A comparative study on the NOx storage and reduction performance of Pt/Ni1Mg2Al1Ox and Pt/Mn1Mg2Al1Ox catalysts

摘要

A series of Ni1Mg2Al1Ox, Mn1Mg2Al1Ox, 0.5Pt/Ni1Mg2Al1Ox and 0.5Pt/Mn1Mg2Al1Ox catalysts were carefully prepared and their NOx storage and reduction (NSR) performance including NOx oxidation efficiency (NOE), NOx storage capacity (NSC), NOx conversion rate (X-NO), N-2 selectivity (S-N2), N2O selectivity (SN2O) and NH3 selectivity (S-NH3), was systematically investigated. A SO2 resistance test was also performed in the presence of 100 ppm SO2. The NOE and NSC experimental results revealed that the Ni1Mg2Al1Ox catalyst possesses a higher NSC, while the Mn1Mg2Al1Ox catalyst possesses a better NOE. With regard to X-NO, 0.5Pt/Ni1Mg2Al1Ox presented higher results at 200 degrees C and 400 degrees C, while 0.5Pt/Mn1Mg2Al1Ox obtained the highest result at 300 degrees C, which was more than 60% for both. In addition, compared to 0.5Pt/Ni1Mg2Al1Ox, 0.5Pt/Mn1Mg2Al1Ox exhibited a relatively higher S-N2 and lower SN2O and S-NH3. The NOx-TPD and H-2-TPSR results indicated that NOx adsorbed on Ni1Mg2Al1Ox and 0.5Pt/Ni1Mg2Al1Ox is more stable, and that NH3 can be formed in large amounts in a lower temperature range. Both Pt-containing catalysts presented a quite stable X-NO in ten cycles in the presence of 100 ppm SO2, and their S-N2 can be remarkably enhanced to more than 80%, which could be attributed to the reactions of NH3-SCR and SO2 + NH3. We believe this new insight can provide a new way of thinking for the development of NSR catalysts.