A MOF-supported Pd1–Au1 dimer catalyses the semihydrogenation reaction of acetylene in ethylene with a nearly barrierless activation energy

The removal of acetylene from ethylene streams is key in industry for manufacturing polyethylene. Here we show that a well-defined Pd1–Au1 dimer, anchored to the walls of a metal–organic framework (MOF), catalyses the selective semihydrogenation of acetylene to ethylene with ≥99.99% conversion (≤1 ppm of acetylene) and >90% selectivity in extremely rich ethylene streams (1% acetylene, 89% ethylene, 10% H2, simulated industrial front-end reaction conditions). The reaction proceeds with an apparent activation energy of ∼1 kcal mol–1, working even at 35 °C, and with operational windows (>100 °C) and weight hourly space velocities (66,000 ml g−1 cat h−1) within industrial specifications. A combined experimental and computational mechanistic study shows the cooperativity between both atoms, and between atoms and support, to enable the barrierless semihydrogenation of acetylene.