Direct synthesis of extra-heavy olefins from carbon monoxide and water.

Extra-heavy olefins (C 12+ = ), feedstocks to synthesize a wide range of value-added products, are conventionally generated from fossil resources via energy-intensive wax cracking or multi-step processes. Fischer-Tropsch synthesis with sustainably obtained syngas as feed-in provides a potential way to produce C 12+ = , though there is a trade-off between enhancing C-C coupling and suppressing further hydrogenation of olefins. Herein, we achieve selective production of C 12+ = via the overall conversion of CO and water, denoted as Kölbel-Engelhardt synthesis (KES), in polyethylene glycol (PEG) over a mixture of Pt/Mo 2 N and Ru particles. KES provides a continuously high CO/H 2 ratio, thermodynamically favoring chain propagation and olefin formation. PEG serves as a selective extraction agent to hinder hydrogenation of olefins. Under an optimal condition, the yield ratio of CO 2 to hydrocarbons reaches the theoretical minimum, and the C 12+ = yield reaches its maximum of 1.79 mmol with a selectivity (among hydrocarbons) of as high as 40.4%.