Study On Catalytic Conversion Process Of Flue Gas With Low Concentration Of Sulfur Dioxide

Sulfur containing fuel plays an important role in China’s energy structure.The sulfur-containing flue gas emitted during fuel use has a great negative impact on the atmospheric environment,and the corresponding air pollutant emission control standards are increasingly strict.Compared with the traditional limestone gypsum desulfurization technology,FGD can control the emission and make more effective use of resources,significantly reduce the emission of solid waste,so it has been widely concerned.Considering that most of the existing flue gas desulfurization and acid making processes have strict requirements on SO₂concentration or flue gas temperature,there are still some problems in operation cost and start-up period.Therefore,it is necessary to try to develop a flue gas desulfurization and acid making process suitable for a wider temperature range and SO₂concentration.In this study,the liquid-phase oxidation process of low concentration sulfur dioxide in sulfur-containing tail gas under mild conditions is studied,mainly focusing on the sulfur conversion efficiency of different oxidant types,non catalytic/activated carbon catalytic oxidation and other different process conditions:Firstly,the performance of different oxidants in the non catalytic oxidation system was investigated:Ozone,hydrogen peroxide and sodium persulfate were used as oxidants in the experiment to explore the main influencing factors of sulfur conversion.According to the experimental results,it can be found that hydrogen peroxide and sodium persulfate have better oxidation effect on sulfur dioxide,and residence time and oxidant concentration are the main influencing factors of sulfur dioxide conversion.Secondly,the process of acid production by oxidation catalyzed by activated carbon was studied:By adding activated carbon catalyst in the oxidation system,hydrogen peroxide and sodium persulfate were used to evaluate the catalytic oxidation of sulfuric acid,and sodium persulfate with better catalytic oxidation effect was selected as oxidant.This study also analyzed the influence of different reaction conditions,confirmed that the adsorption of sulfur dioxide and the activation of persulfate by activated carbon can significantly promote the catalytic oxidation of acid.In addition,the effect of different carbon material treatment methods on the reaction performance was also explored.In order to further improve the adsorption performance of activated carbon and the activation effect of persulfate,copper loaded activated carbon was prepared and used for catalytic oxidation to acid.Acid treatment and high temperature calcination can improve the specific surface area and pore structure of activated carbon,and increase the adsorption of sulfur dioxide;Cuprous oxide and copper particles on the active surface can promote the activation of persulfate.Under the combined action of the above two factors,the conversion rate of SO₂is further improved:When the acid concentration is 1mol/L,the mass fraction of copper nitrate in the impregnation solution is 7.5%,and the calcination temperature is 500℃,the SO₂conversion rate reaches the highest（79.2%）.