Development of the Structured Catalysts for the Exhaust Gas Treatment

V. Tomašić and Z. Gomzi

Abstract
Experimental and theoretical investigation of NOdecomposition in a catalytic monolith reactor has been performed. Preparation of the monolith catalyst, composed of cordierite substrate as an inert carrier and copper containing ZSM-5 zeolite as catalytic washcoat, is described in details. The reaction was examined in the temperature range from 573 K to 773 K and at different flow rates. One-dimensional (1D) heterogeneous model was applied to describe a single channel of the monolith.The model included the processes of external mass transfer and chemical reaction on the surface of the catalyst. Mass transfer coefficient was estimated from correlation available in the literature. Kinetics of NOdecomposition was described by Langmuir-Hinshelwood type of rate equation. The reactor model was verified by comparing experimental data with theoretical predictions. Generally, good agreement has been achieved. However, the rate constant was found to increase with the increase in the thickness of the catalytic washcoat. Consequently, the internal mass transfer, even within a very thin layer of the catalytic washcoat, must also be included in the reactor model for the monolith channel to adequately describe behavior of such a reactor system.

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Keywords
Catalytic decomposition of NO, Cu/ZSM-5 zeolite, mathematical model, monolith catalyst, washcoat