Experimental and theoretical study of NH$_{3}$ adsorption and desorption over a Cu-chabazite NH$_{3}$-SCR catalyst

Authors : Selmi Erim BOZBAĞ, Mutlu ŞİMŞEK, Onur DEMİR, Deniz Şanli YILDIZ, Hüseyin Barkin ÖZENER, Gökhan HİSAR, Can ERKEY

Pages : 1768-1780

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Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :NH$_{3}$ adsorption and desorption behavior of a commercial Cu-chabazite insert ignore into journalissuearticles values(CHA); NH$_{3}$ selective catalytic reduction insert ignore into journalissuearticles values(NH$_{3}$-SCR); catalyst was studied in the presence and absence of H$_{2}$O. NH$_{3}$ uptake values at various adsorption temperatures were obtained during various steps of the adsorption and temperature-programmed desorption insert ignore into journalissuearticles values(TPD); experiments. Total NH$_{3}$ uptake decreased from 4.6 to 1.6 g NH$_{3}$/L catalyst when the adsorption temperature was increased from 50 to 300 $^{\circ}$C. Three major adsorption sites for NH$_{3}$ adsorption could be identified and quantified using TPD experiments, namely loosely, moderately, and strongly bound NH$_{3}$ with peak centers at around 147, 266, and 447 $^{\circ}$C. The total NH$_{3}$ uptake was significantly affected by the presence of H$_{2}$O in the feed. This resulted in a significant uptake loss insert ignore into journalissuearticles values(nearly 60); for the loosely bound NH$_{3}$. Three single-site and one three-site model were developed and compared in terms of NH$_{3}$ uptake and release. The effects of site density values and thermodynamic restrictions in one-site models were investigated. The model using site density values obtained during the TPD phase resulted in the best fit among one-site models. The three-site model, which uses site density values obtained using dry adsorption of NH$_{3}$, best represented the experimental data.
Keywords : Copper, chabazite, monolith, NH 3, adsorption, storage, desorption, model, kinetics