Study on the characteristics and role of the soluble fractions during direct liquefaction for two low rank coals. Part I: Structural comparison between the soluble fractions obtained from soxhlet and thermal extraction

Juan Chen, Zongqing Bai, Hongyan Zheng, Wang Li, Tingting Zhang, Yuxing Jia, Yujie Hou, Zhenxing Guo, Lingxue Kong, Jin Bai, Wen Li