Synergetic promotion of 4Mn10Ce/γ-Al2O3 catalyst to Pt/xBa/Ce0.5Zr0.5O2 catalysts for NOx removal from diesel exhausts

Abstract

In this investigation, Pt/xBa/Ce0.5Zr0.5O2 catalysts were prepared by deposition and incipient wetness impregnation method and the physio-chemical properties of samples were characterized with XRD and BET. The experiments were carried out to evaluate the effect of 4Mn10Ce/γ-Al2O3 on the removal of NOx over the Pt/xBa/Ce0.5Zr0.5O2 catalysts and NO-TPD was employed for determining the NOx adsorption. The results showed that the larger diffraction peak width of Ce-Zr oxides and specific area were found over Pt/15Ba/Ce0.5Zr0.5O2. Based on the NOx storage and storage-reduction experiments, it was found that the decline of NOx storage efficiency was attributed to the decomposition of nitrites and nitrates under high temperatures beyond 350℃, and the inhibition of reactions of NOx with Ba by the NO oxidation. NO2 was stored more easily and faster than NO, which contributed to NOx storage after 4Mn10Ce/γ-Al2O3 catalyst added. The stability of stored species was undermined at higher temperature due to H2 consumption by 4Mn10Ce/γ-Al2O3 catalyst leading to shortage of reductant and more reaction heat. The optimal concentration of O2 at around 7.5% can provide more OⅡ for the oxidation process of NO and improve the performance of NOx reduction.