Preliminary Study On Catalytic Reduction Of SO₂ By CeO₂-La₂O₃/γ-Al₂O₃ In The Presence Of Oxygen

The power industry of our country relies mainly on generating electricity with coal, the coal-fired generation accounts for about 70% of the national total generation. The coal-fired power plant has already become the greatest pollution source of SO₂. Flue gas desulfurization technology is still the major technology to control the coal-fired power plant's SO₂ pollution. It is important to study and develop flue gas desulfurization technology which has intellectual property right of independence and is suitable for the national conditions of our country. Compared with a great deal of traditional desulphurization crafts, the catalytic reduction of SO₂ with CO to elemental sulfur is considered to be the best technology for the removal of SO₂ from flue gas. It must develop the catalyst with high selectivity and high stability. The development of the catalyst is undoubtedly a key to the technology. Adding rare earth oxide CeO₂ with varible valences to La₂O₃ formed a mixture of rare earth oxides. By means of dipping CeO₂,La₂O₃ and their mixture, whose carriers are allγ-Al2O3, are used as the catalyst for the reduction of SO₂ by CO.The activation process of this catalyst without O₂ were investigated. Furthermore, the catalytic reduction experiment in the presence of oxygen was done. In the presence of O₂ the impact of the concentration of O₂, ratio of SO₂ to CO, volume of catalyst, temperature and diameter of γ-Al₂O₃ carrier have been analyzed. The result shows that the rare earth oxide mixture composing of CeO₂ and La₂O₃, as the catalyst for the reduction of SO₂ by CO, can remove SO₂ mostly without O₂.In the presence of O₂ the result shows that the catalyst will be poisoned by oxygen and SO₂ conversion drops almostly to 0. This kind of poisone influnce is reversible partly. The structure of catalyst is not destroyed thoroughly. But different catalyst has different performance. The effect of O₂ is significantly lower at higher temperature. The time of SO₂ conversion dropping almostly to 0 will be prolonged when increasing volume of catalyst or ratio of CO to SO₂.The method of changing diameter of γ-Al₂O₃ carrier can improve mixture composing catalyst's performance.