Supported mononuclear carbonyl ruthenate as a catalyst for gas-phase ammonia synthesis. Effect of short-term exposure of the catalyst to air

The catalyst for ammonia synthesis from dinitrogen and dihydrogen based on mononuclear potassium carbonyl ruthenate K₂[Ru(CO)₄] (precursor of catalytically active species) deposited on graphite-like carbon Sibunit exhibits an interesting feature when promoted with metallic potassium and BuⁿLi. Namely, the activity of the catalyst based on K₂[Ru(CO)₄]/Sibunit noticeably increases after thermal removal of CO ligands followed by short-term exposure to air compared to the activity of the standard K₂[Ru(CO)₄]/Sibunit sample not exposed to air. Unlike the latter, the air-exposed catalyst simultaneously promoted with both metallic potassium and BuⁿLi becomes much more efficient than the air-exposed catalyst promoted with metallic potassium only.