Boreskov Institute of Catalysis of the Siberian Branch of Russian ...

OP-III-2powder sample with the same total copper content in order to define the best preparationprocedure.A very good adhesion of uniform zeolite washcoat layer (Fig. 1) has been obtained bydip-coating technique using a low amount of silica binder. The preparation method stronglyaffects the nature of copper in the monolith catalyst determining different catalytic propertiesof the structured reactors and suggesting that the copper exchange represents a crucial step forthese systems. Release of active copper cations from the zeolite powder suspended in thesolvent during the coating step or a bad control of the exchange of the zeolite layer depositedon the structured support, due to the complexity of the system ceramicmonolith/binder/zeolite, are the possible phenomena occurring during the preparationprocedure.Activity in the presence of water vapour, strongly deactivating Cu-ZSM5 powder, hasbeen studied for monoliths as well, determining the effect of zeolite dispersion on thehydrothermal stability. A surprisingly better hydrothermal resistance was found for monolithcatalysts, whatever the preparation procedure used, likely due to a buffer effect of the ceramicsupport.CORDIERITECORDIERITEZEOLITEWASHCOATZEOLITEWASHCOATFigure 1 – SEM image of the ZSM5 monolith cross section and magnification of the selected area (90° rotated).References1. V. Tomašić, Catal. Today 119 (2007) 106.2. P. Avila, M. Montes, E. E. Miró, Chem . Eng. J. 109 (2005) 11.3. V. Tomašić, Z. Gomzi, Chem. Eng. Proc. 43 (2004) 765.4. V.I. Pârvulescu, P. Grange and B. Delmon, Catal. Today 46 (1998) 369.5. J.M. Zamaro, M.A. Ulla, E.E. Mirò, Chem. Eng. J.106 (2005) 25.96