Steam gasification of chars of ash-free coals extracted using 1-methylnaphthalene and N-methyl-2-pyrrolidone

•Gasification behavior of solvent-extracted ash-free coal (AF) chars was evaluated.•Reactivity of AFs was affected by the polarity of extraction solvent.•Ash-free AF chars can be a proper feedstock for the catalytic coal gasification.•AF chars with tailorable composition are applicable as functional carbons.