Sustainable synthesis of polymer-grade ethylene via electrified acetylene semihydrogenation

The electrocatalytic semihydrogenation of acetylene (C₂H₂), powered by renewable electricity, provides an energy- and cost-efficient alternative to conventional thermocatalytic methods for purifying crude ethylene (C₂H₄) streams. This approach provides a more sustainable route to polymer-grade C₂H₄ by reducing greenhouse gas emissions, yet its commercial potential remains limited by the scarcity of high-performance catalysts and the absence of comprehensive techno-economic analyses for large-scale implementation. In this study, we conduct an extensive screening and evaluation of monodisperse metal nanoparticle (NP) catalysts (Cu, Ag, Au, Pd, Bi) with tunable particle sizes and morphologies for the electrocatalytic semihydrogenation of C₂H₂ in flow reactors. Among these candidates, 45 nm Cu nanocubes and 8 nm Ag NPs exhibited the highest performance. In a simulated crude ethylene stream (C₂H₂: C₂H₄ = 1:80), Cu nanocubes achieved 99.7% C₂H₂ removal at room temperature with a specific selectivity of 86.7% for C₂H₄ and maintained stability for 120 h. Meanwhile, 8 nm Ag NPs exhibited a high specific selectivity of 98.9%, with 96.7% conversion and 24-h stability under the same conditions. A detailed techno-economic analysis confirms the feasibility of electrocatalytic systems for industrial-scale crude ethylene treatment, with an optimal conversion cost of $0.74 per kg of C₂H₂, compared to $1.34 per kg for the optimized thermocatalytic system. Furthermore, our life cycle assessment highlights the environmental benefits of the electrocatalytic pathway with a carbon emission reduction of over 50%. Our electrified, efficient C₂H₂ semihydrogenation in C₂H₄ crude streams minimizes environmental impact and optimizes resource use, contributing to a more sustainable future.