Pyrolysis of Acidic Ionic Liquid 1-Sulfonic Acid Butyl-3-methylimidazolium Trifluoromethanesulfonate-Treated Lignin for Phenolics Production

Abstract

The effect of pretreatment of lignin with acidic ionic liquid 1-sulfonic acid butyl-3-methylimidazolium trifluoromethanesulfonate ([B(SO3H)mim]OTf) on lignin pyrolysis behavior and the distribution of phenolics in tar were investigated in this paper. It is found that [B(SO3H)mim]OTf pretreatment under mild conditions (such as 50 °C) leads to an increase in lignin pyrolysis tar yield of 11.8% and a simultaneous decrease in the yield of heavy tar. The tar obtained from pyrolysis of [B(SO3H)mim]OTf-treated lignin are mainly phenols and phenol derivatives, accounting for more than 90% of all components. Pretreatment with [B(SO3H)mim]OTf results in significant increase of the yields of phenol, crepsol, guaiacol, 2-ethylphenol, 4-ethyl-2-methoxy-phenol, and 4-methoxyguaiacol in light tar. The yield of light components obtained from pyrolysis of [B(SO3H)mim]OTf-pretreated lignin increased by 1.50 times compared with that of lignin. The results of FTIR analysis indicate that [B(SO3H)mim]OTf pretreatment of lignin...