Electron and Proton Separation on Ru-Based Catalysts Promotes Ammonia Synthesis

• • N-MWNT-1 supported Ba-Ru catalyst achieves 7.4× higher NH3 production rate than conventional BaO-promoted Ru catalysts at 573 K and 1.0 MPa, directly reducing operational energy intensity and enabling downscaled, renewable-powered ammonia plants. • • Optimal Ba/Ru molar ratio of 0.75 balances active-site accessibility and electron enrichment; exceeding this ratio blocks Ru surfaces and collapses activity, defining a narrow compositional window for industrial catalyst formulation. • • Carbon support work function governs performance: N-MWNTs with 10–20 nm diameter exhibit the lowest work function among eleven screened carbons, maximizing long-range H+/e− pair migration and electron back-donation to N≡N antibonding orbitals. • • Feedstock purity thresholds (O2 <0.4 ppm, H2O <0.7 ppm) are mandatory to prevent catalyst poisoning; industrial implementation must incorporate stringent gas purification, adding capex but ensuring stability over extended operation.