Removal Of Low Concentration SO₂ With Activated Carbon

Sulfur dioxide is a kind of gas with irritative odor and harms to humans;also it is the main reason for acidic rain. There is a mass of sulfur dioxide in the tail gases coming from fire power plants, steel-making plants, chemical plants etc. A mass of sulfur dioxide in the air badly pollutes the environment, and the forming acidic rain brings about great calamities for animals, plants and humans. On the other hand, some gas resources are limited to recycle and reuse because of low concentration sulfur dioxide in them. So it is very significant to remove sulfur dioxide from some gas resources, especially low concentration of sulfur dioxide. It is a very effective method to remove low concentration of sulfur dioxide with activate carbons, which is low cost, easily operated and high efficient. On the basis of the researches that are conducted before, how to remove low concentration of sulfur dioxide with activated carbons was studied from four aspects systemicly in this dissertation. The main contents were listed as follows:1. A study on removal of low concentration SO₂ with activated carbons modified by Na₂CO₃, NaHCO₃, NaOH and K₂CO₃Some activated carbons were modified by Na₂CO₃, NaHCO₃, NaOH and K₂CO₃ respectively with impregnation method. The desulfurization performance of all kinds of modified activated carbons was studied with or without O₂ presence. Many factors that affect the efficiency of desulfurization were investigated on the fixed-bed reactor in detail, such as the concentration of impregnated agents, the temperature of reaction, the humidity of feed gas etc. It was showed that the activated carbon modified by 10% Na₂CO₃ (wt%) had a high sulfur capacity with or without O₂ presence, which its sulfur capacity had been enhanced greatly comparing with unmodified activated carbons.2. A study on removal of low concentration SO₂ by modified activated carbons that contain transitional metalsWith impregnation method, activated carbons were modified by some transitional metal ions such as CO²⁺, Fe³⁺, Cr3⁺, Zn²⁺, Ni²⁺ etc. The performance of removing sulfur dioxide for modified carbons was studied with O₂ presence. Some factors which maybe affect the performance of removing sulfur dioxide such as the kinds and the concentration of transitional metal ions, the temperature of reaction, the components of feed gas etc. were investigated in detail on the fixed-bed reactor. It was showed that the modified activated carbons had a higher sulfur capacity, comparing with unmodified activated carbon. Finally,the mechanism of removal sulfur dioxide with modified activated carbons that contain transitional metals was deduced.3. A study on removal of low concentration SO2 with modified activated carbons in the N2-O2-CO2 systemThe modified activated carbons containing 5% Na2CO3 ,5%NaHCC^ 5%NaOH (wt%) were obtained respectively by impregnation method. The performance of removing sulfur dioxide for modified activated carbons was studied in the N2-O2-CO2 system. Many factors that affect the efficiency of desulfurization were investigated in detail, such as the kinds of impregnated agents, the temperature of reaction, the humidity of feed gas etc. The effect of amount of CO2 in the feed gas on desulfurization was investigated in ambient temperature (25 °C) and high temperature (350°C) respectively. It was showed that in ambient temperature the sulfur capacity of activated carbons would be reduced when amount of CO2 was increased in the feed gas. However, the sulfur capacity would be enhanced in high temperature.4. A study on regeneration method for activated carbons used by removing low concentration SO2Activated carbons used by removing low concentration of SO2 were regenerated with solvent method and gas method respectively. During the course of regeneration, some factors that maybe affect the regeneration effect, such as the time and the temperature of regeneration were studied through investigating the performance of desulfuration of regenerated carbons on the fixed-bed flow reactor. It was showed that solvent regeneration method and gas regeneration method were all effective regeneration methods. The values of BET and pH were very important parameters for regenerated carbons. Finally, some issues about regeneration in desulfurization industry were discussed.Though the studies above, the mechanism of removing SO2 with activated carbons and how all the factors affect on the performance of desulfurization were understood more clearly. These basal data were very useful for how to enhance the sulfur capacity of activated carbons and how to realize the recycling use of them in desulfurization industry.