Nickel‐Functionalized Zirconium MOFs as Catalyst in Ethylene Oligomerization: The Effect of Anchoring Sites

ABSTRACT Ethylene oligomerization, a reaction of significant industrial relevance, was effectively catalyzed by Ni(II) immobilized within two distinct zirconium‐based MOFs, namely, UiO‐67 and UiO‐67bpydc (bpydc = (2,2′‐bipyridine)‐5,5′‐dicarboxylic acid). These frameworks differ in the nature of their anchoring sites, which in turn influences their catalytic performance. Under identical reaction conditions—1730 eq. of Et 2 AlCl as co‐catalyst, 10 bar of ethylene, 24°C, 1 h, and toluene as solvent—Ni(II) coordinated to the zirconium clusters of UiO‐67 exhibited superior catalytic activity compared to Ni(II) bound to the bpydc linkers of UiO‐67bpydc (1578 vs. 196 mmol Ni −1 h −1 , respectively). Variation in the amount of Et 2 AlCl co‐catalyst and the applied ethylene pressure revealed that reducing the co‐catalyst concentration to 870 eq. enhanced its catalytic activity (1930 mmol Ni −1 h −1 ) relative to 1730 eq., whereas further reduction led to complete loss of activity. In addition, the optimal ethylene pressure for achieving maximum activity was identified as 10 bar, while reactions conducted at 5 and 20 bar afforded lower activities of 1077 and 1464 mmol Ni −1 h −1 , respectively.