Details

Autor(en) / Beteiligte

• Qian, Jin
• An, Qi
• Fortunelli, Alessandro
• Nielsen, Robert J
• Goddard, William A

Titel

Reaction Mechanism and Kinetics for Ammonia Synthesis on the Fe(111) Surface

Ist Teil von

• Journal of the American Chemical Society, 2018-05, Vol.140 (20), p.6288-6297

Ort / Verlag

United States: American Chemical Society

Erscheinungsjahr

2018

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• The Haber-Bosch industrial process for synthesis of ammonia (NH3) from hydrogen and nitrogen produces the millions of tons of ammonia gas annually needed to produce nitrates for fertilizers required to feed the earth’s growing populations. This process has been optimized extensively, but it still uses enormous amounts of energy (2% of the world’s supply), making it essential to dramatically improve its efficiency. To provide guidelines to accelerate this improvement, we used quantum mechanics to predict reaction mechanisms and kinetics for NH3 synthesis on Fe(111)the best Fe single crystal surface for NH3 synthesis. We predicted the free energies of all reaction barriers for all steps in the mechanism and built these results into a kinetic Monte Carlo model for predicting steady state catalytic rates to compare with single-crystal experiments at 673 K and 20 atm. We find excellent agreement with a predicted turnover frequency (TOF) of 17.7 s–1 per 2 × 2 site (5.3 × 10–9 mol/cm2/sec) compared to TOF = 10 s–1 per site from experiment.