Experimental and theoretical study of NH3 adsorption and desorption over a Cu-chabazite NH3-SCR catalyst

NH3 adsorption and desorption behavior of a commercial Cu-chabazite (CHA) NH3 selective catalytic reduction (NH3 -SCR) catalyst was studied in the presence and absence of H2O. NH3 uptake values at various adsorption temperatures were obtained during various steps of the adsorption and temperature-programmed desorption (TPD) experiments. Total NH3 uptake decreased from 4.6 to 1.6 g NH3/L catalyst when the adsorption temperature was increased from 50 to 300◦C. Three major adsorption sites for NH3 adsorption could be identified and quantified using TPD experiments, namely loosely, moderately, and strongly bound NH3 with peak centers at around 147, 266, and 447◦C.