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

Cu-ZSM5 BASED MONOLITH REACTORS FOR NODECOMPOSITIONL. Lisi 1 , R. Pirone 1 , G. Russo 2 , V. Stanzione 21 Istituto di Ricerche sulla Combustione, CNR, P.le Tecchio, 80; 80125 Napoli,e-mail: lisi@irc.cnr.it, tel.: +39 0817682279, fax: +39 0815936936;2 Dipartimento di Ingegneria Chimica, Università Federico II, Napoli,e-mail: genrusso@unina.it, tel.: +39 0817682279, fax: +39 0815936936;OP-III-2IntroductionMonolith catalysts are widely used in environmental applications due to the severaladvantages they offer like low pressure drop even at high space velocity, high geometricsurface area, good mechanical strength and durability [1-3]. In particular, monolith catalystsare used in DeNOx catalysis both for mobile and stationary source.The catalytic decomposition of NO into N 2 and O 2 would be a very attractive solution forNOx abatement since no addition of reducing agent is required [4]. Cu-ZSM5 provides thebest performances for this reaction. Although widely investigated as powder catalyst,Cu-ZSM5 dispersion on a structured support has been poorly studied.ResultsDeposition of a zeolite on ceramic monoliths can be made by in-situ hydrothermalsynthesis or by deposition from a slurry of fine pre-synthesized zeolite powder (dip-coating)[5]. The advantage of the first method is the stronger adhesion of the coating to the support.Nevertheless, it is more complex and diffusion limitations can occur through the dense layerwith small intercrystalline pores. On the other hand, the main advantage of the dip-coatingmethod are the shorter diffusion distances.In this paper a ZSM5 (Si/Al = 25) powder sample has been deposited on cordieritemonoliths by dip-coating using colloidal alumina or silica as binders in aqueous suspension.After a preliminary study to determine the best binder and the best zeolite/binder ratio toobtain a ZSM5 washcoat with a good mechanical resistance, monolith catalysts have beenprepared according to two different procedures: i) deposition of a Cu exchanged ZSM5ii) deposition of a H-ZSM5 followed by copper exchange of the structured catalyst.The monolith catalysts have been investigated by morphological (SEM/EDX), physical(BET and porosity), chemical (ICP/MS, H 2 TPR) and catalytic (NO decomposition tests in aflow reactor) analysis. Results have been compared with those obtained on a Cu-ZSM595