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

Fischer-Tropsch synthesis is challenged by the trade-off between enhancing C-C coupling and suppressing further hydrogenation of olefins. Here the authors break this challenge by developing a universal strategy to synthesis extra-heavy olefins from carbon monoxide and water via the sustained release of hydrogen and selective extraction of olefins. 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 Kolbel-Engelhardt synthesis (KES), in polyethylene glycol (PEG) over a mixture of Pt/Mo2N 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 CO2 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%.

Automated summary

The authors develop a universal strategy to synthesize extra-heavy olefins through the sustained release of hydrogen and selective extraction of olefins. They achieve the selective production of C(12+)(=) from CO and water using Pt/Mo2N and Ru particles as catalysts in polyethylene glycol (PEG). PEG acts as a selective extraction agent to hinder hydrogenation of olefins. Under optimal conditions, the yield ratio of CO2 to hydrocarbons reaches the theoretical minimum, and the C(12+)(=) yield reaches its maximum with a selectivity of 40.4%.