Exploration of other non-iron catalyst for ammonia synthesis

3 Exploration of other non-iron catalyst for ammonia synthesis 

In the early research stages of ammonia synthesis catalyst, Mittasch et al. studied almost all metal elements and their bimetallic alloy in the Periodic Table. Several metals have no or less catal3dic functions themselves. However, the addition of some promoter could increase their activities. The addition of a secondary metal into Fe, Mo, W, Co, Ni, Pd, Pt, Os, Mn enhances their activities. The different ratio between two metals leads to a different activity. It can be concluded from these results that the addition of metals in Vlff or VI groups favors enhancing of iron-based catalyst activity. For example, Fe-Mo (1 1) catalyst has high activity. If the Mo content is less than 80%, the activity decreases after running for a long-time. These catalysts are prepared by calcinations of metal nitrates and ammonium molybdate 

Mn-Fe alloy catalysts with 32%-40% of Mn have high activities. The addition of 3%-7% of Ru02 into Fe-based catalyst containing cobalt ferrite (25%-359c of Co), magnesium ferrite (20%-25% of Mg), K2O (0.5%-2%) and iron oxide increases activities and heat-resistant properties of catalysts.  

Transition metals can be activated by alloys with positive charges. In contrast to activity of Ru as per area, Raney Ru catalyst prepared by Al-Ru alloy has higher activity than pure Ru catalyst. When added with metallic K, this catalyst has higher activity, and it also has activity even at 373 K. Raney Ru is also very active by using CsNOa as promoter.  

Catalyst Surface area/ (m /g) Rates(588K)/ [m mol NH3/(g-h) Activation energy/ (kcal/mol) 

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