity of the product C 4 can reach 82%, and the remaining product is C 6 -C 10 .…”