1. Shanxi Research Institute of Applied Chemistry; Taiyuan; 030027; Shanxi; China
2. Research Institute of Special Chemicals; Taiyuan University of Technology; Taiyuan; 030024; Shanxi; China
3. Key Laboratory of Coal Science and Technology, Ministry of Education and Shanxi Province; Taiyuan University of Technology; Taiyuan; 030024; Shanxi, China