Turkish Journal of Engineering

Yazarlar: Selmi Erim BOZBAĞ

Konular:Mühendislik

DOI:10.31127/tuje.931038

Anahtar Kelimeler:NO2 Storage,NH3 storage,Kinetic model,TPD,NH3-SCR

Özet: Kinetic modeling of NH3 Selective Catalytic Reduction (NH3-SCR) of NOx in Cu-chabazite washcoated monolithic reactors has recently become an important task for design, control and calibration of heavy-duty engine aftertreatment systems. Development of detailed and accurate kinetic models rely on the correct simulation of the NO 2 and NH 3 storage at different conditions. Here, different kinetic schemes for NO 2 adsorption and desorption were developed and compared to experimental data. For this purpose, firstly, realistic values of the active Cu sites in the Cu-zeolite were obtained using the temperature programmed desorption (TPD) of NH 3 and NO 2 which showed fractional coverages of 0.04 and 0.17 for the so-called ZCuOH and Z 2Cu species which reside in the 8 and 6 membered rings (MR) of the zeolitic framework, respectively. Active site concentrations were used in the kinetic models which included simultaneous formation of nitrate/nitrite species or the formation of HNO3 intermediate which in turn resulted in the formation of nitrates or nitrites over the ZCuOH. Models also included or excluded the NO 2 storage over the so called secondary Z 2Cu sites. It was shown that models taking into account HNO3 intermediate formation along with two NO 2 storage sites were better fits to the experimental data. 

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