Kinetic model for reduction of fused iron catalyst

2 Kinetic model for reduction of fused iron catalyst 

The experimental reduction results of iron oxides show that the reduction rate is controlled by combined mechanisms of boundary reaction and gas diffusion. It is in consequence that the mechanism is simply attributed to controlling of one factor. This conclusion can be obtained by the following analysis.  

For spherical pellets, if the initial radius is R and density is po, fc is the radius of the unreduced oxide at any time t, gas concentration is C Ag at R, Cas and Tc, equilibrium concentration is Cq, then the reaction rate at boundary is  

In a steady state the diffusion rate of the gas should be equal to the surface reaction rate, that is, Ug = Ug, the following equation can be obtained  

The reduction degree of ammonia synthesis catalysts can be defined as Amount of the oxygen removed from particle Amount of the oxygen can be removed in particle The relationship between the mass of reacted and initial mass of particle can be expressed as xg, 

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