1. State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, China
2. National Energy Center for Coal to Liquids, Synfuels China Co., Ltd., Huairou District, Beijing 101400, China
3. University of Chinese Academy of Sciences, No.19A Yuquan Road, Beijing 100049, China
4. Department of Physics, West Virginia University, Morgantown, West Virginia 26506-6315, United States