Models ammonia synthesis single crystal data

Another test of validity is to check the performance of the model against experimental rate data obtained far from equilibrium. The microkinetic model presented in Table 7.3.1 predicts within a factor of 5 the turnover frequency of ammonia synthesis on magnesia-supported iron particles at 678 K and an ammonia concentration equal to 20 percent of the equilibrium value. This level of agreement is reasonable considering that the catalyst did not contain promoters and that the site density may have been overestimated. The model in Table 7.3.1 also predicts within a factor of 5 the rate of ammonia synthesis over an Fe(lll) single crystal at 20 bar and 748 K at ammonia concentrations less than 1.5 percent of the equilibrium value. 

Similar microkinetic models developed by other groups [37-39] revealed similar close agreement between the experimental data from single crystal studies and "real" catalysis, and at a symposium in honor of H. Topsoe and A. Nielsen, two of the leaders in industrial ammonia synthesis, general agreement was reached that the main aspects of catalytic ammonia synthesis are now essentially understood [40]. 

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