Study On The Effect Of Modified Pyrolysis Char Of Lignite To Desulfurization Performance Of Flue Gas

Burning coal is the main source of sulfur dioxide pollution in our country, and facing the urgent status of resources and environment, the new technology to solve the problem of flue gas desulfurization of coal burning is particularly important. Pyrolysis char which is product of coal pyrolysis attracts extensive attention because it can not only meet the demand of environment but also fully use of resources.In this article the pyrolysis tar of ordos Lignite is selected as raw material and has also been modified through the nitric acid oxidation modification, water vapor activation and dipped metallic oxide. The supported catalyst by calcinating precursor at a high temperature is used as the model to discusses the catalytic action of the modified pyrolysis tar and desulfurization mechanism of flue gas desulfurization reaction, and the effect causes and regularity of different modification technology and process conditions on desulfurization performance of modified pyrolysis char are analyzed.Incipient impregnation is taken as immersion method in this paper and 14 kinds of metal oxide are selected as an active component on the carrier of pyrolysis char to prepared the supported catalyst. The the effect of desulfurization effect of different active component on supported catalyst on fixed bed reactor, and the catalyst morphology, pore structure and the desulfurization law are studied by scanning electron microscope（SEM）, X-ray diffraction（XRD）,and the results show that the similarity of desulfurization performance of metal oxide in the same group is related to the type of semiconductor, and the differences of characteristics of desulfurization performance of metal oxide of Fe, Co, Ni in the eighth group is associated with their d percentage（%）.Secondly pyrolysis tar catalyst is prepared and through the nitric acid oxidation modification and water vapor activation modified.The catalysts of different desulfurization effect through the desulfurization experiment are selected as the carrier and analyzed theeffect of different process conditions on the catalyst desulfurization, and order of influence factors is: the types of modified solution > roasting time >modification solutionconcentration>solid-liquid ratio > roasting temperature. Effect of nitric acid oxidation modification is best, and the time of the desulfurization rate 100% is the longest, and more acid concentration can absorb more sulfur dioxide;desulfurization performance of the pyrolysis tar after modification is improved,and the order of three factors of desulfurization effect of modified- activation pyrolysis tar is : activation temperature >activator flow >activation time. Eventually active component and carrier through the experiment will filter to prepare supported catalyst and test desulfurization performance.Compared with test results, modified-activation pyrolysis tar has the best desulfurization effect in several groups of type catalyst and penetration time is about 3 min, and the time of desulfurization efficiency 70% is 6 min.The supported catalyst of modified-activation pyrolysis tar is prepared through the optimal condition of preparation.Compared and analysis with other desulfurization process new and efficient desulfurization catalyst is prepared by combination with carrier and active component.The analysis supports this new catalyst has good application prospect to removal SO₂ from flue gas and it is a kind of efficient desulfurization method and it is good for environmental protection.