SEPARATION OF FULLERENES BY CHROMATOGRAPHY ON COAL

A crude mixture of C-60 and C-70 fullerenes was chromatographed on coa ls of rank varying from brown coal to 'pseudo' semianthracite to deter mine their capability as a separation medium for purifying C,, fullere ne. Considerable variation in separation performance was found between the coals. Treatment of all these coals with tetrahydrofuran improved their subsequent performance, probably owing to swelling of the coal, resulting in a more favourable pore structure. No correlation was obs erved between separation performance and carbon aromaticity as measure d by n.m.r. Coals which are expected to have a high porosity in the tr ansitional (mesopore) range (2-50 nm) appear to perform best, probably because this pore size is appropriate for fullerene separation.