Study On Modification And Desulphurization Capability Of Rare Earth Catalyst Supported On γ-Al₂O₃

The pollution of SO₂ produced from coal-fired smoke has been becoming a global problem, and there is none effectual technique to resolve it. Therefore, the direct reduction of SO₂ technology has been brought forward nowadays, as the characteristics of this technology is that the finally production is element sufur and no water pollution or solid waste pollution in the process of desulphurization. Because coal can not be fired completely, in the coal-fired smoke, there must be some deoxidized CO which is deleterious. Using CO from flue gas as the reducing agent to reduce fulfur dioxids to element fulfur by catalyst is one of the distinct characteristics of rare earth catalyst supported onγ-Al₂O₃. Though, in the desulphurization process, the high reaction temperature needed is one prodigious disadvantage of this kind of catalyst for catalystic reduction of fulfur dioxides, if this problem can be solved by modification means, the modification catalyst may be used in the field of flue gas desulphurization gradually. So, in this thesis, CO is used as reducing agent and Ce, Fe and Ti are used as additive to modificate La/γ-Al₂O₃ aiming to prepare a kind of catalyst which can keep high activities in relatively lower reaction temperature in the process of desulphurization.Ce, Fe and Ti are used to modify La/γ-Al₂O₃ cataly, and the research content are described as following:1. a series of catalysts ofγ-Al₂O₃ loaded by rare earth: La/γ-Al₂O₃,La-Ce/γ-Al₂O₃,La-Fe-Ce/γ-Al₂O₃ and La-Fe-Ce-Ti/γ-Al₂O₃ have been prepared by dipping Ce,Fe,Ti and La intoγ-Al₂O₃ to study the feasible prepare ratio and bake temperature.2. In a suit of lab experimental simulation system, all the experiments are carried out in order to study the desulphurization activities of modification catalyst and the influence for the desulphurization activitie in deffrent baking temperature.3. In this thesis, BET, XRD and SEM are used to research the component changing of modification catalysts. And researching the desulphurization mechanism of modification catalysts is another aim of this thesis. Disquisitions indicate that, in the desulphurization experiment, the activity of catalyst 9%La-5%Ce/γ-Al₂O₃ is much higher than single catalyst 9%La/γ-Al₂O₃ and the reaction temperature of catalyst 9%La-5%Ce/γ-Al₂O₃ is 600 centigrade, while the SO₂ conversion rate is 98.7%; The reaction temperature of catalyst 9%La-3%Fe-5%Ce/γ-Al₂O₃ is 500 centigrade, while the SO₂ conversion rate is 98.8%; And, The reaction temperature of catalyst 9%La-3%Fe-5%Ce- 0.8%Ti/γ-Al₂O₃ is 420 centigrade, while the SO₂ conversion rate is 99.3%. La2O2S, FeS, FeS2 are the active phases of the catalyst 9%La-3%Fe-5%Ce-0.8%Ti/γ-Al₂O₃, furthermore, CeO2 and TiO2 which have the abilities to deposit and transport oxygen in the reaction are both the active phases too. The desulphurization mechanism of catalyst 9%La-3%Fe-5%Ce-0.8%Ti/γ-Al₂O₃ is the cooperative process of medial producetion mechanism and oxygen vacancy mechanism.