Reactor model for the selective catalytic reduction of NO over Ag/Al2O3 in a gas-phase microreactor
Special Symposium - EPIC-1: European Process Intensification Conference - 1
EPIC-1: Poster Session (EPIC - Poster) - P1
Keywords: Microreactor, reactor model, HC-SCR, Ag/Al2O3
During the last few years, microreactors and microflows have attracted a great interest in science. Microdevices for laboratory testing offer new opportunities for kinetic studies and new fabrication techniques and materials have been developed recently for process intensification. Due to higher mass and heat transfer capabilities, microreactors permit a better administration of the heat and an improved control of the reaction conditions compared to those in industrial-scale reactors. In order to design and use these microdevices accurately for research and later for industrial purposes, the behaviour of the gas flow of reactants and products inside the microchannels is to be characterized and explained. New methods must be developed for predicting and describing this flow.
On the other hand, strong environmental policies have arisen and it has become compulsory to drastically reduce the emissions of pollutants in mobile and stationary sources.
The present work presents a three-dimensional mathematical model that describes the behaviour of the gas flow inside the microchannels of a microreactor with two inlets (A and B) for the selective catalytic reduction of NO using octane (HC-SCR) over a Ag/Al2O3 catalyst. The microchannels were previously coated with alumina and further impregnated with silver. The catalyst was characterized by means of Laser ablation – Inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) and Scanning Electron Microscopy (SEM). The activity of the catalyst was tested at temperatures varying from 100-500 ºC and hydrogen/NO ratio from 1 to 7. These experimental results are compared to those predicted by the reactor model proposed obtaining good correspondence. The presented model explains the performance of the gas flow in the HC-SCR reaction. It is demonstrated that most of the diffusion takes place at the inlets (A and B) and outlet of the microreactor (C), while it is almost negligible within the microchannels. The diffusion added by the measuring device (mass spectrometer) was calculated and taking into account in the diffusion term of the expression.
Finally, computational fluid dynamics (CFD) calculations are done with the geometry of the reactor and the results are compared to the offered model.
The final expression of the model allows us to mathematically describe the gas flow inside the microchannels predicting the behaviour of this important reaction of interest for the industry.
Presented Wednesday 19, 13:30 to 14:40, in session EPIC-1 Poster Session (EPIC - Poster) - P1.
