Experiment On Law Of Alkali Metal Poisoning And Alkali Resistance Of V₂O₅-WO₃/TiO₂ Catalysts

SCR denitration technology is widely used with its advantages like highly reactive high NOx reduction efficiency and no by-product,and the catalyst is the core of the SCR denitration technology. At present the commercial catalyst called V₂O₅-WO₃/TiO₂ is commonly used that usually deployed in a air passage high temperature and dust, but denitrification performance is easily reduced by the influence of all kinds of alkali metal component in fly ash, at the same time operating cost of coal-fired power station system is increasing, It is a big problem for the application of biomass fuel or with high alkali metal. The rearch that poisoning rules of main alkali metal in the coal for the catalyst and the development of catalyst with high resistance to alkali metal poisoning have practical significance.Firstly, the commercial V₂O₅-WO₃/TiO₂ catalyst is selected as the research object in the article, and study for the catalysts with different form of alkali metal sodium salt?NaOH, NaCl, NaNO3, Na2SO4 and NaHSO4?. Based on the activity test, catalyst is represented by NH₃-TPD, N₂-TPR, BET, SEM, XRD, getting different mechanism of intoxication from the different alkali metal for catalyst. The results showed that different forms of alkali metal calcined under different temperature have different effects on catalyst poisoning. In the low temperature 200?, NaOH will react with catalyst, causing the catalyst deactivation, other alkali metals have the influence on catalyst activity is not obvious; In the temperature 300?-400?, NaCl and NaNO3 reduce the catalyst activity significantly; under different temperature, two kinds of alkali metal called NaCl and NaNO3 promote the NOx reduction efficiency of catalyst. By the representation of TPD and TPR can know that alkali metal load will reduce the number of acid sites, NH₃ adsorption ability and reaction activity of adsorption and reduction, therefore reduce the denitration activity of catalyst.Secondly, a new type of V2O5-Ce?SO₄?₂/TiO2 with high resistance to alkali metal poisoning of catalyst was prepared, based on the commercial catalyst of V2O5-Ce?SO₄?₂ /TiO2, it is improved by using Ce?SO₄?₂ instead of WO3, Through the study of denitration activity of new catalyst before and after poisoning, crystal morphology, microstructure, surface acidity and REDOX ability, find the best load ratio of and resistance to poisoning mechanism of the new typeof catalyst. Results show that when the load ratio of Ce?SO₄?₂ are 10% and 13%, Fresh catalysts V2O5-Ce?SO₄?₂/TiO2 calcined in high temperature 330?³30?has the higher denitration efficiency than the commercial catalyst V₂O₅-WO₃/TiO₂; after poisoning, catalyst V2O5-Ce?SO₄?₂/TiO2 of denitration efficiency calcined under this temperature period is about 40% higher than commercial catalyst V₂O₅-WO₃/TiO₂, the catalyst has the best performance of resistance to alkali metal poisoning.when new catalysts Ce?SO₄?₂ load proportion is 10% and 13%. From TPD and TPR we can see that after improving the catalyst, catalyst formes rich acid on the surface, at the same time, catalyst oxidation reduction ability has improved significantly. After poisoning of alkali metal NaNO3, traditional commercial V2O5-WO3 /TiO2 catalyst is higher than that of V2O5-Ce?SO₄?₂/TiO2 catalyst in acid quantity reduction;new type of V2O5-Ce?SO₄?₂/TiO2 catalyst significantly higher than that of V₂O₅-WO₃/TiO₂ catalyst in the acid number.On the REDOX properties, V2O5- Ce?SO₄?₂ /TiO2 catalyst before and after the poisoning on the REDOX capacity of higher than V₂O₅-WO₃/TiO₂ catalyst. Therefore, Through the above analysis, the new type of catalyst surface acid and REDOX ability is superior to the traditional commercial catalyst before and after the catalyst poisoning, V2O5-Ce?SO₄?₂/TiO2 catalysts have high efficiency of the performance of resistance to alkali metal poisoning.