1. Training Base of State Key Laboratory of Coal Science and Technology Jointly Constructed by Shanxi Province and Ministry of Science and TechnologyTaiyuan University of Technology Taiyuan 030024 P.R. China
2. Department of ChemistryIndian Institute of Technology Bombay Mumbai 400076, Maharashtra India
3. Department of Chemistry and Chemical EngineeringXi'an University of Technology Xi'an 710054 PR China