1. Laboratory of Basic Research in Biomass Conversion and Utilization Department of Thermal Science and Energy Engineering University of Science and Technology of China Hefei 230026 P. R. China
2. Institute of Energy Hefei Comprehensive National Science Center Hefei 230031 China
3. National & Local Joint Engineering Research Center of Precision Coal Mining Anhui University of Science and Technology Huainan 232001 P. R. China