1. Department of Applied Chemistry,
Graduate School of Engineering, University of Toyama, Gofuku 3190, Toyama 930-8555, Japan
2. State Key Laboratory of Heavy
Oil Processing, China University of Petroleum, Shandong, Qingdao 266555, P. R. China
3. Institute of Coal Chemistry, Chinese Academy of Sciences, Taiyuan 030001, P. R.
China