1. Neste Oy, P.O. Box 310, FIN-06101 Porvoo, Finland, Department of Technical Physics, Helsinki University of Technology, FIN-02150 Espoo, Finland, VTT Chemical Technology, P.O. Box 1401, FIN-02044, Finland, and Departments of Chemistry, Chemical Engineering, and Materials Science, Polytechnic University, Brooklyn, New York 11201