Effect of benzene on product evolution in a H2S/O2 flame under Claus condition

• Effect of trace amounts of benzene (0.3%, 0.5% and 1%) to H2S combustion process.
• Benzene favored formation of H2 and reduced conversion of H2S.
• Benzene reduced SO2 formation to impact sulfur production.
• Benzene addition promoted CO and COS formation and degraded sulfur quality.

Experimental results are presented on the role of benzene addition to H2S combustion at an equivalence ratio of three with respect to H2S (Claus condition) and complete combustion of benzene. The results are reported with 0.3%, 0.5% and 1% benzene addition to H2S/O2 flame. Combustion of H2S and benzene mixtures is of practical value for sulfur recovery during combustion of acid gases. The results showed that H2S combustion caused H2S to decompose to a minimum mole fraction with high conversion of H2S while the SO2 mole fraction reached a maximum value. Addition of benzene decreased the conversion of H2S with reduced mole fraction of SO2 in the reactor to subsequently reduce the formation of elemental sulfur. Benzene also caused significant production of H2, CO and COS formation along with faster decomposition of the formed SO2. Presence of benzene, even in trace amounts, in acid gas hinders sulfur conversion in a Claus reactor and increases emission of unwanted sulfur bearing compounds. Increased hydrogen production with benzene offers potential value for hydrogen recovery under certain conditions.