Suppressing cross-linking reactions during pyrolysis of lignite pretreated by pyridine

A Chinese lignite Yitai (YT) was pretreated by pyridine vapor and pyridine solvent. The effects of the treatments on the pyrolysis behavior of the pretreated coals were studied by thermogravimetric mass spectrometry (TG-MS). The results showed that both treatments could suppress the cross-linking reactions (CLRs) during pyrolysis of the treated coal, but the suppressing temperature range and mechanism were different. Some inherent hydrogen bonds (HBs) in the coal were broken by pyridine vapor treatment and new stronger N—OH HBs were formed. Thus, low temperature CLRs (below 400°C) that were related to the hydrogen-bonded COOH—COOH and COOH—OH were suppressed. However, pyridine solvent pretreatment influenced the pyrolysis behavior by reducing the association interactions between the low molecular weight compounds and macromolecular network, thus, relaxing the three-dimensional network of coal and enhancing the transmission efficiency of hydrogen in coal.