Kinetics synthesis over ruthenium

Describe the main differences in the kinetics of ammonia synthesis over iron catalysts compared to ruthenium catalysts. 

In a recent communication (250), deviations from Schulz-Flory kinetics were observed for a RuNaY synthesis gas conversion catalyst (see Fig. 24). A comparative catalyst, prepared by impregnating silica with ruthenium, i.e., Ru/SiOz, and tested under the same conditions, yielded a product distribution which gave a good fit to Schulz-Flory kinetics. The sharp decrease in chain growth probability for Cf0 products over RuNaY is perhaps surprising for such a relatively large-pore zeolite. Further studies (251-253) on this system indicated that there was a correlation between the ruthenium particle size in the zeolite and the product distribution. 

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