Abstract:

Samples of La-Ce-Cu series were prepared with ammonium nitrate (NH_4NO_3) comelted method and the compositions of the samples were analyzed by XRD, XRF results showed that all the samples were O-defect compounds. The superficial structure were characterized by TEM. It was found that Cu segregates towards the surface and forms a new compound with S with the deepening of SO2 poisoning which causes the distortion of the original crystal structure. It, also showed that pure CeO2 will not be poisoned by sulphur. XPS analysis showed that after poisoning reaction Cu seperates from La2CuO4 and combines with S to form CuSO4. Correspondingly CeO2 participates in the poisoning reaction and forms Ce2O3, i.e.La2CuO4 + 2CeO2 + SO2 = CuSO4 + La2O3 + Ce2O3.

Key words: La-Ce-Cu catalysts, SO₂ poisoning, Structure characterization