| As an abundant fossil fuel, coal has made a great contribution to the development of human society. And the important position of coal as main energy source in China will not change in the future for a long time. However, there are a lot of harmful elements in coal, such as sulfur, arsenic, mercury and so on. Raw gas produced from the gasification and pyrolysis of coal contains a lot of pollutants, such as dust, sulfur-containing gas and so on. The sulfur-containing gas, which mainly contains hydrogen sulfide, can lead to the corrosion of equipments and poison the catalyst. In addition, the emission of sulfur dioxide from the oxidation of the sulfur-containing gas can form acid rain. Thus, it is necessary to clean the raw gas.In this paper, Fe2O3/Lignite semi-coke was prepared with assistant of ultrasonic irradiation and the regeneration performance of absorbent was tested in the fixed bed reactor in different atmosphere. Then the sorbents were regenerated by oxygen and the mixed atmosphere of oxygen and water vapour, the impacts of temperature, space velocity and gas concentration to the regeneration of sorbent were tested, and then the sorbents were characterized by XRD, XPS, BET and SEM. And the regeneration mechanism of sorbents in different atmosphere was discussed further. The regeneration kinetics were studied by thermogravimetric analyzer (TGA) in oxygen atmosphere. The main conclusions as following:(1) In oxygen atmosphere of the regeneration, the mainly components of exhaust gas were SO2and a little elemental sulfur. The regenerated sorbents were mainly composed by Fe2O3; Improving the regeneration temperature, space velocity and oxygen concentration could reduce the time of regeneration reaction; Under the premise of regeneration time and regeneration conversion, it indicated that the best conditions:regeneration temperature is650℃, space velocity is3000h-1, concentration of oxygen is6vol.%.(2)The regeneration behavior of the sorbents in O2atmosphere were tested in the thermogravimetric analyzer. The experimental results show that:higher temperature and oxygen concentration could improve the regeneration conversion; According to the uniform conversion model, the regeneration reaction of the sorbents in oxygen atmosphere can reasonably be assumed as first-order reaction. The kinetics parameters could be calculated by Arrhenius equation, the chemical reaction activation energy and corresponding frequency factor are14.73kJ/mol and4.43×10-2m/s, respectively. While the diffusion activation energy and corresponding frequency factor are31.32kJ/mol and5.77×10-4m2/s, respectively. (3) In H2O～O2mixtures atmosphere of the regeneration, the mainly components of exhaust gas were SO2, H2S and a large amount of elemental sulfur. The regenerated sorbents were mainly composed by Fe2O3. The experiment proved that low temperature and high H2O/O2were beneficial to the formation ratio of sulfur. Under the premise of regeneration conversion, try to improve the formation ratio of sulfur, it indicated that the best conditions: regeneration temperature is600℃, space velocity is3000h-1, H2O/O2=40.By XRD and XPS characterization methods to analyzed the change of the phases transformation for the regeneration, Come to the main chemical reaction and the mechanism. |
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