Pyrolysis of lignite following low temperature ionic liquid pretreatment

A new and effective method, lignite pyrolysis with pretreatment with ionic liquid 1-butyl-3-methyl-imidazolium chloride ([Bmim]Cl) at low temperature, was studied. It is found that [Bmim]Cl pretreatment increased the total yield of liquid products and oil fractions compared to original lignite. The pretreatment temperature and the ratio of [Bmim]Cl to lignite play key roles on the increase of total liquid yield and the change of tar composition. The increases of liquid products yield and oil fractions content are found to be caused by the changes of composition of oxygen-containing functional groups in lignite through [Bmim]Cl pretreatment. It is also found that [Bmim]Cl can be efficiently recovered and the pretreatment performance of regenerated [Bmim]Cl is slightly lower than that of fresh [Bmim]Cl.