Economies of scale in ammonia synthesis loops embedded with iron- and ruthenium-based catalysts

The economies of scale were analyzed in ammonia synthesis loops embedded with iron-based catalysts (Fe) and ruthenium-based catalysts (Ru/C). Aspen Plus© was utilized to simulate the synthesis and separation processes with the product range from ammonia 0.1–500 tonne/day. The detailed kinetic models, the Temkin equation and the modified one, were employed to evaluate catalytic activity in reactors precisely. The result shows the cost advantage of Ru/C on a small scale. Besides, on a small scale, the costs of heat exchangers and reactors are dominant, while the catalyst cost of Ru/C itself is not dominant on any scales. For the ammonia synthesis based on renewable energy, Ru/C catalyst under mild pressure, i.e., Ru/C-50 bar, is preferable. The direction of the future research on the catalyst of ammonia synthesis from the viewpoint of cost is also discussed.