1. State Key Laboratory of Coal Conversion Institute of Coal Chemistry Chinese Academy of Sciences Taiyuan 030001 P. R. China
2. University of Chinese Academy of Sciences Beijing 100049 P. R. China
3. Department of Applied Chemistry School of Engineering University of Toyama Toyama 930-8555 Japan
4. State Key Laboratory of High-efficiency Utilization of Coal and Green Chemical Engineering Ningxia University Yinchuan 750021 P. R. China