Pyrolysis of ionic liquid pretreated lignite: Effect of 1-butyl-3-methylimidazolium methyl sulfate pretreatment on kinetic and thermodynamic parameters of lignite

Abstract

ABSTRACT In this work, the effect of ionic liquid (IL) pretreatment on the pyrolytic behavior of lignite was analyzed by examining reactivity, kinetic, and thermodynamic parameters. Pretreatment of lignite with 1-butyl-3-methylimidazolium methyl sulfate ([Bmim][MeSO4]) was carried out at 150°C and 30 min followed by thermal analysis under an inert environment, at a constant ramp rate of 20°C/min. Ten Coats–Redfern (CR) models were applied to the TGA data to evaluate kinetic and thermodynamic parameters. IL-treated lignite increased volatile matter from 46.39% to 57.81% and reduced ash from 21.71% to 8.50%. DTG profiles indicated that [Bmim][MeSO4] accelerated the thermal degradation of lignite by breaking the hydrogen bonding structure of coal, which was statistically confirmed by a higher average rate of thermal degradation, mean relative reactivity (Rm), pyrolysis factor (PF), and lower activation energy (Eα) than untreated lignite. This study shows that [Bmim][MeSO4] could be an attractive eco-friendly pretreatment solvent for the thermochemical conversion of lignite.