Sulfur removal and release behaviors of sulfur-containing model compounds during pyrolysis under inert atmosphere

摘要

In this study, sulfur containing model compounds, tetradecyl mercaptan, dibutyl sulfide,phenylsulfide, 2-methyl thiophene, benzothiophene and dibenzothiophene, were selected toinvestigate their sulfur removal and release behaviors during pyrolysis under inert atmosphere bythermo-gravimetric analyzer with mass spectrometer (TG-MS) and pyrolysis connected with gaschromatogram (Py-GC). It is found that the order of sulfur removal is tetradecyl mercaptan >dibutyl sulfide > 2-methyl thiophene > benzo thiophene > phenylsulfide > dibenzothiophene.Except for phenylsulfide, this rule is contrary to the decomposition temperature order of the sulfurfunctional groups. SO_2 evolution was detected by MS and GC for all those model compounds; COSevolution was also detected except for phenylsulfide and dibenzothiophene; While H2S evolutionwas measured only for tetradecyl mercaptan, dibutyl sulfide and 2-methyl thiophene. However SO_2content is much higher than H2S and COS in pyrolysis gas for each model compound, this may becaused by that indigenous hydrogen is much less than indigenous oxygen under inert atmosphere,when active carbon used to carrier. Thus most of sulfur radicals can connect with indigenousoxygen and release in the form of SO_2. For phenyl sulfide, benzothiophene and dibenzothiophene,as their indigenous hydrogen is not enough to react with sulfur radicals, therefore no H2S wasmeasured during pyrolysis under inert atmosphere, while SO_2 was measured and its content is veryhigh in pyrolysis gas.