1. State Key Laboratory of Chemical Resource Engineering, School of Chemistry, Beijing University of Chemical Technology, Beijing 100029, P. R. China
2. State Key Laboratory of Coal Conversion, Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan, Shanxi 030001, P. R. China
3. National Energy Center for Coal to Clean Fuels, Synfuels China Co., Ltd, Huairou District, Beijing 101400, P. R. China
4. University of Chinese Academy of Sciences, No. 19A Yuquan Road, Beijing 100049, P. R. China
5. Physics Department, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia