The effect of diabietic acid on the coking of oxidised solvent-extracted coal

Abstract

Refcoal is a refined carbon source obtained by extraction of coal with dimethylformamide (DMF). During the coking process, Refcoal goes through a mesophase (fluid) stage to form an anisotropic coke. In contrast, oxidised Refcoal does not undergo such a mesophase stage during the carbonisation process. Thus it does not yield an anisotropic coke, but forms an isotropic coke. The objective of this study is to produce an anisotropic coke from oxidised Refcoal. For this purpose, diabietic acid, a hydrogen donor, was considered as a suitable additive. Coking was performed in sealed glass capillary tubes as diabietic acid proved to be volatile at the carbonisation temperature of 500 °C. The resultant cokes were analysed using thermogravimetric analysis, Raman spectroscopy and optical microscopy. The results show that the degree of anisotropy increased with diabietic acid content (3, 5 and 10 mass %).