Zsuplhated-ZrO_2 prepared by impregnation with ammonium, sodium, or copper sulphate: catalytic activity for NO abatement with propene in the presence of oxygen

摘要

Suphated zirconia samples were prepared by impregnation of hydrous zirconia dried at 383 K or calcined at 823 K (monoclinic ZrO_2) with aqueous solutions of (NH_4)_2SO_4, Na_2SO_4, or CuSO_4. After calcining at 823 K, samples prepared with hydrous zirconia dried at 383 K were tetragonal. At the same suphate content, (NH_4)_2SO_4/ZrO_2 and CuSO_4/ZrO_2 contained sulphates of the same type. As the total suphate content increased, IR indicated an increasing (polynuclear)/(mononuclear) sulphates ratio. (NH_4)_2SO_4/ZrO_2 and CuSO_4/ZrO_2were both active for the abatement of NO with propene in the presence of oxygen, (NH_4)_2SO_4/ZrO_2 had several drawbacks: (i) CO fromed in large amounts, (ii) N_2O formed, (iii) the catalyst surface coked, and (iv) catallytic activity changed as a function of time on stream. CuSO_4/ZrO_2 catalysts had practically none of these unfavourable features. For a comparison, some catalytic experiments were also run using propane or methane as reducing agent.