engleski

Influence of diffusional phenomena on performance of a monolith reactor

Monolithic or structured catalyst supports and reactors are widely used for gas treatment applications, such as cleaning of automotive exhaust gases and industrial off-gases [1]. This work describes development and validation of a heterogeneous two-dimensional model of a catalytic monolith reactor, which accounts for inter- and intra-phase diffusional limitations. Direct decomposition of nitric oxide (NO) was used as a model reaction. A home-made monolith reactor was based on Cu/ZSM-5 as the main catalytic material. The prepared monolith samples were characterized by several techniques. Laboratory scale activity tests were carried out in an integral monolith reactor, operating under atmospheric pressure at different temperatures and at various space times. The catalyst activity for NO removal was evaluated by conversion of NO into N2, when the reaction reached steady state. The details about the experimental apparatus and procedures for the reaction product analysis are given elsewhere [2]. The proposed model was validated by comparing the experimental data and values predicted by the reactor model. NO decomposition kinetics was described by LHHW type of rate equation. The kinetic parameters were estimated from the experimental data using the modified differential method and Nelder-Mead method of non-linear optimization. The interphase mass transfer coefficients were derived from the concentration gradients, applying appropriate boundary conditions. Additional validation of the reactor model was based on independent experimental measurement of the effective diffusion coefficient of NO in the catalytic layer. For this purpose a modified Wicke- Kallenbach diffusion cell was used.

monolithic reactors ; Cu/ZSM-5 zeolite ; direct decomposition

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