KINETICS OF THE REACTION BETWEEN HYDROGEN AND SULFUR UNDER HIGH-TEMPERATURE CLAUS FURNACE CONDITIONS

The reaction H2+ (1/2)S2[*] H2S has been studied as a function of temperature and residence time over the ranges 602-1290 °C and 0.03-1.5 s in the absence of a catalyst. This study shows that the combination of H2and elemental sulfur vapor under the high-temperature conditions typical of a Claus sulfur recovery unit proceeds via a reversible homogeneous gas-phase reaction that is first order in both H2and sulfur concentration and follows the rate law-d[H2]/dt = k1[H2][S2]-k2[H2S] with a second-order recombination rate constant k1= 1-1 x 103atm-1s-1(A1= (4.3 ± 0.2) x 106atm-1s-1; Δ\H1‡= 26 ± 1 kcal/mol) and first-order decomposition rate constant k2= 4 X 10-4-70s-1(A2= (3.6 ± 1) x 106s-1; ΔH2‡= 48 ± 1 kcal/mol) over the temperature range studied. These findings can be used to exploit opportunities in acid gas processing, such as effecting improved efficiencies for O2usage in oxygen-blown Claus units and maximizing H2content in the tail gas. © 1990, American Chemical Society. All rights reserved.