Microreactor and Monolith Reactor Tests

The first stage of the investigation includes steady and transient microreactor experiments for the determination of the intrinsic kinetics of the various NH3 NO t reactions. According to this approach, a part of the initial extruded or washcoated catalyst is crushed into a fine powder form and placed inside a microreactor. 

The latter consists of a tubular fixed bed reactor encased in a furnace through which the reacting feed flows. This experimental setup guarantees negligible transport limitations, measurement of fast transients, and controlled isothermal conditions. 

A typical experiment for the investigation of the NH3 adsorption-desorption reaction is shown in Fig. 13.7. The figure shows the evolution of the outlet NH3 concentration during a step of NH3 inlet feed followed by a temperature programmed desorption. 

The second stage of the scale-up approach involves monolith reactor experiments over small catalyst samples with a volume of a few cubic centimeters. The data obtained from this intermediate stage serve either as a primary validation of the intrinsic reaction kinetics or for kinetic parameter estimation in case microreactor experiments have been omitted. Monolith reactor experiments are able to reproduce more accurately the phenomena prevailing in real full-scale converters taking into account the catalyst s geometry, the flow dynamics along the channel, and the intraporous diffusion over the washcoat. At the same time, the experiments are performed under controlled laboratory conditions, involving isothermal operation and the use of synthetic gas mixtures. 

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