Catalytic formation of ammonia: a lattice gas non-thermal Langmuir–Hinshelwood mechanism

The catalytic formation of ammonia synthesis through dimers N2 and H2 has been studied through Monte-Carlo simulation via a model based on lattice gas non-thermal Langmuir–Hinshelwood mechanism, which involves the precursor motion of H2 molecule. The most interesting feature of this model is it yields a steady reactive window, which is separated by continuous and discontinuous irreversible phase transitions. The phase diagram is qualitatively similar to well-known ZGB model. The width of the window depends upon the mobility of precursors. The continuous transition disappears when mobility of precursors is extended to third nearest neighbourhood. The dependence of production rate on partial pressure of hydrogen is predicted by simple mathematical equations in our model. Some more interesting results are observed when reaction between precursors and chemisorbed hydrogen atoms is considered.