1. State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, Shanxi 030001, P. R. China
2. National Energy Center for Coal to Clean Fuels, Synfuels China Co., Ltd., Huairou District, Beijing 101400, P. R. China
3. University of Chinese
Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, P. R. China
4. Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109, United States