Anionic ruthenium cluster K 2[Ru 4(CO) 13] as precursor of catalytically active ruthenium particles and potassium promoter. New efficient ammonia synthesis catalysts based on supported K 2[Ru 4(CO) 13

Abstract

New efficient potassium-promoted catalysts for ammonia synthesis are reported. For preparation of the catalysts, anionic ruthenium cluster K 2[Ru 4(CO) 13] was used as a precursor of both catalytically active metal particles and potassium promoter while magnesium oxide and new original graphite-like active carbon CFC-1 were employed as supports. The catalysts found are capable of catalysing the ammonia synthesis starting from 250°C (1 atm) and exceed markedly in their activity at 300–400°C and atmospheric pressure the industrial ammonia synthesis catalyst (SA-1). Especially effective is the K 2[Ru 4(CO) 13] catalyst on MgO. The replacement of MgO by γ-Al 2O 3 and SiO 2 results in a sharp decrease in activity of the catalyst in ammonia synthesis. This indicates the importance of the basic properties of a support for the achievement of high ammonia synthesis rates.