Pyrolysis property of solvent extracts from a direct coal liquefaction residue

The pyrolysis behavior of solvent extracts (hexane solubles HS, asphaltenes A, preasphaltenes PA and THF insolubles THFIS) from a direct coal liquefaction residue (SHR) of Shenhua process were investigated by thermogravimetric analysis (TGA) and temperature programmed decomposition coupled with a mass spectrometry (TPD-MS) techniques. An attempt was made to understand the relationship between the cracking and hydrogenation activities. It shows that the hydrogenation activity of the extracts is related to their cracking ability. The synergetic effect among the fractions inhibits some of the components in HS and A fractions releasing through evaporation at 450℃ but cracking in 400℃~450℃ as free radicals. Then a positive effect can be observed. However, the presence of PA enhances the polymerization of the free radicals and then results in a negative effect on liquefaction of SHR.