Mechanisms of radical removal by SO2

Christian Lund Rasmussen, Peter Glarborg, Paul Marshall

Research output: Contribution to journalJournal articleResearchpeer-review


It is well established from experiments in premixed, laminar flames, jet-stirred reactors, flow reactors, and batch reactors that SO2 acts to catalyze hydrogen atom removal at stoichiometric and reducing conditions. However, the commonly accepted mechanism for radical removal, SO2 + H(+M) reversible arrow HOSO(+M), HOSO + H/OH reversible arrow SO2 + H-2/H2O, has been challenged by recent theoretical and experimental results. Based on ab initio calculations for key reactions, we update the kinetic model for this chemistry and re-examine the mechanism of fuel/SO2 interactions. We find that the interaction of SO, with the radical pool is more complex than previously assumed, involving HOSO and SO, as well as, at high temperatures also HSO, SH, and S. The revised mechanism with a high rate constant for H + SO2 recombination and with SO + H2O, rather than SO2 + H-2, as major products of the HOSO + H reaction is in agreement with a range of experimental results from batch and flow reactors, as well as laminar flames.
Original languageEnglish
JournalProceedings of the Combustion Institute
Pages (from-to)339-347
Publication statusPublished - 2007


  • inhibition
  • sulfur chemistry
  • kinetics

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