Preparation of fullerenes using carbon rods manufactured from Chinese hard coals

We report a feasibility study of producing fullerenes (C60 and C70) using carbon rods manufactured from Chinese coal which is one of the cheapest natural resources of carbon. A DC arc method is employed using coal-derived carbon rods as electrode materials. The carbon rods are prepared from seven typical Chinese hard coals including bituminous coals and anthracite. The results show that all Chinese coals tested can be used to produce significant quantities of fullerenes. Their yields are strongly affected by the methods of preparing carbon electrodes and the parameters of the arc process, which are directly related to the coal properties and characteristics. Our results show that the two-step carbonisation method is significantly better than the one-step hot-pressing method with regard to the fullerene yields, as such the two-step method is recommended for fullerenes production from Chinese coals. It is found that the fullerene yield increases as the carbon content in coal increases and as ash content in coal decreases. This suggests that the mineral matter in coals could somehow inhibit the fullerenes production. An interesting linear relationship between the C60/C70 ratios and the volatile matter content in Chinese coals is also noted.