Behavior of organic sulfur model compounds in pyrolysis under coal-like environment

To simulate coal-like environment, five organic sulfur compounds, representing some of the organic sulfur structures in coal, were impregnated on a charcoal and subjected to pyrolysis in N2. The pyrolysis was carried out in a temperature-programmed reactor at a heating rate of 5 °C min−1 up to 800 °C. The gases released (including H2S, COS, SO2, CS2 and the main hydrocarbons) from the pyrolysis were analyzed by an on-line mass spectrometer (MS). It is found that the behavior of sulfur-containing compounds evolved into the gas phase depends on the structure of the compounds as well as on the functional groups on the charcoal. Sulfur radical is likely to be the main intermediate sulfur form which has strong interactions with the charcoal to form H2S, COS, SO2 and CS2, and stable non-volatile sulfur compounds which crack at higher temperatures to form also H2S, COS, SO2 and CS2. The carbon in COS and CS2 are likely to come from the charcoal, and the oxygen in COS, SO2 have close relation with the evolution of CO and CO2, respectively. Dibenzothiophene is stable under the conditions employed.