[1] Max Planck Inst Kohlenforsch, D-45470 Mulheim, Germany
[2] Ctr Res & Technol Hellas, Chem Proc Engn Res Inst, POB 361, Thessaloniki 57001, Greece
[3] Int Hellen Univ, Sch Sci & Technol, POB 361, Thessaloniki 57001, Greece
[4] Imperial Coll London, Dept Chem Engn, South Kensington Campus, London SW7 2AZ, England