FULLERENES FROM COAL - A SELF-CONSISTENT PREPARATION AND PURIFICATION PROCESS

Fullerenes were prepared from a suite of coals of different ranks covering brown coal to semianthracite. Each coal was first converted to coke by heating between 1010 and 1300-degrees-C for 5-19 h. Under these conditions, the cokes do not undergo significant graphitization. Electrical arcing of the coke in helium produced fullerenes in yields of 2-8.6%, which compare favorably to using graphite as a source carbon under similar conditions. The presence of mineral matter and heteroatoms in the coke does not inhibit fullerene formation but does reduce fullerene yield. Moreover, coke prepared in a two-stage process with semicoke as an intermediate in an argon flow produces a higher fullerene yield than coke prepared in a single stage in a sealed atmosphere. No clear trend can be drawn between fullerene yields and coal ranks or electrical resistivities of the coke. In addition, Yarrabee semianthracite is demonstrated to be a useful chromatographic material to purify C60.