Enhancement of NO2 adsorption performance during adsorption-regeneration cycles over Pt/Ba/Al2O3 catalyst

In this study, NO2 adsorption on Pt/Ba/Al2O3 was investigated. Results show that NO2 adsorption on fresh samples quickly begins to penetrate due to the NO slip. However, after several adsorption-regeneration cycles by NH3, the NO slip significantly decreased and the NO2 adsorption amount apparently increased from 2.59 mg/g to about 47 mg/g at 90% adsorption efficiency. In situ diffuse reflectance Fourier transform infrared spectroscopy (DRIFTS) experiments indicated that the adsorbed NOx can be well reduced by NH3 at 250 degrees C, and the by-product of this process is extremely low. Combining the experimental results of electron paramagnetic resonance (EPR), it can be found that a non-reduced Ba-NO2 structure remains on the surface of the regenerated sample. At the same time, apparently signals of unpaired electrons were detected by EPR, which were considered to play an important role in NO2 adsorption. Pt/Ba/Al2O3 is considered for the capture of NO2 under unconstant concentration conditions in industrial flue gas due to its excellent adsorption-regeneration properties.