1. Chemical Reaction Engineering and Competence Centre for Catalysis, Chalmers University of Technology, SE-412 96 Göteborg, Sweden, General Motors R&D Center, Chemical and Environmental Sciences Laboratory, 30500 Mound Rd, Warren, Michigan 48090-9055 and General Motors R&D India Science Lab, Creator Building, 2nd Floor, ITPB, Whitefield Road, Bangalore 560066, India