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 Pd-1-Au-1 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% H-2, simulated industrial front-end reaction conditions). The reaction proceeds with an apparent activation energy of similar to 1 kcal mol(-1), working even at 35 degrees C, and with operational windows (>100 degrees C) and weight hourly space velocities (66,000mlg(cat)(-1)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.