1. Univ. Lille CNRS Centrale Lille ENSCL Univ. Artois UMR 8181 UCCSUnité de Catalyse et Chimie du Solide Lille F-59000 Lille France
2. Department of Chemical EngineeringFederal University of Rio Grande do Sul UFRGS Rua Luiz Englert, s/n° Porto Alegre 90040-040 Brazil