Enhanced oxidation of methane (CH₄) by addition of carbon disulfide (CS₂)

This contribution reports a promotion effect of carbon disulfide (CS2) on methane (CH4) oxidation with experiments conducted in a jet-stirred reactor (JSR). The experiments include neat oxidation of CS2/O2 and CH4/O2, as compared with co-oxidation of CS2/CH4/O2 under stoichiometry condition. The addition of CS2, in trace amount, leads to a lower ignition temperature of CH4 at 1210 K, as compared with neat oxidation at 1290 K under equivalent condition. On the contrary, the presence of CH4 significantly inhibits the oxidation of CS2 at low temperature range (below 1100 K), implying a latent interaction between CH4 and sulfur radicals. Kinetic modelling has been conducted for the neat oxidation of CH4/O2 and CS2/O2, respectively. The accumulation of O radical from CS2 conversion process initiates the oxidation of CH4 at lower temperature. We also propose competing channels between consumption and formation of CS2 through interaction between sulfur radicals and hydrocarbon under limited supply of O2, accounting for the inhibition effect of CH4 on CS2 oxidation. The detailed interaction reactions between hydrocarbon and sulfur radicals requires further investigations to illustrate the role of sulfur impurities in natural gas.