Effect of Cross-linking Reactions on Evolution Mechanism of Crystalline-Amorphous Carbon during Bituminous Coal Carbonization

Abstract

Abstract. Crystalline carbon and amorphous carbon are two of the major carbon structures found in coal. The influence of cross-linking reactions (CLRs) on the evolution mechanism of crystalline-amorphous carbon during bituminous coal carbonization was studied using X-ray and Raman crystallographic methods. These results showed that firstly low-temperature CLRs enhanced the transformation of amorphous carbon into crystalline carbon at the begin of carbonization, then affected the mean size of crystalline structures, and finally facilitated degradation processes that resulted in the transformation of crystalline carbon into amorphous carbon. However, different effects were observed for moderate-temperature CLRs on crystalline-amorphous carbon. Firstly, the disruption of weak bonds led to the transformation of crystalline carbon into amorphous carbon. Then moderate-temperature CLRs led to the appearance of small layers in amorphous carbon structures and initiated the transformation of amorphous carbon into crystalline carbon. Finally, the amount of crystalline carbon with respect to amorphous carbon continued to grow.