Bimetallic Metal Sites in Metal–Organic Frameworks Facilitate the Production of 1-Butene from Electrosynthesized Ethylene

Abstract

Converting CO₂ to synthetic hydrocarbon fuels is of increasing interest. In light of progress in electrified CO₂ to ethylene, we explored routes to dimerize to 1-butene, an olefin that can serve as a building block to ethylene longer-chain alkanes. With goal of selective and active dimerization, we investigate a series of metal-organic frameworks having bimetallic catalytic sites. We find that the tunable pore structure enables optimization of selectivity and that periodic pore channels enhance activity. In a tandem system for the conversion of CO₂ to 1-C₄H₈, wherein the outlet cathodic gas from a CO₂-to-C₂H₄ electrolyzer is fed directly (via a dehumidification stage) into the C₂H₄ dimerizer, we study the highest-performing MOF found herein: M' = Ru and M″ = Ni in the bimetallic two-dimensional M'₂(OAc)₄M″(CN)₄ MOF. We report a 1-C₄H₈ production rate of 1.3 mol g_cat^-1 h^-1 and a C₂H₄ conversion of 97%. From these experimental data, we project an estimated cradle-to-gate carbon intensity of -2.1 kg-CO₂e/kg-1-C₄H₈ when CO₂ is supplied from direct air capture and when the required energy is supplied by electricity having the carbon intensity of wind.