| Abstract
| - The effects of an iron oxide precursor of an ammonia synthesis catalyst on the N2 desorptionperformance and catalytic activity were studied by means of N2 temperature-programmeddesorption. The results show that there are close relationships among the N2 adsorption/desorption performance on a catalyst surface, catalytic activity, and the type and compositionof the iron oxide precursor. The N2 desorption activation energy, the temperature for desorption,and the amounts of desorption species are apparently different because of a different oxideprecursor. Among the three precursors being studied, which are Fe3O4, Fe1-xO, and their mixture,the order of the N2 desorption activation energy is as follows: Fe3O4 + FeO > Fe3O4> Fe1-xO.The desorption temperature has similar changes, but the desorption volume is just the opposite.The N2 desorption activation energy is similar to the reaction activation energy for ammoniasynthesis. Furthermore, their sequences for different iron oxide precursors are the same. Thisproves that the dissociative adsorption of N2 is the rate-determined step for an ammonia synthesisreaction. The experimental results indicate that the precursor has a notable effect on the N2adsorption/desorption performance and catalytic activity, and the Fe1-xO-based catalyst has thehighest activity among all of the fused iron catalysts for ammonia synthesis.
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