1. State Key Laboratory of Heavy Oil ProcessingChina University of Petroleum-Beijing Beijing 102249 P. R. China
2. Department of ChemistryIowa State University Ames IA 50011 USA
3. School of Chemistry and Chemical EngineeringHubei University Wuhan 430062 P. R. China
4. Department of Mechanical EngineeringIowa State University Ames IA 50011 USA