Exploration of non-iron and alloy catalysts

Since 1970s, the scientists began to look for a new non-iron metallic catalyst to replace iron-based catalyst, and studied widely the element which has activity for activation of N2 in Periodic Table, because they did not expect to further increase the activity of conventional Fe304-based catalyst. 

Based on the research results of monometallic catalysts, scientists also studied on bimetallic catalysts for N2 activation. They realized that the adsorption energy of N2 determines the catalysts properties. Under specific reaction conditions, it can estimate adsorption energy of N2 on catalyst. The catalytic efficiency of the elements for the synthesis and decomposition of ammonia was correlated with the chemisorption energy of nitrogen. An inverted parabolic function (volcano curve) was obtained by Ozaki et in which iron, ruthenium, and osmium mark the top of the volcano. 

The synthesis conditions are 400°C, 50 bar, gas composition (H2 N2) 3 1 containing 5% NH3. The numbers are obtained by combining a micro-kinetic model describing ammonia synthesis rates with the linear relation existing between the potential energy and the activation energy for N2 dissociation. The known entropy barrier for N2 dissociation and the effect of adding electropositive promoters such as K and Cs have been taken into account in the model. 

Catalyst compositions Source of precursor Cost of catalysts Operating conditions Energy Consumption/ (GJ/t) 

The results in Fig. 10.3 indicate that activation energies and bond energies are strongly correlated. Different active sites correspond to different points along 

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