Sulfur-assisted urea synthesis from carbon monoxide and ammonia in water

Efficient conversion of carbon monoxide into urea in an aqueous ammonia solution was demonstrated through coupling with the elemental sulfur reduction to polysulfides. Polysulfides control the overall reaction rate while suppressing the accumulation of a by-product, hydrogen sulfide. These functions follow basic kinetic and thermodynamic theories, enabling prediction-based reaction control. This operational merit, together with the superiority of water as a green solvent, suggests that our demonstrated urea synthesis is a promising option for sulfur utilization beneficial for agricultural production.