Addressing a Burning Issue: Complete combustion of methane is required in order to avoid the unproductive emission of this greenhouse gas into the atmosphere. Palladium catalysts can help to promote complete combustion, but high-temperature operating conditions also promote aggregation of catalyst particles (“sintering”) that lowers their surface area and overall activity. Cargnello et al. (p. 713 ; see the Perspective by Farrauto ) report that cerium oxide–coated Pd catalyst particles could be fully dispersed on an alumina surface prepared with a hydrophobic coating. This treatment resisted Pd sintering up to temperatures of 800°C, and also enabled complete combustion of methane to occur at temperatures as low as 400°C.

Metal single-atom catalysts (SACs) promise great rewards in terms of metal atom efficiency. However, the requirement of particular conditions and supports for their synthesis, together with the need of solvents and additives for catalytic implementation, often precludes their use under industrially viable conditions. Here, we show that palladium single atoms are spontaneously formed after dissolving tiny amounts of palladium salts in neat benzyl alcohols, to catalyze their direct aerobic oxidation to benzoic acids without ligands, additives, or solvents. With this result in hand, the gram-scale preparation and stabilization of Pd SACs within the functional channels of a novel methyl-cysteine-based metal–organic framework (MOF) was accomplished, to give a robust and crystalline solid catalyst fully characterized with the help of single-crystal X-ray diffraction (SCXRD). These results illustrate the advantages of metal speciation in ligand-free homogeneous organic reactions and the translation into solid catalysts for potential industrial implementation.

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 ( $$66{,}000\,{\mathrm{ml}}\,{\mathrm{g}}^{-1}_{\mathrm{cat}}\,{\mathrm{h}}^{-1}$$66 , 000 ml g 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.