Influence of pyrite on hydrocarbon generation during pyrolysis of type-III kerogen

One coal sample containing type-III kerogen was selected from the Junggar Basin and investigated for gas generation using anhydrous pyrolysis either or not added pyrite at 250 °C, 300 °C, 350 °C and 400 °C for 72 h each. The gases generated in these experiments were quantitatively collected and analyzed for chemical compositions and stable isotopes of carbon. The solid residues were also quantitatively collected and analyzed for iron species using Mossbauer spectroscopy. The results showed that hydrocarbon generation from organic matters would be significantly increased by catalysis of pyrite. The produced hydrocarbons were also evaluated with the following observations: (1) the generation of gaseous hydrocarbons and bitumen can be potentially increased by 0.5–1.0 times and 0.2–1.0 times due to pyrite, respectively; (2) the peak generation of bitumen was shifted forward by 50 °C due to the catalysis of pyrite; and (3) the added pyrite was conversed into pyrrhotite and sulfur since heating temperature at 300 °C, indicating that pyrite may act indirectly as a catalytic agent and/or directly as an inducer via sulfur, and further enhance free radicals’ formation and hydrocarbons generation.