Reactions and Thermodynamics of Sulfuric Acid Production

The overall reaction of sulfuric add production based on elementary sulfur (other feedstocks see Section 6.3.2) reads as  

The majority of elementary sulfur is produced as a by-product of petroleum and natural gas processing and only 4% comes from native sources [mainly native mined elemental sulfur from China and extracted sulfur (Frasch process) from underground deposits in Poland]. 

Subsequently, SO2 is further oxidized catalytically to sulfur trioxide SO2 + O.5O2 SO3 = -98 kJ mol  

In contrast to sulfur oxidation to SO2, the oxidation to SO3 is limited by thermodynamic constraints (Example 4.2.3), and is the crucial reaction step in H2SO4 production. According to Eqs. (4.2.19) and (4.2.20), the equilibrium constant Ky based on the molar fractions of SO2, O2, and SO3 (with p as total pressure) is given by  

The standard reaction Gibbs function ArG° (= ArH — TArS°) is calculated by Eqs. (4.2.14)-(4.2.17) and the tabulated values of the standard enthalpies of formation ApH and the standard entropies S (Table 4.2.1). If we neglect that ArI-I and ArS° depend slightly on temperature and use the values at 298 K we obtain  

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