1. Research Institute of Special Chemicals, College of Chemistry and Chemical Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi, P. R. China
2. Shanxi Key Laboratory of Gas Energy Efficient and Clean Utilization, Taiyuan 030024, Shanxi, P. R. China
3. Key Laboratory of Coal Science and Technology, Taiyuan University of Technology, Taiyuan 030024, Shanxi, P. R. China