Study of the Cu-Ce synergism for NO reduction with CO in the presence of O2, H2O and SO2 in FCC operation

Three catalysts, CuMgAlO (Cu-cat), CeMgAlO (Ce-cat), and CuCeMgAlO (CuCe-cat), were prepared by coprecipitation and characterized by XRD, XPS and N2 adsorption–desorption. The NO reduction activity with CO in the presence of O2, H2O and SO2 was investigated under conditions similar to those found in the dense phase bed of fluid catalytic cracking (FCC) regenerator. Under NO+CO+O2 reaction system and low temperature, NO conversion was much higher over CuCe-cat than that over Ce-cat or Cu-cat. The addition of H2O to the feed significantly hindered the NO reduction over Cu-cat while it markedly promoted the activity of CuCe-cat at low temperature. The presence of SO2 in the feed deactivated Cu-cat and Ce-cat drastically while no deactivation of CuCe-cat was observed. These results indicate that for NO reduction with CO, CuCe-cat has high activity and excellent resistance to H2O and SO2 poisoning. The enhanced performance of CuCe-cat can be explained by the synergistic effect between copper and cerium ions, which results in the formation of large amounts of Cu+ ions and oxygen vacancies in the sample.