The mechanisms of ammonia decomposition

Based on Temkin-Pyzhev mechanisms (steps 1- 3), the rates for ammonia decomposition can be expressed by Eq. (2.27), and its kinetic parameters calculated from equation V = fc (PnH3) /(Eh2) are given in Table 2.7. The value of parameter n/m in Table 2.7 is about 3/2, demonstrating that the Temkin Pjrahev mechanisms can be used for most metal catalysts, such as Re, Fe, Co, Ni, Ru and Rh, at the common conditions of ammonia decomposition. 

However, reaction order of hydrogen is zero for timgsten and platinmn catalysts, which should be elucidated by different reaction mechanisms. The ammonia 

The rate of nitrogen desorption from surface increases with  

The rate of nitrogen adsorption decreases with 0n, and increases with the Pnh3 

The conclusion obtained from these data is as follows the overall reaction rate (14) comes from djmamic reaction equilibrium between two continuous rate determining steps, 2NH3 — 2N(a) + 3H2(Va) and 2N(a) — N2(Vd)  

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