Structure change and organic sulfur forms transformation during pyrolysis of high-sulfur vitrinite

High purity vitrinite was separated and concentrated from New Zealand(NXL; S_t,ad=1.84%) and Shanxi(SX; S_t,ad=1.80%) coal which have similar sulfur content. The vitrinite was pyrolyzed in a tube furnace reactor under argon at 300, 500, 700 and 1 000 ℃. The effect of temperature on the functional group content and organic sulfur forms transformation was examined by Fourier transform infrared spectrum and X-ray photoelectron spectrum, respectively. The FT-IR experiments show that aliphatic hydrogen content in SX vitrinite and its reactivity is higher than those of NXL vitrinite at same temperature. The aliphatic hydrogen in both vitrinites decreases with increasing temperature. The aliphatic hydrogen content in SX and NXL vitrinite is unchanged when the temperature is above 500 and 700 ℃, respectively. The aromatic hydrogen increases first and then decreases with increasing temperature. The XPS results show that the organic sulphide, which is more thermal unstable, is richer on surface of SX vitrinite than that of NXL. It is decomposed completely below 300 and 700 ℃ for SX and NXL, respectively. The content of thiophenic compounds increases with increasing temperature, but that of sulfones compounds is just the reverse.