1. State Key Laboratory of Clean and Efficient Utilization of Coal-based Energy, Taiyuan University of Technology, Taiyuan 030024, P. R. China
2. Key Laboratory of Coal Science and Technology of Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, P. R. China
3. State Key Laboratory of Coal Liquefaction and Coal Chemical Technology, Shandong Energy Group Co., Ltd., Shanghai 201203, P. R. China