Co-catalyst free ethene dimerization over Zr-based metal-organic framework (UiO-67) functionalized with Ni and bipyridine

Ni functionalized metal organic frameworks (MOF) are promising heterogeneous ethene dimerization catalysts. Activities comparable to or higher than Ni-aluminosilicates have been reported in literature. However, unlike the Ni-aluminosilicates, those Ni-MOFs require a large excess of co-catalyst initiate process and some catalysts generate polymers which lead catalyst deactivation. Herein, we report series Ni(II) 2,2?-bipyridine-5,5?-dicarboxylate (bpy) UiO-67 MOF that catalyze reaction free. The were active for (up 850 mg butene gcat?1 h?1) after activation at 300 °C 10 % O2 360 min subsequent exposure flowing (P(ethene) =26 bar, 250 °C) 240 min. yielded up 6 conversion with 99 selectivity linear 1- 2-butenes, formed non-equilibrated ratios. Overall, test data indicate all three butenes on single site, accordance Cossee-Arlman mechanism. Ex situ XAS CO FT-IR spectroscopy studies point towards monomers or, plausibly, low-nuclearity Ni-multimers, docked bpy linkers Ni-Ni distances > 4 Å, as main site reaction.