Selective Gas-Phase Ethylene Dimerization to 1-Butene in a Scalable Metal-Organic Framework

High-purity 1-butene is a crucial feedstock for the plastics industry and is currently produced by homogeneously catalyzed ethylene dimerization. Processes of this scale can benefit from heterogeneous catalysis, especially if reactants are delivered in the gas phase, to allow product recovery in flow. However, catalysts for gas-phase ethylene dimerization are exceedingly rare and generally show very low activity or reduced selectivity. Here, we report the use of a scalable, robust MOF catalyst (nickel-exchanged CFA-1, Ni-CFA-1) for the continuous gas-phase dimerization of ethylene to produce 1-butene. Operating under solvent-free conditions in a packed-bed reactor containing the MOF catalyst preactivated with a simple and straightforward approach, MeNi-CFA-1 delivers excellent selectivity (96%), turnover frequencies greater than 800,000 mol ethylene·mol Ni^-1·h^-1, and total turnover numbers of 1.23 × 10⁸ mol ethylene·mol Ni^-1, all exceeding the values observed for the commercial homogeneous catalyst. This flow process produces 49.4 kg 1-butene·g MOF^-1 without requiring catalyst reactivation. The elimination of solvent allows a significantly higher concentration of ethylene near the Ni active sites, while the flow process drives away the butene product, thus suppressing undesired isomerization and oligomerization byproducts. Overall, this work highlights how MOFs can facilitate reactivity inconceivable for a molecular analogue and bridge the gap between molecular precision and industrial practicality, broadly illustrating the value of MOFs for the development of novel, selective, and scalable heterogeneous processes for the production of commodity chemicals.