Industrial Multi Catalyst Bed SO2 Oxidation

Industrial SO2 oxidation is done in a sequence of 3 to 5 catalyst beds. Figs. 7.6 and 7.7. This section and Fig. 7.8 describe passage of warm feed gas through three catalyst beds with gas cooling between. The sequence is  

Addition of a fourth bed would probably not be worthwhile from the SO3 production (hence H2SO4 production) point of view. It might, however, be worthwhile from the point of view of minimizing SO2 escape to the environment (because SO2 passes untouched through subsequent H2SO4 making). These factors are detailed in Chapters 12 to 22. 

This chapter describes SO2 oxidation in single contact acid plants. These plants  

Its advantage is more efficient SO2 oxidation and H2SO4 production. Its disadvantage is more equipment and more heating and cooling. 

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This explains the success of industrial multi-catalyst bed SO2 oxidation. 

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