Reduction rate of catalyst in industrial reactor

For industrial installations, the goals and requirements for catalyst reduction are l. to ensure that all the catalysts are thoroughly reduced, where thoroughly means entire catalyst in the reactor from the top to the bottom and each particle of catalyst from outside to inside are completely reduced 2. to ensure that the catalytic activity of the reduced catalyst is not decreased. The former is for quantity, and the latter is for the quality, and both are indispensable. 

In industrial reactor, the reduction rate of the catalyst is expressed and controlled by the generation speed of water or concentration of the water vapor. The relationship between the concentration of water vapor and the reduction rate are as follow. 

It is seen from the Eq. (5.107) that the effective reducing time is not directly related to the size of reactor. The average water vapor concentration is inversely proportional to space velocity, reduction time and catalysts volume and proportional to water being formed. 

Therefore, in industrial installations, the reduction rate and quality of catalysts is ensured by the strict controlling of the concentration of water vapor. Generally, the vapor concentrations are limited in (0.7 — 1.0) g/m for small and medium-scale ammonia plants, and 3.0g/m for large-scale ammonia plants. 

After determining the standard of water vapor concentration, the required reduction time of whole catalyst can be estimated by Eq. (5.107). However, it should be noted that t, calculated according to Eq. (5.107), is the real effective reduction time. It is the actual water generation time, and does not include the time of warming and decreasing temperature for reactor or the abnormal break time. 

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